Bug 1930690 - certificate transparency: support static-ct-api ("tiled") logs a=diannaS

Differential Revision: https://phabricator.services.mozilla.com/D258972
2025-07-29 20:16:42 +00:00
parent c68862e175
commit e85c3d250f
27 changed files with 691 additions and 169 deletions
--- a/security/certverifier/CertVerifier.cpp
+++ b/security/certverifier/CertVerifier.cpp
@@ -219,7 +219,8 @@ void CertVerifier::LoadKnownCTLogs() {

    const CTLogOperatorInfo& logOperator =
        kCTLogOperatorList[log.operatorIndex];
-    CTLogVerifier logVerifier(logOperator.id, log.state, log.timestamp);
+    CTLogVerifier logVerifier(logOperator.id, log.state, log.format,
+                              log.timestamp);
    rv = logVerifier.Init(publicKey);
    if (rv != Success) {
      MOZ_ASSERT_UNREACHABLE("Failed initializing a known CT Log");
--- a/security/ct/CTKnownLogs.h
+++ b/security/ct/CTKnownLogs.h
@@ -14,7 +14,7 @@

 #include <stddef.h>

-static const PRTime kCTExpirationTime = INT64_C(1759749898000000);
+static const PRTime kCTExpirationTime = INT64_C(1759796803000000);

 namespace mozilla::ct {

@@ -23,10 +23,16 @@ enum class CTLogState {
  Retired,
 };

+enum class CTLogFormat {
+  RFC6962,
+  Tiled,
+};
+
 struct CTLogInfo {
  // See bug 1338873 about making these fields const.
  const char* name;
  CTLogState state;
+  CTLogFormat format;
  uint64_t timestamp;
  // Index within kCTLogOperatorList.
  size_t operatorIndex;
@@ -41,7 +47,7 @@ struct CTLogOperatorInfo {
 };

 const CTLogInfo kCTLogList[] = {
-    {"Google 'Argon2025h1' log", CTLogState::Admissible,
+    {"Google 'Argon2025h1' log", CTLogState::Admissible, CTLogFormat::RFC6962,
     1701000000000,  // 2023-11-26T12:00:00Z
     0,              // operated by Google
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -51,7 +57,7 @@ const CTLogInfo kCTLogList[] = {
     "\xfb\xae\xbe\xc8\x23\x52\x20\x2b\xaa\x44\x05\xfe\x54\xf9\xd5\xf1\x1d\x45"
     "\x9a",
     91},
-    {"Google 'Argon2025h2' log", CTLogState::Admissible,
+    {"Google 'Argon2025h2' log", CTLogState::Admissible, CTLogFormat::RFC6962,
     1701000000000,  // 2023-11-26T12:00:00Z
     0,              // operated by Google
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -61,7 +67,7 @@ const CTLogInfo kCTLogList[] = {
     "\x56\x4e\x98\xe8\xaa\x26\x29\x36\x1e\x28\x60\x6f\xeb\x15\x6e\xf7\x7c\xd0"
     "\xba",
     91},
-    {"Google 'Argon2026h1' log", CTLogState::Admissible,
+    {"Google 'Argon2026h1' log", CTLogState::Admissible, CTLogFormat::RFC6962,
     1727734767000,  // 2024-09-30T22:19:27Z
     0,              // operated by Google
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -71,7 +77,7 @@ const CTLogInfo kCTLogList[] = {
     "\x06\x4f\x64\x58\x75\x14\x5d\x56\x52\xe6\x6a\x2b\x14\x4c\xec\x81\xd1\xea"
     "\x3e",
     91},
-    {"Google 'Argon2026h2' log", CTLogState::Admissible,
+    {"Google 'Argon2026h2' log", CTLogState::Admissible, CTLogFormat::RFC6962,
     1727734767000,  // 2024-09-30T22:19:27Z
     0,              // operated by Google
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -81,7 +87,7 @@ const CTLogInfo kCTLogList[] = {
     "\xf5\x35\x50\x9c\xa1\xd3\x49\x4d\x13\xd5\x3b\x6a\x0e\xea\x45\x9d\x24\x13"
     "\x22",
     91},
-    {"Google 'Xenon2025h1' log", CTLogState::Admissible,
+    {"Google 'Xenon2025h1' log", CTLogState::Admissible, CTLogFormat::RFC6962,
     1701000000000,  // 2023-11-26T12:00:00Z
     0,              // operated by Google
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -91,7 +97,7 @@ const CTLogInfo kCTLogList[] = {
     "\x12\xe6\x54\x78\x50\xdc\xff\x6d\xfd\x1c\xa7\xb6\x3a\x1f\xf9\x26\xa9\x1b"
     "\xbd",
     91},
-    {"Google 'Xenon2025h2' log", CTLogState::Admissible,
+    {"Google 'Xenon2025h2' log", CTLogState::Admissible, CTLogFormat::RFC6962,
     1701000000000,  // 2023-11-26T12:00:00Z
     0,              // operated by Google
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -101,7 +107,7 @@ const CTLogInfo kCTLogList[] = {
     "\xa0\x3e\x9d\x94\x1c\xb2\xb7\x4a\xf2\x51\xec\x40\xed\x62\x47\xa4\x03\x49"
     "\x86",
     91},
-    {"Google 'Xenon2026h1' log", CTLogState::Admissible,
+    {"Google 'Xenon2026h1' log", CTLogState::Admissible, CTLogFormat::RFC6962,
     1727734767000,  // 2024-09-30T22:19:27Z
     0,              // operated by Google
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -111,7 +117,7 @@ const CTLogInfo kCTLogList[] = {
     "\xeb\x03\x0a\x30\xcc\x63\x6c\xd9\x3c\xbe\xf5\x7b\x94\xba\x94\xd3\xbf\x88"
     "\x4c",
     91},
-    {"Google 'Xenon2026h2' log", CTLogState::Admissible,
+    {"Google 'Xenon2026h2' log", CTLogState::Admissible, CTLogFormat::RFC6962,
     1727734767000,  // 2024-09-30T22:19:27Z
     0,              // operated by Google
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -121,7 +127,7 @@ const CTLogInfo kCTLogList[] = {
     "\x8a\x72\x30\x65\x86\x43\x53\xdc\x11\x44\x18\x49\x98\x25\x68\xa7\x3c\x05"
     "\xbf",
     91},
-    {"Cloudflare 'Nimbus2025'", CTLogState::Admissible,
+    {"Cloudflare 'Nimbus2025'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1702969200000,  // 2023-12-19T07:00:00Z
     1,              // operated by Cloudflare
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -131,7 +137,7 @@ const CTLogInfo kCTLogList[] = {
     "\x81\x5b\x4a\x14\x41\xec\xaf\xa9\x5d\x0e\xab\x12\x19\x71\xcd\x43\xef\xbb"
     "\x97",
     91},
-    {"Cloudflare 'Nimbus2026'", CTLogState::Admissible,
+    {"Cloudflare 'Nimbus2026'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1731088800000,  // 2024-11-08T18:00:00Z
     1,              // operated by Cloudflare
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -141,7 +147,7 @@ const CTLogInfo kCTLogList[] = {
     "\xbf\x91\x64\x46\x6e\x0e\x27\x13\xea\xbb\x6f\x46\x27\x58\x86\xef\x40\x21"
     "\xa3",
     91},
-    {"DigiCert Yeti2025 Log", CTLogState::Retired,
+    {"DigiCert Yeti2025 Log", CTLogState::Retired, CTLogFormat::RFC6962,
     1753315200000,  // 2025-07-24T00:00:00Z
     2,              // operated by DigiCert
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -151,7 +157,7 @@ const CTLogInfo kCTLogList[] = {
     "\x95\x24\x7c\xd8\x91\x98\x48\x3b\xf0\xf0\xdf\x21\xf1\xb0\x81\x5a\x59\x25"
     "\x43",
     91},
-    {"DigiCert Nessie2025 Log", CTLogState::Retired,
+    {"DigiCert Nessie2025 Log", CTLogState::Retired, CTLogFormat::RFC6962,
     1744758000000,  // 2025-04-15T23:00:00Z
     2,              // operated by DigiCert
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -161,7 +167,7 @@ const CTLogInfo kCTLogList[] = {
     "\x75\x80\xb7\x53\xa7\x85\xd5\xbc\xab\x47\x06\x55\xdb\xb5\xdf\x88\xa1\x6f"
     "\x38",
     91},
-    {"DigiCert 'Wyvern2025h1' Log", CTLogState::Retired,
+    {"DigiCert 'Wyvern2025h1' Log", CTLogState::Retired, CTLogFormat::RFC6962,
     1744670000000,  // 2025-04-14T22:33:20Z
     2,              // operated by DigiCert
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -171,7 +177,7 @@ const CTLogInfo kCTLogList[] = {
     "\x0d\x96\x58\x44\x9d\x3b\x8a\x80\xc5\xc8\xbe\xe1\x89\x46\x6b\x48\x4c\xd6"
     "\x09",
     91},
-    {"DigiCert 'Wyvern2025h2' Log", CTLogState::Admissible,
+    {"DigiCert 'Wyvern2025h2' Log", CTLogState::Admissible, CTLogFormat::RFC6962,
     1724900983000,  // 2024-08-29T03:09:43Z
     2,              // operated by DigiCert
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -181,7 +187,7 @@ const CTLogInfo kCTLogList[] = {
     "\x1c\x63\xde\x95\xe2\x81\x69\x97\x8d\x1e\xa8\xb7\x66\x51\x25\x75\x4d\x78"
     "\x2e",
     91},
-    {"DigiCert 'Wyvern2026h1'", CTLogState::Admissible,
+    {"DigiCert 'Wyvern2026h1'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1731024000000,  // 2024-11-08T00:00:00Z
     2,              // operated by DigiCert
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -191,7 +197,7 @@ const CTLogInfo kCTLogList[] = {
     "\xd5\xd1\x83\xf8\x7a\xdf\x1e\x07\xbc\x15\xcd\xc0\x4a\xcd\x2a\x31\x71\x07"
     "\x55",
     91},
-    {"DigiCert 'Wyvern2026h2'", CTLogState::Admissible,
+    {"DigiCert 'Wyvern2026h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1731024000000,  // 2024-11-08T00:00:00Z
     2,              // operated by DigiCert
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -201,7 +207,7 @@ const CTLogInfo kCTLogList[] = {
     "\xde\x9b\x8c\x13\x92\xb7\xad\x3d\x0f\xa1\x9c\x8f\x48\xce\x74\x27\x18\x23"
     "\x99",
     91},
-    {"DigiCert 'Sphinx2025h1' Log", CTLogState::Retired,
+    {"DigiCert 'Sphinx2025h1' Log", CTLogState::Retired, CTLogFormat::RFC6962,
     1744670000000,  // 2025-04-14T22:33:20Z
     2,              // operated by DigiCert
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -211,7 +217,7 @@ const CTLogInfo kCTLogList[] = {
     "\x45\x31\x17\xd3\x8d\xf2\xe7\xce\x18\x11\x58\x98\x2c\x60\x6f\x58\x20\x36"
     "\x6e",
     91},
-    {"DigiCert 'Sphinx2025h2' Log", CTLogState::Admissible,
+    {"DigiCert 'Sphinx2025h2' Log", CTLogState::Admissible, CTLogFormat::RFC6962,
     1724900983000,  // 2024-08-29T03:09:43Z
     2,              // operated by DigiCert
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -221,7 +227,7 @@ const CTLogInfo kCTLogList[] = {
     "\x1a\x27\x54\x85\x5d\xc1\x7b\x24\xa8\x34\xe3\xcd\x88\xce\xd4\x50\x1b\xbe"
     "\x69",
     91},
-    {"DigiCert 'Sphinx2026h1'", CTLogState::Admissible,
+    {"DigiCert 'Sphinx2026h1'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1731024000000,  // 2024-11-08T00:00:00Z
     2,              // operated by DigiCert
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -231,7 +237,7 @@ const CTLogInfo kCTLogList[] = {
     "\xbc\xc3\x9e\x05\x02\x9a\x08\x01\xb5\x49\x23\x35\xc4\xd3\x50\x2b\x51\xe9"
     "\xf4",
     91},
-    {"DigiCert 'Sphinx2026h2'", CTLogState::Admissible,
+    {"DigiCert 'Sphinx2026h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1731024000000,  // 2024-11-08T00:00:00Z
     2,              // operated by DigiCert
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -241,7 +247,7 @@ const CTLogInfo kCTLogList[] = {
     "\x38\x8c\xa4\x38\x2e\xac\x95\x0c\xeb\xed\x4f\x64\xbc\x45\x42\xf7\x06\x7a"
     "\xcd",
     91},
-    {"Sectigo 'Sabre2025h1'", CTLogState::Admissible,
+    {"Sectigo 'Sabre2025h1'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1701000000000,  // 2023-11-26T12:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -251,7 +257,7 @@ const CTLogInfo kCTLogList[] = {
     "\x41\xae\x70\xb3\x31\xa2\xe3\xfa\x3d\x5f\x2c\x5d\x04\xcd\xb4\x9d\x55\xab"
     "\x41",
     91},
-    {"Sectigo 'Sabre2025h2'", CTLogState::Admissible,
+    {"Sectigo 'Sabre2025h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1701000000000,  // 2023-11-26T12:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -261,7 +267,7 @@ const CTLogInfo kCTLogList[] = {
     "\xaf\x89\x8b\xf5\x58\xd8\xba\xeb\x7b\x83\x52\xe9\xf4\xe0\xa5\xcd\xcd\x92"
     "\xcc",
     91},
-    {"Sectigo 'Mammoth2025h1'", CTLogState::Admissible,
+    {"Sectigo 'Mammoth2025h1'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1701000000000,  // 2023-11-26T12:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -271,7 +277,7 @@ const CTLogInfo kCTLogList[] = {
     "\x9b\x4e\x72\x62\x4b\x3c\x0c\x32\xdd\x86\xfb\xeb\x3e\x66\xcd\x77\x58\x5b"
     "\xe5",
     91},
-    {"Sectigo 'Mammoth2025h2'", CTLogState::Admissible,
+    {"Sectigo 'Mammoth2025h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1701000000000,  // 2023-11-26T12:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -281,7 +287,7 @@ const CTLogInfo kCTLogList[] = {
     "\xb1\x15\x67\x66\xa0\x7c\x0b\x5b\x62\x7f\x6c\x9a\x6a\x30\x9b\x68\x02\x16"
     "\x6f",
     91},
-    {"Sectigo 'Mammoth2026h1'", CTLogState::Admissible,
+    {"Sectigo 'Mammoth2026h1'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1728925200000,  // 2024-10-14T17:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -291,7 +297,7 @@ const CTLogInfo kCTLogList[] = {
     "\x9b\x50\x28\xe2\x9e\x58\xa5\xa5\xfa\xf9\xe3\xfa\x15\x25\xe3\x14\x13\x32"
     "\xc4",
     91},
-    {"Sectigo 'Mammoth2026h2'", CTLogState::Admissible,
+    {"Sectigo 'Mammoth2026h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1728925200000,  // 2024-10-14T17:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -301,7 +307,7 @@ const CTLogInfo kCTLogList[] = {
     "\xff\xc2\x97\x71\xe5\x7e\x27\xf5\x72\xb1\x8f\x24\x27\x57\x0a\x0d\x74\xc0"
     "\xb6",
     91},
-    {"Sectigo 'Sabre2026h1'", CTLogState::Admissible,
+    {"Sectigo 'Sabre2026h1'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1728925200000,  // 2024-10-14T17:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -311,7 +317,7 @@ const CTLogInfo kCTLogList[] = {
     "\x46\x67\x51\xf0\xde\xb6\xc9\x9e\xaa\xe2\x80\x6d\xce\x25\x81\x34\xd7\x6a"
     "\x60",
     91},
-    {"Sectigo 'Sabre2026h2'", CTLogState::Admissible,
+    {"Sectigo 'Sabre2026h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1728925200000,  // 2024-10-14T17:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -321,7 +327,7 @@ const CTLogInfo kCTLogList[] = {
     "\x65\x35\x63\xf0\x49\xbe\x72\xd1\xaa\x9d\xaf\x7d\x08\xc4\xb4\x8d\x59\x3d"
     "\x73",
     91},
-    {"Sectigo 'Elephant2025h2'", CTLogState::Admissible,
+    {"Sectigo 'Elephant2025h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1747100000000,  // 2025-05-13T01:33:20Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -331,7 +337,7 @@ const CTLogInfo kCTLogList[] = {
     "\xc3\xc4\x42\xc1\x5b\x0a\x85\x16\xce\xa8\xc1\x0e\xc5\x6e\x10\xda\x9e\x0a"
     "\x42",
     91},
-    {"Sectigo 'Elephant2026h1'", CTLogState::Admissible,
+    {"Sectigo 'Elephant2026h1'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1747100000000,  // 2025-05-13T01:33:20Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -341,7 +347,7 @@ const CTLogInfo kCTLogList[] = {
     "\xc9\x65\x87\xe0\xd4\x7f\x0c\x22\x5a\xd9\xb0\x2e\x98\x7a\xd7\x25\xd0\x1c"
     "\x69",
     91},
-    {"Sectigo 'Elephant2026h2'", CTLogState::Admissible,
+    {"Sectigo 'Elephant2026h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1747100000000,  // 2025-05-13T01:33:20Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -351,7 +357,7 @@ const CTLogInfo kCTLogList[] = {
     "\x09\xfc\xdd\x0f\xbc\x5c\x56\x39\x90\x62\x96\xed\x35\x48\x71\x44\xc4\x6d"
     "\x98",
     91},
-    {"Sectigo 'Elephant2027h1'", CTLogState::Admissible,
+    {"Sectigo 'Elephant2027h1'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1747100000000,  // 2025-05-13T01:33:20Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -361,7 +367,7 @@ const CTLogInfo kCTLogList[] = {
     "\xa0\x6a\xda\x7f\xb0\x64\xcc\xa6\x5f\xec\xf0\xbc\x81\x80\x12\x73\x0d\xb0"
     "\xa0",
     91},
-    {"Sectigo 'Elephant2027h2'", CTLogState::Admissible,
+    {"Sectigo 'Elephant2027h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1747100000000,  // 2025-05-13T01:33:20Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -371,7 +377,7 @@ const CTLogInfo kCTLogList[] = {
     "\x1e\xdc\x8a\xec\x20\x61\x7e\x52\x25\x32\x4e\xd3\xd9\x0a\xe7\xe3\x0f\xed"
     "\xf2",
     91},
-    {"Sectigo 'Tiger2025h2'", CTLogState::Admissible,
+    {"Sectigo 'Tiger2025h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1752066000000,  // 2025-07-09T13:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -381,7 +387,7 @@ const CTLogInfo kCTLogList[] = {
     "\xd8\xa1\x24\x59\x2f\xb8\x4f\xbf\xdb\x60\xe5\xef\xe1\xd0\xcd\xcf\x3a\xc4"
     "\xc6",
     91},
-    {"Sectigo 'Tiger2026h1'", CTLogState::Admissible,
+    {"Sectigo 'Tiger2026h1'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1752066000000,  // 2025-07-09T13:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -391,7 +397,7 @@ const CTLogInfo kCTLogList[] = {
     "\xef\xf5\xd0\x63\x03\x85\xb7\xd1\x5e\x6f\xc4\xf0\x41\x6f\xa6\xa9\x73\x79"
     "\xc6",
     91},
-    {"Sectigo 'Tiger2026h2'", CTLogState::Admissible,
+    {"Sectigo 'Tiger2026h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1752066000000,  // 2025-07-09T13:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -401,7 +407,7 @@ const CTLogInfo kCTLogList[] = {
     "\x08\x44\xb5\x10\xbd\x41\xfb\x60\x44\x0b\xe3\xf9\x6d\x47\xf0\x17\x8e\x25"
     "\x9c",
     91},
-    {"Sectigo 'Tiger2027h1'", CTLogState::Admissible,
+    {"Sectigo 'Tiger2027h1'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1752066000000,  // 2025-07-09T13:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -411,7 +417,7 @@ const CTLogInfo kCTLogList[] = {
     "\xdc\xd8\x27\x5c\x35\xf0\x9b\x22\x5c\x17\x04\x58\x81\x53\x81\x32\x16\x98"
     "\x84",
     91},
-    {"Sectigo 'Tiger2027h2'", CTLogState::Admissible,
+    {"Sectigo 'Tiger2027h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1752066000000,  // 2025-07-09T13:00:00Z
     3,              // operated by Sectigo
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -421,7 +427,7 @@ const CTLogInfo kCTLogList[] = {
     "\xa3\x4f\x6b\xa3\x37\xdd\xaa\x18\xde\x8a\x12\x25\xdb\x9c\xbd\x03\x72\x61"
     "\xc9",
     91},
-    {"Let's Encrypt 'Oak2025h1'", CTLogState::Admissible,
+    {"Let's Encrypt 'Oak2025h1'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1701000000000,  // 2023-11-26T12:00:00Z
     4,              // operated by Let's Encrypt
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -431,7 +437,7 @@ const CTLogInfo kCTLogList[] = {
     "\xf9\x3c\x58\x54\x5b\x37\x10\xb1\xab\xd8\x83\xfb\x84\xf1\x95\x3f\x2e\x2f"
     "\x1c",
     91},
-    {"Let's Encrypt 'Oak2025h2'", CTLogState::Admissible,
+    {"Let's Encrypt 'Oak2025h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1701000000000,  // 2023-11-26T12:00:00Z
     4,              // operated by Let's Encrypt
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -441,7 +447,7 @@ const CTLogInfo kCTLogList[] = {
     "\xc9\xd7\x3d\xbb\xc1\xf7\x71\x86\x69\xf4\xb3\x5f\x90\x09\xaa\xae\xbd\x8d"
     "\xa9",
     91},
-    {"Let's Encrypt 'Oak2026h1'", CTLogState::Admissible,
+    {"Let's Encrypt 'Oak2026h1'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1730678400000,  // 2024-11-04T00:00:00Z
     4,              // operated by Let's Encrypt
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -451,7 +457,7 @@ const CTLogInfo kCTLogList[] = {
     "\x48\x90\x23\x40\xde\x7a\x4d\x89\x32\xfb\xd7\x0a\xeb\x5e\x8c\xa2\xf1\xf6"
     "\x49",
     91},
-    {"Let's Encrypt 'Oak2026h2'", CTLogState::Admissible,
+    {"Let's Encrypt 'Oak2026h2'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1730678400000,  // 2024-11-04T00:00:00Z
     4,              // operated by Let's Encrypt
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -461,7 +467,7 @@ const CTLogInfo kCTLogList[] = {
     "\xf4\xfc\x5c\xa9\x8c\x5f\xfb\x0d\x60\xe4\x2c\x0f\x16\xec\x2a\xb2\x6d\xeb"
     "\x15",
     91},
-    {"TrustAsia Log2025a", CTLogState::Admissible,
+    {"TrustAsia Log2025a", CTLogState::Admissible, CTLogFormat::RFC6962,
     1701000000000,  // 2023-11-26T12:00:00Z
     5,              // operated by TrustAsia
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -471,7 +477,7 @@ const CTLogInfo kCTLogList[] = {
     "\x90\x58\xba\x22\xd5\xf9\xf5\x69\x54\xb7\xa8\x94\x4e\x32\x09\xae\x26\x11"
     "\x4d",
     91},
-    {"TrustAsia Log2025b", CTLogState::Admissible,
+    {"TrustAsia Log2025b", CTLogState::Admissible, CTLogFormat::RFC6962,
     1701000000000,  // 2023-11-26T12:00:00Z
     5,              // operated by TrustAsia
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -481,7 +487,7 @@ const CTLogInfo kCTLogList[] = {
     "\xbd\x2f\xa9\xcf\xe8\x7b\x5e\xe1\x4b\x60\xe5\x38\x43\x60\x97\xc1\x5b\x2f"
     "\x65",
     91},
-    {"TrustAsia 'log2026a'", CTLogState::Admissible,
+    {"TrustAsia 'log2026a'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1726790400000,  // 2024-09-20T00:00:00Z
     5,              // operated by TrustAsia
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -491,7 +497,7 @@ const CTLogInfo kCTLogList[] = {
     "\x89\x17\xe8\x5b\x2e\xc5\xac\x00\x05\xc9\x76\x37\x45\x97\x03\x15\xff\x60"
     "\x59",
     91},
-    {"TrustAsia 'log2026b'", CTLogState::Admissible,
+    {"TrustAsia 'log2026b'", CTLogState::Admissible, CTLogFormat::RFC6962,
     1726790400000,  // 2024-09-20T00:00:00Z
     5,              // operated by TrustAsia
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -501,7 +507,7 @@ const CTLogInfo kCTLogList[] = {
     "\x9d\x7d\x05\x53\xc7\x9e\x94\xea\x9b\x57\x46\xbf\x4f\xa4\x7e\xfb\xdf\xfa"
     "\x85",
     91},
-    {"Bogus placeholder log to unbreak misbehaving CT libraries", CTLogState::Retired,
+    {"Bogus placeholder log to unbreak misbehaving CT libraries", CTLogState::Retired, CTLogFormat::RFC6962,
     1750489200000,  // 2025-06-21T07:00:00Z
     6,              // operated by Geomys
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -511,8 +517,38 @@ const CTLogInfo kCTLogList[] = {
     "\x75\xe3\x66\x75\xa9\x59\x70\x2d\xe2\x5a\x8b\xc0\x7c\x0a\x6f\x5d\x2d\xf7"
     "\x37",
     91},
+    {"Geomys 'Tuscolo2025h2'", CTLogState::Admissible, CTLogFormat::Tiled,
+     1749782400000,  // 2025-06-13T02:40:00Z
+     6,              // operated by Geomys
+     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
+     "\xce\x3d\x03\x01\x07\x03\x42\x00\x04\x2b\xd7\x78\x18\x6b\x73\x6e\x4c\x30"
+     "\xb1\x8a\x44\xb6\xf9\xd4\xf4\xa2\xa0\x66\xbe\xbb\x32\xc1\xa5\x07\xb9\xa7"
+     "\x17\xc0\xd6\xf5\xb1\xe7\x9e\x01\xf3\x3f\x35\xcf\x6d\xda\x3b\x9f\xe1\x72"
+     "\x0b\x04\x83\x62\xa1\x07\x6d\xa9\x75\x67\x40\x82\x57\x26\x43\xeb\x04\x3f"
+     "\xa3",
+     91},
+    {"Geomys 'Tuscolo2026h1'", CTLogState::Admissible, CTLogFormat::Tiled,
+     1749782400000,  // 2025-06-13T02:40:00Z
+     6,              // operated by Geomys
+     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
+     "\xce\x3d\x03\x01\x07\x03\x42\x00\x04\x7e\x5c\x73\x32\x0d\x80\x8e\x38\x3b"
+     "\x87\x5f\x99\x22\xf4\x3d\x2d\x5e\xb2\x16\xf7\x63\xea\xe4\x62\xf5\x86\xef"
+     "\xb5\x19\xd2\x0a\x04\xb6\x49\xa9\xa4\x1f\x9e\x96\x70\xf4\x5a\x05\x34\x58"
+     "\x01\x13\xc3\x22\xbe\x49\xc0\xba\xa0\x24\x05\x40\xfc\xdb\xc3\xc5\xd2\x57"
+     "\x3b",
+     91},
+    {"Geomys 'Tuscolo2026h2'", CTLogState::Admissible, CTLogFormat::Tiled,
+     1749782400000,  // 2025-06-13T02:40:00Z
+     6,              // operated by Geomys
+     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
+     "\xce\x3d\x03\x01\x07\x03\x42\x00\x04\x68\x0e\x8f\xd2\x2e\xc9\x4e\xc7\x7d"
+     "\x5d\xfc\xc5\xd7\xfe\xfa\x6a\xf4\x56\x03\x75\xd7\x23\x83\x52\xb6\xc1\x4e"
+     "\xfd\xa1\x6d\x06\x9e\x92\x63\xba\x25\x0c\x43\x22\x3d\x21\x52\xc4\x6c\xc5"
+     "\x42\x32\x80\xd6\xbf\x6f\x80\x6f\xe8\x15\x0c\x2e\xae\x55\x8c\xcb\xd1\x50"
+     "\x37",
+     91},
 #ifdef DEBUG
-    {"Mozilla Test RSA Log 1", CTLogState::Admissible,
+    {"Mozilla Test RSA Log 1", CTLogState::Admissible, CTLogFormat::RFC6962,
     1721666666000,  // 2024-07-22T16:44:26Z
     7,              // operated by Mozilla Test Org 1
     "\x30\x82\x01\x22\x30\x0d\x06\x09\x2a\x86\x48\x86\xf7\x0d\x01\x01\x01\x05"
@@ -535,7 +571,7 @@ const CTLogInfo kCTLogList[] = {
     294},
 #endif  // DEBUG
 #ifdef DEBUG
-    {"Mozilla Test EC Log", CTLogState::Admissible,
+    {"Mozilla Test EC Log", CTLogState::Admissible, CTLogFormat::RFC6962,
     1721666666000,  // 2024-07-22T16:44:26Z
     7,              // operated by Mozilla Test Org 1
     "\x30\x59\x30\x13\x06\x07\x2a\x86\x48\xce\x3d\x02\x01\x06\x08\x2a\x86\x48"
@@ -547,7 +583,7 @@ const CTLogInfo kCTLogList[] = {
     91},
 #endif  // DEBUG
 #ifdef DEBUG
-    {"Mozilla Test RSA Log 2", CTLogState::Admissible,
+    {"Mozilla Test RSA Log 2", CTLogState::Admissible, CTLogFormat::RFC6962,
     1721666666000,  // 2024-07-22T16:44:26Z
     8,              // operated by Mozilla Test Org 2
     "\x30\x82\x01\x22\x30\x0d\x06\x09\x2a\x86\x48\x86\xf7\x0d\x01\x01\x01\x05"
@@ -569,6 +605,29 @@ const CTLogInfo kCTLogList[] = {
     "\xbb\x02\x03\x01\x00\x01",
     294},
 #endif  // DEBUG
+#ifdef DEBUG
+    {"Mozilla Test RSA Log 4", CTLogState::Admissible, CTLogFormat::Tiled,
+     1750853366000,  // 2025-06-25T12:09:26Z
+     9,              // operated by Mozilla Test Org 3
+     "\x30\x82\x01\x22\x30\x0d\x06\x09\x2a\x86\x48\x86\xf7\x0d\x01\x01\x01\x05"
+     "\x00\x03\x82\x01\x0f\x00\x30\x82\x01\x0a\x02\x82\x01\x01\x00\xb5\x49\x89"
+     "\x5c\x9d\x00\x10\x8d\x11\xa1\xf9\x9f\x87\xa9\xe3\xd1\xa5\xdb\x5d\xfa\xec"
+     "\xf1\x88\xda\x57\xbf\x64\x13\x68\x8f\x2c\xe4\x72\x2c\xff\x10\x90\x38\xc1"
+     "\x74\x02\xc9\x3a\x2a\x47\x3d\xbd\x28\x6a\xed\x3f\xdc\xd3\x63\xcf\x5a\x29"
+     "\x14\x77\x01\xbd\xd8\x18\xd7\x61\x5b\xf9\x35\x6b\xd5\xd3\xc8\x33\x6a\xaa"
+     "\x8c\x09\x71\x36\x8a\x06\xc3\xcd\x44\x61\xb9\x3e\x51\x42\x4e\x17\x44\xbb"
+     "\x2e\xaa\xd4\x6a\xab\x38\xce\x19\x68\x21\x96\x1f\x87\x71\x4a\x16\x63\x69"
+     "\x3f\x09\x76\x1c\xdf\x4d\x6b\xa1\x25\xea\xce\xc7\xbe\x27\x0d\x38\x8f\x78"
+     "\x9f\x6c\xdf\x78\xae\x31\x44\xed\x28\xc4\x5e\x79\x29\x38\x63\xa7\xa2\x2a"
+     "\x48\x98\x0a\x36\xa4\x0e\x72\xd5\x79\xc9\xb9\x25\xdf\xf8\xc7\x93\x36\x2f"
+     "\xfd\x68\x97\xa7\xc1\x75\x4c\x5e\x97\xc9\x67\xc3\xea\xdd\x1a\xae\x8a\xa2"
+     "\xcc\xce\x34\x8a\x01\x69\xb8\x0e\x28\xa2\xd7\x0c\x1a\x96\x0c\x6f\x33\x5f"
+     "\x2d\xa0\x9b\x9b\x64\x3f\x5a\xbf\xba\x49\xe8\xaa\xa9\x81\xe9\x60\xe2\x7d"
+     "\x87\x48\x0b\xdd\x55\xdd\x94\x17\xfa\x18\x50\x9f\xbb\x55\x4c\xcf\x81\xa4"
+     "\x39\x7e\x8b\xa8\x12\x8a\x34\xbd\xf2\x78\x65\xc1\x89\xe5\x73\x4f\xb2\x29"
+     "\x05\x02\x03\x01\x00\x01",
+     294},
+#endif  // DEBUG
 };

 const CTLogOperatorInfo kCTLogOperatorList[] = {
@@ -585,6 +644,9 @@ const CTLogOperatorInfo kCTLogOperatorList[] = {
 #ifdef DEBUG
    {"Mozilla Test Org 2", 8},
 #endif  // DEBUG
+#ifdef DEBUG
+    {"Mozilla Test Org 3", 9},
+#endif  // DEBUG
 };

 }  // namespace mozilla::ct
--- a/security/ct/CTLogVerifier.cpp
+++ b/security/ct/CTLogVerifier.cpp
@@ -114,10 +114,11 @@ class SignatureParamsTrustDomain final : public TrustDomain {
 };

 CTLogVerifier::CTLogVerifier(CTLogOperatorId operatorId, CTLogState state,
-                             uint64_t timestamp)
+                             CTLogFormat format, uint64_t timestamp)
    : mSignatureAlgorithm(DigitallySigned::SignatureAlgorithm::Anonymous),
      mOperatorId(operatorId),
      mState(state),
+      mFormat(format),
      mTimestamp(timestamp) {}

 pkix::Result CTLogVerifier::Init(Input subjectPublicKeyInfo) {
--- a/security/ct/CTLogVerifier.h
+++ b/security/ct/CTLogVerifier.h
@@ -30,9 +30,10 @@ class CTLogVerifier {
 public:
  // |operatorId| The numeric ID of the log operator.
  // |logState| "Qualified", "Usable", "ReadOnly", or "Retired".
+  // |logFormat| "RFC6962" or "Tiled"
  // |timestamp| timestamp associated with logState.
  CTLogVerifier(CTLogOperatorId operatorId, CTLogState logState,
-                uint64_t timestamp);
+                CTLogFormat logFormat, uint64_t timestamp);

  // Initializes the verifier with the given subjectPublicKeyInfo.
  // |subjectPublicKeyInfo| is a DER-encoded SubjectPublicKeyInfo.
@@ -46,6 +47,7 @@ class CTLogVerifier {

  CTLogOperatorId operatorId() const { return mOperatorId; }
  CTLogState state() const { return mState; }
+  CTLogFormat format() const { return mFormat; }
  uint64_t timestamp() const { return mTimestamp; }

  // Verifies that |sct| contains a valid signature for |entry|.
@@ -74,6 +76,7 @@ class CTLogVerifier {
  DigitallySigned::SignatureAlgorithm mSignatureAlgorithm;
  CTLogOperatorId mOperatorId;
  CTLogState mState;
+  CTLogFormat mFormat;
  uint64_t mTimestamp;
 };

--- a/security/ct/CTPolicyEnforcer.cpp
+++ b/security/ct/CTPolicyEnforcer.cpp
@@ -75,11 +75,13 @@ bool LogWasQualifiedForSct(const VerifiedSCT& verifiedSct,
 // lifetime of the certificate. If the certificate lifetime is less than or
 // equal to 180 days, N is 2. Otherwise, N is 3.
 // Among these SCTs, at least two must be issued from distinct log operators.
+// Additionally, at least one must be issued from an RFC6962 log.
 CTPolicyCompliance EmbeddedSCTsCompliant(const VerifiedSCTList& verifiedScts,
                                         uint64_t certIssuanceTime,
                                         Duration certLifetime) {
  size_t admissibleCount = 0;
  size_t admissibleOrRetiredCount = 0;
+  size_t rfc6962Count = 0;
  std::set<CTLogOperatorId> logOperators;
  std::set<Buffer> logIds;
  for (const auto& verifiedSct : verifiedScts) {
@@ -90,6 +92,14 @@ CTPolicyCompliance EmbeddedSCTsCompliant(const VerifiedSCTList& verifiedScts,
        !LogWasQualifiedForSct(verifiedSct, certIssuanceTime)) {
      continue;
    }
+    // SCTs from tiled logs "MUST" have a valid leaf index extension.
+    if (verifiedSct.logFormat == CTLogFormat::Tiled &&
+        verifiedSct.sct.leafIndex.isNothing()) {
+      continue;
+    }
+    if (verifiedSct.logFormat == CTLogFormat::RFC6962) {
+      rfc6962Count++;
+    }
    // Note that a single SCT can count for both the "from a log that was
    // admissible" case and the "from a log that was admissible or retired"
    // case.
@@ -104,7 +114,8 @@ CTPolicyCompliance EmbeddedSCTsCompliant(const VerifiedSCTList& verifiedScts,
  }

  size_t requiredEmbeddedScts = GetRequiredEmbeddedSctsCount(certLifetime);
-  if (admissibleCount < 1 || admissibleOrRetiredCount < requiredEmbeddedScts) {
+  if (admissibleCount < 1 || admissibleOrRetiredCount < requiredEmbeddedScts ||
+      rfc6962Count < 1) {
    return CTPolicyCompliance::NotEnoughScts;
  }
  if (logIds.size() < requiredEmbeddedScts || logOperators.size() < 2) {
@@ -117,10 +128,12 @@ CTPolicyCompliance EmbeddedSCTsCompliant(const VerifiedSCTList& verifiedScts,
 // or OCSP response):
 // There must be at least two SCTs from logs that were Admissible (i.e.
 // Qualified, Usable, or ReadOnly) at the time of the check. Among these SCTs,
-// at least two must be issued from distinct log operators.
+// at least two must be issued from distinct log operators. Additionally, at
+// least one must be issued from an RFC6962 log.
 CTPolicyCompliance NonEmbeddedSCTsCompliant(
    const VerifiedSCTList& verifiedScts) {
  size_t admissibleCount = 0;
+  size_t rfc6962Count = 0;
  std::set<CTLogOperatorId> logOperators;
  std::set<Buffer> logIds;
  for (const auto& verifiedSct : verifiedScts) {
@@ -130,12 +143,20 @@ CTPolicyCompliance NonEmbeddedSCTsCompliant(
    if (verifiedSct.logState != CTLogState::Admissible) {
      continue;
    }
+    // SCTs from tiled logs "MUST" have a valid leaf index extension.
+    if (verifiedSct.logFormat == CTLogFormat::Tiled &&
+        verifiedSct.sct.leafIndex.isNothing()) {
+      continue;
+    }
    admissibleCount++;
+    if (verifiedSct.logFormat == CTLogFormat::RFC6962) {
+      rfc6962Count++;
+    }
    logIds.insert(verifiedSct.sct.logId);
    logOperators.insert(verifiedSct.logOperatorId);
  }

-  if (admissibleCount < 2) {
+  if (admissibleCount < 2 || rfc6962Count < 1) {
    return CTPolicyCompliance::NotEnoughScts;
  }
  if (logIds.size() < 2 || logOperators.size() < 2) {
--- a/security/ct/CTSerialization.cpp
+++ b/security/ct/CTSerialization.cpp
@@ -360,6 +360,11 @@ Result DecodeSignedCertificateTimestamp(Reader& reader,
  InputToBuffer(extensions, result.extensions);
  result.timestamp = timestamp;

+  rv = result.DecodeExtensions();
+  if (rv != Success) {
+    return rv;
+  }
+
  output = std::move(result);
  return Success;
 }
--- a/security/ct/CTVerifyResult.cpp
+++ b/security/ct/CTVerifyResult.cpp
@@ -13,11 +13,12 @@ namespace ct {

 VerifiedSCT::VerifiedSCT(SignedCertificateTimestamp&& sct, SCTOrigin origin,
                         CTLogOperatorId logOperatorId, CTLogState logState,
-                         uint64_t logTimestamp)
+                         CTLogFormat logFormat, uint64_t logTimestamp)
    : sct(std::move(sct)),
      origin(origin),
      logOperatorId(logOperatorId),
      logState(logState),
+      logFormat(logFormat),
      logTimestamp(logTimestamp) {}

 void CTVerifyResult::Reset() {
--- a/security/ct/CTVerifyResult.h
+++ b/security/ct/CTVerifyResult.h
@@ -28,13 +28,14 @@ enum class SCTOrigin {
 struct VerifiedSCT {
  VerifiedSCT(SignedCertificateTimestamp&& sct, SCTOrigin origin,
              CTLogOperatorId logOperatorId, CTLogState logState,
-              uint64_t logTimestamp);
+              CTLogFormat logFormat, uint64_t logTimestamp);

  // The original SCT.
  SignedCertificateTimestamp sct;
  SCTOrigin origin;
  CTLogOperatorId logOperatorId;
  CTLogState logState;
+  CTLogFormat logFormat;
  uint64_t logTimestamp;
 };

--- a/security/ct/MultiLogCTVerifier.cpp
+++ b/security/ct/MultiLogCTVerifier.cpp
@@ -178,7 +178,8 @@ pkix::Result MultiLogCTVerifier::VerifySingleSCT(
  }

  VerifiedSCT verifiedSct(std::move(sct), origin, matchingLog->operatorId(),
-                          matchingLog->state(), matchingLog->timestamp());
+                          matchingLog->state(), matchingLog->format(),
+                          matchingLog->timestamp());
  result.verifiedScts.push_back(std::move(verifiedSct));
  return Success;
 }
--- a/security/ct/SignedCertificateTimestamp.cpp
+++ b/security/ct/SignedCertificateTimestamp.cpp
@@ -6,9 +6,72 @@

 #include "SignedCertificateTimestamp.h"

+#include "CTUtils.h"
+
 namespace mozilla {
 namespace ct {

+pkix::Result SignedCertificateTimestamp::DecodeExtensions() {
+  if (extensions.empty()) {
+    return pkix::Success;
+  }
+
+  // `extensions` is a sequence of Extension:
+  //     struct {
+  //         ExtensionType extension_type;
+  //         opaque extension_data<0..2^16-1>;
+  //     } Extension;
+  const size_t kExtensionDataLengthBytes = 2;
+  // Currently, the only supported extension type is `leaf_index`. Others are
+  // ignored.
+  //     enum {
+  //         leaf_index(0), (255)
+  //     } ExtensionType;
+  const size_t kExtensionTypeLength = 1;
+  const uint8_t kExtensionTypeLeafIndex = 0;
+
+  pkix::Input input;
+  pkix::Result rv = input.Init(extensions.data(), extensions.size());
+  if (rv != pkix::Success) {
+    return rv;
+  }
+  pkix::Reader reader(input);
+  while (!reader.AtEnd()) {
+    uint8_t extensionType;
+    rv = ReadUint<kExtensionTypeLength>(reader, extensionType);
+    if (rv != pkix::Success) {
+      return rv;
+    }
+    pkix::Input extensionData;
+    rv = ReadVariableBytes<kExtensionDataLengthBytes>(reader, extensionData);
+    if (rv != pkix::Success) {
+      return rv;
+    }
+    if (extensionType == kExtensionTypeLeafIndex) {
+      // Duplicate extensions are not allowed.
+      if (leafIndex.isSome()) {
+        return pkix::Result::ERROR_EXTENSION_VALUE_INVALID;
+      }
+      // A leaf index is a big-endian, unsigned 40-bit value. In other words,
+      // it is 5 8-bit bytes, like so:
+      //     uint8 uint40[5];
+      //     uint40 LeafIndex;
+      const size_t kLeafIndexLength = 5;
+      uint64_t leafIndexValue;
+      pkix::Reader leafIndexReader(extensionData);
+      rv = ReadUint<kLeafIndexLength>(leafIndexReader, leafIndexValue);
+      if (rv != pkix::Success) {
+        return rv;
+      }
+      if (!leafIndexReader.AtEnd()) {
+        return pkix::Result::ERROR_EXTENSION_VALUE_INVALID;
+      }
+      leafIndex.emplace(leafIndexValue);
+    }
+  }
+  return pkix::Success;
+}
+
 void LogEntry::Reset() {
  type = LogEntry::Type::X509;
  leafCertificate.clear();
--- a/security/ct/SignedCertificateTimestamp.h
+++ b/security/ct/SignedCertificateTimestamp.h
@@ -8,6 +8,7 @@
 #define SignedCertificateTimestamp_h

 #include "Buffer.h"
+#include "mozilla/Maybe.h"
 #include "mozpkix/Input.h"
 #include "mozpkix/Result.h"

@@ -65,12 +66,17 @@ struct SignedCertificateTimestamp {
    V1 = 0,
  };

+  pkix::Result DecodeExtensions();
+
  Version version;
  Buffer logId;
  // "timestamp" is the current time in milliseconds, measured since the epoch,
  // ignoring leap seconds. See RFC 6962, Section 3.2.
  uint64_t timestamp;
  Buffer extensions;
+  // Maybe the index of the entry in the log, if specified by a LeafIndex
+  // extension in `extensions`.
+  Maybe<uint64_t> leafIndex;
  DigitallySigned signature;
 };

--- a/security/ct/tests/gtest/CTLogVerifierTest.cpp
+++ b/security/ct/tests/gtest/CTLogVerifierTest.cpp
@@ -33,7 +33,8 @@ class CTLogVerifierTest : public ::testing::Test {
  void TearDown() override { signature_cache_free(mSignatureCache); }

 protected:
-  CTLogVerifier mLog = CTLogVerifier(-1, CTLogState::Admissible, 0);
+  CTLogVerifier mLog =
+      CTLogVerifier(-1, CTLogState::Admissible, CTLogFormat::RFC6962, 0);
  // For some reason, the templating makes it impossible to use UniquePtr here.
  SignatureCache* mSignatureCache;
 };
@@ -115,7 +116,7 @@ TEST_F(CTLogVerifierTest, ExcessDataInPublicKey) {
  std::string extra = "extra";
  key.insert(key.end(), extra.begin(), extra.end());

-  CTLogVerifier log(-1, CTLogState::Admissible, 0);
+  CTLogVerifier log(-1, CTLogState::Admissible, CTLogFormat::RFC6962, 0);
  EXPECT_NE(Success, log.Init(InputForBuffer(key)));
 }

--- a/security/ct/tests/gtest/CTObjectsExtractorTest.cpp
+++ b/security/ct/tests/gtest/CTObjectsExtractorTest.cpp
@@ -39,7 +39,8 @@ class CTObjectsExtractorTest : public ::testing::Test {
  Buffer mEmbeddedCert;
  Buffer mCaCert;
  Buffer mCaCertSPKI;
-  CTLogVerifier mLog = CTLogVerifier(-1, CTLogState::Admissible, 0);
+  CTLogVerifier mLog =
+      CTLogVerifier(-1, CTLogState::Admissible, CTLogFormat::RFC6962, 0);
 };

 TEST_F(CTObjectsExtractorTest, ExtractPrecert) {
--- a/security/ct/tests/gtest/CTPolicyEnforcerTest.cpp
+++ b/security/ct/tests/gtest/CTPolicyEnforcerTest.cpp
@@ -35,25 +35,30 @@ class CTPolicyEnforcerTest : public ::testing::Test {

  void AddSct(VerifiedSCTList& verifiedScts, size_t logNo,
              CTLogOperatorId operatorId, SCTOrigin origin, uint64_t timestamp,
-              CTLogState logState = CTLogState::Admissible) {
+              CTLogState logState = CTLogState::Admissible,
+              CTLogFormat logFormat = CTLogFormat::RFC6962,
+              Maybe<uint64_t> leafIndex = Nothing()) {
    SignedCertificateTimestamp sct;
    sct.version = SignedCertificateTimestamp::Version::V1;
    sct.timestamp = timestamp;
+    sct.leafIndex = leafIndex;
    Buffer logId;
    GetLogId(logId, logNo);
    sct.logId = std::move(logId);
    VerifiedSCT verifiedSct(std::move(sct), origin, operatorId, logState,
-                            LOG_TIMESTAMP);
+                            logFormat, LOG_TIMESTAMP);
    verifiedScts.push_back(std::move(verifiedSct));
  }

  void AddMultipleScts(VerifiedSCTList& verifiedScts, size_t logsCount,
                       uint8_t operatorsCount, SCTOrigin origin,
                       uint64_t timestamp,
-                       CTLogState logState = CTLogState::Admissible) {
+                       CTLogState logState = CTLogState::Admissible,
+                       CTLogFormat logFormat = CTLogFormat::RFC6962) {
    for (size_t logNo = 0; logNo < logsCount; logNo++) {
      CTLogOperatorId operatorId = logNo % operatorsCount;
-      AddSct(verifiedScts, logNo, operatorId, origin, timestamp, logState);
+      AddSct(verifiedScts, logNo, operatorId, origin, timestamp, logState,
+             logFormat);
    }
  }

@@ -292,5 +297,84 @@ TEST_F(CTPolicyEnforcerTest,
  }
 }

+TEST_F(CTPolicyEnforcerTest, ConformsToCTPolicyWithAtLeastOneRFC6962Log) {
+  VerifiedSCTList scts;
+
+  AddSct(scts, LOG_1, OPERATOR_1, ORIGIN_TLS, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::Tiled, Some(23));
+  AddSct(scts, LOG_2, OPERATOR_2, ORIGIN_TLS, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::RFC6962);
+
+  CheckCompliance(scts, DEFAULT_LIFETIME, CTPolicyCompliance::Compliant);
+}
+
+TEST_F(CTPolicyEnforcerTest,
+       ConformsToCTPolicyWithAtLeastOneRFC6962LogEmbedded) {
+  VerifiedSCTList scts;
+
+  // 3 embedded SCTs required for DEFAULT_LIFETIME.
+  AddSct(scts, LOG_1, OPERATOR_1, ORIGIN_EMBEDDED, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::Tiled, Some(23));
+  AddSct(scts, LOG_2, OPERATOR_1, ORIGIN_EMBEDDED, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::Tiled, Some(23));
+  AddSct(scts, LOG_3, OPERATOR_2, ORIGIN_EMBEDDED, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::RFC6962);
+
+  CheckCompliance(scts, DEFAULT_LIFETIME, CTPolicyCompliance::Compliant);
+}
+
+TEST_F(CTPolicyEnforcerTest, DoesNotConformToCTPolicyWithNoRFC6962Logs) {
+  VerifiedSCTList scts;
+
+  AddSct(scts, LOG_1, OPERATOR_1, ORIGIN_TLS, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::Tiled, Some(23));
+  AddSct(scts, LOG_2, OPERATOR_2, ORIGIN_TLS, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::Tiled, Some(23));
+
+  CheckCompliance(scts, DEFAULT_LIFETIME, CTPolicyCompliance::NotEnoughScts);
+}
+
+TEST_F(CTPolicyEnforcerTest,
+       DoesNotConformToCTPolicyWithNoRFC6962LogsEmbedded) {
+  VerifiedSCTList scts;
+
+  // 3 embedded SCTs required for DEFAULT_LIFETIME.
+  AddSct(scts, LOG_1, OPERATOR_1, ORIGIN_EMBEDDED, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::Tiled, Some(23));
+  AddSct(scts, LOG_2, OPERATOR_1, ORIGIN_EMBEDDED, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::Tiled, Some(23));
+  AddSct(scts, LOG_3, OPERATOR_2, ORIGIN_EMBEDDED, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::Tiled, Some(23));
+
+  CheckCompliance(scts, DEFAULT_LIFETIME, CTPolicyCompliance::NotEnoughScts);
+}
+
+TEST_F(CTPolicyEnforcerTest,
+       DoesNotConformToCTPolicyWithSCTFromTiledLogWithNoLeafIndex) {
+  VerifiedSCTList scts;
+
+  AddSct(scts, LOG_1, OPERATOR_1, ORIGIN_TLS, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::Tiled, Nothing());
+  AddSct(scts, LOG_2, OPERATOR_2, ORIGIN_TLS, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::RFC6962);
+
+  CheckCompliance(scts, DEFAULT_LIFETIME, CTPolicyCompliance::NotEnoughScts);
+}
+
+TEST_F(CTPolicyEnforcerTest,
+       DoesNotConformToCTPolicyWithSCTFromTiledLogWithNoLeafIndexEmbedded) {
+  VerifiedSCTList scts;
+
+  // 3 embedded SCTs required for DEFAULT_LIFETIME.
+  AddSct(scts, LOG_1, OPERATOR_1, ORIGIN_EMBEDDED, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::Tiled, Some(23));
+  AddSct(scts, LOG_2, OPERATOR_1, ORIGIN_EMBEDDED, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::Tiled, Nothing());
+  AddSct(scts, LOG_3, OPERATOR_2, ORIGIN_EMBEDDED, TIMESTAMP_1,
+         CTLogState::Admissible, CTLogFormat::RFC6962);
+
+  CheckCompliance(scts, DEFAULT_LIFETIME, CTPolicyCompliance::NotEnoughScts);
+}
+
 }  // namespace ct
 }  // namespace mozilla
--- a/security/ct/tests/gtest/CTSerializationTest.cpp
+++ b/security/ct/tests/gtest/CTSerializationTest.cpp
@@ -192,6 +192,90 @@ TEST_F(CTSerializationTest, DecodesSignedCertificateTimestamp) {
  const size_t expectedSignatureLength = 71;
  EXPECT_EQ(expectedSignatureLength, sct.signature.signatureData.size());
  EXPECT_TRUE(sct.extensions.empty());
+  EXPECT_TRUE(sct.leafIndex.isNothing());
+}
+
+TEST_F(CTSerializationTest,
+       DecodesSignedCertificateTimestampWithLeafIndexExtension) {
+  Buffer encodedSctBuffer =
+      GetTestSignedCertificateTimestampWithLeafIndexExtension();
+  Input encodedSctInput = InputForBuffer(encodedSctBuffer);
+  Reader encodedSctReader(encodedSctInput);
+
+  SignedCertificateTimestamp sct;
+  ASSERT_EQ(Success, DecodeSignedCertificateTimestamp(encodedSctReader, sct));
+  EXPECT_EQ(SignedCertificateTimestamp::Version::V1, sct.version);
+  EXPECT_EQ(GetTestPublicKeyId(), sct.logId);
+  const uint64_t expectedTime = 1365181456089;
+  EXPECT_EQ(expectedTime, sct.timestamp);
+  const size_t expectedSignatureLength = 71;
+  EXPECT_EQ(expectedSignatureLength, sct.signature.signatureData.size());
+  EXPECT_FALSE(sct.extensions.empty());
+  ASSERT_TRUE(sct.leafIndex.isSome());
+  EXPECT_EQ(sct.leafIndex.value(), 52U);
+}
+
+TEST_F(CTSerializationTest,
+       FailsDecodingSignedCertificateTimestampWithTwoLeafIndexExtensions) {
+  Buffer encodedSctBuffer =
+      GetTestSignedCertificateTimestampWithTwoLeafIndexExtensions();
+  Input encodedSctInput = InputForBuffer(encodedSctBuffer);
+  Reader encodedSctReader(encodedSctInput);
+
+  SignedCertificateTimestamp sct;
+  ASSERT_EQ(Result::ERROR_EXTENSION_VALUE_INVALID,
+            DecodeSignedCertificateTimestamp(encodedSctReader, sct));
+}
+
+TEST_F(CTSerializationTest,
+       DecodesSignedCertificateTimestampWithUnknownExtension) {
+  Buffer encodedSctBuffer =
+      GetTestSignedCertificateTimestampWithUnknownExtension();
+  Input encodedSctInput = InputForBuffer(encodedSctBuffer);
+  Reader encodedSctReader(encodedSctInput);
+
+  SignedCertificateTimestamp sct;
+  ASSERT_EQ(Success, DecodeSignedCertificateTimestamp(encodedSctReader, sct));
+  EXPECT_EQ(SignedCertificateTimestamp::Version::V1, sct.version);
+  EXPECT_EQ(GetTestPublicKeyId(), sct.logId);
+  const uint64_t expectedTime = 1365181456089;
+  EXPECT_EQ(expectedTime, sct.timestamp);
+  const size_t expectedSignatureLength = 71;
+  EXPECT_EQ(expectedSignatureLength, sct.signature.signatureData.size());
+  EXPECT_FALSE(sct.extensions.empty());
+  EXPECT_TRUE(sct.leafIndex.isNothing());
+}
+
+TEST_F(CTSerializationTest,
+       DecodesSignedCertificateTimestampWithUnknownAndLeafIndexExtensions) {
+  Buffer encodedSctBuffer =
+      GetTestSignedCertificateTimestampWithUnknownAndLeafIndexExtensions();
+  Input encodedSctInput = InputForBuffer(encodedSctBuffer);
+  Reader encodedSctReader(encodedSctInput);
+
+  SignedCertificateTimestamp sct;
+  ASSERT_EQ(Success, DecodeSignedCertificateTimestamp(encodedSctReader, sct));
+  EXPECT_EQ(SignedCertificateTimestamp::Version::V1, sct.version);
+  EXPECT_EQ(GetTestPublicKeyId(), sct.logId);
+  const uint64_t expectedTime = 1365181456089;
+  EXPECT_EQ(expectedTime, sct.timestamp);
+  const size_t expectedSignatureLength = 71;
+  EXPECT_EQ(expectedSignatureLength, sct.signature.signatureData.size());
+  EXPECT_FALSE(sct.extensions.empty());
+  ASSERT_TRUE(sct.leafIndex.isSome());
+  EXPECT_EQ(sct.leafIndex.value(), 81U);
+}
+
+TEST_F(CTSerializationTest,
+       FailsDecodingSignedCertificateTimestampWithTooShortExtension) {
+  Buffer encodedSctBuffer =
+      GetTestSignedCertificateTimestampWithTooShortExtension();
+  Input encodedSctInput = InputForBuffer(encodedSctBuffer);
+  Reader encodedSctReader(encodedSctInput);
+
+  SignedCertificateTimestamp sct;
+  ASSERT_EQ(Result::ERROR_BAD_DER,
+            DecodeSignedCertificateTimestamp(encodedSctReader, sct));
 }

 TEST_F(CTSerializationTest, FailsDecodingInvalidSignedCertificateTimestamp) {
--- a/security/ct/tests/gtest/CTTestUtils.cpp
+++ b/security/ct/tests/gtest/CTTestUtils.cpp
@@ -87,6 +87,55 @@ const char kTestSignedCertificateTimestamp[] =
    "08dfbfe9ef536cf7f2022100beb29c72d7d06d61d06bdb38a069469aa86fe12e18bb7cc456"
    "89a2c0187ef5a5";

+// The signatures on the following "SCT"s are not actually valid. The intent is
+// to test the parsing of extensions.
+const char kTestSignedCertificateTimestampWithLeafIndexExtension[] =
+    "00df1c2ec11500945247a96168325ddc5c7959e8f7c6d388fc002e0bbd3f74d7640000013d"
+    "db27ded9"
+    "0008"              // 8 bytes of extensions
+    "0000050000000034"  // leaf_index of 52
+    "0403004730450220606e10ae5c2d5a1b0aed49dc4937f48de71a4e9784e9c2"
+    "08dfbfe9ef536cf7f2022100beb29c72d7d06d61d06bdb38a069469aa86fe12e18bb7cc456"
+    "89a2c0187ef5a5";
+
+const char kTestSignedCertificateTimestampWithTwoLeafIndexExtensions[] =
+    "00df1c2ec11500945247a96168325ddc5c7959e8f7c6d388fc002e0bbd3f74d7640000013d"
+    "db27ded9"
+    "0010"              // 16 bytes of extensions
+    "0000050000000034"  // leaf_index of 52
+    "0000050000000051"  // leaf_index of 81
+    "0403004730450220606e10ae5c2d5a1b0aed49dc4937f48de71a4e9784e9c2"
+    "08dfbfe9ef536cf7f2022100beb29c72d7d06d61d06bdb38a069469aa86fe12e18bb7cc456"
+    "89a2c0187ef5a5";
+
+const char kTestSignedCertificateTimestampWithUnknownExtension[] =
+    "00df1c2ec11500945247a96168325ddc5c7959e8f7c6d388fc002e0bbd3f74d7640000013d"
+    "db27ded9"
+    "0008"              // 8 bytes of extensions
+    "0100050000000034"  // an (unknown) extension with id 1
+    "0403004730450220606e10ae5c2d5a1b0aed49dc4937f48de71a4e9784e9c2"
+    "08dfbfe9ef536cf7f2022100beb29c72d7d06d61d06bdb38a069469aa86fe12e18bb7cc456"
+    "89a2c0187ef5a5";
+
+const char kTestSignedCertificateTimestampWithUnknownAndLeafIndexExtensions[] =
+    "00df1c2ec11500945247a96168325ddc5c7959e8f7c6d388fc002e0bbd3f74d7640000013d"
+    "db27ded9"
+    "0010"              // 16 bytes of extensions
+    "0100050000000034"  // an (unknown) extension with id 1
+    "0000050000000051"  // leaf_index of 81
+    "0403004730450220606e10ae5c2d5a1b0aed49dc4937f48de71a4e9784e9c2"
+    "08dfbfe9ef536cf7f2022100beb29c72d7d06d61d06bdb38a069469aa86fe12e18bb7cc456"
+    "89a2c0187ef5a5";
+
+const char kTestSignedCertificateTimestampWithTooShortExtension[] =
+    "00df1c2ec11500945247a96168325ddc5c7959e8f7c6d388fc002e0bbd3f74d7640000013d"
+    "db27ded9"
+    "0008"          // 8 bytes of extensions
+    "000005000034"  // 3 bytes of extension data when there should be 5
+    "0403004730450220606e10ae5c2d5a1b0aed49dc4937f48de71a4e9784e9c2"
+    "08dfbfe9ef536cf7f2022100beb29c72d7d06d61d06bdb38a069469aa86fe12e18bb7cc456"
+    "89a2c0187ef5a5";
+
 // ct-server-key-public.pem
 const char kEcP256PublicKey[] =
    "3059301306072a8648ce3d020106082a8648ce3d0301070342000499783cb14533c0161a5a"
@@ -527,6 +576,27 @@ Buffer GetTestSignedCertificateTimestamp() {
  return HexToBytes(kTestSignedCertificateTimestamp);
 }

+Buffer GetTestSignedCertificateTimestampWithLeafIndexExtension() {
+  return HexToBytes(kTestSignedCertificateTimestampWithLeafIndexExtension);
+}
+
+Buffer GetTestSignedCertificateTimestampWithTwoLeafIndexExtensions() {
+  return HexToBytes(kTestSignedCertificateTimestampWithTwoLeafIndexExtensions);
+}
+
+Buffer GetTestSignedCertificateTimestampWithUnknownExtension() {
+  return HexToBytes(kTestSignedCertificateTimestampWithUnknownExtension);
+}
+
+Buffer GetTestSignedCertificateTimestampWithUnknownAndLeafIndexExtensions() {
+  return HexToBytes(
+      kTestSignedCertificateTimestampWithUnknownAndLeafIndexExtensions);
+}
+
+Buffer GetTestSignedCertificateTimestampWithTooShortExtension() {
+  return HexToBytes(kTestSignedCertificateTimestampWithTooShortExtension);
+}
+
 Buffer GetTestInclusionProof() { return HexToBytes(kTestInclusionProof); }

 Buffer GetTestInclusionProofUnexpectedData() {
--- a/security/ct/tests/gtest/CTTestUtils.h
+++ b/security/ct/tests/gtest/CTTestUtils.h
@@ -39,8 +39,13 @@ Buffer GetTestDigitallySigned();
 // Returns the source data of the test DigitallySigned.
 Buffer GetTestDigitallySignedData();

-// Returns the binary representation of a test serialized SCT.
+// Returns the binary representation of various test SCTs.
 Buffer GetTestSignedCertificateTimestamp();
+Buffer GetTestSignedCertificateTimestampWithLeafIndexExtension();
+Buffer GetTestSignedCertificateTimestampWithTwoLeafIndexExtensions();
+Buffer GetTestSignedCertificateTimestampWithUnknownExtension();
+Buffer GetTestSignedCertificateTimestampWithUnknownAndLeafIndexExtensions();
+Buffer GetTestSignedCertificateTimestampWithTooShortExtension();

 // Returns the binary representation of a test serialized InclusionProof.
 Buffer GetTestInclusionProof();
--- a/security/ct/tests/gtest/MultiLogCTVerifierTest.cpp
+++ b/security/ct/tests/gtest/MultiLogCTVerifierTest.cpp
@@ -30,7 +30,8 @@ class MultiLogCTVerifierTest : public ::testing::Test {
      abort();
    }

-    CTLogVerifier log(mLogOperatorID, CTLogState::Admissible, 0);
+    CTLogVerifier log(mLogOperatorID, CTLogState::Admissible,
+                      CTLogFormat::RFC6962, 0);
    ;
    ASSERT_EQ(Success, log.Init(InputForBuffer(GetTestPublicKey())));
    mVerifier.AddLog(std::move(log));
@@ -222,7 +223,8 @@ TEST_F(MultiLogCTVerifierTest, IdentifiesSCTFromUnknownLog) {
 TEST_F(MultiLogCTVerifierTest, IdentifiesSCTFromDisqualifiedLog) {
  MultiLogCTVerifier verifier;
  const uint64_t retiredTime = 12345u;
-  CTLogVerifier log(mLogOperatorID, CTLogState::Retired, retiredTime);
+  CTLogVerifier log(mLogOperatorID, CTLogState::Retired, CTLogFormat::RFC6962,
+                    retiredTime);
  ASSERT_EQ(Success, log.Init(InputForBuffer(GetTestPublicKey())));
  verifier.AddLog(std::move(log));

--- a/security/manager/ssl/tests/unit/test_ct.js
+++ b/security/manager/ssl/tests/unit/test_ct.js
@@ -51,6 +51,12 @@ function add_tests_in_mode(mode) {
    Ci.nsITransportSecurityInfo.CERTIFICATE_TRANSPARENCY_POLICY_COMPLIANT,
    true
  );
+  // This certificate has an embedded SCT from a tiled log.
+  add_ct_test(
+    "ct-tiled-valid.example.com",
+    Ci.nsITransportSecurityInfo.CERTIFICATE_TRANSPARENCY_POLICY_COMPLIANT,
+    true
+  );
  // This certificate has only 2 embedded SCTs, and so is not policy-compliant.
  add_ct_test(
    "ct-insufficient-scts.example.com",
--- a/security/manager/ssl/tests/unit/test_ct/ct-tiled-valid.example.com.pem
+++ b/security/manager/ssl/tests/unit/test_ct/ct-tiled-valid.example.com.pem
@@ -0,0 +1,34 @@
+-----BEGIN CERTIFICATE-----
+MIIF5TCCBM2gAwIBAgIUa+BUsfUwwqRLVgVlQikCG31eMmkwDQYJKoZIhvcNAQEL
+BQAwEjEQMA4GA1UEAwwHVGVzdCBDQTAiGA8yMDIzMTEyODAwMDAwMFoYDzIwMjYw
+MjA1MDAwMDAwWjAlMSMwIQYDVQQDDBpjdC10aWxlZC12YWxpZC5leGFtcGxlLmNv
+bTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBALqIUahEjhbWQf1utogG
+NhA9PBPZ6uQ1SrTs9WhXbCR7wcclqODYH72xnAabbhqG8mvir1p1a2pkcQh6pVqn
+RYf3HNUknAJ+zUP8HmnQOCApk6sgw0nk27lMwmtsDu0Vgg/xfq1pGrHTAjqLKkHu
+p3DgDw2N/WYLK7AkkqR9uYhheZCxV5A90jvF4LhIH6g304hD7ycW2FW3ZlqqfgKQ
+Lzp7EIAGJMwcbJetlmFbt+KWEsB1MaMMkd20yvf8rR0l0wnvuRcOp2jhs3svIm9p
+47SKlWEd7ibWJZ2rkQhONsscJAQsvxaLL+Xxj5kXMbiz/kkj+nJRxDHVA6zaGAo1
+7Y0CAwEAAaOCAxowggMWMBgGA1UdEQQRMA+CDSouZXhhbXBsZS5jb20wggL4Bgor
+BgEEAdZ5AgQCBIIC6ASCAuQC4gEvAFQiJZjzPTZIBULa7ODmuU3hXA7ujFkUykjX
+XjxIToA/AAABUfp73AAAAAQBAQCJabucDWdKUJvzuE80Np7eZUCW2ZbLR3l/jX+N
+o9R0I7QhVmvugafYV3Hy2yjAJUXIBCAFq/MKlSfbFGfg3aR7h1Y31zdaF7YMb3kF
+1yvv7dmoxmF+ELqjmKALZBoLWq66uvOKrSfXfWo256tlc30FPAHQjisFxkw7LeJO
+eZbuIIVBHMnyX/sVeDaIlXysiFVDrXs0c0Bv0vn+E7kiPScZfEAzW4tmN5ursFIy
+PFR2CnzcpsQTr62nl1th2qteaQ3bb/kARlJk2cmFdWFhDs7NR4JVJ5cedknYyH5X
+cximwIlAArlHSL/Angeuo51gqHwOdGPfdTfr/BfOLL3mpilFAHYAKrgwRDO5FN7S
+8x5CB/JRwXo3oJJoUtkIAgb4Xlc5FioAAAFR+nvcAAAABAMARzBFAiBcdVGfExFQ
+zV2K3iCjvAYwkf+yc3VfMWTs/ctCgApw5gIhAJZLBL70dv/nqol8uqJmab2wTrSz
+tGQVeFOuTEbraKzRATcA6Mz6YX3GS9LYtKJsKw/1dnHx5n3gb4uVYfJVLXuUA5oA
+AAFR+nvcAAAIAAAFhCHKllMEAQEAgLcoyQ3a159aRMB5gZkQ3vZQu7V9c+geuNPa
+HqRfubtFYQU9PFuyaGf0WoxFuN38f0f7vhvCZ8mDnC3yj8DnoEx3gMfwtSRTWQHk
+k0KSC61wlz3OI6Lf/B9uN8cw9cLSodBoyB6lDUGSlq3wz03+YXHHcCwospoZ8nwv
+iiPo0N11M1IJYThYrpv270YIVjlTpln4TjmUKsIaB+JQgXWrzqjKmBxX/CkHQ6ul
+Z/0rjVzBv8R1OjETk8MIlyB51N7Vb018Pek7AKo8M5QiwC2YHxhd4a55QfbTCMGC
+//VaWYIvw1zMNocF6UKDPgZtqpzG04BHp502eDm4TYMfVpGISzANBgkqhkiG9w0B
+AQsFAAOCAQEAR0KdN8iwoqCH+F8HL+vmlDXc2p/gGoRAHDS07bRi/cMlWFiWPfgp
+iWVbXzuPDqZFHU3vYcmrZhi/MFlnnU/G5cRxPFRcJ8BPzNlnLb86PYYDSXTpiLsD
+tdnwdMK7f1axuXjaNxlCznoQYjWh4hre9lzUjkPkO8l9kjtOxypSUnXQu96zLhnl
+GrLe26P6NkUNagupy3za7USCi4Gej6nxFMH8Cou7mXdjPZMTWzf1DvgETOCFAwX7
+lrPnJgl5GQ2u8C9H0FE1iI05krYaeNHGVb2Cq+4g5/ECEYPoTq9a75l7SeSngQEd
+jSTJxocud+zZajmigOfMIvcYUKVD3ieiLg==
+-----END CERTIFICATE-----
--- a/security/manager/ssl/tests/unit/test_ct/ct-tiled-valid.example.com.pem.certspec
+++ b/security/manager/ssl/tests/unit/test_ct/ct-tiled-valid.example.com.pem.certspec
@@ -0,0 +1,4 @@
+issuer:Test CA
+subject:ct-tiled-valid.example.com
+extension:subjectAlternativeName:*.example.com
+extension:embeddedSCTList:default:20160101,secp256r1:20160101,ev:20160101:567502607955
--- a/security/manager/ssl/tests/unit/test_ct/ct-unknown-log.example.com.pem
+++ b/security/manager/ssl/tests/unit/test_ct/ct-unknown-log.example.com.pem
@@ -1,5 +1,5 @@
 -----BEGIN CERTIFICATE-----
-MIIF3DCCBMSgAwIBAgIUS2SODmE9dXhGEYS8JfCogtARiyEwDQYJKoZIhvcNAQEL
+MIIFRTCCBC2gAwIBAgIUG4/k+n+iibx5ZgMTEJsAirIw46YwDQYJKoZIhvcNAQEL
 BQAwEjEQMA4GA1UEAwwHVGVzdCBDQTAiGA8yMDIzMTEyODAwMDAwMFoYDzIwMjYw
 MjA1MDAwMDAwWjAlMSMwIQYDVQQDDBpjdC11bmtub3duLWxvZy5leGFtcGxlLmNv
 bTCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBALqIUahEjhbWQf1utogG
@@ -8,27 +8,24 @@ RYf3HNUknAJ+zUP8HmnQOCApk6sgw0nk27lMwmtsDu0Vgg/xfq1pGrHTAjqLKkHu
 p3DgDw2N/WYLK7AkkqR9uYhheZCxV5A90jvF4LhIH6g304hD7ycW2FW3ZlqqfgKQ
 Lzp7EIAGJMwcbJetlmFbt+KWEsB1MaMMkd20yvf8rR0l0wnvuRcOp2jhs3svIm9p
 47SKlWEd7ibWJZ2rkQhONsscJAQsvxaLL+Xxj5kXMbiz/kkj+nJRxDHVA6zaGAo1
-7Y0CAwEAAaOCAxEwggMNMBgGA1UdEQQRMA+CDSouZXhhbXBsZS5jb20wggLvBgor
-BgEEAdZ5AgQCBIIC3wSCAtsC2QEvAFQiJZjzPTZIBULa7ODmuU3hXA7ujFkUykjX
-XjxIToA/AAABUfp73AAAAAQBAQCgHd8Scrtd8aIdXafr8o2gFUYzajTu2N0sbfC4
-yb8C8KTCT2jcJJUoDvZ7KP2uPbzBwRvZvzMho885x+empY6u7esgTsq32PkW+rX5
-NR0xWIcyWvgPIwk6IR/Y8WGI7ZYyEBNoqjxDKa+MpPUTMFn3W7WpidwCH7Fa7J49
-hWxPLQ1G4RWoj5GjG0e/tFTzvQUWAbYROfQbbLQnJPXzEjt3C+3T6zCT/yo/HSiW
-lC/ylgGc3lBgqnXqtmrGVvTez4ydnSM6DEKUCVtMyBCfVw3HSGzbrtMGvUUcsEI0
-LcATaRJG/WdWjRLdacf2eO9bG8ngpLJQImK5p/9UOKM1TJW8AHUAKrgwRDO5FN7S
-8x5CB/JRwXo3oJJoUtkIAgb4Xlc5FioAAAFR+nvcAAAABAMARjBEAiBcdVGfExFQ
-zV2K3iCjvAYwkf+yc3VfMWTs/ctCgApw5gIgWAl+GxbSxwqeZmp4wx+zK38l6zW3
-2KrjPq4QHn+9Fb4BLwDozPphfcZL0ti0omwrD/V2cfHmfeBvi5Vh8lUte5QDmgAA
-AVH6e9wAAAAEAQEARvV0PDIvS8wZzGKzNBPdsAP/XPfF/ZzEA6z63dEKpIyiPgo1
-vgoKc8EPyZfMirlvXU4pRSkuXFqmD7xKVjbfk6FdGlDeHm35qcQhg0wmmjGhJ+lJ
-jVZB7Hqs6qCLxAR01HQy1sMkLT8iku+jvey+rdzF+hJLKZhACB+R0GR3gPnqN+mW
-0HSCUwvYso0FIAkO8Xursq3jpjykaZVkAx2ETk3lnBwuMEw01Opn5497wyddA6WI
-knVhzORNwH9NeH4vjo3vD49B57WbGN95G+DH7RHlrEwgyczOkS+BBwnt9u64pBxS
-FgJj4PRggejuuQ/Eihu9GL5pbMPfUps4QTnFaDANBgkqhkiG9w0BAQsFAAOCAQEA
-araaEEpMCOVu0Wi1DcyHdW1fdYPU+dX9GStO666LlgfJm9w3hcLCxVmn8Y4WUYbw
-fmPghlsr0MNLg+6pyxmthDSKkE4yieckNkTUYybKZaEvFpaZQamHMtWzuPS9Uvab
-XbxgC6/Z50nN3cPd6tLK7eyq2ZXzQf94vfn/EcJjkRGVdubPTw6URgu27FEJAxX1
-XAJpdu5HwOj2+4aCNw6drMg+b/Dig+EpOTSBhalofyJxi3Lv/Kedzc9wlxqvmUvm
-iMxWJob8wwaFRoL4YNBxxZEYI+Hebw8kePHhtwZ7h9q/BsgFajsWn5ay3PXmVvD2
-Em16teHaNfB2r3e6sjuZBw==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 -----END CERTIFICATE-----
--- a/security/manager/ssl/tests/unit/test_ct/ct-unknown-log.example.com.pem.certspec
+++ b/security/manager/ssl/tests/unit/test_ct/ct-unknown-log.example.com.pem.certspec
@@ -1,4 +1,4 @@
 issuer:Test CA
 subject:ct-unknown-log.example.com
 extension:subjectAlternativeName:*.example.com
-extension:embeddedSCTList:default:20160101,secp256r1:20160101,ev:20160101
+extension:embeddedSCTList:default:20160101,secp256r1:20160101,secp384r1:20160101
--- a/security/manager/tools/log_list.json
+++ b/security/manager/tools/log_list.json
@@ -1,6 +1,6 @@
 {
-  "version": "59.18",
-  "log_list_timestamp": "2025-07-27T12:54:32Z",
+  "version": "59.19",
+  "log_list_timestamp": "2025-07-28T12:53:51Z",
  "operators": [
    {
      "name": "Google",
--- a/security/manager/tools/pycert.py
+++ b/security/manager/tools/pycert.py
@@ -36,7 +36,7 @@ certificatePolicies:[<policy OID>,...]
 nameConstraints:{permitted,excluded}:[<dNSName|directoryName>,...]
 nsCertType:sslServer
 TLSFeature:[<TLSFeature>,...]
-embeddedSCTList:[<key specification>:<YYYYMMDD>,...]
+embeddedSCTList:[<key specification>:<YYYYMMDD>[:<leaf index>],...]
 delegationUsage:

 Where:
@@ -109,12 +109,12 @@ class UnknownBaseError(Error):
    """Base class for handling unexpected input in this module."""

    def __init__(self, value):
-        super(UnknownBaseError, self).__init__()
+        super().__init__()
        self.value = value
        self.category = "input"

    def __str__(self):
-        return 'Unknown %s type "%s"' % (self.category, repr(self.value))
+        return f'Unknown {self.category} type "{repr(self.value)}"'


 class UnknownAlgorithmTypeError(UnknownBaseError):
@@ -210,18 +210,18 @@ class InvalidSCTSpecification(Error):
    """Helper exception type to handle invalid SCT specifications."""

    def __init__(self, value):
-        super(InvalidSCTSpecification, self).__init__()
+        super().__init__()
        self.value = value

    def __str__(self):
-        return repr('invalid SCT specification "{}"' % self.value)
+        return f'invalid SCT specification "{self.value}"'


 class InvalidSerialNumber(Error):
    """Exception type to handle invalid serial numbers."""

    def __init__(self, value):
-        super(InvalidSerialNumber, self).__init__()
+        super().__init__()
        self.value = value

    def __str__(self):
@@ -254,7 +254,7 @@ def stringToDN(string, tag=None):
    optional implicit tag in cases where the Name needs to be tagged
    differently."""
    if string and "/" not in string:
-        string = "/CN=%s" % string
+        string = f"/CN={string}"
    rdns = rfc2459.RDNSequence()
    pattern = "/(C|ST|L|O|OU|CN|emailAddress)="
    split = re.split(pattern, string)
@@ -621,10 +621,11 @@ class Certificate:
    def addCertificatePolicies(self, policyOIDs, critical):
        policies = rfc2459.CertificatePolicies()
        for pos, policyOID in enumerate(policyOIDs.split(",")):
-            if policyOID == "any":
-                policyOID = "2.5.29.32.0"
+            policyOIDMapped = policyOID
+            if policyOIDMapped == "any":
+                policyOIDMapped = "2.5.29.32.0"
            policy = rfc2459.PolicyInformation()
-            policyIdentifier = rfc2459.CertPolicyId(policyOID)
+            policyIdentifier = rfc2459.CertPolicyId(policyOIDMapped)
            policy["policyIdentifier"] = policyIdentifier
            policies.setComponentByPosition(pos, policy)
        self.addExtension(rfc2459.id_ce_certificatePolicies, policies, critical)
@@ -696,15 +697,20 @@ class Certificate:
        (scts, critical) = self.savedEmbeddedSCTListData
        encodedSCTs = []
        for sctSpec in scts.split(","):
-            match = re.search(r"(\w+):(\d{8})", sctSpec)
+            match = re.search(r"(\w+):(\d{8}):?(\d+)?", sctSpec)
            if not match:
                raise InvalidSCTSpecification(sctSpec)
            keySpec = match.group(1)
+            leafIndex = match.group(3)
+            if leafIndex:
+                leafIndex = int(leafIndex)
            key = pykey.keyFromSpecification(keySpec)
            time = datetime.datetime.strptime(match.group(2), "%Y%m%d")
            tbsCertificate = self.getTBSCertificate()
            tbsDER = encoder.encode(tbsCertificate)
-            sct = pyct.SCT(key, time, pyct.PrecertEntry(tbsDER, self.issuerKey))
+            sct = pyct.SCT(
+                key, time, pyct.PrecertEntry(tbsDER, self.issuerKey), leafIndex
+            )
            signed = sct.signAndEncode()
            lengthPrefix = pack("!H", len(signed))
            encodedSCTs.append(lengthPrefix + signed)
--- a/security/manager/tools/pyct.py
+++ b/security/manager/tools/pyct.py
@@ -16,6 +16,7 @@ to the output object. The specification is as follows:
 timestamp:<YYYYMMDD>
 [key:<key specification>]
 [tamper]
+[leafIndex:<leaf index>]
 certificate:
 <certificate specification>

@@ -48,7 +49,7 @@ class InvalidKeyError(Exception):
        self.key = key

    def __str__(self):
-        return 'Invalid key: "%s"' % str(self.key)
+        return f'Invalid key: "{str(self.key)}"'


 class UnknownSignedEntryType(Exception):
@@ -58,7 +59,7 @@ class UnknownSignedEntryType(Exception):
        self.signedEntry = signedEntry

    def __str__(self):
-        return 'Unknown SignedEntry type: "%s"' % str(self.signedEntry)
+        return f'Unknown SignedEntry type: "{str(self.signedEntry)}"'


 class SignedEntry:
@@ -84,11 +85,12 @@ class X509Entry(SignedEntry):
 class SCT:
    """SCT represents a Signed Certificate Timestamp."""

-    def __init__(self, key, date, signedEntry):
+    def __init__(self, key, date, signedEntry, leafIndex=None):
        self.key = key
        self.timestamp = calendar.timegm(date.timetuple()) * 1000
        self.signedEntry = signedEntry
        self.tamper = False
+        self.leafIndex = leafIndex

    def signAndEncode(self):
        """Returns a signed and encoded representation of the
@@ -100,8 +102,7 @@ class SCT:
        # entry_type (two bytes (one 0 byte followed by one 0 byte for
        #             X509Entry or one 1 byte for PrecertEntry)
        # signed_entry (bytes of X509Entry or PrecertEntry)
-        # extensions (2-byte-length-prefixed, currently empty (so two 0
-        #             bytes))
+        # extensions (2-byte-length-prefixed)
        # A X509Entry is:
        # certificate (3-byte-length-prefixed data)
        # A PrecertEntry is:
@@ -125,7 +126,18 @@ class SCT:
            )
        else:
            raise UnknownSignedEntryType(self.signedEntry)
-        data = b"\0\0" + timestamp + b"\0" + entry_with_type + b"\0\0"
+        extensions = []
+        if self.leafIndex:
+            # An extension consists of 1 byte to identify the extension type, 2
+            # big-endian bytes for the length of the extension data, and then
+            # the extension data.
+            # The type of leaf_index is 0, and its data consists of 5 bytes.
+            extensions = [b"\0\0\5" + self.leafIndex.to_bytes(5, byteorder="big")]
+        extensionsLength = sum(map(len, extensions))
+        extensionsEncoded = extensionsLength.to_bytes(2, byteorder="big") + b"".join(
+            extensions
+        )
+        data = b"\0\0" + timestamp + b"\0" + entry_with_type + extensionsEncoded
        if isinstance(self.key, pykey.ECCKey):
            signatureByte = b"\3"
        elif isinstance(self.key, pykey.RSAKey):
@@ -143,8 +155,7 @@ class SCT:
        # id (32 bytes of SHA-256 hash of the signing key, as
        #     DER-encoded SPKI)
        # timestamp (8 bytes, milliseconds since the epoch)
-        # extensions (2-byte-length-prefixed data, currently
-        #             empty)
+        # extensions (2-byte-length-prefixed data)
        # hash (one 4 byte representing sha256)
        # signature (one byte - 1 for RSA and 3 for ECDSA)
        # signature (2-byte-length-prefixed data)
@@ -156,7 +167,8 @@ class SCT:
            b"\0"
            + key_id
            + timestamp
-            + b"\0\0\4"
+            + extensionsEncoded
+            + b"\4"
            + signatureByte
            + signature_len_prefix
            + signature
@@ -168,26 +180,30 @@ class SCT:
        certificateSpecification = StringIO()
        readingCertificateSpecification = False
        tamper = False
+        leafIndex = None
        for line in specStream.readlines():
-            line = line.strip()
+            lineStripped = line.strip()
            if readingCertificateSpecification:
-                print(line, file=certificateSpecification)
-            elif line == "certificate:":
+                print(lineStripped, file=certificateSpecification)
+            elif lineStripped == "certificate:":
                readingCertificateSpecification = True
-            elif line.startswith("key:"):
-                key = pykey.keyFromSpecification(line[len("key:") :])
-            elif line.startswith("timestamp:"):
+            elif lineStripped.startswith("key:"):
+                key = pykey.keyFromSpecification(lineStripped[len("key:") :])
+            elif lineStripped.startswith("timestamp:"):
                timestamp = datetime.datetime.strptime(
-                    line[len("timestamp:") :], "%Y%m%d"
+                    lineStripped[len("timestamp:") :], "%Y%m%d"
                )
-            elif line == "tamper":
+            elif lineStripped == "tamper":
                tamper = True
+            elif lineStripped.startswith("leafIndex:"):
+                leafIndex = int(lineStripped[len("leafIndex:") :])
            else:
-                raise pycert.UnknownParameterTypeError(line)
+                raise pycert.UnknownParameterTypeError(lineStripped)
        certificateSpecification.seek(0)
        certificate = pycert.Certificate(certificateSpecification).toDER()
        sct = SCT(key, timestamp, X509Entry(certificate))
        sct.tamper = tamper
+        sct.leafIndex = leafIndex
        return sct


--- a/taskcluster/docker/periodic-updates/scripts/getCTKnownLogs.py
+++ b/taskcluster/docker/periodic-updates/scripts/getCTKnownLogs.py
@@ -58,10 +58,16 @@ enum class CTLogState {
  Retired,
 };

+enum class CTLogFormat {
+  RFC6962,
+  Tiled,
+};
+
 struct CTLogInfo {
  // See bug 1338873 about making these fields const.
  const char* name;
  CTLogState state;
+  CTLogFormat format;
  uint64_t timestamp;
  // Index within kCTLogOperatorList.
  size_t operatorIndex;
@@ -122,7 +128,7 @@ def get_operator_index(json_data, target_name):


 LOG_INFO_TEMPLATE = """\
-    {$description, $state,
+    {$description, $state, $log_format,
     $timestamp,  // $timestamp_comment
     $operator_index,$spaces  // $operator_comment
 $indented_log_key,
@@ -140,56 +146,71 @@ def map_state(state):
    states to be included are 'qualified', 'usable', 'readonly', or 'retired'.
    Valid states that are not to be included are 'pending' or 'rejected'.
    """
-    if state == "qualified" or state == "usable" or state == "readonly":
+    if state in {"qualified", "usable", "readonly"}:
        return "CTLogState::Admissible"
    elif state == "retired":
        return "CTLogState::Retired"
-    elif state == "pending" or state == "rejected":
+    elif state in {"pending", "rejected"}:
        return None
    else:
-        raise UnhandledLogStateException("unhandled log state '%s'" % state)
+        raise UnhandledLogStateException(f"unhandled log state '{state}'")
+
+
+def get_initializer_for_log(log, operator, json_data, log_format):
+    log_key = base64.b64decode(log["key"])
+    operator_name = operator["name"]
+    operator_index = get_operator_index(json_data, operator_name)
+    state = list(log["state"].keys())[0]
+    timestamp_comment = log["state"][state]["timestamp"]
+    timestamp = get_timestamp(timestamp_comment)
+    state = map_state(state)
+    if state is None:
+        return None
+    is_test_log = "test_only" in operator and operator["test_only"]
+    prefix = ""
+    suffix = ","
+    if is_test_log:
+        prefix = "#ifdef DEBUG\n"
+        suffix = ",\n#endif  // DEBUG"
+    num_spaces = len(str(timestamp)) - len(str(operator_index))
+    spaces = " " * num_spaces
+    tmpl = Template(LOG_INFO_TEMPLATE)
+    toappend = tmpl.substitute(
+        # Use json.dumps for C-escaping strings.
+        # Not perfect but close enough.
+        description=json.dumps(log["description"]),
+        operator_index=operator_index,
+        operator_comment=f"operated by {operator_name}".replace("/", "|"),
+        state=state,
+        log_format=log_format,
+        timestamp=timestamp,
+        spaces=spaces,
+        timestamp_comment=timestamp_comment,
+        # Maximum line width is 80.
+        indented_log_key="\n".join([f'     "{l}"' for l in get_hex_lines(log_key, 74)]),
+        log_key_len=len(log_key),
+    )
+    return prefix + toappend + suffix


 def get_log_info_structs(json_data):
    """Return array of CTLogInfo initializers for the known logs."""
-    tmpl = Template(LOG_INFO_TEMPLATE)
    initializers = []
    for operator in json_data["operators"]:
-        operator_name = operator["name"]
-        for log in operator["logs"]:
-            log_key = base64.b64decode(log["key"])
-            operator_index = get_operator_index(json_data, operator_name)
-            state = list(log["state"].keys())[0]
-            timestamp_comment = log["state"][state]["timestamp"]
-            timestamp = get_timestamp(timestamp_comment)
-            state = map_state(state)
-            if state is None:
-                continue
-            is_test_log = "test_only" in operator and operator["test_only"]
-            prefix = ""
-            suffix = ","
-            if is_test_log:
-                prefix = "#ifdef DEBUG\n"
-                suffix = ",\n#endif  // DEBUG"
-            num_spaces = len(str(timestamp)) - len(str(operator_index))
-            spaces = " " * num_spaces
-            toappend = tmpl.substitute(
-                # Use json.dumps for C-escaping strings.
-                # Not perfect but close enough.
-                description=json.dumps(log["description"]),
-                operator_index=operator_index,
-                operator_comment=f"operated by {operator_name}".replace("/", "|"),
-                state=state,
-                timestamp=timestamp,
-                spaces=spaces,
-                timestamp_comment=timestamp_comment,
-                # Maximum line width is 80.
-                indented_log_key="\n".join(
-                    [f'     "{l}"' for l in get_hex_lines(log_key, 74)]
-                ),
-                log_key_len=len(log_key),
-            )
-            initializers.append(prefix + toappend + suffix)
+        if "logs" in operator:
+            for log in operator["logs"]:
+                initializer = get_initializer_for_log(
+                    log, operator, json_data, "CTLogFormat::RFC6962"
+                )
+                if initializer:
+                    initializers.append(initializer)
+        if "tiled_logs" in operator:
+            for log in operator["tiled_logs"]:
+                initializer = get_initializer_for_log(
+                    log, operator, json_data, "CTLogFormat::Tiled"
+                )
+                if initializer:
+                    initializers.append(initializer)
    return initializers


@@ -301,8 +322,34 @@ def patch_in_test_logs(json_data):
            }
        ],
    }
+    mozilla_test_operator_3 = {
+        "name": "Mozilla Test Org 3",
+        "id": max_id + 3,
+        "test_only": True,
+        "tiled_logs": [
+            {
+                "description": "Mozilla Test RSA Log 4",
+                # `openssl x509 -noout -pubkey -in <path/to/evroot.pem>`
+                "key": """
+            MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAtUmJXJ0AEI0Rofmfh6nj
+            0aXbXfrs8YjaV79kE2iPLORyLP8QkDjBdALJOipHPb0oau0/3NNjz1opFHcBvdgY
+            12Fb+TVr1dPIM2qqjAlxNooGw81EYbk+UUJOF0S7LqrUaqs4zhloIZYfh3FKFmNp
+            Pwl2HN9Na6El6s7HvicNOI94n2zfeK4xRO0oxF55KThjp6IqSJgKNqQOctV5ybkl
+            3/jHkzYv/WiXp8F1TF6XyWfD6t0aroqizM40igFpuA4ootcMGpYMbzNfLaCbm2Q/
+            Wr+6SeiqqYHpYOJ9h0gL3VXdlBf6GFCfu1VMz4GkOX6LqBKKNL3yeGXBieVzT7Ip
+            BQIDAQAB
+        """,
+                "state": {
+                    "qualified": {
+                        "timestamp": "2025-06-25T12:09:26Z",
+                    },
+                },
+            }
+        ],
+    }
    json_data["operators"].append(mozilla_test_operator_1)
    json_data["operators"].append(mozilla_test_operator_2)
+    json_data["operators"].append(mozilla_test_operator_3)


 def get_content_at(url):
@@ -348,7 +395,7 @@ def run(args):
        hash_alg = rsa.verify(json_text, signature, key)
        if hash_alg != "SHA-256":
            raise UnsupportedSignatureHashAlgorithmException(
-                "unsupported hash algorithm '%s'" % hash_alg
+                f"unsupported hash algorithm '{hash_alg}'"
            )
        print("Writing output: ", args.json_file_out)
        with open(args.json_file_out, "wb") as json_file_out:
@@ -373,7 +420,7 @@ def parse_arguments_and_run():
        "Downloads the JSON file from the known source "
        "of truth by default, but can also operate on a "
        "previously-downloaded file. See https://certificate.transparency.dev/google/",
-        epilog="Example: ./mach python %s" % os.path.basename(sys.argv[0]),
+        epilog=f"Example: ./mach python {os.path.basename(sys.argv[0])}",
    )

    arg_parser.add_argument(