net: retain leading zero bytes in X.509 serial numbers.

X.509 serial numbers should be a positive numbers according to the spec.
However, certificates have been issued with negative serial numbers. Negative
serial numbers are indicated with a most-significant bit of one. Positive
numbers which would have a MSB of 1 have a zero byte prepended to avoid the
ambiguity.

Previously we removing leading zero bytes because we were only matching against
a blacklist of serial numbers, none of which were negative.

This change moves the handling of serial numbers to the place where they are
used, rather than where they are parsed.

BUG=none
TEST=none


Review URL: http://codereview.chromium.org/8381017

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@107956 0039d316-1c4b-4281-b951-d872f2087c98

8 files changed, 30 insertions, 284 deletions

diff --git a/net/base/crl_set.cc b/net/base/crl_set.cc
index 5b28be7..5c5a376 100644
--- a/net/base/crl_set.cc
+++ b/net/base/crl_set.cc
@@ -408,6 +408,18 @@ bool CRLSet::ApplyDelta(base::StringPiece data,
 CRLSet::Result CRLSet::CheckCertificate(
     const base::StringPiece& serial_number,
     const base::StringPiece& parent_spki) const {
+  base::StringPiece serial(serial_number);
+
+  if (!serial.empty() && serial[0] >= 0x80) {
+    // This serial number is negative but the process which generates CRL sets
+    // will reject any certificates with negative serial numbers as invalid.
+    return UNKNOWN;
+  }
+
+  // Remove any leading zero bytes.
+  while (serial.size() > 1 && serial[0] == 0x00)
+    serial.remove_prefix(1);
+
   std::map<std::string, size_t>::const_iterator i =
       crls_index_by_issuer_.find(parent_spki.as_string());
   if (i == crls_index_by_issuer_.end())
@@ -416,7 +428,7 @@ CRLSet::Result CRLSet::CheckCertificate(
 
   for (std::vector<std::string>::const_iterator i = serials.begin();
        i != serials.end(); ++i) {
-    if (base::StringPiece(*i) == serial_number)
+    if (base::StringPiece(*i) == serial)
       return REVOKED;
   }
 
diff --git a/net/base/x509_certificate.cc b/net/base/x509_certificate.cc
index d36bfad..2762154 100644
--- a/net/base/x509_certificate.cc
+++ b/net/base/x509_certificate.cc
@@ -708,278 +708,30 @@ bool X509Certificate::IsBlacklisted() const {
     // Subject: CN=login.yahoo.com
     // subjectAltName dNSName: login.yahoo.com
     {0x3e,0x75,0xce,0xd4,0x6b,0x69,0x30,0x21,0x21,0x88,0x30,0xae,0x86,0xa8,0x2a,0x71},
-
-    // Bad DigiNotar leaf certificates for non-Google sites.
-    {0x95,0x32,0x18,0xb7,0x04,0xcc,0x62,0xb2,0x40,0xa4,0xd0,0x18,0x0e,0x81,0x93,0xf2},
-    {0x5f,0x41,0xfe,0x52,0x93,0x75,0xb1,0x4b,0xd1,0x56,0x37,0x53,0xa2,0xc9,0xc6,0x49},
-    {0x22,0xec,0x36,0x83,0x9f,0x44,0x65,0xe7,0xa1,0x34,0x7b,0xae,0x69,0x2f,0x5d,0x2a},
-    {0x46,0xaf,0xa2,0x75,0x58,0x2e,0x27,0x34,0xe2,0xa5,0x22,0xfc,0x6c,0x2e,0x80,0x55},
-    {0xc8,0x63,0x14,0x89,0xc3,0xa6,0xaf,0xde,0xdc,0x70,0xd6,0xc1,0xb5,0x81,0xc0,0x19},
-    {0x26,0xf6,0x2a,0xee,0x2b,0xae,0x06,0xee,0x71,0xe7,0xc4,0x8a,0x2b,0x4d,0x60,0xfe},
-    {0xb6,0x73,0x9c,0x1a,0xdd,0x2b,0x52,0x19,0x6c,0x53,0x36,0xef,0xb6,0x7b,0x26,0x0f},
-    {0x9e,0x4e,0x87,0x07,0x55,0xd9,0x4c,0xf5,0xc4,0x67,0x81,0xe6,0x83,0x49,0xe3,0xd3},
-    {0x7e,0x82,0x25,0xf6,0xb4,0xbe,0x3d,0x1c,0x13,0x72,0xbb,0xc3,0x65,0xf5,0xf6,0xb6},
-    {0xff,0x2e,0x1b,0xda,0xa2,0xf4,0xc9,0x51,0x02,0x65,0xf7,0x26,0x11,0xdd,0x0c,0x44},
-    {0x1f,0xe8,0x4c,0xbe,0x99,0xe5,0xd2,0x68,0x4c,0x67,0x8d,0xef,0x7f,0xc0,0xbd,0xaa},
-    {0x4b,0x72,0xe8,0x49,0x97,0x38,0x82,0x99,0xf5,0x83,0xcb,0x37,0x60,0xab,0x1b,0x20},
-    {0xcf,0x61,0x90,0x78,0xde,0x6c,0x9d,0x9a,0x50,0x72,0xb5,0xe3,0xb1,0x3c,0xa9,0x9f},
-    {0xa8,0x22,0xeb,0x37,0xb7,0x35,0xa6,0x3e,0x6c,0xa9,0xa9,0x96,0x80,0x08,0x21,0xfc},
-    {0xe3,0xb6,0x00,0xb1,0x07,0x39,0xb0,0x94,0xab,0x47,0x4c,0x88,0x8d,0x97,0x25,0x0d},
-    {0x36,0xe8,0x57,0x1d,0x39,0x46,0x34,0x2c,0x74,0x20,0x81,0xc0,0xfa,0xab,0x34,0x3a},
-    {0x77,0x17,0x07,0x87,0x3d,0xa4,0x91,0xa8,0xd5,0xcc,0x5b,0x07,0xdc,0x50,0x8c,0x72},
-    {0x1e,0x94,0xcf,0x79,0x06,0x58,0x7b,0xdf,0x45,0xc4,0x61,0xfb,0xdd,0x74,0x3e,0x25},
-    {0x58,0x7c,0xd9,0xe3,0xd9,0xa8,0xab,0x10,0xfd,0xb0,0xc7,0x0b,0xcd,0x8a,0xe7,0x28},
-    {0x7e,0xd8,0x0b,0x93,0x20,0x50,0x8d,0xa6,0xcf,0x5d,0x96,0xba,0x53,0x30,0x43,0xd7},
-    {0xf8,0x6d,0x1e,0x22,0xbd,0x20,0x68,0x47,0x1e,0x20,0x13,0x6b,0x30,0x21,0x0e,0xae},
-    {0x2c,0x86,0x94,0x86,0xec,0x04,0x75,0x97,0x82,0x91,0x6e,0x68,0x04,0xdb,0x48,0xfd},
-    {0x35,0x19,0x81,0x98,0xd1,0xbc,0xaf,0xcf,0x43,0x86,0xe6,0xb8,0x87,0xba,0xe6,0x1b},
-    {0x4a,0x66,0x2b,0xa9,0xe4,0x5d,0x06,0xff,0xc5,0x0d,0x1d,0xbb,0xe2,0x25,0xa8,0xbb},
-    {0x89,0x9a,0xe1,0x20,0xcd,0x44,0xfc,0xec,0x0f,0xfc,0xd6,0x2f,0x6f,0xc4,0xbb,0x81},
-    {0x7d,0xd1,0x6c,0x03,0xdf,0x04,0x38,0xb2,0xbe,0x5f,0xc1,0xd3,0xe1,0x9f,0x13,0x8b},
-    {0xaf,0xe2,0x66,0x30,0x8f,0x50,0x1d,0x49,0x37,0xc1,0xaa,0xf0,0x00,0xc5,0x68,0x97},
-    {0x53,0xd9,0xf7,0x50,0x84,0xf2,0x62,0xfb,0x40,0x91,0x27,0xab,0x1e,0x04,0x44,0x2e},
-    {0x35,0xec,0x66,0x4c,0xbd,0x19,0x42,0xa2,0x36,0xc3,0xba,0x0e,0xb2,0xc6,0x81,0x3f},
-    {0x5c,0x94,0xc8,0xbd,0x9d,0x50,0x4a,0xd8,0x8d,0x96,0x59,0x36,0xef,0x5f,0xa0,0x21},
-    {0x88,0x82,0xc0,0xa1,0xd6,0x4b,0xab,0xb7,0xdb,0x82,0x07,0x3e,0xcd,0x77,0x72,0x2f},
-    {0x81,0xc4,0x84,0x5a,0x97,0x2f,0x37,0x4d,0x1c,0xe5,0x83,0x08,0x44,0x54,0xdd,0x50},
-    {0x04,0x1d,0x36,0xbb,0x4d,0xd3,0x9e,0x4a,0xce,0x8c,0x5b,0x4e,0x72,0x27,0x79,0xa4},
-    {0xe6,0xc0,0xb6,0x11,0xb2,0x84,0x0a,0xac,0xc4,0x00,0xd0,0x3f,0xf2,0x7c,0x86,0xb7},
-    {0xb5,0x94,0xa1,0x02,0xf8,0x9a,0xe2,0x9a,0xf6,0x2d,0x68,0x96,0x5f,0x49,0x0d,0x65},
-    {0xa5,0xbe,0x65,0x4d,0xcc,0xf8,0xaa,0x3b,0xd3,0x15,0x64,0x8d,0x95,0x79,0x12,0x29},
-    {0x5b,0x1d,0xd6,0x43,0xb9,0x80,0xa8,0x17,0xf7,0x86,0x71,0x16,0x97,0xd2,0x84,0x0d},
-    {0x4c,0x06,0x16,0x26,0x9a,0x64,0xa3,0xe5,0x7b,0xe9,0xd0,0xeb,0x9d,0x1b,0x59,0x97},
-    {0x10,0x2c,0x47,0x9d,0x70,0x61,0xdb,0x7e,0xf1,0x55,0xba,0xa6,0x41,0x0b,0x11,0x20},
-    {0xd1,0x62,0x65,0x70,0x77,0x9a,0x69,0x32,0x66,0x28,0x2f,0x9f,0xdc,0x5a,0x72,0x3f},
-    {0x0f,0x50,0x0a,0xe6,0x0b,0xf8,0x69,0x67,0x16,0xf2,0x67,0xc8,0x0e,0x13,0xdc,0x09},
-    {0x8b,0x22,0xbf,0xf4,0x66,0xe4,0x15,0x26,0x65,0x8a,0x56,0x8d,0x40,0x00,0x70,0xfd},
-    {0x4e,0xf7,0x05,0xc3,0x1e,0xff,0xc8,0x5a,0x0f,0x6f,0x74,0x52,0x8c,0x84,0xa7,0x72},
-    {0x77,0x1d,0x89,0xbc,0xa1,0xd2,0x53,0xd1,0xb5,0x6a,0x61,0x41,0xcf,0x29,0xe1,0xbb},
-    {0x33,0x73,0x97,0x6f,0xb7,0xe8,0x21,0xdc,0x3d,0x68,0xf9,0x47,0xfa,0xed,0xb2,0xb0},
-    {0x30,0xc2,0x0f,0xff,0x9b,0xe7,0xc3,0xd5,0x82,0xc8,0x0b,0xc2,0xcb,0xeb,0x04,0x62},
-    {0xc5,0x2e,0xde,0x8f,0x68,0xb3,0x98,0x38,0x83,0x34,0x44,0x25,0x2c,0xb6,0x4f,0x73},
-    {0x94,0x53,0x95,0x11,0x88,0x67,0x56,0x53,0x13,0xa2,0x66,0x98,0xb9,0x5f,0x1e,0x3e},
-    {0xc3,0xac,0x62,0x96,0xff,0x90,0xf0,0x9b,0xf1,0x82,0xfb,0x81,0xf8,0x65,0x00,0xda},
-    {0x92,0x72,0xf9,0x8c,0xfe,0x35,0x00,0x00,0xd6,0xbc,0xaf,0x30,0x63,0x74,0x72,0x98},
-    {0x36,0x9a,0xaa,0x6a,0x97,0x3d,0x0f,0x76,0x32,0x1c,0x53,0x2d,0xed,0xb3,0xbf,0xc6},
-    {0x73,0x02,0x4e,0x7c,0x99,0x8b,0x3d,0xdd,0x24,0x4c,0xfd,0x31,0x3d,0x5e,0x43,0xb6},
-    {0xd7,0xfb,0x96,0xe0,0x29,0x1e,0xbe,0x3e,0x01,0x5e,0x93,0xe5,0x86,0xcf,0xc7,0xd1},
-    {0xb0,0x1d,0x8c,0x6f,0x2d,0x53,0x73,0xea,0xbf,0x0c,0x00,0x31,0x9e,0x92,0xae,0x95},
-    {0xd7,0x06,0x98,0xd2,0x7e,0x7c,0xfa,0xfd,0x81,0x8d,0xe7,0xe2,0xea,0x31,0x9f,0x7f},
-    {0x96,0x43,0x10,0xa7,0xec,0x83,0x47,0x6c,0xcd,0x99,0xd8,0x89,0x63,0x6a,0xc2,0xba},
-    {0x54,0x17,0x57,0xb5,0x43,0x6f,0x1d,0x0b,0x3e,0xea,0x7d,0xce,0x49,0x8f,0x8a,0x0a},
-    {0x89,0x86,0xa0,0xfc,0x6f,0xd1,0xe6,0x1b,0xef,0x2f,0xc7,0x45,0x64,0xa7,0x0b,0x18},
-    {0x57,0x38,0x70,0x4f,0x75,0xa3,0xff,0x3b,0x86,0xa6,0x0a,0x55,0x96,0xed,0x09,0xb3},
-    {0x09,0xe1,0xc3,0xd2,0x6b,0xaf,0x74,0xe6,0xf9,0xa1,0x2f,0x9f,0x3f,0x2d,0xe9,0xa5},
-    {0x81,0xf7,0xb1,0x28,0xcd,0x71,0xbd,0x1a,0x59,0x50,0x74,0x45,0x00,0xc7,0x25,0xd4},
-    {0x26,0xc6,0x83,0xa0,0x88,0x71,0x2b,0x79,0x3f,0xf4,0x1d,0x8a,0x0c,0x0e,0xc0,0x45},
-    {0xd0,0x37,0xe2,0x1b,0x2f,0xe6,0xf1,0x9c,0x00,0x74,0x6e,0xb5,0xd6,0x32,0x9a,0xa2},
-    {0x06,0xdb,0x21,0x87,0x57,0x84,0xe5,0x35,0x6a,0x5b,0x97,0x99,0x15,0x0f,0x84,0x4c},
-    {0x2b,0x33,0xcb,0x52,0xae,0xff,0xb2,0x2e,0x23,0x30,0x9d,0x8b,0xc1,0x97,0x66,0x85},
-    {0xb9,0xb4,0x53,0x1c,0xf7,0x1c,0xb2,0x60,0x72,0x8e,0x42,0x43,0x85,0xcd,0x5c,0x7e},
-    {0xc4,0xfb,0xd4,0xa1,0x4c,0x59,0x5a,0xdf,0xb3,0xd2,0x44,0xfd,0x6d,0x46,0x9a,0x53},
-    {0xe6,0x56,0xed,0x4a,0xa2,0x98,0xed,0xb4,0x91,0xb0,0xb7,0x20,0x86,0x8a,0x11,0x2b},
-    {0x75,0x07,0x6e,0xc6,0xa2,0x1d,0x7e,0x4d,0xa8,0x7a,0x30,0x4e,0x9e,0xdd,0x02,0x62},
-    {0x27,0xdf,0x84,0xc1,0x2b,0xf8,0x37,0xac,0x68,0x1f,0xfd,0x26,0x63,0x93,0x88,0xf7},
-    {0x94,0xc7,0x5f,0x32,0xf1,0x00,0xa3,0xc3,0x2d,0x47,0xd0,0x1a,0xa9,0x8c,0xf9,0xa8},
-    {0x83,0x51,0x2c,0xc6,0x89,0x5b,0x44,0x15,0x14,0xa0,0xa4,0x15,0xf3,0x14,0x2a,0x6c},
-    {0x37,0x47,0xfe,0x8b,0x81,0xcb,0x6e,0x65,0x29,0x87,0x2d,0xe5,0x07,0x5c,0x3b,0xcb},
-    {0x33,0x87,0x0a,0xc7,0x1c,0x7a,0x8e,0xc6,0x68,0xcd,0x68,0x65,0xb1,0x15,0x84,0xb6},
-    {0x8a,0xa4,0x4a,0x11,0x84,0xdc,0x25,0xf9,0xa5,0x44,0x2c,0xd6,0xe1,0x39,0x16,0x5d},
-    {0xdc,0x7e,0x23,0xb3,0x8c,0x34,0xea,0x5c,0xd1,0x24,0xc6,0x74,0x00,0x46,0xd4,0x3c},
-    {0xdb,0x8f,0x84,0x41,0x38,0x05,0x89,0xf4,0x49,0xef,0xb9,0xe8,0xf0,0x8e,0x21,0x0c},
-    {0x86,0x63,0x3b,0x95,0x72,0x80,0xbc,0x65,0xa5,0xad,0xfd,0x1d,0x15,0x3b,0xde,0x52},
-    {0xb0,0x62,0x55,0xfa,0xe2,0x88,0xba,0xa6,0x6c,0x83,0xcb,0xf0,0x3f,0x5d,0x16,0x09},
-    {0x1a,0x07,0xd8,0xd6,0xdd,0xc7,0xe6,0x23,0xe7,0x12,0x05,0x07,0x4a,0x05,0xce,0xa2},
-    {0x97,0x00,0x4b,0x3d,0x85,0x6f,0x36,0x2c,0x3d,0x7c,0xd6,0x46,0xf6,0x05,0xcf,0xa5},
-    {0x2c,0xd3,0xaa,0x47,0x3e,0x64,0x48,0x1a,0xbd,0x68,0xe0,0xb1,0x0d,0x28,0x70,0xdf},
-    {0x3e,0x83,0x78,0xf1,0xe2,0x48,0x4c,0xe2,0x31,0x91,0x06,0x16,0xe4,0xb9,0x10,0x30},
-    {0xd4,0x48,0x44,0xe3,0x38,0xa1,0x02,0x53,0x6c,0x0c,0x23,0x8f,0x76,0xe0,0x7e,0xd2},
-    {0xed,0x52,0x13,0x57,0xb7,0x34,0x2f,0xb6,0xb5,0x6e,0x6b,0x7e,0x03,0xec,0xec,0x21},
-    {0x7f,0x3d,0x39,0x52,0x19,0xc7,0xb9,0xb8,0xc6,0x0e,0x4f,0x52,0xd9,0x33,0x50,0xb2},
-    {0xbe,0x69,0x1e,0x23,0x68,0x70,0xd9,0x01,0x4e,0xda,0x67,0xd3,0x9b,0x3f,0x80,0xa9},
-    {0x4b,0xf3,0x02,0x0d,0x00,0xff,0xb8,0x31,0xf3,0x8a,0xf3,0x1e,0x26,0xb9,0x04,0x9a},
-    {0x44,0x0e,0xea,0x70,0x5a,0x9f,0x79,0x15,0x35,0x60,0xbf,0xc4,0x4a,0x13,0x5d,0x99},
-    {0xe9,0x92,0x00,0x82,0x28,0x03,0xad,0x53,0x65,0x27,0xb5,0x90,0x4d,0xac,0x04,0x6f},
-    {0x63,0xf8,0x79,0x61,0x7a,0x3d,0x48,0xc0,0xc9,0x39,0x06,0xb6,0xa5,0xc9,0x99,0x8f},
-    {0xd6,0xbe,0x78,0x3f,0x1f,0x34,0x35,0x79,0x63,0x0a,0xa4,0xbe,0x60,0xc8,0xb4,0xc8},
-    {0xbb,0x83,0x3b,0x51,0xa8,0x2f,0x7e,0xb9,0xab,0x5c,0xff,0x4b,0x6f,0x0a,0x58,0x9e},
-    {0x85,0x36,0x66,0x57,0x3c,0xdb,0xc6,0x80,0x74,0x0c,0xad,0x26,0x25,0x05,0x4a,0x22},
-    {0xd6,0x2c,0x3d,0x36,0xc3,0xa9,0xa5,0xd8,0xcf,0xcb,0x76,0x0d,0x5b,0xcb,0xb1,0xf2},
-    {0x46,0x0c,0x33,0x8e,0x89,0xba,0xa1,0x45,0x26,0x1f,0x2a,0x06,0x6c,0x56,0x86,0x2e},
-    {0x5d,0x27,0x8c,0x8f,0xcd,0x78,0x9e,0xda,0x9d,0xef,0x09,0x6c,0x91,0xe1,0x15,0xe1},
-    {0xcb,0xae,0xad,0xd5,0x76,0x4b,0x56,0x91,0xa1,0xb0,0xef,0x87,0xae,0x2b,0xb7,0xc6},
-    {0x33,0x1e,0x3c,0x0b,0x5b,0x8e,0xd3,0xac,0xbf,0x72,0x7a,0x27,0x4c,0xf9,0xd4,0x32},
-    {0xe5,0x66,0xe1,0x8a,0x28,0xc6,0xc4,0x4c,0xb1,0x29,0x55,0x23,0x9a,0x38,0x08,0xe3},
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-    {0x38,0x68,0x36,0x7a,0xd1,0x7a,0x77,0x07,0xed,0x7e,0x19,0xb3,0x71,0x56,0x7e,0xdb},
-    {0x0a,0x75,0x86,0x4a,0x93,0xb8,0xaf,0x71,0x09,0xae,0xa3,0x57,0xcc,0x45,0xb6,0x38},
-    {0xed,0x15,0xbc,0xce,0x02,0x64,0x46,0x8a,0x58,0xc2,0xef,0xdb,0xc4,0x57,0xa6,0x0f},
-    {0xd9,0x13,0xc8,0xae,0xf9,0x7a,0xc7,0x62,0x66,0x4f,0xe0,0x91,0xab,0xdb,0x0b,0x5b},
-    {0xa2,0xcb,0xd5,0x32,0xed,0x71,0x07,0x63,0x25,0x59,0xfb,0x06,0xfa,0xb0,0xbd,0x70},
-    {0x6e,0x23,0x5e,0x65,0x9c,0xc6,0xcd,0x89,0xba,0x68,0xa2,0x92,0x28,0xb3,0x74,0x10},
-    {0x50,0x0d,0x88,0x2a,0x93,0x19,0x9b,0xf0,0x97,0x0e,0x96,0x62,0xbe,0x94,0x6d,0x02},
-    {0x0c,0xc7,0x0a,0xc8,0xb1,0xad,0xbf,0xda,0xce,0x8b,0x51,0x34,0x16,0x85,0x8a,0xf2},
-    {0xff,0x78,0x96,0x32,0xb8,0xd4,0xae,0xcd,0x94,0xa0,0xaa,0xb3,0x30,0x74,0xa0,0x58},
-    {0x8a,0xd2,0x35,0xc1,0x09,0x65,0x23,0x39,0xbd,0xea,0x3a,0xc8,0x32,0x55,0xb2,0x88},
-    {0x45,0xcf,0x0b,0x3f,0x9d,0xa8,0xd2,0x17,0x6e,0x5c,0x53,0x0c,0xe2,0xa7,0x4e,0xe6},
-    {0xec,0x35,0x8a,0x4b,0xaa,0x38,0x45,0xeb,0x24,0xaf,0x6c,0x0c,0x34,0xef,0xb2,0xeb},
-    {0x73,0xfd,0xd6,0xc7,0x65,0x3c,0xde,0xdc,0x9a,0xda,0x88,0xc8,0xe9,0x7e,0x5e,0x77},
-    {0xf0,0x88,0x2a,0x36,0x10,0xa5,0xe8,0x5f,0x8a,0x17,0x49,0xb9,0x77,0x9d,0xb7,0x3c},
-    {0xfe,0x73,0x90,0xdb,0x0d,0x7f,0x6c,0x64,0xba,0x20,0xfa,0xb8,0x98,0x6b,0x07,0xac},
-    {0x87,0x07,0x70,0x09,0xd7,0x96,0xf7,0x0f,0xc1,0x79,0xf3,0x98,0xbc,0x94,0x7a,0x0d},
-    {0x44,0x08,0x71,0x99,0x1c,0xf0,0x1e,0x3d,0x7f,0x58,0xc4,0x5e,0x20,0x3e,0xa5,0xed},
-    {0x64,0xd2,0x35,0x96,0x94,0x7a,0xe5,0x1a,0xcb,0xc8,0xa2,0x4f,0xaf,0x22,0xd4,0x83},
-    {0x8b,0x01,0x1d,0xaa,0x9f,0x3b,0x72,0xda,0x93,0x67,0x03,0x6c,0x8a,0x89,0xe8,0x0d},
-    {0x61,0xd3,0x0f,0x6b,0x8a,0x2a,0x10,0x3d,0xcf,0x37,0x1d,0xa4,0xc0,0x04,0x60,0x02},
-    {0x66,0xe4,0x6e,0x5b,0x8d,0x57,0x42,0x81,0xc9,0x35,0xe6,0x34,0x03,0x8e,0x87,0x7b},
-    {0xf8,0x4b,0x75,0xfc,0xe8,0xbd,0x1f,0xf1,0x3f,0xa0,0x79,0xcc,0x39,0xd4,0x51,0x64},
-    {0x62,0xf0,0x91,0x47,0xb1,0xac,0x01,0x4d,0x88,0x92,0xc0,0xf8,0x29,0x4d,0x0b,0x66},
-    {0xe7,0xf5,0x86,0x83,0x06,0x61,0x12,0xdc,0x5e,0xb2,0x44,0xfc,0xf2,0x08,0xe8,0x50},
-    {0x97,0x0c,0x55,0xe7,0x2e,0x6a,0x7b,0xfc,0x51,0x12,0xd8,0xa0,0xb5,0x7f,0x2e,0x18},
-    {0x19,0xf1,0xf7,0xdf,0xba,0xfd,0xd3,0xf1,0x20,0x75,0xb0,0xa2,0xfa,0x78,0x84,0x8d},
-    {0x9e,0xaf,0xe6,0xd3,0x83,0x69,0x72,0x39,0x64,0xbe,0x9f,0x4f,0x19,0x8e,0x36,0x16},
-    {0x35,0x80,0x30,0xbc,0x92,0xa9,0x9b,0x61,0xe9,0x6a,0xee,0x63,0x0e,0x32,0xa9,0xc3},
-    {0x2e,0x34,0xe5,0x92,0xca,0xbd,0xe8,0x9b,0xde,0x01,0xe7,0xfb,0xd4,0x25,0xcc,0x93},
-    {0x83,0xef,0x75,0x79,0x05,0xde,0xcd,0x9f,0x97,0x3c,0x60,0x2f,0x4b,0x1e,0x1a,0x96},
-    {0x5b,0xec,0xea,0x91,0x8f,0x7a,0x1a,0xe9,0xe8,0xd7,0xc7,0xa4,0xc0,0x25,0x65,0xe1},
-    {0x32,0x50,0xb9,0xbe,0x0d,0xd0,0x0a,0x10,0x64,0xab,0xc9,0xbf,0xb3,0xba,0x56,0x92},
-    {0x31,0x4b,0xc4,0xfb,0x88,0x16,0x17,0xd7,0x5b,0x7f,0xcc,0x8a,0xbe,0xd1,0xf9,0x19},
-    {0x10,0x34,0x3e,0x96,0x72,0x69,0x92,0x7b,0x5d,0x8f,0x92,0xdc,0xae,0x4b,0xf6,0x55},
-    {0x65,0x7e,0xfa,0xec,0x2e,0xdf,0x76,0x0b,0x9d,0x59,0xe2,0xd0,0x0b,0x1b,0xb9,0x8a},
-    {0xb0,0x31,0x6b,0xd2,0x63,0xb0,0x28,0x79,0xb3,0x64,0x5f,0x45,0xdc,0x98,0x58,0xa0},
-    {0xed,0x1a,0x10,0x08,0x19,0x0a,0x5d,0x16,0x54,0xd1,0x38,0xeb,0x8f,0xd1,0x15,0x4a},
-    {0xad,0x7c,0x7f,0x0c,0xfe,0x66,0x6f,0xbe,0xde,0xf2,0x0a,0xa9,0x5f,0x22,0xf9,0x0b},
   };
 
-  if (serial_number_.size() == kSerialBytes) {
+  if (!serial_number_.empty() && serial_number_[0] >= 0x80) {
+    // This is a negative serial number, which isn't technically allowed but
+    // which probably happens. In order to avoid confusing a negative serial
+    // number with a positive one once the leading zeros have been removed, we
+    // disregard it.
+    return false;
+  }
+
+  base::StringPiece serial(serial_number_);
+  // Remove leading zeros.
+  while (serial.size() > 1 && serial[0] == 0)
+    serial.remove_prefix(1);
+
+  if (serial.size() == kSerialBytes) {
     for (unsigned i = 0; i < kNumSerials; i++) {
-      if (memcmp(kSerials[i], serial_number_.data(), kSerialBytes) == 0) {
+      if (memcmp(kSerials[i], serial.data(), kSerialBytes) == 0) {
         UMA_HISTOGRAM_ENUMERATION("Net.SSLCertBlacklisted", i, kNumSerials + 1);
         return true;
       }
     }
   }
 
-  // Special case for DigiNotar: this serial number had a leading 0x00 byte
-  static const uint8 kDigiNotarLeadingZero[15] = {
-    0x17,0x7f,0xb6,0x53,0x6b,0x98,0xce,0x40,0xd5,0x4b,0x8b,0x24,0xe3,0x16,0x05
-  };
-
-  if (serial_number_.size() == sizeof(kDigiNotarLeadingZero) &&
-      memcmp(serial_number_.data(), kDigiNotarLeadingZero,
-             sizeof(kDigiNotarLeadingZero)) == 0) {
-    UMA_HISTOGRAM_ENUMERATION("Net.SSLCertBlacklisted", kNumSerials,
-                              kNumSerials + 1);
-    return true;
-  }
-
   return false;
 }
 
diff --git a/net/base/x509_certificate.h b/net/base/x509_certificate.h
index aee2447..8a16088 100644
--- a/net/base/x509_certificate.h
+++ b/net/base/x509_certificate.h
@@ -433,12 +433,7 @@ class NET_EXPORT X509Certificate
                      CRLSet* crl_set,
                      CertVerifyResult* verify_result) const;
 
-  // The serial number, DER encoded.
-  // NOTE: keep this method private, used by IsBlacklisted only.  To simplify
-  // IsBlacklisted, we strip the leading 0 byte of a serial number, used to
-  // encode a positive DER INTEGER (a signed type) with a most significant bit
-  // of 1.  Other code must not use this method for general purpose until this
-  // is fixed.
+  // The serial number, DER encoded, possibly including a leading 00 byte.
   const std::string& serial_number() const { return serial_number_; }
 
   // IsBlacklisted returns true if this certificate is explicitly blacklisted.
diff --git a/net/base/x509_certificate_mac.cc b/net/base/x509_certificate_mac.cc
index 0b65c77..3adaed4 100644
--- a/net/base/x509_certificate_mac.cc
+++ b/net/base/x509_certificate_mac.cc
@@ -203,10 +203,6 @@ std::string GetCertSerialNumber(X509Certificate::OSCertHandle cert_handle) {
     break;
   }
 
-  // Remove leading zeros.
-  while (ret.size() > 1 && ret[0] == 0)
-    ret = ret.substr(1, ret.size() - 1);
-
   return ret;
 }
 
diff --git a/net/base/x509_certificate_nss.cc b/net/base/x509_certificate_nss.cc
index 4a8a4e0..0a5c902 100644
--- a/net/base/x509_certificate_nss.cc
+++ b/net/base/x509_certificate_nss.cc
@@ -682,9 +682,6 @@ void X509Certificate::Initialize() {
   serial_number_ = std::string(
       reinterpret_cast<char*>(cert_handle_->serialNumber.data),
       cert_handle_->serialNumber.len);
-  // Remove leading zeros.
-  while (serial_number_.size() > 1 && serial_number_[0] == 0)
-    serial_number_ = serial_number_.substr(1, serial_number_.size() - 1);
 }
 
 // static
diff --git a/net/base/x509_certificate_openssl.cc b/net/base/x509_certificate_openssl.cc
index 0c74bc5..ac5b75c 100644
--- a/net/base/x509_certificate_openssl.cc
+++ b/net/base/x509_certificate_openssl.cc
@@ -332,9 +332,6 @@ void X509Certificate::Initialize() {
     serial_number_ = std::string(
         reinterpret_cast<char*>(num->data),
         num->length);
-    // Remove leading zeros.
-    while (serial_number_.size() > 1 && serial_number_[0] == 0)
-      serial_number_ = serial_number_.substr(1, serial_number_.size() - 1);
   }
 
   ParsePrincipal(cert_handle_, X509_get_subject_name(cert_handle_), &subject_);
diff --git a/net/base/x509_certificate_unittest.cc b/net/base/x509_certificate_unittest.cc
index a42799e..d54a36f 100644
--- a/net/base/x509_certificate_unittest.cc
+++ b/net/base/x509_certificate_unittest.cc
@@ -429,7 +429,7 @@ TEST(X509CertificateTest, SerialNumbers) {
           reinterpret_cast<const char*>(paypal_null_der),
           sizeof(paypal_null_der)));
 
-  static const uint8 paypal_null_serial[2] = {0xf0, 0x9b};
+  static const uint8 paypal_null_serial[3] = {0x00, 0xf0, 0x9b};
   ASSERT_EQ(sizeof(paypal_null_serial),
             paypal_null_cert->serial_number().size());
   EXPECT_TRUE(memcmp(paypal_null_cert->serial_number().data(),
diff --git a/net/base/x509_certificate_win.cc b/net/base/x509_certificate_win.cc
index 041fe4d5..0c355b6 100644
--- a/net/base/x509_certificate_win.cc
+++ b/net/base/x509_certificate_win.cc
@@ -552,9 +552,6 @@ void X509Certificate::Initialize() {
     serial_bytes[i] = serial->pbData[serial->cbData - i - 1];
   serial_number_ = std::string(
       reinterpret_cast<char*>(serial_bytes.get()), serial->cbData);
-  // Remove leading zeros.
-  while (serial_number_.size() > 1 && serial_number_[0] == 0)
-    serial_number_ = serial_number_.substr(1, serial_number_.size() - 1);
 }
 
 // IsIssuedByKnownRoot returns true if the given chain is rooted at a root CA