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-rw-r--r--includes/lib/check_weak_key.php108
1 files changed, 87 insertions, 21 deletions
diff --git a/includes/lib/check_weak_key.php b/includes/lib/check_weak_key.php
index 241d4f3..59c6cd6 100644
--- a/includes/lib/check_weak_key.php
+++ b/includes/lib/check_weak_key.php
@@ -65,7 +65,7 @@ function checkWeakKeyX509($cert, $encoding = "PEM")
$status = runCommand("openssl x509 -inform $encoding -text -noout",
$cert, $certText);
if ($status === true) {
- return failWithId("checkWeakKeyCSR(): Failed to start OpenSSL");
+ return failWithId("checkWeakKeyX509(): Failed to start OpenSSL");
}
if ($status !== 0 || $certText === "") {
@@ -92,7 +92,7 @@ function checkWeakKeySPKAC($spkac, $spkacname = "SPKAC")
$spkacname = escapeshellarg($spkacname);
$status = runCommand("openssl spkac -spkac $spkacname", $spkac, $spkacText);
if ($status === true) {
- return failWithId("checkWeakKeyCSR(): Failed to start OpenSSL");
+ return failWithId("checkWeakKeySPKAC(): Failed to start OpenSSL");
}
if ($status !== 0 || $spkacText === "") {
@@ -128,16 +128,15 @@ function checkWeakKeyText($text)
if ($algorithm === "rsaEncryption")
{
- if (!preg_match('/^\s*RSA Public Key: \((\d+) bit\)$/m', $text,
- $keysize))
+ if (!preg_match('/^\s*RSA Public Key: \((\d+) bit\)$/m', $text, $keysize))
{
return failWithId("checkWeakKeyText(): Couldn't parse the RSA ".
"key size.\nData:\n$text");
} else {
$keysize = intval($keysize[1]);
}
-
- if ($keysize < 1024)
+
+ if ($keysize < 2048)
{
return sprintf(_("The keys that you use are very small ".
"and therefore insecure. Please generate stronger ".
@@ -145,14 +144,8 @@ function checkWeakKeyText($text)
"found in %sthe wiki%s"),
"<a href='//wiki.cacert.org/WeakKeys#SmallKey'>",
"</a>");
- } elseif ($keysize < 2048) {
- // not critical but log so we have some statistics about
- // affected users
- trigger_error("checkWeakKeyText(): Certificate for small ".
- "key (< 2048 bit) requested", E_USER_NOTICE);
}
-
-
+
$debianVuln = checkDebianVulnerability($text, $keysize);
if ($debianVuln === true)
{
@@ -170,7 +163,7 @@ function checkWeakKeyText($text)
"checkDebianVulnerability().\nKeysize: $keysize\n".
"Data:\n$text");
}
-
+
if (!preg_match('/^\s*Exponent: (\d+) \(0x[0-9a-fA-F]+\)$/m', $text,
$exponent))
{
@@ -180,7 +173,7 @@ function checkWeakKeyText($text)
$exponent = $exponent[1]; // exponent might be very big =>
//handle as string using bc*()
- if (bccomp($exponent, "3") === 0)
+ if (bccomp($exponent, "65537") < 0)
{
return sprintf(_("The keys you use might be insecure. ".
"Although there is currently no known attack for ".
@@ -192,9 +185,9 @@ function checkWeakKeyText($text)
"<a href='//wiki.cacert.org/WeakKeys#SmallExponent'>",
"</a>");
} elseif (!(bccomp($exponent, "65537") >= 0 &&
- (bccomp($exponent, "100000") === -1 ||
- // speed things up if way smaller than 2^256
- bccomp($exponent, bcpow("2", "256")) === -1) )) {
+ (bccomp($exponent, "100000") === -1 ||
+ // speed things up if way smaller than 2^256
+ bccomp($exponent, bcpow("2", "256")) === -1) )) {
// 65537 <= exponent < 2^256 recommended by NIST
// not critical but log so we have some statistics about
// affected users
@@ -203,10 +196,83 @@ function checkWeakKeyText($text)
E_USER_NOTICE);
}
}
- }
- /* No weakness found */
- return "";
+ // No weakness found
+ return "";
+ } // End RSA
+
+/*
+//Fails to work due to outdated OpenSSL 0.9.8o
+//For this to work OpenSSL 1.0.1f or newer is required
+//which is currently unavailable on the systems
+//If DSA2048 or longer is used the CSR hangs pending on the signer.
+ if ($algorithm === "dsaEncryption")
+ {
+ if (!preg_match('/^\s*Public Key Algorithm:\s+dsaEncryption\s+pub:\s+([0-9a-fA-F:\s]+)\s+P:\s+([0-9a-fA-F:\s]+)\s+Q:\s+([0-9a-fA-F:\s]+)\s+G:\s+([0-9a-fA-F:\s]+)\s+$/sm', $text, $keydetail))
+ {
+ return failWithId("checkWeakKeyText(): Couldn't parse the DSA ".
+ "key size.\nData:\n$text");
+ }
+
+ $key_pub = strtr(preg_replace("/[^0-9a-fA-F]/", "", $keydetail[1]), "ABCDEF", "abcdef");
+ $key_P = strtr(preg_replace("/[^0-9a-fA-F]/", "", $keydetail[2]), "ABCDEF", "abcdef");
+ $key_Q = strtr(preg_replace("/[^0-9a-fA-F]/", "", $keydetail[3]), "ABCDEF", "abcdef");
+ $key_G = strtr(preg_replace("/[^0-9a-fA-F]/", "", $keydetail[4]), "ABCDEF", "abcdef");
+
+ //Verify the numbers provided by the client
+ $num_pub = @gmp_init($key_pub, 16);
+ $num_P = @gmp_init($key_P, 16);
+ $num_Q = @gmp_init($key_Q, 16);
+ $num_G = @gmp_init($key_G, 16);
+
+ $bit_P = ltrim(gmp_strval($num_P, 2), "0");
+ $keysize = strlen($bit_P);
+
+ if ($keysize < 2048) {
+ return sprintf(_("The keys that you use are very small ".
+ "and therefore insecure. Please generate stronger ".
+ "keys. More information about this issue can be ".
+ "found in %sthe wiki%s"),
+ "<a href='//wiki.cacert.org/WeakKeys#SmallKey'>",
+ "</a>");
+ }
+
+ //Following checks based on description of key generation in Wikipedia
+ //These checks do not ensure a strong key, but at least check for enough sanity in the key material
+ // cf. https://en.wikipedia.org/wiki/Digital_Signature_Algorithm#Key_generation
+
+ //Check that P is prime
+ if(!gmp_testprime($num_P)) {
+ return failWithId("checkWeakKeyText(): The supplied DSA ".
+ "key does seem to have a non-prime public modulus.\nData:\n$text");
+ }
+
+ //Check that Q is prime
+ if(!gmp_testprime($num_Q)) {
+ return failWithId("checkWeakKeyText(): The supplied DSA ".
+ "key does seem to have a non-prime Q-value.\nData:\n$text");
+ }
+
+ //Check if P-1 is diviseable by Q
+ if(0 !== gmp_cmp("1", gmp_mod($num_P, $num_Q))) {
+ return failWithId("checkWeakKeyText(): The supplied DSA ".
+ "key does seem to have P mod Q === 1 (i.e. P-1 is not diviseable by Q).\nData:\n$text");
+ }
+
+ //Check the numbers are all less than the public modulus P
+ if(0 <= gmp_cmp($num_Q, $num_P) || 0 <= gmp_cmp($num_G, $num_P) || 0 <= gmp_cmp($num_pub, $num_P)) {
+ return failWithId("checkWeakKeyText(): The supplied DSA ".
+ "key does seem to be normalized to have Q < P, G < P and pub < P.\nData:\n$text");
+ }
+
+ // No weakness found
+ return "";
+ } // End DSA
+*/
+
+
+ return _("The keys you supplied use an unrecognized algorithm. ".
+ "For security reasons these keys can not be signed by CAcert.");
}
/**