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authorMichael Tänzer <neo@nhng.de>2014-03-09 03:00:33 +0100
committerMichael Tänzer <neo@nhng.de>2014-03-09 03:00:33 +0100
commit7b251cbd28ebddadbf9f1ee0f4faf0bddbae3c5f (patch)
treed108f6846fb305db9936672eac83089c37f836d1
parent5476ac472c00936c1687541b4eb2b0a40f4eec79 (diff)
downloadcacert-devel-7b251cbd28ebddadbf9f1ee0f4faf0bddbae3c5f.tar.gz
cacert-devel-7b251cbd28ebddadbf9f1ee0f4faf0bddbae3c5f.tar.xz
cacert-devel-7b251cbd28ebddadbf9f1ee0f4faf0bddbae3c5f.zip
bug 1255: Check for other algorithms than RSA in check_weak_keys()
Implemented a check for DSA but is currently disable because the OpenSSL on the signer would fail anyway. Unknown algorithms are now blocked. Signed-off-by: Michael Tänzer <neo@nhng.de>
-rw-r--r--includes/lib/check_weak_key.php96
1 files changed, 85 insertions, 11 deletions
diff --git a/includes/lib/check_weak_key.php b/includes/lib/check_weak_key.php
index 217b885..7f96a88 100644
--- a/includes/lib/check_weak_key.php
+++ b/includes/lib/check_weak_key.php
@@ -126,17 +126,16 @@ function checkWeakKeyText($text)
}
- if ($algorithm === "rsaEncryption")
- {
- if (!preg_match('/^\s*RSA Public Key: \((\d+) bit\)$/m', $text,
- $keysize))
+ switch ((string)$algorithm) {
+ case "rsaEncryption":
+ 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 ($keysize < 2048)
{
return sprintf(_("The keys that you use are very small ".
@@ -146,8 +145,7 @@ function checkWeakKeyText($text)
"<a href='//wiki.cacert.org/WeakKeys#SmallKey'>",
"</a>");
}
-
-
+
$debianVuln = checkDebianVulnerability($text, $keysize);
if ($debianVuln === true)
{
@@ -165,7 +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,
$exponent))
{
@@ -187,9 +185,9 @@ function checkWeakKeyText($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($exponent, bcpow("2", "256")) === -1) )) {
// 65537 <= exponent < 2^256 recommended by NIST
// not critical but log so we have some statistics about
// affected users
@@ -198,6 +196,82 @@ function checkWeakKeyText($text)
E_USER_NOTICE);
}
}
+
+ break;
+
+/*
+//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.
+ case "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);
+
+ $bit_pub = ltrim(gmp_strval($num_pub, 2), "0");
+ $bit_P = ltrim(gmp_strval($num_P, 2), "0");
+ $bit_Q = ltrim(gmp_strval($num_Q, 2), "0");
+ $bit_G = ltrim(gmp_strval($num_G, 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_Y, $num_P))) {
+ return failWithId("checkWeakKeyText(): The supplied DSA ".
+ "key does seem to be normalized to have Q < P, G < P and Y < P.\nData:\n$text");
+ }
+
+ break;
+*/
+
+ default:
+ return _("The keys you supplied use an unrecognized algorithm. ".
+ "For security reasons these keys can not be signed by CAcert.");
}
/* No weakness found */