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RSA: support "strict" PKCS1 sigs without NULLs

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This commit is contained in:
terrafrost 2021-04-03 16:00:42 -05:00
parent e02c8452d4
commit 9af9d69c19
1 changed files with 54 additions and 2 deletions
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56
phpseclib/Crypt/RSA.php
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@ -3001,6 +3001,56 @@ class Crypt_RSA
return $em;
}
/**
* EMSA-PKCS1-V1_5-ENCODE (without NULL)
*
* Quoting https://tools.ietf.org/html/rfc8017#page-65,
*
* "The parameters field associated with id-sha1, id-sha224, id-sha256,
* id-sha384, id-sha512, id-sha512/224, and id-sha512/256 should
* generally be omitted, but if present, it shall have a value of type
* NULL"
*
* @access private
* @param string $m
* @param int $emLen
* @return string
*/
function _emsa_pkcs1_v1_5_encode_without_null($m, $emLen)
{
$h = $this->hash->hash($m);
if ($h === false) {
return false;
}
switch ($this->hashName) {
case 'sha1':
$t = pack('H*', '301f300706052b0e03021a0414');
break;
case 'sha256':
$t = pack('H*', '302f300b06096086480165030402010420');
break;
case 'sha384':
$t = pack('H*', '303f300b06096086480165030402020430');
break;
case 'sha512':
$t = pack('H*', '304f300b06096086480165030402030440');
}
$t.= $h;
$tLen = strlen($t);
if ($emLen < $tLen + 11) {
user_error('Intended encoded message length too short');
return false;
}
$ps = str_repeat(chr(0xFF), $emLen - $tLen - 3);
$em = "\0\1$ps\0$t";
return $em;
}
/**
* RSASSA-PKCS1-V1_5-SIGN
*
@ -3067,13 +3117,15 @@ class Crypt_RSA
// EMSA-PKCS1-v1_5 encoding
$em2 = $this->_emsa_pkcs1_v1_5_encode($m, $this->k);
if ($em2 === false) {
$em3 = $this->_emsa_pkcs1_v1_5_encode_without_null($m, $this->k);
if ($em2 === false || $em3 === false) {
user_error('RSA modulus too short');
return false;
}
// Compare
return $this->_equals($em, $em2);
return $this->_equals($em, $em2) || $this->_equals($em, $em3);
}
/**