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<?php |
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namespace montross50\SSHPubKeyValidator; |
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use phpseclib\Crypt\RSA; |
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class SSHPubKeyValidator |
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{ |
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/** |
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* @var $crypto RSA |
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*/ |
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private $crypto; |
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private $strict; |
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const RSA_MIN_LENGTH_STRICT = 1024; |
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const RSA_MAX_LENGTH_STRICT = 16384; |
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const RSA_MIN_LENGTH_LOOSE = 768; |
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const RSA_MAX_LENGTH_LOOSE = 16384; |
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public function __construct($crypto = null, $strict = true) |
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{ |
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if ($crypto === null) { |
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$crypto = new RSA(); |
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} |
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$this->crypto = $crypto; |
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$this->strict = $strict; |
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} |
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public function validateKey($pubkey) |
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{ |
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//first we check basic validity |
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$key_parts = explode(' ', $pubkey, 3); |
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if (count($key_parts) < 2) { |
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return false; |
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} |
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$algorithm = $key_parts[0]; |
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$key = $key_parts[1]; |
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if (!in_array($algorithm, array('ssh-rsa'))) { |
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return false; |
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} |
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$key_base64_decoded = base64_decode($key, true); |
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if ($key_base64_decoded === false) { |
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return false; |
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} |
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$check = base64_decode(substr($key, 0, 16)); |
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$check = preg_replace("/[^\w\-]/", "", $check); |
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if ((string) $check !== (string) $algorithm) { |
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return false; |
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} |
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//now we check if the key is truly valid |
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$this->crypto->loadKey($pubkey, RSA::PUBLIC_FORMAT_OPENSSH); |
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$pkcs8key = $this->crypto->getPublicKey(RSA::PUBLIC_FORMAT_PKCS8); |
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$opensslPubKey = openssl_pkey_get_public($pkcs8key); |
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if ($opensslPubKey === false) { |
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return false; |
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} |
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$keyData = openssl_pkey_get_details($opensslPubKey); |
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if ($keyData === false) { |
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return false; |
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} |
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if ($this->strict) { |
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$minLength = self::RSA_MIN_LENGTH_STRICT; |
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$maxLength = self::RSA_MAX_LENGTH_STRICT; |
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} else { |
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$minLength = self::RSA_MIN_LENGTH_LOOSE; |
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$maxLength = self::RSA_MAX_LENGTH_LOOSE; |
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} |
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if (isset($keyData['bits'])) { |
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if ($keyData['bits'] < $minLength) { |
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return false; |
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} |
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if ($keyData['bits'] > $maxLength) { |
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return false; |
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} |
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} else { |
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return false; |
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} |
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//everything is valid it seems |
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return true; |
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} |
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public function getFingerprint($pubkey, $algo = 'md5') |
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{ |
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$this->crypto->loadKey($pubkey, RSA::PUBLIC_FORMAT_OPENSSH); |
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return $this->crypto->getPublicKeyFingerprint($algo); |
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} |
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} |
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montross50 /
sshpubkey-validator
