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Encryption support

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This commit is contained in:
Stephen Paul Weber
2013-01-26 17:01:26 -05:00
parent a56799955f
commit 7d776fd605
4 changed files with 127 additions and 6 deletions
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63
lib/openpgp_crypt_aes_tripledes.php
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@@ -1,10 +1,49 @@
<?php
require_once dirname(__FILE__).'/openpgp.php';
@include_once dirname(__FILE__).'/openpgp_crypt_rsa.php';
require_once 'Crypt/AES.php';
require_once 'Crypt/TripleDES.php';
require_once 'Crypt/Random.php';
class OpenPGP_Crypt_AES_TripleDES {
public static function encrypt($passphrases_and_keys, $message, $symmetric_algorithm=9) {
list($cipher, $key_bytes, $key_block_bytes) = self::getCipher($symmetric_algorithm);
$prefix = self::randomBytes($key_block_bytes);
$prefix .= substr($prefix, -2);
$key = self::randomBytes($key_bytes);
$cipher->setKey($key);
$to_encrypt = $prefix . $message->to_bytes();
$mdc = new OpenPGP_ModificationDetectionCodePacket(hash('sha1', $to_encrypt . "\xD3\x14", true));
$to_encrypt .= $mdc->to_bytes();
$encrypted = array(new OpenPGP_IntegrityProtectedDataPacket($cipher->encrypt($to_encrypt)));
if(!is_array($passphrases_and_keys) && !($passphrases_and_keys instanceof IteratorAggregate)) {
$passphrases_and_keys = (array)$passphrases_and_keys;
}
foreach($passphrases_and_keys as $pass) {
if($pass instanceof OpenPGP_PublicKeyPacket) {
if(!in_array($pass->algorithm, array(1,2,3))) throw new Exception("Only RSA keys are supported.");
$crypt_rsa = new OpenPGP_Crypt_RSA($pass);
$rsa = $crypt_rsa->public_key();
$rsa->setEncryptionMode(CRYPT_RSA_ENCRYPTION_PKCS1);
$esk = $rsa->encrypt(chr($symmetric_algorithm) . $key . pack('n', self::checksum($key)));
$esk = pack('n', OpenPGP::bitlength($esk)) . $esk;
array_unshift($encrypted, new OpenPGP_AsymmetricSessionKeyPacket($pass->algorithm, $pass->fingerprint(), $esk));
} else if(is_string($pass)) {
$s2k = new OpenPGP_S2K(crypt_random() . crypt_random() . crypt_random());
$cipher->setKey($s2k->make_key($pass, $key_bytes));
$esk = $cipher->encrypt(chr($symmetric_algorithm) . $key);
array_unshift($encrypted, new OpenPGP_SymmetricSessionKeyPacket($s2k, $esk, $symmetric_algorithm));
}
}
return new OpenPGP_Message($encrypted);
}
public static function decryptSymmetric($pass, $m) {
$epacket = self::getEncryptedData($m);
@@ -41,16 +80,13 @@ class OpenPGP_Crypt_AES_TripleDES {
if($packet->s2k_useage == 254) {
$chk = substr($material, -20);
$material = substr($material, 0, -20);
if($chk != hash('sha1', $material)) return NULL;
if($chk != hash('sha1', $material, true)) return NULL;
} else {
$chk = unpack('n', substr($material, -2));
$chk = reset($chk);
$material = substr($material, 0, -2);
$mkChk = 0;
for($i = 0; $i < strlen($material); $i++) {
$mkChk = ($mkChk + ord($material{$i})) % 65536;
}
$mkChk = self::checksum($material);
if($chk != $mkChk) return NULL;
}
@@ -139,4 +175,21 @@ class OpenPGP_Crypt_AES_TripleDES {
}
throw new Exception("Can only decrypt EncryptedDataPacket");
}
public static function randomBytes($n) {
$key = '';
for($i = 0; $i < $n; $i++) {
$key .= crypt_random();
}
$s2k = new OpenPGP_S2K(crypt_random() . crypt_random() . crypt_random());
return $s2k->make_key($key, $n);
}
public static function checksum($s) {
$mkChk = 0;
for($i = 0; $i < strlen($s); $i++) {
$mkChk = ($mkChk + ord($s{$i})) % 65536;
}
return $mkChk;
}
}