I am trying to pass some encrypted data to a flash , but I got stuck somewhere in the middle.
Im using RIJNDAEL algorithm to encode the data in PHP :
function encrypt($text){
$key = "53cded30ff7ba54d65b939fd594e3d63";
$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC); //get vector size on CBC mode
$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND); //Creating the vector
$cryptedtext = mcrypt_encrypt (MCRYPT_RIJNDAEL_256, $key, $text, MCRYPT_MODE_CBC, $iv); //Encrypting using MCRYPT_RIJNDAEL_256 algorithm
return $cryptedtext;
}
And im using the AS3CRYPT library to decrypt the value in flash.
The problem is that if I try to decode the value in flash or even in the demo of AS3CRYPT, it doesnt work.
I also tried to return the data from PHP encoded with base64_encode but still not working.
The output from PHP is something like : flashvar=Á žJcV—µg)7¾1´‘5{Ò<¶Ù$þS„§”
Probably I did something wrong in the PHP ...
PHP doesn't add any padding, which is likely needed.
You'll have to pad it manually, take a look at this post on PHP.net which explains one method of achieving PKCS7 padding compatibility.
Beyond that, make sure you're setting the matching confidentiality mode (CBC) and cipher within "AS3CRYPTO".
Related
I am working on a project that requires the AES encryption of a soap envelope using the requirements below.
Encryption key: myKey-1234567abcdef
AES-256 encryption
128 block size
PKCS7 padding
16 bit vector (vector is attached before encrypted message)
Cipher Block Chaining (CBC)
This is what I tried:
$key = 'myKey-1234567abcdef';
$encryptionMethod = "AES-256-CBC";
$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC);
$iv = substr(mcrypt_create_iv($iv_size, MCRYPT_RAND), 0, 16);
$xml = openssl_encrypt($xml,$encryptionMethod, $key, 0, $iv);
I am currently getting a 400 bad request error and there seems to be lots of options for argument constants mcrypt functions, was wondering if my implementation satisfies the needs for padding, block size and vector?
I appreciate any suggestions, thanks in advance!
First: Your key isn't an appropriate length for AES-256. I realize the key you're using here is an example, but make sure that the one you've been provided is 32 characters (256 bits) long. If it isn't, ask the recipient for clarification.
Second: You're mixing the mcrypt and openssl extensions inappropriately here. You shouldn't be using mcrypt anyway, as it's unmaintained, sometimes broken, and will be removed entirely in PHP 7.2. Instead, hard-code the IV size as 16 and use openssl_random_pseudo_bytes to generate it:
$iv = openssl_random_pseudo_bytes(16);
$xml = openssl_encrypt($xml, $encryptionMethod, $key, 0, $iv);
Third: By default, openssl_encrypt() encodes its output as Base64. The recipient may not be expecting this. Pass OPENSSL_RAW_DATA as the fourth argument to openssl_encrypt() (replacing 0) to get unencoded output.
echo '<a class="bigbtn" href="'.'videoview.php?song_id='.$video['song_id'].'&'.'title='.$video['VideoTITLE'].'&'.'group='.$video['GroupName'].'&'.'artist='.$video['ByArtist'].'"></a>' ;
what is the best way to encrypt the link when appear in the browser a that user cannot tamper with them?. it's not mission critical link. but want to make it a little more secure.
i was trying with the urlencode and decode with base64 , but i try to assign the value to a variable like that.
$song_id = urldecode(base64_decode($_Get['song_id']));
but the conversion didnot happen.
,the decode didnot happen the way that i was thinking.
Base64 is a way to represent binary data in an ASCII string format, it has nothing to do with encryption.
Assuming that the encryption/decryption is to happen server side:
Encrypt with: mcrypt-encrypt.
Then, decrypt with: mcrypt-decrypt
An implementation example:
<?php
$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
$key = "secret";
$text = "Keep it secret, keep it safe";
//encrypt
$crypttext = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $text, MCRYPT_MODE_ECB, $iv);
//decrypt
$originaltext = mcrypt_decrypt (MCRYPT_RIJNDAEL_256, $key ,$crypttext , MCRYPT_MODE_ECB, $iv);
?>
Obfuscating variables or id's almost never pays off: if you want to protect a resource, use authorization.
If you want to protect against scraping of massive download, use IP monitoring to watch for access/quota.
But plain query / url messing is a cheap solution that won't pay in the long term in my opinion.
Problem
I need to encrypt data in Javascript and decrypt it in PHP. Mcrypt seems the way to go on the PHP side, and AES seems thoroughly good enough, but I'm having trouble finding a javascript decryption algorithm that matches it. Any suggestions? I'm open to replacing any of the assumptions (mcrypt, aes, ECB, etc) if it'll help get a compatible js encryption/decryption library.
Code
The PHP looks pretty much like this:
$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
$encrypted = mcrypt_encrypt( MCRYPT_RIJNDAEL_256, $key, $plaintext,
MCRYPT_MODE_ECB,$iv );
Rationale
Not that it matters, but the point here is to encrypt some credentials to an external system so that we can pass it around our server without our analytics and logging servers picking it up in the clear. It'll eventually be decrypted in the PHP just before it's sent to the external system.
I ended up using the SlowAES library, which has parallel implementations in PHP and JS:
http://kevinkuchta.com/_site/2011/08/matching-php-and-js-encryption/
I'm trying to perform encryption and decryption (Rijndael 256, ecb mode) in two different components:
1. PHP - Server Side (using mcrypt)
2. C + + - Client Side (using gcrypt)
I ran into a problem when the client side could not decrypt correctly the encrypted data (made by the server side)
so... i checked the:
1. initial vector - same same (32 length)
2. the key - again the same key on both sides..
so i wrote some code in C++ that will encrypt the data (with the same parameters like in the php)
and i found out that the encrypted data contains different bytes (maybe encoding issue??)
I'll be more than glad to get some help
PHP - MCrypt
// Encrypt Function
function mc_encrypt($encrypt, $mc_key) {
$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB);
$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
$iv = "static_init_vector_static_init_v";
echo "IV-Size: " . $iv_size . "\n";
echo "IV: " . $iv . "\n";
$passcrypt = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $mc_key, $encrypt, MCRYPT_MODE_ECB, $iv);
print_hex($passcrypt);
return $encode;
}
mc_encrypt("Some text which should be encrypted...","keykeykeykeykeykeykeykeykeykeyke");
I'll post the C++ code in a comment
Thanks,
Johnny Depp
OK. I'll make my comment an answer:
An Initialization Vector (IV) isn't used in ECB mode. If it is provided different implementations might work differently.
If you want to be sure the implementations will work correctly then use an IV of 0 (zero). Even though you provide the IV, both implementations SHOULD ignore it but one can never be sure about that. Not providing an IV in ECB mode should work aswell but again, it all depends on the implementations.
According to the PHP documentation MCrypt will ignore it. GCrypt I'm not sure about.
mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_ECB) should actually return 0 since you specify ECB mode.
Edit:
Do not call mcrypt_get_iv_size or mcrypt_create_iv.
Instead call mcrypt_encrypt without an IV. According to the PHP documentation all bytes in the IV will be set to '\0'.
Same goes for the C++ code. No need to set any IV at all. The libgcrypt code is complex but from glancing at the source of version 1.4.5 then in ECB mode it seems the IV isn't used at all.
If the resulting ciphertext still differs then the problem is something else.
A couple of possibilities comes to mind:
Encoding - Is the same encoding used in both the server and the client?
Endianness - What type of systems are the server and the client? Big- vs Little-endian?
I need medium to strong encryption on serverside, so I thought I would use mcrypt with PHP. If I use the functions below the beginning of my original string turns into binary garbage after decryption. (This is not the usual problem of getting appended additional garbage, instead my string is altered.) According to the documentation, mcrypt_encrypt() should have padded enough characters to match the block size of the selected algorithm but I suspect it does not work.
However, if I pad it manually to the block size of 128 bit (16 bytes) of Rijndael, it doesn't work either. The only way I can get this to work is by prepending some string long enough to (likely) cover the garbaged block and add a known prefix like "DATA#" between that string and my data. After decryption that block has been partially mangled but my prefix and all data after that has been correctly decrypted.
$GLOBALS['encryptionmarker'] = 'DATA#';
function encrypt($plain, $key) {
/*
// workaround because beginning of decrypted string is being mangled
// so we simply prefix with some text plus marker
$prefix = str_pad('', 128, '#', STR_PAD_RIGHT).$GLOBALS['encryptionmarker'];
$plain = $prefix.$plain;
*/
$encrypted = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $plain, MCRYPT_MODE_CFB,
mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CFB),
MCRYPT_DEV_URANDOM));
return $encrypted;
}
function decrypt($encrypted, $key) {
$decrypted = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $encrypted, MCRYPT_MODE_CFB,
mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CFB),
MCRYPT_DEV_URANDOM));
/*
// workaround: remove garbage
$pos = strpos($decrypted, $GLOBALS['encryptionmarker']);
$decrypted = trim(substr($decrypted, $pos + strlen($GLOBALS['encryptionmarker'])));
*/
return $decrypted;
}
What's wrong with my functions? Why do I have to prefix my data like that (I consider it a dirty workaround, so I would like to fix it)?
Storing the encrypted data is not the problem; decrypting it immediately after encryption without storing it to a database results in the same errors.
Your problem is that you are generating a new, different, random IV on the receiving side. This doesn't work, as you've seen.
The receiver needs to know the IV that the sender used; so you have to send it along with the encrypted data and pass it to mcrypt_decrypt().
Note that you must also use mhash() with a key (a different key to the encryption key) to generate an HMAC over the message, and check it on the receiving side. If you do not, a man-in-the-middle can trivially modify parts of your message without you detecting it.
Use the same IV in en- and decryption. The IV is not a shared secret, but has to be shared. You may consult Wikipedia: IV
$IV = mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CFB),
MCRYPT_DEV_URANDOM));
The IV must be transferred ONCE. You may want to increment the value of IV for each packet. But this can be done on both sides independently.