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Digg mcrypt_decrypt
Decrypts crypttext with given parameters
(PHP 4 >= 4.0.2, PHP 5)
mcrypt_decrypt() decrypts the data and returns the unencrypted data. Cipher is one of the MCRYPT_ciphername constants of the name of the algorithm as string.
Key is the key with which the data
is encrypted. If it's smaller that the required keysize, it
is padded with '
Data is the data that will be decrypted
with the given cipher and mode. If the size of the data is not
n * blocksize, the data will be padded with ' Mode is one of the MCRYPT_MODE_modename constants of one of "ecb", "cbc", "cfb", "ofb", "nofb" or "stream".
The IV parameter is used for the
initialisation in CBC, CFB, OFB modes, and in some algorithms
in STREAM mode. If you do not supply an IV, while it is needed
for an algorithm, the function issues a warning and uses an
IV with all bytes set to ' Code Examples / Notes » mcrypt_decryptsmp_info
Since the returned data seems to be still padded with extra characters, you can get *only* the original data that was encrypted by str_replace()'ing the \x0 characters. <?php $decryptedData = str_replace("\x0", '', $encryptedData); ?> eddiec
It appears that mcrypt_decrypt pads the *RETURN STRING* with nulls ('\0') to fill out to n * blocksize. For old C-programmers, like myself, it is easy to believe the string ends at the first null. In PHP it does not: strlen("abc\0\0") returns 5 and *NOT* 3 strcmp("abc", "abc\0\0") returns -2 and *NOT* 0 I learned this lesson painfully when I passed a string returned from mycrypt_decrypt into a NuSoap message, which happily passed the nulls along to the receiver, who couldn't figure out what I was talking about. My solution was: <? $retval = mcrypt_decrypt( ...etc ...); $retval = rtrim($retval, "\0"); // trim ONLY the nulls at the END ?> kooktroop
Following on from the mcrypt_encrypt() example: <?php $text = "boggles the inivisble monkey will rule the world"; $key = "This is a very secret key"; $iv_size = mcrypt_get_iv_size(MCRYPT_XTEA, MCRYPT_MODE_ECB); $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND); echo strlen($text) . " "; $enc = mcrypt_encrypt(MCRYPT_XTEA, $key, $text, MCRYPT_MODE_ECB, $iv); echo strlen($enc) . " "; $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND); $key = "This is a very secret key"; $text = "Meet me at 11 o'clock behind the monument."; echo strlen($text) . " "; $crypttext = mcrypt_decrypt(MCRYPT_XTEA, $key, $enc, MCRYPT_MODE_ECB, $iv); echo "$crypttext "; ?> |
Change Language
mcrypt_cbc mcrypt_cfb mcrypt_create_iv mcrypt_decrypt mcrypt_ecb mcrypt_enc_get_algorithms_name mcrypt_enc_get_block_size mcrypt_enc_get_iv_size mcrypt_enc_get_key_size mcrypt_enc_get_modes_name mcrypt_enc_get_supported_key_sizes mcrypt_enc_is_block_algorithm_mode mcrypt_enc_is_block_algorithm mcrypt_enc_is_block_mode mcrypt_enc_self_test mcrypt_encrypt mcrypt_generic_deinit mcrypt_generic_end mcrypt_generic_init mcrypt_generic mcrypt_get_block_size mcrypt_get_cipher_name mcrypt_get_iv_size mcrypt_get_key_size mcrypt_list_algorithms mcrypt_list_modes mcrypt_module_close mcrypt_module_get_algo_block_size mcrypt_module_get_algo_key_size mcrypt_module_get_supported_key_sizes mcrypt_module_is_block_algorithm_mode mcrypt_module_is_block_algorithm mcrypt_module_is_block_mode mcrypt_module_open mcrypt_module_self_test mcrypt_ofb mdecrypt_generic |
