mcrypt_decrypt

(PHP 4 >= 4.0.2, PHP 5, PHP 7 < 7.2.0, PECL mcrypt >= 1.0.0)

mcrypt_decrypt — Decrypts crypttext with given parameters

Advertencia

Esta función ha sido declarada OBSOLETA a partir de PHP 7.1.0 y será ELIMINADA a partir de PHP 7.2.0. Su uso está totalmente desaconsejado.

Descripción

mcrypt_decrypt(
    string $cipher,
    string $key,
    string $data,
    string $mode,
    string $iv = ?
): string|false

Decrypts the data and returns the unencrypted data.

Parámetros

cipher: Una de las constantes MCRYPT_nombredelcifrado, o el nombre del algoritmo como string.
key: The key with which the data was encrypted. If the provided key size is not supported by the cipher, the function will emit a warning and return false
data: 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 '\0'.
mode: Una de las constantes MCRYPT_MODE_nombredelmodo, o una de las siguientes strings: "ecb", "cbc", "cfb", "ofb", "nofb" o "stream".
iv: Utilizado para la inicialización en los modos CBC, CFB, OFB, y en algunos algoritmos en el modo STREAM. Si el tamañlo del IV proporcionado no está soportado por el modo de encadenamiento o no se proporcionó ninún IV, y el modo de encadenamiento requiere uno, la función emitirá una advertencia y devolverá false.

Valores devueltos

Returns the decrypted data as a string o false en caso de error.

Ver también

mcrypt_encrypt() - Encrypts plaintext with given parameters

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User Contributed Notes 1 note

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eddiec at stararcher dot com ¶

19 years ago

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:

<?php

    $retval = mcrypt_decrypt( ...etc ...);

    $retval = rtrim($retval, "\0");     // trim ONLY the nulls at the END

?>

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