mcrypt_encrypt

(PHP 4 >= 4.0.2, PHP 5)

mcrypt_encrypt — Encrypts plaintext with given parameters

说明

string mcrypt_encrypt ( string $cipher , string $key , string $data , string $mode [, string $iv ] )

Encrypts the data and returns it.

参数

cipher

MCRYPT_ciphername 常量中的一个，或者是字符串值的算法名称。

key

The key with which the data will be encrypted. If it's smaller than the required keysize, it is padded with '\0'. It is better not to use ASCII strings for keys.

It is recommended to use the mhash functions to create a key from a string.

data

The data that will be encrypted with the given cipher and mode. If the size of the data is not n * blocksize, the data will be padded with '\0'.

The returned crypttext can be larger than the size of the data that was given by data.

mode

MCRYPT_MODE_modename 常量中的一个，或以下字符串中的一个："ecb"，"cbc"，"cfb"，"ofb"，"nofb" 和 "stream"。

iv

在 CBC, CFB, OFB 模式中用于初始化过程，在 STREAM 模式中用于某些算法。如果未提供 IV 并且在某算法中需要，本函数发出一条警告并使用一个全部字节设为 "\0" 的 IV。

返回值

Returns the encrypted data, as a string.

范例

Example #1 mcrypt_encrypt() Example


<?php
    # --- ENCRYPTION ---

    # the key should be random binary, use scrypt, bcrypt or PBKDF2 to
    # convert a string into a key
    # key is specified using hexadecimal
    $key = pack('H*', "bcb04b7e103a0cd8b54763051cef08bc55abe029fdebae5e1d417e2ffb2a00a3");
    
    # show key size use either 16, 24 or 32 byte keys for AES-128, 192
    # and 256 respectively
    $key_size =  strlen($key);
    echo "Key size: " . $key_size . "\n";
    
    $plaintext = "This string was AES-256 / CBC / ZeroBytePadding encrypted.";

    # create a random IV to use with CBC encoding
    $iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
    $iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
    
    # use an explicit encoding for the plain text
    $plaintext_utf8 = utf8_encode($plaintext);
    
    # creates a cipher text compatible with AES (Rijndael block size = 128)
    # to keep the text confidential 
    # only suitable for encoded input that never ends with value 00h
    # (because of default zero padding)
    $ciphertext = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key,
                                 $plaintext_utf8, MCRYPT_MODE_CBC, $iv);

    # prepend the IV for it to be available for decryption
    $ciphertext = $iv . $ciphertext;
    
    # encode the resulting cipher text so it can be represented by a string
    $ciphertext_base64 = base64_encode($ciphertext);

    echo  $ciphertext_base64 . "\n";

    # === WARNING ===

    # Resulting cipher text has no integrity or authenticity added
    # and is not protected against padding oracle attacks.
    
    # --- DECRYPTION ---
    
    $ciphertext_dec = base64_decode($ciphertext_base64);
    
    # retrieves the IV, iv_size should be created using mcrypt_get_iv_size()
    $iv_dec = substr($ciphertext_dec, 0, $iv_size);
    
    # retrieves the cipher text (everything except the $iv_size in the front)
    $ciphertext_dec = substr($ciphertext_dec, $iv_size);

    # may remove 00h valued characters from end of plain text
    $plaintext_utf8_dec = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key,
                                         $ciphertext_dec, MCRYPT_MODE_CBC, $iv_dec);
    
    echo  $plaintext_utf8_dec . "\n";
?>

以上例程会输出：

Key size: 32
ENJW8mS2KaJoNB5E5CoSAAu0xARgsR1bdzFWpEn+poYw45q+73az5kYi4j+0haevext1dGrcW8Qi59txfCBV8BBj3bzRP3dFCp3CPQSJ8eU=
This string was AES-256 / CBC / ZeroBytePadding encrypted.

See also mcrypt_module_open() for a more advanced API and an example.