openssl_encrypt

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

openssl_encrypt — Encrypts data

Descrição

openssl_encrypt(
    #[\SensitiveParameter] string $data,
    string $cipher_algo,
    #[\SensitiveParameter] string $passphrase,
    int $options = 0,
    string $iv = "",
    string &$tag = null,
    string $aad = "",
    int $tag_length = 16
): string|false

Encrypts given data with given method and passphrase, returns a raw or base64 encoded string

Parâmetros

data

The plaintext message data to be encrypted.

cipher_algo

The cipher method. For a list of available cipher methods, use openssl_get_cipher_methods().

passphrase

The passphrase. If the passphrase is shorter than expected, it is silently padded with NUL characters; if the passphrase is longer than expected, it is silently truncated.

Caution

There is no key derivation function used for passphrase as its name might suggest. The only operation used is padding with NUL characters or truncation if the length is different than expected.

options

options is a bitwise disjunction of the flags OPENSSL_RAW_DATA, and OPENSSL_ZERO_PADDING or OPENSSL_DONT_ZERO_PAD_KEY.

iv

A non-null Initialization Vector. If the IV is shorter than expected, it is padded with NUL characters and warning is emitted; if the passphrase is longer than expected, it is truncated and warning is emitted.

tag

The authentication tag passed by reference when using AEAD cipher mode (GCM or CCM).

aad

Additional authenticated data.

tag_length

The length of the authentication tag. Its value can be between 4 and 16 for GCM mode.

Valor Retornado

Returns the encrypted string on success ou false em caso de falha.

Erros/Exceções

Emits an E_WARNING level error if an unknown cipher algorithm is passed in via the cipher_algo parameter.

Emits an E_WARNING level error if an empty value is passed in via the iv parameter.

Registro de Alterações

Versão Descrição
7.1.0 The tag, aad and tag_length parameters were added.

Exemplos

Example #1 AES Authenticated Encryption in GCM mode example for PHP 7.1+

<?php
//$key should have been previously generated in a cryptographically safe way, like openssl_random_pseudo_bytes
$plaintext = "message to be encrypted";
$cipher = "aes-128-gcm";
if (in_array($cipher, openssl_get_cipher_methods()))
{
    $ivlen = openssl_cipher_iv_length($cipher);
    $iv = openssl_random_pseudo_bytes($ivlen);
    $ciphertext = openssl_encrypt($plaintext, $cipher, $key, $options=0, $iv, $tag);
    //store $cipher, $iv, and $tag for decryption later
    $original_plaintext = openssl_decrypt($ciphertext, $cipher, $key, $options=0, $iv, $tag);
    echo $original_plaintext."\n";
}
?>

Example #2 AES Authenticated Encryption example prior to PHP 7.1

<?php
//$key previously generated safely, ie: openssl_random_pseudo_bytes
$plaintext = "message to be encrypted";
$ivlen = openssl_cipher_iv_length($cipher="AES-128-CBC");
$iv = openssl_random_pseudo_bytes($ivlen);
$ciphertext_raw = openssl_encrypt($plaintext, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);
$hmac = hash_hmac('sha256', $ciphertext_raw, $key, $as_binary=true);
$ciphertext = base64_encode( $iv.$hmac.$ciphertext_raw );

//decrypt later....
$c = base64_decode($ciphertext);
$ivlen = openssl_cipher_iv_length($cipher="AES-128-CBC");
$iv = substr($c, 0, $ivlen);
$hmac = substr($c, $ivlen, $sha2len=32);
$ciphertext_raw = substr($c, $ivlen+$sha2len);
$original_plaintext = openssl_decrypt($ciphertext_raw, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);
$calcmac = hash_hmac('sha256', $ciphertext_raw, $key, $as_binary=true);
if (hash_equals($hmac, $calcmac))// timing attack safe comparison
{
    echo $original_plaintext."\n";
}
?>

Veja Também