sodium_crypto_stream_xchacha20_xor_ic

sodium_crypto_stream_xchacha20_xor_ic

Encrypts a message using a nonce and a secret key (no authentication)

string **sodium_crypto_stream_xchacha20_xor_ic** string $message string $nonce int $counter string $key

The function is similar to but adds the ability to set the initial value of the block counter to a non-zero value. This permits direct access to any block without having to compute the previous ones. sodium_crypto_stream_xchacha20_xor

Let op: > This encryption is unauthenticated, and does not prevent chosen-ciphertext attacks. Make sure to combine the ciphertext with a Message Authentication Code, for example with function, or . sodium_crypto_aead_xchacha20poly1305_ietf_encrypt``sodium_crypto_auth

messageThe message to encrypt.

nonce24-byte nonce.

counterThe initial value of the block counter.

key Key, possibly generated from . sodium_crypto_stream_xchacha20_keygen

Encrypted message, return.falseforfailure.

Voorbeeld: example

<?php
$n2 = random_bytes(SODIUM_CRYPTO_STREAM_XCHACHA20_NONCEBYTES);
$left  = str_repeat("\x01", 64);
$right = str_repeat("\xfe", 64);

// All at once:
$stream7_unified = sodium_crypto_stream_xchacha20_xor($left . $right, $n2, $key);

// Piecewise, with initial counter:
$stream7_left  = sodium_crypto_stream_xchacha20_xor_ic($left, $n2, 0, $key);
$stream7_right = sodium_crypto_stream_xchacha20_xor_ic($right, $n2, 1, $key);
$stream7_concat = $stream7_left . $stream7_right;

var_dump(strlen($stream7_concat));
var_dump($stream7_unified === $stream7_concat);
?>

int(128)
bool(true)

sodium_crypto_stream_xchacha20_xor