sodium_crypto_sign

(PHP 7 >= 7.2.0, PHP 8)

sodium_crypto_sign — Sign a message

Description

sodium_crypto_sign(string $message, #[\SensitiveParameter] string $secret_key): string

Sign a message with a secret key, that can be verified by the corresponding public key. This function attaches the signature to the message. See sodium_crypto_sign_detached() for detached signatures.

Parameters

message: Message to sign.
secret_key: Secret key. See sodium_crypto_sign_secretkey()

Return Values

Signed message (not encrypted).

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User Contributed Notes 1 note

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craig at craigfrancis dot co dot uk ¶

6 years ago

Here's a quick example on how to use sodium_crypto_sign(); where you have a message that you want to sign, so anyone with the public key can confirm that the message hasn't been tampered with.

This is similar to sodium_crypto_sign_detached(), but the returned string contains the original message as well (in plain text, at the end, so anyone can read it).

<?php

// $sign_seed = random_bytes(SODIUM_CRYPTO_SIGN_SEEDBYTES);
// $sign_pair = sodium_crypto_sign_seed_keypair($sign_seed);

$sign_pair = sodium_crypto_sign_keypair();
$sign_secret = sodium_crypto_sign_secretkey($sign_pair);
$sign_public = sodium_crypto_sign_publickey($sign_pair);

//--------------------------------------------------
// Person 1, signing

$message = 'Hello';

$message_signed = sodium_crypto_sign($message, $sign_secret);

//--------------------------------------------------
// Person 2, verifying

$message = sodium_crypto_sign_open($message_signed, $sign_public);

echo $message . "\n";

?>

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