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(PHP 7 >= 7.2.0, PHP 8)

sodium_crypto_signSign a message


sodium_crypto_sign ( string $message , 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.



Message to sign.


Secret key. See sodium_crypto_sign_secretkey()

Return Values

Signed message (not encrypted).

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User Contributed Notes 1 note

craig at craigfrancis dot co dot uk
2 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).


// $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);

$message . "\n";

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