NAME

lib1305 - C API for the lib1305 implementation of the Poly1305 one-time authenticator

SYNOPSIS

Using lib1305:

#include <lib1305.h>

Link with -l1305.

Authenticating a message:

unsigned char a[poly1305_BYTES];
const unsigned char m[mlen];
const unsigned char k[poly1305_KEYBYTES];

poly1305(a,m,mlen,k);

Verifying an authenticator:

const unsigned char a[poly1305_BYTES];
const unsigned char m[mlen];
const unsigned char k[poly1305_KEYBYTES];
int result;

result = poly1305_verify(a,m,mlen,k);

DESCRIPTION

lib1305 is an implementation of the Poly1305 one-time authenticator. The lib1305 functions follow the SUPERCOP onetimeauth API except that

• the function names are lib1305-specific instead of crypto_onetimeauth_*,
• message lengths are long long instead of unsigned long long, and
• the poly1305 function returns void instead of int.

The poly1305 function generates an authenticator a[0], a[1], ..., a[poly1305_BYTES-1] given a message m[0], m[1], ..., m[mlen-1] and a secret key k[0], k[1], ..., k[poly1305_KEYBYTES-1]. "One-time" means that the secret key must not be reused to generate an authenticator of another message.

The poly1305_verify function verifies an authenticator a[0], a[1], ..., a[poly1305_BYTES-1] given a message m[0], m[1], ..., m[mlen-1] and a secret key k[0], k[1], ..., k[poly1305_KEYBYTES-1]. It returns 0 if the authenticator is valid, otherwise nonzero.

SEE ALSO

randombytes(3)

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Version: This is version 2025.04.07 of the "API" web page.