encrypt.c

/*
The eXtended Keccak Code Package (XKCP)
https://github.com/XKCP/XKCP

Xoodyak, designed by Joan Daemen, Seth Hoffert, Michaël Peeters, Gilles Van Assche and Ronny Van Keer.

Implementation by Ronny Van Keer, hereby denoted as "the implementer".

For more information, feedback or questions, please refer to the Keccak Team website:
https://keccak.team/

To the extent possible under law, the implementer has waived all copyright
and related or neighboring rights to the source code in this file.
http://creativecommons.org/publicdomain/zero/1.0/
*/

#include "crypto_aead.h"
#include "api.h"
#include "Xoodyak.h"
#include <string.h>

#if !defined(CRYPTO_KEYBYTES)
    #define CRYPTO_KEYBYTES     16
#endif
#if !defined(CRYPTO_NPUBBYTES)
    #define CRYPTO_NPUBBYTES    16
#endif

#define TAGLEN  16

int crypto_aead_encrypt(
    unsigned char *c, unsigned long long *clen,
    const unsigned char *m, unsigned long long mlen,
    const unsigned char *ad, unsigned long long adlen,
    const unsigned char *nsec,
    const unsigned char *npub,
    const unsigned char *k)
{
    Xoodyak_Instance    instance;

    (void)nsec;

    Xoodyak_Initialize(&instance, k, CRYPTO_KEYBYTES, NULL, 0, NULL, 0);
    Xoodyak_Absorb(&instance, npub, CRYPTO_NPUBBYTES);
    Xoodyak_Absorb(&instance, ad, (size_t)adlen);
    Xoodyak_Encrypt(&instance, m, c, (size_t)mlen);
    Xoodyak_Squeeze(&instance, c + mlen, TAGLEN);
    *clen = mlen + TAGLEN;
    #if 0
    {
        unsigned int i;
        for (i = 0; i < *clen; ++i )
        {
            printf("\\x%02x", c[i] );
        }
        printf("\n");
    }
    #endif
    return 0;
}

int crypto_aead_decrypt(
    unsigned char *m, unsigned long long *mlen,
    unsigned char *nsec,
    const unsigned char *c, unsigned long long clen,
    const unsigned char *ad, unsigned long long adlen,
    const unsigned char *npub,
    const unsigned char *k)
{
    Xoodyak_Instance    instance;
    unsigned char        tag[TAGLEN];
    unsigned long long    mlen_;

    (void)nsec;

    *mlen = 0;
    if (clen < TAGLEN) {
        return -1;
    }
    mlen_ = clen - TAGLEN;
    Xoodyak_Initialize(&instance, k, CRYPTO_KEYBYTES, NULL, 0, NULL, 0);
    Xoodyak_Absorb(&instance, npub, CRYPTO_NPUBBYTES);
    Xoodyak_Absorb(&instance, ad, (size_t)adlen);
    Xoodyak_Decrypt(&instance, c, m, (size_t)mlen_);
    Xoodyak_Squeeze(&instance, tag, TAGLEN);
    if (memcmp(tag, c + mlen_, TAGLEN) != 0) {
        memset(m, 0, (size_t)mlen_);
        return -1;
    }
    *mlen = mlen_;
    return 0;
}