KeePass/Sources/Sodium/crypto_box/crypto_box_seal.c

#include <string.h>

#include "crypto_box.h"
#include "crypto_generichash.h"
#include "private/common.h"
#include "utils.h"

static int
_crypto_box_seal_nonce(unsigned char *nonce,
                       const unsigned char *pk1, const unsigned char *pk2)
{
    crypto_generichash_state st;

    crypto_generichash_init(&st, NULL, 0U, crypto_box_NONCEBYTES);
    crypto_generichash_update(&st, pk1, crypto_box_PUBLICKEYBYTES);
    crypto_generichash_update(&st, pk2, crypto_box_PUBLICKEYBYTES);
    crypto_generichash_final(&st, nonce, crypto_box_NONCEBYTES);

    return 0;
}

int
crypto_box_seal(unsigned char *c, const unsigned char *m,
                unsigned long long mlen, const unsigned char *pk)
{
    unsigned char nonce[crypto_box_NONCEBYTES];
    unsigned char epk[crypto_box_PUBLICKEYBYTES];
    unsigned char esk[crypto_box_SECRETKEYBYTES];
    int           ret;

    if (crypto_box_keypair(epk, esk) != 0) {
        return -1; /* LCOV_EXCL_LINE */
    }
    memcpy(c, epk, crypto_box_PUBLICKEYBYTES);
    _crypto_box_seal_nonce(nonce, epk, pk);
    ret = crypto_box_easy(c + crypto_box_PUBLICKEYBYTES, m, mlen,
                          nonce, pk, esk);
    sodium_memzero(esk, sizeof esk);
    sodium_memzero(epk, sizeof epk);
    sodium_memzero(nonce, sizeof nonce);

    return ret;
}

int
crypto_box_seal_open(unsigned char *m, const unsigned char *c,
                     unsigned long long clen,
                     const unsigned char *pk, const unsigned char *sk)
{
    unsigned char nonce[crypto_box_NONCEBYTES];

    if (clen < crypto_box_SEALBYTES) {
        return -1;
    }
    _crypto_box_seal_nonce(nonce, c, pk);

    COMPILER_ASSERT(crypto_box_PUBLICKEYBYTES < crypto_box_SEALBYTES);
    return crypto_box_open_easy(m, c + crypto_box_PUBLICKEYBYTES,
                                clen - crypto_box_PUBLICKEYBYTES,
                                nonce, c, sk);
}

size_t
crypto_box_sealbytes(void)
{
    return crypto_box_SEALBYTES;
}