int
crypto_aead_chacha20poly1305_ietf_decrypt(unsigned char *m,
unsigned long long *mlen_p,
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)
{
unsigned long long mlen = 0ULL;
int ret = -1;
if (clen >= crypto_aead_chacha20poly1305_ietf_ABYTES) {
ret = crypto_aead_chacha20poly1305_ietf_decrypt_detached
(m, nsec,
c, clen - crypto_aead_chacha20poly1305_ietf_ABYTES,
c + clen - crypto_aead_chacha20poly1305_ietf_ABYTES,
ad, adlen, npub, k);
}
if (mlen_p != NULL) {
if (ret == 0) {
mlen = clen - crypto_aead_chacha20poly1305_ietf_ABYTES;
}
*mlen_p = mlen;
}
return ret;
}
psResSize_t psChacha20Poly1305IetfDecryptDetached(
psChacha20Poly1305Ietf_t Context_p[PS_EXACTLY(1)],
const unsigned char *Ciphertext_p,
psSizeL_t CiphertextNBytes,
const unsigned char Iv_p[PS_EXACTLY(PS_CHACHA20POLY1305_IETF_NPUBBYTES)],
const unsigned char *Aad_p,
psSizeL_t AadNBytes,
const unsigned char Mac_p[PS_EXACTLY(PS_CHACHA20POLY1305_IETF_ABYTES)],
unsigned char *Plaintext_p)
{
psSizeL_t plaintextNBytes = CiphertextNBytes; /* Plaintext length is the same than ciphertext length. */
/* Check input is not too large for this API. */
if (plaintextNBytes > (psSizeL_t)(psResSize_t)PS_RES_SIZE_OK_MAX)
{
return PS_ARG_FAIL;
}
if (crypto_aead_chacha20poly1305_ietf_decrypt_detached(
Plaintext_p,
NULL,
Ciphertext_p,
(unsigned long long)CiphertextNBytes,
(const unsigned char *)Mac_p,
(const unsigned char *)Aad_p,
(unsigned long long)AadNBytes,
(const unsigned char *)Iv_p,
(const unsigned char *)Context_p->key) != 0)
{
psTraceCrypto("chacha20 poly1305 AEAD didn't authenticate\n");
return PS_AUTH_FAIL;
}
return (psResSize_t)plaintextNBytes;
}
