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
)
{
unsigned long long i;
unsigned char plaintextblock[16], ciphertextblock[16];
unsigned char tag[16];
unsigned char check = 0;
__m128i aegis128_state[5];
if (clen < 16) return -1;
aegis128_initialization(k, npub, aegis128_state);
//process the associated data
for (i = 0; (i+16) <= adlen; i += 16) {
aegis128_enc_aut_step(ad+i, ciphertextblock, aegis128_state);
}
//deal with the partial block of associated data
//in this program, we assume that the message length is multiple of bytes.
if ( (adlen & 0xf) != 0 ) {
memset(plaintextblock, 0, 16);
memcpy(plaintextblock, ad+i, adlen & 0xf);
aegis128_enc_aut_step(plaintextblock, ciphertextblock, aegis128_state);
}
//decrypt the ciphertext
*mlen = clen - 16;
for (i = 0; (i+16) <= *mlen; i += 16) {
aegis128_dec_aut_step(m+i, c+i, aegis128_state);
}
// Deal with the partial block
// In this program, we assume that the message length is multiple of bytes.
if ( (*mlen & 0xf) != 0 ) {
memset(ciphertextblock, 0, 16);
memcpy(ciphertextblock, c+i, *mlen & 0xf);
aegis128_dec_aut_step(plaintextblock, ciphertextblock, aegis128_state);
memcpy(m+i, plaintextblock, *mlen & 0xf);
//need to modify the state here (because in the last block, keystream is wrongly used to update the state)
memset(plaintextblock, 0, *mlen & 0xf);
aegis128_state[0] = _mm_xor_si128( aegis128_state[0], _mm_load_si128((__m128i*)plaintextblock) ) ;
}
//we assume that the tag length is multiple of bytes
aegis128_tag_generation(*mlen, adlen, 16, tag, aegis128_state);
//verification
for (i = 0; i < 16; i++) check |= (tag[i] ^ c[i+*mlen]);
if (check == 0) return 0;
else return -1;
}
//encrypt a message.
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
)
{
unsigned long i;
unsigned char plaintextblock[16], ciphertextblock[16], mac[16];
unsigned char aegis128_state[80];
//initialization stage
aegis128_initialization(k, npub, aegis128_state);
//process the associated data
for (i = 0; (i+16) <= adlen; i += 16) {
aegis128_enc_aut_step(ad+i, ciphertextblock, aegis128_state);
}
//deal with the partial block of associated data
//in this program, we assume that the message length is multiple of bytes.
if ( (adlen & 0xf) != 0 ) {
memset(plaintextblock, 0, 16);
memcpy(plaintextblock, ad+i, adlen & 0xf);
aegis128_enc_aut_step(plaintextblock, ciphertextblock, aegis128_state);
}
//encrypt the plaintext
for (i = 0; (i+16) <= mlen; i += 16) {
aegis128_enc_aut_step(m+i, c+i, aegis128_state);
}
// Deal with the partial block
// In this program, we assume that the message length is multiple of bytes.
if ( (mlen & 0xf) != 0 ) {
memset(plaintextblock, 0, 16);
memcpy(plaintextblock, m+i, mlen & 0xf);
aegis128_enc_aut_step(plaintextblock, ciphertextblock, aegis128_state);
memcpy(c+i,ciphertextblock, mlen & 0xf);
}
//finalization stage, we assume that the tag length is a multiple of bytes
aegis128_tag_generation(mlen, adlen, 16, mac, aegis128_state);
*clen = mlen + 16;
memcpy(c+mlen, mac, 16);
return 0;
}
