/////////////////////////////////////////////////////////////////////////////////////////////////
// TagGeneration - Reads chunks from a file and xor them with r as well.
// * INPUT: stream of bytes m, Chunk r
// * OUTPUT: Chunk tag
/////////////////////////////////////////////////////////////////////////////////////////////////
void TagGeneration(const unsigned char *m, Chunk r, Chunk tag,
unsigned long long numOfChunks)
{
Chunk temp;
int i, j, k;
memset(tag, 0, SIZE);
for (i = 0; i < numOfChunks - 2; i++)
{
memcpy(temp, m + (SIZE * i), SIZE);
if (i == numOfChunks - 2)
{
for (j = 0; j < SIZE; j++)
if (temp[j] == EOT)
{
for (k = j; k < SIZE; k++)
temp[k] = 0x00;
break;
}
}
ModularAddition(tag, temp);
}
for (i = 0; i < SIZE; i++)
temp[i] = r[i];
ModularAddition(tag, temp);
}
/////////////////////////////////////////////////////////////////////////////////////////////////
// crypto_aead_decrypt -The code for the cipher implementation (decryption part) goes here.
// * INPUT: ciphertext c,associated data ad,
// public message number or nonce npub, and secret key k.
// * OUTPUT: plaintext m
/////////////////////////////////////////////////////////////////////////////////////////////////
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)
{
int i;
int isValid = -1; //not valid message
Byte PCMACKey[kSIZE];
Chunk RMACKey;
Chunk prime;
Chunk PCMACTag; //tag of PCMAC
Chunk RMACTag; //tag of RMAC
Chunk tagFromCipher; // tag retrieved from the cipher
Byte nonce[kSIZE] =
{ 0 };
for (i = 0; i < SIZE; i++)
tagFromCipher[i] = c[clen - SIZE + i];
clen -= SIZE; //actual clen without the tag
for (i = 0; i < kSIZE; i++)
PCMACKey[i] = k[i];
for (i = 0; i < SIZE; i++)
{
RMACKey[i] = k[i + kSIZE];
prime[i] = k[i + SIZE + kSIZE];
}
for (i = SIZE; i < CRYPTO_NPUBBYTES; i++)
nonce[i - SIZE] = npub[i];
isValid = PCMACDec(PCMACTag, m, mlen, c, clen, nonce, PCMACKey);
if (isValid != 0)
return isValid;
Sign(prime, RMACKey, ad, adlen, RMACTag);
ModularAddition(RMACTag, PCMACTag);
isValid = Verify(RMACTag, tagFromCipher);
return isValid;
}
/////////////////////////////////////////////////////////////////////////////////////////////////
// crypto_aead_encrypt - The code for the cipher implementation (encryption part) goes here.
// * INPUT: plaintext m , associated data ad,
// secret message number nsec, public message number or nonce npub,
// and secret key k.
// * OUTPUT: ciphertext c
/////////////////////////////////////////////////////////////////////////////////////////////////
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)
{
Byte PCMACKey[kSIZE];
Chunk RMACKey;
Chunk prime;
int i; //counter
Chunk PCMACTag; //tag of PCMAC
Chunk RMACTag; //tag of RMAC
Chunk r;
Byte nonce[kSIZE] =
{ 0 };
unsigned long long numOfChunks = (unsigned long long) ceil(
(float) mlen / SIZE) + 2; //length of plain message plus r plus tag
for (i = 0; i < kSIZE; i++)
PCMACKey[i] = k[i];
for (i = 0; i < SIZE; i++)
{
RMACKey[i] = k[i + kSIZE];
prime[i] = k[i + SIZE + kSIZE];
r[i] = npub[i];
}
for (i = SIZE; i < CRYPTO_NPUBBYTES; i++)
nonce[i - SIZE] = npub[i];
PCMACEnc(PCMACTag, c, clen, m, mlen, nonce, r, PCMACKey);
Sign(prime, RMACKey, ad, adlen, RMACTag);
ModularAddition(RMACTag, PCMACTag);
for (i = 0; i < SIZE; i++)
c[*clen - SIZE + i] = RMACTag[i];
return 0;
}
