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pqcrypto/crypto_kem/kyber768/clean/symmetric-fips202.c
2019-05-20 10:23:22 +02:00

65 lines
2.7 KiB
C

#include "fips202.h"
#include "symmetric.h"
#include <stdlib.h>
/*************************************************
* Name: PQCLEAN_KYBER768_CLEAN_kyber_shake128_absorb
*
* Description: Absorb step of the SHAKE128 specialized for the Kyber context.
*
* Arguments: - shake128ctx *s: pointer to (uninitialized) output Keccak state
* - const unsigned char *input: pointer to KYBER_SYMBYTES input to be absorbed into s
* - unsigned char i additional byte of input
* - unsigned char j additional byte of input
**************************************************/
void PQCLEAN_KYBER768_CLEAN_kyber_shake128_absorb(shake128ctx *s, const unsigned char *input, unsigned char x, unsigned char y) {
unsigned char extseed[KYBER_SYMBYTES + 2];
int i;
for (i = 0; i < KYBER_SYMBYTES; i++) {
extseed[i] = input[i];
}
extseed[i++] = x;
extseed[i] = y;
shake128_absorb(s, extseed, KYBER_SYMBYTES + 2);
}
/*************************************************
* Name: PQCLEAN_KYBER768_CLEAN_kyber_shake128_squeezeblocks
*
* Description: Squeeze step of SHAKE128 XOF. Squeezes full blocks of SHAKE128_RATE bytes each.
* Modifies the state. Can be called multiple times to keep squeezing,
* i.e., is incremental.
*
* Arguments: - unsigned char *output: pointer to output blocks
* - size_t nblocks: number of blocks to be squeezed (written to output)
* - shake128ctx *s: pointer to in/output Keccak state
**************************************************/
void PQCLEAN_KYBER768_CLEAN_kyber_shake128_squeezeblocks(unsigned char *output, size_t nblocks, shake128ctx *s) {
shake128_squeezeblocks(output, nblocks, s);
}
/*************************************************
* Name: PQCLEAN_KYBER768_CLEAN_shake256_prf
*
* Description: Usage of SHAKE256 as a PRF, concatenates secret and public input
* and then generates outlen bytes of SHAKE256 output
*
* Arguments: - unsigned char *output: pointer to output
* - size_t outlen: number of requested output bytes
* - const unsigned char * key: pointer to the key (of length KYBER_SYMBYTES)
* - const unsigned char nonce: single-byte nonce (public PRF input)
**************************************************/
void PQCLEAN_KYBER768_CLEAN_shake256_prf(unsigned char *output, size_t outlen, const unsigned char *key, unsigned char nonce) {
unsigned char extkey[KYBER_SYMBYTES + 1];
size_t i;
for (i = 0; i < KYBER_SYMBYTES; i++) {
extkey[i] = key[i];
}
extkey[i] = nonce;
shake256(output, outlen, extkey, KYBER_SYMBYTES + 1);
}