78 lines
2.8 KiB
C
78 lines
2.8 KiB
C
#include "SABER_indcpa.h"
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#include "SABER_params.h"
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#include "api.h"
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#include "fips202.h"
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#include "randombytes.h"
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#include "verify.h"
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#include <stddef.h>
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#include <stdint.h>
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int PQCLEAN_FIRESABER_CLEAN_crypto_kem_keypair(uint8_t *pk, uint8_t *sk) {
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size_t i;
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PQCLEAN_FIRESABER_CLEAN_indcpa_kem_keypair(pk, sk); // sk[0:SABER_INDCPA_SECRETKEYBYTES-1] <-- sk
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for (i = 0; i < SABER_INDCPA_PUBLICKEYBYTES; i++) {
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sk[i + SABER_INDCPA_SECRETKEYBYTES] = pk[i]; // sk[SABER_INDCPA_SECRETKEYBYTES:SABER_INDCPA_SECRETKEYBYTES+SABER_INDCPA_SECRETKEYBYTES-1] <-- pk
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}
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sha3_256(sk + SABER_SECRETKEYBYTES - 64, pk, SABER_INDCPA_PUBLICKEYBYTES); // Then hash(pk) is appended.
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randombytes(sk + SABER_SECRETKEYBYTES - SABER_KEYBYTES, SABER_KEYBYTES); // Remaining part of sk contains a pseudo-random number.
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// This is output when check in PQCLEAN_FIRESABER_CLEAN_crypto_kem_dec() fails.
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return (0);
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}
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int PQCLEAN_FIRESABER_CLEAN_crypto_kem_enc(uint8_t *c, uint8_t *k, const uint8_t *pk) {
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uint8_t kr[64]; // Will contain key, coins
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uint8_t buf[64];
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randombytes(buf, 32);
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sha3_256(buf, buf, 32); // BUF[0:31] <-- random message (will be used as the key for client) Note: hash doesnot release system RNG output
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sha3_256(buf + 32, pk, SABER_INDCPA_PUBLICKEYBYTES); // BUF[32:63] <-- Hash(public key); Multitarget countermeasure for coins + contributory KEM
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sha3_512(kr, buf, 64); // kr[0:63] <-- Hash(buf[0:63]);
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// K^ <-- kr[0:31]
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// noiseseed (r) <-- kr[32:63];
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PQCLEAN_FIRESABER_CLEAN_indcpa_kem_enc(c, buf, kr + 32, pk); // buf[0:31] contains message; kr[32:63] contains randomness r;
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sha3_256(kr + 32, c, SABER_BYTES_CCA_DEC);
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sha3_256(k, kr, 64); // hash concatenation of pre-k and h(c) to k
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return (0);
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}
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int PQCLEAN_FIRESABER_CLEAN_crypto_kem_dec(uint8_t *k, const uint8_t *c, const uint8_t *sk) {
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size_t i;
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uint8_t fail;
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uint8_t cmp[SABER_BYTES_CCA_DEC];
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uint8_t buf[64];
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uint8_t kr[64]; // Will contain key, coins
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const uint8_t *pk = sk + SABER_INDCPA_SECRETKEYBYTES;
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PQCLEAN_FIRESABER_CLEAN_indcpa_kem_dec(buf, sk, c); // buf[0:31] <-- message
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// Multitarget countermeasure for coins + contributory KEM
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for (i = 0; i < 32; i++) { // Save hash by storing h(pk) in sk
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buf[32 + i] = sk[SABER_SECRETKEYBYTES - 64 + i];
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}
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sha3_512(kr, buf, 64);
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PQCLEAN_FIRESABER_CLEAN_indcpa_kem_enc(cmp, buf, kr + 32, pk);
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fail = PQCLEAN_FIRESABER_CLEAN_verify(c, cmp, SABER_BYTES_CCA_DEC);
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sha3_256(kr + 32, c, SABER_BYTES_CCA_DEC); // overwrite coins in kr with h(c)
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PQCLEAN_FIRESABER_CLEAN_cmov(kr, sk + SABER_SECRETKEYBYTES - SABER_KEYBYTES, SABER_KEYBYTES, fail);
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sha3_256(k, kr, 64); // hash concatenation of pre-k and h(c) to k
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return (0);
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}
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