80 lines
3.1 KiB
C
80 lines
3.1 KiB
C
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#include "SABER_indcpa.h"
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#include "SABER_params.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 <stdint.h>
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#include <stdio.h>
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#include <string.h>
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int PQCLEAN_LIGHTSABER_CLEAN_crypto_kem_keypair(unsigned char *pk, unsigned char *sk) {
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int i;
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PQCLEAN_LIGHTSABER_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 crypto_kem_dec() fails.
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return (0);
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}
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int PQCLEAN_LIGHTSABER_CLEAN_crypto_kem_enc(unsigned char *ct, unsigned char *ss, const unsigned char *pk) {
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unsigned char kr[64]; // Will contain key, coins
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unsigned char 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_LIGHTSABER_CLEAN_indcpa_kem_enc(buf, kr + 32, pk, ct); // buf[0:31] contains message; kr[32:63] contains randomness r;
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sha3_256(kr + 32, ct, SABER_BYTES_CCA_DEC);
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sha3_256(ss, 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_LIGHTSABER_CLEAN_crypto_kem_dec(unsigned char *ss, const unsigned char *ct, const unsigned char *sk) {
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int i;
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unsigned char fail;
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unsigned char cmp[SABER_BYTES_CCA_DEC];
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unsigned char buf[64];
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unsigned char kr[64]; // Will contain key, coins
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const unsigned char *pk = sk + SABER_INDCPA_SECRETKEYBYTES;
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PQCLEAN_LIGHTSABER_CLEAN_indcpa_kem_dec(sk, ct, buf); // 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_LIGHTSABER_CLEAN_indcpa_kem_enc(buf, kr + 32, pk, cmp);
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fail = PQCLEAN_LIGHTSABER_CLEAN_verify(ct, cmp, SABER_BYTES_CCA_DEC);
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sha3_256(kr + 32, ct, SABER_BYTES_CCA_DEC); // overwrite coins in kr with h(c)
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PQCLEAN_LIGHTSABER_CLEAN_cmov(kr, sk + SABER_SECRETKEYBYTES - SABER_KEYBYTES, SABER_KEYBYTES, fail);
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sha3_256(ss, 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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