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sha3.c
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sha3.c
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/** libkeccak-tiny
*
* A single-file implementation of SHA-3 and SHAKE.
*
* Implementor: David Leon Gil
* License: CC0, attribution kindly requested. Blame taken too,
* but not liability.
*/
#include "sha3.h"
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/******** The Keccak-f[1600] permutation ********/
/*** Constants. ***/
static const uint8_t rho[24] = {1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 2, 14,
27, 41, 56, 8, 25, 43, 62, 18, 39, 61, 20, 44};
static const uint8_t pi[24] = {10, 7, 11, 17, 18, 3, 5, 16, 8, 21, 24, 4,
15, 23, 19, 13, 12, 2, 20, 14, 22, 9, 6, 1};
static const uint64_t RC[24] = {1ULL,
0x8082ULL,
0x800000000000808aULL,
0x8000000080008000ULL,
0x808bULL,
0x80000001ULL,
0x8000000080008081ULL,
0x8000000000008009ULL,
0x8aULL,
0x88ULL,
0x80008009ULL,
0x8000000aULL,
0x8000808bULL,
0x800000000000008bULL,
0x8000000000008089ULL,
0x8000000000008003ULL,
0x8000000000008002ULL,
0x8000000000000080ULL,
0x800aULL,
0x800000008000000aULL,
0x8000000080008081ULL,
0x8000000000008080ULL,
0x80000001ULL,
0x8000000080008008ULL};
/*** Helper macros to unroll the permutation. ***/
#define rol(x, s) (((x) << s) | ((x) >> (64 - s)))
#define REPEAT6(e) e e e e e e
#define REPEAT24(e) REPEAT6(e e e e)
#define REPEAT5(e) e e e e e
#define FOR5(v, s, e) \
v = 0; \
REPEAT5(e; v += s;)
/*** Keccak-f[1600] ***/
static inline
void keccakf(void *state) {
uint64_t *a = (uint64_t *)state;
uint64_t b[5] = {0};
uint64_t t = 0;
uint8_t x, y;
int i;
for (i = 0; i < 24; i++) {
// Theta
FOR5(x, 1, b[x] = 0; FOR5(y, 5, b[x] ^= a[x + y];))
FOR5(x, 1, FOR5(y, 5, a[y + x] ^= b[(x + 4) % 5] ^ rol(b[(x + 1) % 5], 1);))
// Rho and pi
t = a[1];
x = 0;
REPEAT24(b[0] = a[pi[x]]; a[pi[x]] = rol(t, rho[x]); t = b[0]; x++;)
// Chi
FOR5(y, 5,
FOR5(x, 1, b[x] = a[y + x];) FOR5(
x, 1, a[y + x] = b[x] ^ ((~b[(x + 1) % 5]) & b[(x + 2) % 5]);))
// Iota
a[0] ^= RC[i];
}
}
/******** The FIPS202-defined functions. ********/
/*** Some helper macros. ***/
#define _(S) \
do { \
S \
} while (0)
#define FOR(i, ST, L, S) _(size_t i; for (i = 0; i < L; i += ST) { S; })
#define mkapply_ds(NAME, S) \
static inline void NAME( \
uint8_t *dst, const uint8_t *src, size_t len) { \
FOR(i, 1, len, S); \
}
#define mkapply_sd(NAME, S) \
static inline void NAME( \
const uint8_t *src, uint8_t *dst, size_t len) { \
FOR(i, 1, len, S); \
}
mkapply_ds(xorin, dst[i] ^= src[i]) // xorin
mkapply_sd(setout, dst[i] = src[i]) // setout
#define P keccakf
#define Plen 200
// Fold P*F over the full blocks of an input.
#define foldP(I, L, F) \
while (L >= rate) { \
F(a, I, rate); \
P(a); \
I += rate; \
L -= rate; \
}
/** The sponge-based hash construction. **/
static inline
int hash(uint8_t *out, size_t outlen, const uint8_t *in, size_t inlen,
size_t rate, uint8_t delim) {
if ((out == NULL) || ((in == NULL) && inlen != 0) || (rate >= Plen)) {
return -1;
}
uint8_t a[Plen] = {0};
// Absorb input.
foldP(in, inlen, xorin);
// Xor in the DS and pad frame.
a[inlen] ^= delim;
a[rate - 1] ^= 0x80;
// Xor in the last block.
xorin(a, in, inlen);
// Apply P
P(a);
// Squeeze output.
foldP(out, outlen, setout);
setout(a, out, outlen);
memset(a, 0, 200);
return 0;
}
#define defsha3(bits) \
int sha3_##bits(uint8_t *out, size_t outlen, const uint8_t *in, \
size_t inlen) { \
if (outlen > (bits / 8)) { \
return -1; \
} \
return hash(out, outlen, in, inlen, 200 - (bits / 4), 0x01); \
}
/*** FIPS202 SHA3 FOFs ***/
defsha3(256)
defsha3(512)