/** 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;
for (int 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) \
_(for (size_t 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)
