178 lines
4.8 KiB
C
178 lines
4.8 KiB
C
#include <stdint.h>
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#include <string.h>
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/** libkeccak-tiny
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*
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* A single-file implementation of SHA-3 and SHAKE.
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*
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* Implementor: David Leon Gil
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* License: CC0, attribution kindly requested. Blame taken too,
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* but not liability.
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*/
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#define decshake(bits) \
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int shake##bits(uint8_t*, size_t, const uint8_t*, size_t);
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#define deckeccak(bits) \
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int keccak_##bits(uint8_t*, size_t, const uint8_t*, size_t);
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decshake(128)
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decshake(256)
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deckeccak(224)
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deckeccak(256)
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deckeccak(384)
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deckeccak(512)
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/******** The Keccak-f[1600] permutation ********/
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/*** Constants. ***/
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static const uint8_t rho[24] = \
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{ 1, 3, 6, 10, 15, 21,
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28, 36, 45, 55, 2, 14,
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27, 41, 56, 8, 25, 43,
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62, 18, 39, 61, 20, 44};
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static const uint8_t pi[24] = \
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{10, 7, 11, 17, 18, 3,
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5, 16, 8, 21, 24, 4,
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15, 23, 19, 13, 12, 2,
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20, 14, 22, 9, 6, 1};
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static const uint64_t RC[24] = \
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{1ULL, 0x8082ULL, 0x800000000000808aULL, 0x8000000080008000ULL,
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0x808bULL, 0x80000001ULL, 0x8000000080008081ULL, 0x8000000000008009ULL,
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0x8aULL, 0x88ULL, 0x80008009ULL, 0x8000000aULL,
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0x8000808bULL, 0x800000000000008bULL, 0x8000000000008089ULL, 0x8000000000008003ULL,
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0x8000000000008002ULL, 0x8000000000000080ULL, 0x800aULL, 0x800000008000000aULL,
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0x8000000080008081ULL, 0x8000000000008080ULL, 0x80000001ULL, 0x8000000080008008ULL};
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/*** Helper macros to unroll the permutation. ***/
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#define rol(x, s) (((x) << s) | ((x) >> (64 - s)))
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#define REPEAT6(e) e e e e e e
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#define REPEAT24(e) REPEAT6(e e e e)
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#define REPEAT5(e) e e e e e
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#define FOR5(v, s, e) \
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v = 0; \
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REPEAT5(e; v += s;)
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/*** Keccak-f[1600] ***/
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static inline void keccakf(void* state) {
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uint64_t* a = (uint64_t*)state;
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uint64_t b[5] = {0};
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uint64_t t = 0;
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uint8_t x, y;
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int i;
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for (i = 0; i < 24; i++) {
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// Theta
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FOR5(x, 1,
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b[x] = 0;
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FOR5(y, 5,
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b[x] ^= a[x + y]; ))
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FOR5(x, 1,
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FOR5(y, 5,
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a[y + x] ^= b[(x + 4) % 5] ^ rol(b[(x + 1) % 5], 1); ))
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// Rho and pi
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t = a[1];
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x = 0;
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REPEAT24(b[0] = a[pi[x]];
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a[pi[x]] = rol(t, rho[x]);
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t = b[0];
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x++; )
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// Chi
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FOR5(y,
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5,
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FOR5(x, 1,
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b[x] = a[y + x];)
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FOR5(x, 1,
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a[y + x] = b[x] ^ ((~b[(x + 1) % 5]) & b[(x + 2) % 5]); ))
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// Iota
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a[0] ^= RC[i];
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}
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}
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/******** The FIPS202-defined functions. ********/
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/*** Some helper macros. ***/
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#define _(S) do { S } while (0)
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#define FOR(i, ST, L, S) \
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_({size_t i; for (i = 0; i < L; i += ST) { S; }})
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#define mkapply_ds(NAME, S) \
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static inline void NAME(uint8_t* dst, \
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const uint8_t* src, \
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size_t len) { \
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FOR(i, 1, len, S); \
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}
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#define mkapply_sd(NAME, S) \
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static inline void NAME(const uint8_t* src, \
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uint8_t* dst, \
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size_t len) { \
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FOR(i, 1, len, S); \
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}
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mkapply_ds(xorin, dst[i] ^= src[i]) // xorin
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mkapply_sd(setout, dst[i] = src[i]) // setout
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#define P keccakf
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#define Plen 200
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// Fold P*F over the full blocks of an input.
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#define foldP(I, L, F) \
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while (L >= rate) { \
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F(a, I, rate); \
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P(a); \
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I += rate; \
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L -= rate; \
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}
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/** The sponge-based hash construction. **/
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static inline int hash(uint8_t* out, size_t outlen,
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const uint8_t* in, size_t inlen,
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size_t rate, uint8_t delim) {
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if ((out == NULL) || ((in == NULL) && inlen != 0) || (rate >= Plen)) {
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return -1;
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}
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uint8_t a[Plen] = {0};
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// Absorb input.
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foldP(in, inlen, xorin);
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// Xor in the DS and pad frame.
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a[inlen] ^= delim;
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a[rate - 1] ^= 0x80;
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// Xor in the last block.
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xorin(a, in, inlen);
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// Apply P
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P(a);
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// Squeeze output.
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foldP(out, outlen, setout);
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setout(a, out, outlen);
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memset(a, 0, 200);
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return 0;
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}
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/*** Helper macros to define SHA3 and SHAKE instances. ***/
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#define defshake(bits) \
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int shake##bits(uint8_t* out, size_t outlen, \
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const uint8_t* in, size_t inlen) { \
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return hash(out, outlen, in, inlen, 200 - (bits / 4), 0x1f); \
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}
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#define defkeccak(bits) \
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int keccak_##bits(uint8_t* out, size_t outlen, \
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const uint8_t* in, size_t inlen) { \
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if (outlen > (bits/8)) { \
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return -1; \
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} \
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return hash(out, outlen, in, inlen, 200 - (bits / 4), 0x01); \
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}
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/*** FIPS202 SHAKE VOFs ***/
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defshake(128)
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defshake(256)
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/*** FIPS202 SHA3 FOFs ***/
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defkeccak(224)
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defkeccak(256)
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defkeccak(384)
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defkeccak(512)
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