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/*
- based on crypto_auth/siphash24/little2 from supercop-20140622
*/
#include "uint64_pack.h"
#include "uint64_unpack.h"
#include "siphash.h"
#define ROTATE(x,b) x = (x << b) | (x >> (64 - b))
#define ROUND \
do { \
v0 += v1; v2 += v3; \
ROTATE(v1,13); ROTATE(v3,16); \
v1 ^= v0; v3 ^= v2; \
ROTATE(v0,32); \
v2 += v1; v0 += v3; \
ROTATE(v1,17); ROTATE(v3,21); \
v1 ^= v2; v3 ^= v0; \
ROTATE(v2,32); \
} while(0);
int siphash(unsigned char *out, const unsigned char *in, unsigned long long inlen, const unsigned char *k, long long rounds, long long finalrounds) {
crypto_uint64 v0, v1, v2, v3, lastblock = inlen;
unsigned char block[8];
long long i;
v0 = v2 = uint64_unpack(k + 0);
v1 = v3 = uint64_unpack(k + 8);
v0 ^= 0x736f6d6570736575;
v1 ^= 0x646f72616e646f6d;
v2 ^= 0x6c7967656e657261;
v3 ^= 0x7465646279746573;
while (inlen >= 8) {
crypto_uint64 mi = uint64_unpack(in);
in += 8;
v3 ^= mi;
for (i = 0; i < rounds; ++i) ROUND
v0 ^= mi;
inlen -= 8;
}
for (i = 0; i < 7; ++i) block[i] = 0;
for (i = 0; i < inlen; ++i) block[i] = in[i];
block[7] = lastblock;
lastblock = uint64_unpack(block);
v3 ^= lastblock;
for (i = 0; i < rounds; ++i) ROUND
v0 ^= lastblock;
v2 ^= 0xff;
for (i = 0; i < finalrounds; ++i) ROUND
uint64_pack(out, (v0 ^ v1) ^ (v2 ^ v3));
return 0;
}
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