To improve type safety, encapsulate the internal state of the SipHash
algorithm into a dedicated structure type.
Signed-off-by: David Gibson <david(a)gibson.dropbear.id.au>
---
siphash.c | 80 +++++++++++++++++++++++++++++--------------------------
1 file changed, 42 insertions(+), 38 deletions(-)
diff --git a/siphash.c b/siphash.c
index 21c560d..66174c7 100644
--- a/siphash.c
+++ b/siphash.c
@@ -58,33 +58,37 @@
#define ROTL(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))
-#define SIPHASH_INIT(k) { \
+struct siphash_state {
+ uint64_t v[4];
+};
+
+#define SIPHASH_INIT(k) { { \
0x736f6d6570736575ULL ^ (k)[0], \
0x646f72616e646f6dULL ^ (k)[1], \
0x6c7967656e657261ULL ^ (k)[0], \
0x7465646279746573ULL ^ (k)[1] \
- }
+ } }
/**
* sipround() - Perform rounds of SipHash scrambling
* @v: siphash state (4 x 64-bit integers)
* @n: Number of rounds to apply
*/
-static inline void sipround(uint64_t *v, int n)
+static inline void sipround(struct siphash_state *state, int n)
{
int i;
for (i = 0; i < n; i++) {
- v[0] += v[1];
- v[1] = ROTL(v[1], 13) ^ v[0];
- v[0] = ROTL(v[0], 32);
- v[2] += v[3];
- v[3] = ROTL(v[3], 16) ^ v[2];
- v[0] += v[3];
- v[3] = ROTL(v[3], 21) ^ v[0];
- v[2] += v[1];
- v[1] = ROTL(v[1], 17) ^ v[2];
- v[2] = ROTL(v[2], 32);
+ state->v[0] += state->v[1];
+ state->v[1] = ROTL(state->v[1], 13) ^ state->v[0];
+ state->v[0] = ROTL(state->v[0], 32);
+ state->v[2] += state->v[3];
+ state->v[3] = ROTL(state->v[3], 16) ^ state->v[2];
+ state->v[0] += state->v[3];
+ state->v[3] = ROTL(state->v[3], 21) ^ state->v[0];
+ state->v[2] += state->v[1];
+ state->v[1] = ROTL(state->v[1], 17) ^ state->v[2];
+ state->v[2] = ROTL(state->v[2], 32);
}
}
@@ -93,11 +97,11 @@ static inline void sipround(uint64_t *v, int n)
* @v: siphash state (4 x 64-bit integers)
* @in: New value to fold into hash
*/
-static inline void siphash_feed(uint64_t *v, uint64_t in)
+static inline void siphash_feed(struct siphash_state *state, uint64_t in)
{
- v[3] ^= in;
- sipround(v, 2);
- v[0] ^= in;
+ state->v[3] ^= in;
+ sipround(state, 2);
+ state->v[0] ^= in;
}
/**
@@ -106,14 +110,15 @@ static inline void siphash_feed(uint64_t *v, uint64_t in)
* @len: Total length of input data
* @tail: Final data for the hash (<= 7 bytes)
*/
-static inline uint64_t siphash_final(uint64_t *v, size_t len, uint64_t tail)
+static inline uint64_t siphash_final(struct siphash_state *state,
+ size_t len, uint64_t tail)
{
uint64_t b = (uint64_t)(len) << 56 | tail;
- siphash_feed(v, b);
- v[2] ^= 0xff;
- sipround(v, 4);
- return v[0] ^ v[1] ^ v[2] ^ v[3];
+ siphash_feed(state, b);
+ state->v[2] ^= 0xff;
+ sipround(state, 4);
+ return state->v[0] ^ state->v[1] ^ state->v[2] ^ state->v[3];
}
/**
@@ -137,12 +142,11 @@ __attribute__((optimize("-fno-strict-aliasing")))
/* cppcheck-suppress unusedFunction */
uint64_t siphash_8b(const uint8_t *in, const uint64_t *k)
{
- uint64_t v[4] = SIPHASH_INIT(k);
-
- siphash_feed(v, *(uint64_t *)in);
+ struct siphash_state state = SIPHASH_INIT(k);
+ siphash_feed(&state, *(uint64_t *)in);
- return siphash_final(v, 8, 0);
+ return siphash_final(&state, 8, 0);
}
/**
@@ -157,12 +161,12 @@ __attribute__((optimize("-fno-strict-aliasing"))) /* See
siphash_8b() */
/* cppcheck-suppress unusedFunction */
uint64_t siphash_12b(const uint8_t *in, const uint64_t *k)
{
+ struct siphash_state state = SIPHASH_INIT(k);
uint32_t *in32 = (uint32_t *)in;
- uint64_t v[4] = SIPHASH_INIT(k);
- siphash_feed(v, (uint64_t)(*(in32 + 1)) << 32 | *in32);
+ siphash_feed(&state, (uint64_t)(*(in32 + 1)) << 32 | *in32);
- return siphash_final(v, 12, *(in32 + 2));
+ return siphash_final(&state, 12, *(in32 + 2));
}
/**
@@ -176,14 +180,14 @@ uint64_t siphash_12b(const uint8_t *in, const uint64_t *k)
__attribute__((optimize("-fno-strict-aliasing"))) /* See siphash_8b() */
uint64_t siphash_20b(const uint8_t *in, const uint64_t *k)
{
+ struct siphash_state state = SIPHASH_INIT(k);
uint32_t *in32 = (uint32_t *)in;
- uint64_t v[4] = SIPHASH_INIT(k);
int i;
for (i = 0; i < 2; i++, in32 += 2)
- siphash_feed(v, (uint64_t)(*(in32 + 1)) << 32 | *in32);
+ siphash_feed(&state, (uint64_t)(*(in32 + 1)) << 32 | *in32);
- return siphash_final(v, 20, *in32);
+ return siphash_final(&state, 20, *in32);
}
/**
@@ -198,14 +202,14 @@ __attribute__((optimize("-fno-strict-aliasing"))) /* See
siphash_8b() */
/* cppcheck-suppress unusedFunction */
uint64_t siphash_32b(const uint8_t *in, const uint64_t *k)
{
+ struct siphash_state state = SIPHASH_INIT(k);
uint64_t *in64 = (uint64_t *)in;
- uint64_t v[4] = SIPHASH_INIT(k);
int i;
for (i = 0; i < 4; i++, in64++)
- siphash_feed(v, *in64);
+ siphash_feed(&state, *in64);
- return siphash_final(v, 32, 0);
+ return siphash_final(&state, 32, 0);
}
/**
@@ -219,12 +223,12 @@ uint64_t siphash_32b(const uint8_t *in, const uint64_t *k)
__attribute__((optimize("-fno-strict-aliasing"))) /* See siphash_8b() */
uint64_t siphash_36b(const uint8_t *in, const uint64_t *k)
{
+ struct siphash_state state = SIPHASH_INIT(k);
uint32_t *in32 = (uint32_t *)in;
- uint64_t v[4] = SIPHASH_INIT(k);
int i;
for (i = 0; i < 4; i++, in32 += 2)
- siphash_feed(v, (uint64_t)(*(in32 + 1)) << 32 | *in32);
+ siphash_feed(&state, (uint64_t)(*(in32 + 1)) << 32 | *in32);
- return siphash_final(v, 36, *in32);
+ return siphash_final(&state, 36, *in32);
}
--
2.41.0