RE: [PATCH v5 2/4] siphash: add Nu{32,64} helpers

From: David Laight
Date: Fri Dec 16 2016 - 05:40:15 EST


From: Jason A. Donenfeld
> Sent: 15 December 2016 20:30
> These restore parity with the jhash interface by providing high
> performance helpers for common input sizes.
...
> +#define PREAMBLE(len) \
> + u64 v0 = 0x736f6d6570736575ULL; \
> + u64 v1 = 0x646f72616e646f6dULL; \
> + u64 v2 = 0x6c7967656e657261ULL; \
> + u64 v3 = 0x7465646279746573ULL; \
> + u64 b = ((u64)len) << 56; \
> + v3 ^= key[1]; \
> + v2 ^= key[0]; \
> + v1 ^= key[1]; \
> + v0 ^= key[0];

Isn't that equivalent to:
v0 = key[0];
v1 = key[1];
v2 = key[0] ^ (0x736f6d6570736575ULL ^ 0x646f72616e646f6dULL);
v3 = key[1] ^ (0x646f72616e646f6dULL ^ 0x7465646279746573ULL);

Those constants also look like ASCII strings.
What cryptographic analysis has been done on the values?

David