diff options
Diffstat (limited to 'src/crypto/zinc/poly1305/poly1305-x86_64-glue.h')
| -rw-r--r-- | src/crypto/zinc/poly1305/poly1305-x86_64-glue.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/src/crypto/zinc/poly1305/poly1305-x86_64-glue.h b/src/crypto/zinc/poly1305/poly1305-x86_64-glue.h index b1248e8..585b579 100644 --- a/src/crypto/zinc/poly1305/poly1305-x86_64-glue.h +++ b/src/crypto/zinc/poly1305/poly1305-x86_64-glue.h @@ -67,6 +67,15 @@ struct poly1305_arch_internal { struct { u32 r2, r1, r4, r3; } rn[9]; }; +/* The AVX code uses base 2^26, while the scalar code uses base 2^64. If we hit + * the unfortunate situation of using AVX and then having to go back to scalar + * -- because the user is silly and has called the update function from two + * separate contexts -- then we need to convert back to the original base before + * proceeding. It is possible to reason that the initial reduction below is + * sufficient given the implementation invariants. However, for an avoidance of + * doubt and because this is not performance critical, we do the full reduction + * anyway. + */ static void convert_to_base2_64(void *ctx) { struct poly1305_arch_internal *state = ctx; |