&& hash_size != SIPHASH_MAX_DIGEST_SIZE)
return 0;
- ctx->hash_size = hash_size;
+ /*
+ * It's possible that the key was set first. If the hash size changes,
+ * we need to adjust v1 (see SipHash_Init().
+ */
+
+ /* Start by adjusting the stored size, to make things easier */
+ ctx->hash_size = siphash_adjust_hash_size(ctx->hash_size);
+
+ /* Now, adjust ctx->v1 if the old and the new size differ */
+ if ((size_t)ctx->hash_size != hash_size) {
+ ctx->v1 ^= 0xee;
+ ctx->hash_size = hash_size;
+ }
return 1;
}