From: Mark Wooding <mdw@distorted.org.uk>
Date: Mon, 31 Mar 2014 15:01:46 +0000 (+0100)
Subject: pub/dsa-misc.c: Include a magic prefix in the hashing.
X-Git-Tag: 2.2.0~11
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/catacomb/commitdiff_plain/8878e543e2f5555a1a56a73279de38baeb0684df

pub/dsa-misc.c: Include a magic prefix in the hashing.

To prevent protocol interference.  In practice, I think including the
private key should be enough, because nobody would use that in any other
kind of hash, right...?
---

diff --git a/pub/dsa-misc.c b/pub/dsa-misc.c
index 4f68c7bc..8b03271b 100644
--- a/pub/dsa-misc.c
+++ b/pub/dsa-misc.c
@@ -84,6 +84,7 @@ mp *dsa_nonce(mp *d, mp *q, mp *x, const octet *m,
   size_t bsz = 2*n + 2*ch->hashsz;
   octet *b = XS_ALLOC(bsz);
   octet *kb = b, *rb = kb + n, *hb = rb + ch->hashsz;
+  static const char prefix[] = "catacomb-dsa-nonce";
   ghash *h;
 
   mp_storeb(x, kb, n);
@@ -92,6 +93,7 @@ mp *dsa_nonce(mp *d, mp *q, mp *x, const octet *m,
   do {
     for (j = 0; j < n; j += ch->hashsz) {
       h = GH_INIT(ch);
+      GH_HASH(h, prefix, sizeof(prefix));
       GH_HASHBUF32(h, kb, n);
       GH_HASHBUF32(h, m, ch->hashsz);
       if (r) GH_HASHBUF32(h, rb, ch->hashsz);