add a longer hash function (no protocol change, but now longer session keys can be...

[xonotic/d0_blind_id.git] / d0_blind_id.c

diff --git a/d0_blind_id.c b/d0_blind_id.c
index 7c1f010bba395b5b236bd11ae8c3b7066782de42..9a1ddc36c6b989264d5bea2db58995e8c56f05af 100644 (file)
--- a/d0_blind_id.c
+++ b/d0_blind_id.c
@@ -198,6 +198,39 @@ fail:
        return 0;
 }
 
+WARN_UNUSED_RESULT BOOL d0_longhash_destructive(d0_bignum_t *clobberme, char *outbuf, size_t *outbuflen)
+{
+       d0_iobuf_t *out = NULL;
+       static unsigned char convbuf[1024];
+       d0_iobuf_t *conv = NULL;
+       size_t n, sz;
+
+       n = *outbuflen;
+       while(n > SHA_DIGESTSIZE)
+       {
+               conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
+               CHECK(d0_iobuf_write_bignum(conv, temp0));
+               CHECK(d0_iobuf_close(conv, &sz));
+               conv = NULL;
+               memcpy(outbuf, sha(convbuf, sz), SHA_DIGESTSIZE);
+               outbuf += SHA_DIGESTSIZE;
+               n -= SHA_DIGESTSIZE;
+               CHECK(d0_bignum_add(temp0, temp0, one));
+       }
+       conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
+       CHECK(d0_iobuf_write_bignum(conv, temp0));
+       CHECK(d0_iobuf_close(conv, &sz));
+       conv = NULL;
+       memcpy(outbuf, sha(convbuf, sz), n);
+
+       return d0_iobuf_close(out, outbuflen);
+
+fail:
+       if(conv)
+               d0_iobuf_close(conv, &sz);
+       return 0;
+}
+
 void d0_blind_id_clear(d0_blind_id_t *ctx)
 {
        if(ctx->rsa_n) d0_bignum_free(ctx->rsa_n);
@@ -841,33 +874,13 @@ fail:
 
 BOOL d0_blind_id_sessionkey_public_id(d0_blind_id_t *ctx, char *outbuf, size_t *outbuflen)
 {
-       d0_iobuf_t *out = NULL;
-       static unsigned char convbuf[1024];
-       d0_iobuf_t *conv = NULL;
-       size_t n, sz;
-
        USING(r); USING(other_4_to_r); USING(schnorr_G);
 
-       out = d0_iobuf_open_write(outbuf, *outbuflen);
-       conv = d0_iobuf_open_write(convbuf, sizeof(convbuf));
-
        // temps: temp0 result
        CHECK(d0_bignum_mod_pow(temp0, ctx->other_4_to_r, ctx->r, ctx->schnorr_G));
-       CHECK(d0_iobuf_write_bignum(conv, temp0));
-       CHECK(d0_iobuf_close(conv, &sz));
-       conv = NULL;
-
-       n = *outbuflen;
-       if(n > SHA_DIGESTSIZE)
-               n = SHA_DIGESTSIZE;
-       CHECK(d0_iobuf_write_raw(out, sha(convbuf, sz), n) == n);
-
-       return d0_iobuf_close(out, outbuflen);
+       return d0_longhash_destructive(temp0, outbuf, outbuflen);
 
 fail:
-       if(conv)
-               d0_iobuf_close(conv, &sz);
-       d0_iobuf_close(out, outbuflen);
        return 0;
 }