also support signing

[xonotic/d0_blind_id.git] / d0_bignum-openssl.c

diff --git a/d0_bignum-openssl.c b/d0_bignum-openssl.c
index 9c43e8f58e6dff90848576138e97c69d4b223153..0830ab23369333cbbf88b7ad7e86fa51f37cec7d 100644 (file)
--- a/d0_bignum-openssl.c
+++ b/d0_bignum-openssl.c
@@ -293,6 +293,13 @@ d0_bignum_t *d0_bignum_mod_add(d0_bignum_t *r, const d0_bignum_t *a, const d0_bi
        return r;
 }
 
+d0_bignum_t *d0_bignum_mod_sub(d0_bignum_t *r, const d0_bignum_t *a, const d0_bignum_t *b, const d0_bignum_t *m)
+{
+       if(!r) r = d0_bignum_new(); if(!r) return NULL;
+       BN_mod_sub(&r->z, &a->z, &b->z, &m->z, ctx);
+       return r;
+}
+
 d0_bignum_t *d0_bignum_mod_mul(d0_bignum_t *r, const d0_bignum_t *a, const d0_bignum_t *b, const d0_bignum_t *m)
 {
        if(!r) r = d0_bignum_new(); if(!r) return NULL;