From a5b4baa713ed4ffeca70573193ecbc3c0d7421a4 Mon Sep 17 00:00:00 2001 From: Benedict Date: Sun, 18 Dec 2016 00:14:25 +0100 Subject: set6: challenge44: completed --- lib/lib6.c | 15 +++++++++++++++ lib/lib6.h | 3 +++ 2 files changed, 18 insertions(+) (limited to 'lib') diff --git a/lib/lib6.c b/lib/lib6.c index 7239228..ef0db85 100644 --- a/lib/lib6.c +++ b/lib/lib6.c @@ -209,3 +209,18 @@ void dsa_recover_x_from_known_k(struct dsa_public_params *pub, BIGNUM *k, BN_mod_sub(priv->private, priv->private, mess_hash, pub->q, ctx); BN_mod_mul(priv->private, priv->private, r_1, pub->q, ctx); } + +void dsa_recover_k_from_repeated_nonce(BIGNUM *mess1_hash, BIGNUM *mess2_hash, + BIGNUM *s1, BIGNUM *s2, struct dsa_public_params *pub, + struct dsa_per_user_param *priv, BIGNUM *k) +{ + + BIGNUM *diff1 = BN_new(); + + BN_mod_sub(diff1, mess1_hash, mess2_hash, pub->q, ctx); + BN_mod_sub(k, s1, s2, pub->q, ctx); + BN_mod_inverse(k, k, pub->q, ctx); + BN_mod_mul(k, k, diff1, pub->q, ctx); + printf("recoverd k is: \n"); + BN_print(out, k); +} diff --git a/lib/lib6.h b/lib/lib6.h index 88fc530..dbd435b 100644 --- a/lib/lib6.h +++ b/lib/lib6.h @@ -37,4 +37,7 @@ int dsa_verify(char *mess, struct dsa_public_params *pub, struct dsa_per_user_pa *priv); void dsa_recover_x_from_known_k(struct dsa_public_params *pub, BIGNUM *k, struct dsa_per_user_param *priv, BIGNUM *mess_hash); +void dsa_recover_k_from_repeated_nonce(BIGNUM *mess1_hash, BIGNUM *mess2_hash, + BIGNUM *s1, BIGNUM *s2, struct dsa_public_params *pub, + struct dsa_per_user_param *priv, BIGNUM *k); #endif /* __LIB_6_H__ */ -- cgit v1.2.3-70-g09d2