From 6e5aaceed5c89e323acc1ce701f8cdf573058c46 Mon Sep 17 00:00:00 2001
From: Benedict <benedict@0xb8000.de>
Date: Fri, 9 Dec 2016 18:28:21 +0100
Subject: dh: added a dh bignum implementation based on openssl

---
 lib/lib5.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/lib5.h | 16 ++++++++++++++++
 2 files changed, 66 insertions(+)

(limited to 'lib')

diff --git a/lib/lib5.c b/lib/lib5.c
index 722cc46..60b0836 100644
--- a/lib/lib5.c
+++ b/lib/lib5.c
@@ -98,6 +98,56 @@ void do_dh_key_exchange(struct dh_param *dh)
 	dh_get_session_key(dh);
 }
 
+void dh_init_bignum(struct dh_param_bignum *dh)
+{
+	dh->A = BN_new();
+	dh->B = BN_new();
+	dh->a = BN_new();
+	dh->b = BN_new();
+	dh->p = BN_new();
+	dh->g = BN_new();
+	dh->s1 = BN_new();
+	dh->s2 = BN_new();
+	unsigned char *p =
+		"ffffffffffffffffc90fdaa22168c234c4c6628b80dc1cd129024"
+		"e088a67cc74020bbea63b139b22514a08798e3404ddef9519b3cd"
+		"3a431b302b0a6df25f14374fe1356d6d51c245e485b576625e7ec"
+		"6f44c42e9a637ed6b0bff5cb6f406b7edee386bfb5a899fa5ae9f"
+		"24117c4b1fe649286651ece45b3dc2007cb8a163bf0598da48361"
+		"c55d39a69163fa8fd24cf5f83655d23dca3ad961c62f356208552"
+		"bb9ed529077096966d670c354e4abc9804f1746c08ca237327fff"
+		"fffffffffffff";
+	unsigned char *res = malloc(strlen(p));
+	int len_dec = decode_hex_string(p, res);
+	BN_bin2bn(res, len_dec, dh->p);
+	BN_set_word(dh->g, 2);
+}
+void dh_generate_secret_keys_bignum(struct dh_param_bignum *dh)
+{
+	BN_pseudo_rand(dh->a, 8000, -1, -1);
+	BN_pseudo_rand(dh->b, 8000, -1, -1);
+}
+
+void dh_generate_public_keys_bignum(struct dh_param_bignum *dh)
+{
+	BN_mod_exp(dh->A, dh->g, dh->a, dh->p, ctx);
+	BN_mod_exp(dh->B, dh->g, dh->b, dh->p, ctx);
+}
+
+void dh_get_session_key_bignum(struct dh_param_bignum *dh)
+{
+	BN_mod_exp(dh->s1, dh->B, dh->a, dh->p, ctx);
+	BN_mod_exp(dh->s2, dh->A, dh->b, dh->p, ctx);
+}
+
+void do_dh_key_exchange_bignum(struct dh_param_bignum *dh)
+{
+	dh_init_bignum(dh);
+	dh_generate_secret_keys_bignum(dh);
+	dh_generate_public_keys_bignum(dh);
+	dh_get_session_key_bignum(dh);
+}
+
 void sha1_key_from_dh(struct dh_param *dh, unsigned char *key)
 {
 	char *s1_char;
diff --git a/lib/lib5.h b/lib/lib5.h
index d78da21..da3868d 100644
--- a/lib/lib5.h
+++ b/lib/lib5.h
@@ -19,6 +19,17 @@ struct dh_param {
 	mpz_t s2;
 };
 
+struct dh_param_bignum {
+	BIGNUM *A;
+	BIGNUM *B;
+	BIGNUM *a;
+	BIGNUM *b;
+	BIGNUM *p;
+	BIGNUM *g;
+	BIGNUM *s1;
+	BIGNUM *s2;
+};
+
 // global openssl context for auxaliry results
 BN_CTX *ctx;
 BIO *out;
@@ -55,6 +66,11 @@ void dh_generate_secret_keys(struct dh_param *dh);
 void dh_generate_public_keys(struct dh_param *dh);
 void dh_get_session_key(struct dh_param *dh);
 void do_dh_key_exchange(struct dh_param *dh);
+void dh_init_bignum(struct dh_param_bignum *dh);
+void dh_generate_secret_keys_bignum(struct dh_param_bignum *dh);
+void dh_generate_public_keys_bignum(struct dh_param_bignum *dh);
+void dh_get_session_key_bignum(struct dh_param_bignum *dh);
+void do_dh_key_exchange_bignum(struct dh_param_bignum *dh);
 void sha1_key_from_dh(struct dh_param *dh, unsigned char *key);
 void dh_mitm(struct dh_param *dh);
 int rsa_decrypt_bignum(BIGNUM *message, BIGNUM *res, struct rsa_key_bignum *private);
-- 
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