set6: challenge 45: completed

1 files changed, 105 insertions, 0 deletions

diff --git a/set6/task45.c b/set6/task45.c
new file mode 100644
index 0000000..ab6964a
--- /dev/null
+++ b/set6/task45.c
@@ -0,0 +1,105 @@
+#include "../lib/lib.h"
+#include "../lib/lib2.h"
+#include "../lib/lib4.h"
+#include "../lib/lib5.h"
+#include "../lib/lib6.h"
+#include <openssl/sha.h>
+
+int main()
+{
+	struct dsa_public_params dsa_pub;
+	struct dsa_per_user_param dsa_user;
+	struct dsa_per_user_param dsa_user2;
+
+	char *message = "Hello World";
+	char *message2 = "Goodbye World";
+
+	BIGNUM *k = BN_new();
+
+	dsa_user.public = BN_new();
+	dsa_user.private = BN_new();
+	dsa_user.r = BN_new();
+	dsa_user.s = BN_new();
+
+	dsa_user2.public = BN_new();
+	dsa_user2.private = BN_new();
+	dsa_user2.r = BN_new();
+	dsa_user2.s = BN_new();
+
+	out = BIO_new(BIO_s_file());
+	BIO_set_fp(out, stdout, BIO_NOCLOSE);
+	ctx = BN_CTX_new();
+
+	init_dsa_pub_param(&dsa_pub);
+	dsa_compute_per_user_keys(&dsa_pub, &dsa_user);
+	dsa_compute_per_user_keys(&dsa_pub, &dsa_user2);
+
+	// set the pub params
+	BN_zero(dsa_pub.g);
+	printf("with g = 0\n");
+	BN_zero(k);
+	dsa_sign(message, &dsa_pub, &dsa_user, k);
+	printf("signature is:\n");
+	printf("r: ");
+	BN_print(out, dsa_user.r);
+	printf("\ns: ");
+	BN_print(out, dsa_user.s);
+	printf("\nverified?: %i\n", !dsa_verify(message, &dsa_pub, &dsa_user));
+	printf("checking signature for message which hasn't been signed\n");
+	printf("verified?: %i\n", !dsa_verify(message2, &dsa_pub, &dsa_user));
+	// for goodybye
+	printf("sign message %s\n", message2);
+	BN_zero(k);
+	dsa_sign(message2, &dsa_pub, &dsa_user, k);
+	printf("signature is:\n");
+	printf("r: ");
+	BN_print(out, dsa_user.r);
+	printf("\ns: ");
+	BN_print(out, dsa_user.s);
+	printf("\nverified?: %i\n", !dsa_verify(message2, &dsa_pub, &dsa_user));
+	printf("checking signature for message which hasn't been signed\n");
+	printf("verified?: %i\n", !dsa_verify(message, &dsa_pub, &dsa_user));
+	
+	// set g to p+1
+	BIGNUM *tmp = BN_new();
+	BIGNUM *one = BN_new();
+	BN_set_word(one, 1);
+	BN_add(tmp, dsa_pub.p, one);
+	BN_copy(dsa_pub.g, tmp);
+
+	BN_zero(dsa_user.r);
+	BN_zero(dsa_user.s);
+	printf("\nmaking magic signature for g = p + 1...\n");
+	// Generate hash of abitrary string
+	char hash[20];
+	BIGNUM *hash_bn = BN_new();
+	SHA_CTX sha1;
+	SHA1_Init(&sha1);
+	SHA1_Update(&sha1, message, strlen(message));
+	SHA1_Final(hash, &sha1);
+	BN_bin2bn(hash, 20, hash_bn);
+	dsa_generate_magic_signature(&dsa_pub, &dsa_user, hash_bn);
+	printf("signature is:\n");
+	printf("r: ");
+	BN_print(out, dsa_user.r);
+	printf("\ns: ");
+	BN_print(out, dsa_user.s);
+	printf("\nverified?: %i\n", !dsa_verify(message, &dsa_pub, &dsa_user));
+	printf("checking signature for message which hasn't been signed\n");
+	printf("verified?: %i\n", !dsa_verify(message2, &dsa_pub, &dsa_user));
+
+	// generate a signature for second message
+	SHA1_Init(&sha1);
+	SHA1_Update(&sha1, message2, strlen(message2));
+	SHA1_Final(hash, &sha1);
+	BN_bin2bn(hash, 20, hash_bn);
+	dsa_generate_magic_signature(&dsa_pub, &dsa_user, hash_bn);
+	printf("signature is:\n");
+	printf("r: ");
+	BN_print(out, dsa_user.r);
+	printf("\ns: ");
+	BN_print(out, dsa_user.s);
+	printf("\nverified?: %i\n", !dsa_verify(message2, &dsa_pub, &dsa_user));
+	printf("checking signature for message which hasn't been signed\n");
+	printf("verified?: %i\n", !dsa_verify(message, &dsa_pub, &dsa_user));
+}