From 2e4ec7fe0a4b71bff34fa12b47bb0751fc6e995a Mon Sep 17 00:00:00 2001
From: Pavol Rusnak <stick@gk2.sk>
Date: Thu, 30 Jan 2014 20:34:05 +0100
Subject: [PATCH] introduce ecdsa_address_to_hash160

---
 bignum.c | 23 +++++++++++++++++++++++
 bignum.h |  4 ++++
 ecdsa.c  | 26 ++++++++++++++++++++++++++
 ecdsa.h  |  1 +
 tests.c  | 23 ++++++++++++++++++++++-
 5 files changed, 76 insertions(+), 1 deletion(-)

diff --git a/bignum.c b/bignum.c
index 5ad5d89f3..5117d0bed 100644
--- a/bignum.c
+++ b/bignum.c
@@ -154,6 +154,29 @@ void bn_mod(bignum256 *x, const bignum256 *prime)
 	}
 }
 
+// a = a + b
+void bn_addi(bignum256 *a, uint32_t b)
+{
+	uint64_t t = a->val[0];
+	t += b;
+	a->val[0] = t & 0x3FFFFFFFu;
+	t >>= 30;
+	a->val[1] += t;
+}
+
+// a = a * b
+void bn_muli(bignum256 *a, uint32_t b)
+{
+	uint64_t t = 0;
+	int i;
+	for (i = 0; i < 8; i++) {
+		t = (uint64_t)(a->val[i]) * b + t;
+		a->val[i] = t & 0x3FFFFFFFu;
+		t >>= 30;
+	}
+	a->val[8] += t;
+}
+
 // x = k * x
 // both inputs and result may be bigger than prime but not bigger than 2 * prime
 void bn_multiply(const bignum256 *k, bignum256 *x, const bignum256 *prime)
diff --git a/bignum.h b/bignum.h
index 928f56fc6..293d8120f 100644
--- a/bignum.h
+++ b/bignum.h
@@ -73,6 +73,10 @@ void bn_rshift(bignum256 *a);
 
 void bn_mod(bignum256 *x, const bignum256 *prime);
 
+void bn_addi(bignum256 *a, uint32_t b);
+
+void bn_muli(bignum256 *a, uint32_t b);
+
 void bn_multiply(const bignum256 *k, bignum256 *x, const bignum256 *prime);
 
 void bn_fast_mod(bignum256 *x, const bignum256 *prime);
diff --git a/ecdsa.c b/ecdsa.c
index ff9d534b4..ae93334be 100644
--- a/ecdsa.c
+++ b/ecdsa.c
@@ -342,6 +342,32 @@ void ecdsa_get_address(const uint8_t *pub_key, uint8_t version, char *addr)
 	}
 }
 
+int ecdsa_address_to_hash160(const char *addr, uint8_t *hash)
+{
+	if (!addr) return 0;
+	const char code[] = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
+	bignum256 num;
+	uint8_t buf[32];
+	bn_zero(&num);
+	uint32_t k;
+	int i;
+	for (i = 0; i < strlen(addr); i++) {
+		bn_muli(&num, 58);
+		for (k = 0; k <= strlen(code); k++) {
+			if (code[k] == 0) { // char not found -> invalid address
+				return 0;
+			}
+			if (addr[i] == code[k]) {
+				bn_addi(&num, k);
+				break;
+			}
+		}
+	}
+	bn_write_be(&num, buf);
+	memcpy(hash, buf + 8, 20);
+	return 1;
+}
+
 int ecdsa_read_pubkey(const uint8_t *pub_key, curve_point *pub)
 {
 	if (pub_key[0] == 0x04) {
diff --git a/ecdsa.h b/ecdsa.h
index 62b34cb43..1b504ee9f 100644
--- a/ecdsa.h
+++ b/ecdsa.h
@@ -40,6 +40,7 @@ int ecdsa_sign(const uint8_t *priv_key, const uint8_t *msg, uint32_t msg_len, ui
 void ecdsa_get_public_key33(const uint8_t *priv_key, uint8_t *pub_key);
 void ecdsa_get_public_key65(const uint8_t *priv_key, uint8_t *pub_key);
 void ecdsa_get_address(const uint8_t *pub_key, uint8_t version, char *addr);
+int ecdsa_address_to_hash160(const char *addr, uint8_t *hash);
 int ecdsa_read_pubkey(const uint8_t *pub_key, curve_point *pub);
 int ecdsa_verify(const uint8_t *pub_key, const uint8_t *sig, const uint8_t *msg, uint32_t msg_len);
 
diff --git a/tests.c b/tests.c
index d89929370..58e6103c4 100644
--- a/tests.c
+++ b/tests.c
@@ -491,6 +491,23 @@ START_TEST(test_address)
 }
 END_TEST
 
+START_TEST(test_address_to_hash)
+{
+	uint8_t hash[20];
+
+	ecdsa_address_to_hash160("1JwSSubhmg6iPtRjtyqhUYYH7bZg3Lfy1T", hash); ck_assert_mem_eq(hash, fromhex("c4c5d791fcb4654a1ef5e03fe0ad3d9c598f9827"), 20);
+	ecdsa_address_to_hash160("myTPjxggahXyAzuMcYp5JTkbybANyLsYBW", hash); ck_assert_mem_eq(hash, fromhex("c4c5d791fcb4654a1ef5e03fe0ad3d9c598f9827"), 20);
+	ecdsa_address_to_hash160("NEWoeZ6gh4CGvRgFAoAGh4hBqpxizGT6gZ", hash); ck_assert_mem_eq(hash, fromhex("c4c5d791fcb4654a1ef5e03fe0ad3d9c598f9827"), 20);
+	ecdsa_address_to_hash160("LdAPi7uXrLLmeh7u57pzkZc3KovxEDYRJq", hash); ck_assert_mem_eq(hash, fromhex("c4c5d791fcb4654a1ef5e03fe0ad3d9c598f9827"), 20);
+
+	ecdsa_address_to_hash160("1C7zdTfnkzmr13HfA2vNm5SJYRK6nEKyq8", hash); ck_assert_mem_eq(hash, fromhex("79fbfc3f34e7745860d76137da68f362380c606c"), 20);
+	ecdsa_address_to_hash160("mrdwvWkma2D6n9mGsbtkazedQQuoksnqJV", hash); ck_assert_mem_eq(hash, fromhex("79fbfc3f34e7745860d76137da68f362380c606c"), 20);
+	ecdsa_address_to_hash160("N7hMq7AmgNsQXaYARrEwybbDGei9mcPNqr", hash); ck_assert_mem_eq(hash, fromhex("79fbfc3f34e7745860d76137da68f362380c606c"), 20);
+	ecdsa_address_to_hash160("LWLwtfycqf1uFqypLAug36W4kdgNwrZdNs", hash); ck_assert_mem_eq(hash, fromhex("79fbfc3f34e7745860d76137da68f362380c606c"), 20);
+}
+END_TEST
+
+
 // define test suite and cases
 Suite *test_suite(void)
 {
@@ -511,10 +528,14 @@ Suite *test_suite(void)
 	tcase_add_test(tc, test_verify_speed);
 	suite_add_tcase(s, tc);
 
-	tc = tcase_create("addresses");
+	tc = tcase_create("address");
 	tcase_add_test(tc, test_address);
 	suite_add_tcase(s, tc);
 
+	tc = tcase_create("address_to_hash");
+	tcase_add_test(tc, test_address_to_hash);
+	suite_add_tcase(s, tc);
+
 	tc = tcase_create("rijndael");
 	tcase_add_test(tc, test_rijndael);
 	suite_add_tcase(s, tc);