Data commit

Task/Bitcoin-address-validation/C/bitcoin-address-validation.c

@@ -0,0 +1,61 @@
+#include <stdio.h>
+#include <string.h>
+#include <openssl/sha.h>
+
+const char *coin_err;
+#define bail(s) { coin_err = s; return 0; }
+
+int unbase58(const char *s, unsigned char *out) {
+	static const char *tmpl = "123456789"
+		"ABCDEFGHJKLMNPQRSTUVWXYZ"
+		"abcdefghijkmnopqrstuvwxyz";
+	int i, j, c;
+	const char *p;
+
+	memset(out, 0, 25);
+	for (i = 0; s[i]; i++) {
+		if (!(p = strchr(tmpl, s[i])))
+			bail("bad char");
+
+		c = p - tmpl;
+		for (j = 25; j--; ) {
+			c += 58 * out[j];
+			out[j] = c % 256;
+			c /= 256;
+		}
+
+		if (c) bail("address too long");
+	}
+
+	return 1;
+}
+
+int valid(const char *s) {
+	unsigned char dec[32], d1[SHA256_DIGEST_LENGTH], d2[SHA256_DIGEST_LENGTH];
+
+	coin_err = "";
+	if (!unbase58(s, dec)) return 0;
+
+	SHA256(SHA256(dec, 21, d1), SHA256_DIGEST_LENGTH, d2);
+
+	if (memcmp(dec + 21, d2, 4))
+		bail("bad digest");
+
+	return 1;
+}
+
+int main (void) {
+	const char *s[] = {
+		"1Q1pE5vPGEEMqRcVRMbtBK842Y6Pzo6nK9",
+		"1AGNa15ZQXAZUgFiqJ2i7Z2DPU2J6hW62i",
+		"1Q1pE5vPGEEMqRcVRMbtBK842Y6Pzo6nJ9",
+		"1AGNa15ZQXAZUgFiqJ2i7Z2DPU2J6hW62I",
+		0 };
+	int i;
+	for (i = 0; s[i]; i++) {
+		int status = valid(s[i]);
+		printf("%s: %s\n", s[i], status ? "Ok" : coin_err);
+	}
+
+	return 0;
+}