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Bitcoin/address validation: Difference between revisions
→{{header|C}}
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''extra credit'': allow your code to deal with [http://bitcoin.stackexchange.com/questions/3059/what-is-a-compressed-bitcoin-key compressed keys]
=={{header|C}}==
<lang c>#include <stdio.h>
#include <string.h>
#include <openssl/sha.h>
void sha256(unsigned char* str, int len, unsigned char *d) {
SHA256_CTX ctx;
SHA256_Init(&ctx);
SHA256_Update(&ctx, str, len);
SHA256_Final(d, &ctx);
}
char *coin_err;
#define bail(s) { coin_err = s; return 0; }
int unbase58(char *s, unsigned char *out) {
static char *tmpl = "123456789"
"ABCDEFGHJKLMNPQRSTUVWXYZ"
"abcdefghijkmnopqrstuvwxyz";
int i, j, c;
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(char *s) {
unsigned char dec[32], d1[SHA256_DIGEST_LENGTH], d2[SHA256_DIGEST_LENGTH];
coin_err = "";
if (!unbase58(s, dec)) return 0;
sha256(dec, 21, d1);
sha256(d1, SHA256_DIGEST_LENGTH, d2);
if (memcmp(dec + 21, d2, 4))
bail("bad digest");
return 1;
}
int main (void) {
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;
}</lang>
=={{header|Perl}}==
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