I'm currently working on an app, which uses the openssl library (libcrypto) to generate certificates. Now I have to get the hash of a already existing certificate.
When I use my Terminal I am able to generate the hash value by using
openssl x509 -hash -in cert.pem -noout
Output: 01da0e2b
This is my code where I try t generate my hash value by using the library in C.
X509 *cert = NULL;
FILE *fp = fopen(currentCert.UTF8String, "r");
PEM_read_X509(fp, &cert, NULL, NULL);
long hash = X509_subject_name_hash(cert);
char *mdString = malloc(sizeof(long));
sprintf(mdString, "%lx",hash);
printf(mdString);
Output: 1817886a
But actually my output is a different one. Has anybody an idea what am I doing wrong ?
But actually my output is a different one. Has anybody an idea what am I doing wrong ?
Here's how OpenSSL uses it...
$ cd openssl-1.0.2-src
$ grep -R X509_subject_name_hash *
apps/x509.c: BIO_printf(STDout, "%08lx\n", X509_subject_name_hash(x));
apps/x509.c: BIO_printf(STDout, "%08lx\n", X509_subject_name_hash_old(x));
crypto/x509/x509.h:unsigned long X509_subject_name_hash(X509 *x);
crypto/x509/x509.h:unsigned long X509_subject_name_hash_old(X509 *x);
crypto/x509/x509_cmp.c:unsigned long X509_subject_name_hash(X509 *x)
crypto/x509/x509_cmp.c:unsigned long X509_subject_name_hash_old(X509 *x)
...
Then, looking at apps/x509.c
:
...
} else if (subject_hash == i) {
BIO_printf(STDout, "%08lx\n", X509_subject_name_hash(x));
}
...
And your declaration should be:
unsigned long hash = X509_subject_name_hash(cert);
Then:
fprintf(stdout, "%08lx\n", hash);
Also, OpenSSL changed the way in calculates the subject hash sometime around OpenSSL 1.0.1. That's why there is an X509_subject_name_hash
and X509_subject_name_hash_old
.
If you are using or comparing against OpenSSL 0.9.8 (on, say Mac OS X 10), then see Generate Subject Hash of X509Certificate in Java. Though its Java, it details OpenSSL handling of the subject hash.