How to generate ds:X509Certificate value from .p12 in Objective-C? - objective-c

Question

I've a private key file .p12.
I'm using Objective-C.
I need to generate Signed digital signature XML like this:
The problem is, I cannot find out how to generate the value in <ds:X509Certificate>. I know it is a public key base64 encoded. But, I can't get the same string after testing various encoding methods..
Need your help!

Answer 1

Found the solution myself. It is so easy.
Using Apple's security.framework:
NSString* pfile = [[NSBundle mainBundle] pathForResource:#"rsa_user" ofType:#"p12" ];
// Load Certificate
NSData *p12data = [NSData dataWithContentsOfFile:pfile];
CFDataRef inP12data = (__bridge CFDataRef)p12data;
SecIdentityRef myIdentity;
SecTrustRef myTrust;
extractIdentityAndTrust(inP12data, &myIdentity, &myTrust);
SecCertificateRef myCertificate;
SecIdentityCopyCertificate(myIdentity, &myCertificate);
NSData *certificateData = (__bridge NSData *) SecCertificateCopyData(myCertificate);
// Output certificate base64 value. (This value goes to <ds:X509Certificate> tag )
NSLog(#"%#", [certificateData base64EncodedString]);
// Helper function
OSStatus extractIdentityAndTrust(CFDataRef inP12data, SecIdentityRef *identity, SecTrustRef *trust)
{
OSStatus securityError = errSecSuccess;
CFStringRef password = CFSTR("password");
const void *keys[] = { kSecImportExportPassphrase };
const void *values[] = { password };
CFDictionaryRef options = CFDictionaryCreate(NULL, keys, values, 1, NULL, NULL);
CFArrayRef items = CFArrayCreate(NULL, 0, 0, NULL);
securityError = SecPKCS12Import(inP12data, options, &items);
if (securityError == 0) {
CFDictionaryRef myIdentityAndTrust = CFArrayGetValueAtIndex(items, 0);
const void *tempIdentity = NULL;
tempIdentity = CFDictionaryGetValue(myIdentityAndTrust, kSecImportItemIdentity);
*identity = (SecIdentityRef)tempIdentity;
const void *tempTrust = NULL;
tempTrust = CFDictionaryGetValue(myIdentityAndTrust, kSecImportItemTrust);
*trust = (SecTrustRef)tempTrust;
}
if (options) {
CFRelease(options);
}
return securityError;
}