(Objective-C) RSA Signature with Certificate's Private Key from PFX

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Demonstrates how to use a certificate's private key from a PFX file to create an RSA signature.

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#import <CkoCertStore.h>
#import <CkoCert.h>
#import <CkoPrivateKey.h>
#import <NSString.h>
#import <CkoRsa.h>

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// Create an instance of a certificate store object, load a PFX file,
// locate the certificate we need, and use it for signing.
// (a PFX file may contain more than one certificate.)
CkoCertStore *certStore = [[CkoCertStore alloc] init];

// The 1st argument is the filename, the 2nd arg is the 
// PFX file's password:
BOOL success = [certStore LoadPfxFile: @"chilkat.pfx" password: @"test"];
if (success != YES) {
    NSLog(@"%@",certStore.LastErrorText);
    return;
}

CkoCert *cert = [certStore FindCertBySubject: @"Chilkat Software, Inc."];
if (certStore.LastMethodSuccess == NO) {
    NSLog(@"%@",certStore.LastErrorText);
    return;
}

CkoPrivateKey *pkey = [cert ExportPrivateKey];
if (cert.LastMethodSuccess == NO) {
    NSLog(@"%@",cert.LastErrorText);

    return;
}

// Get the private key in XML format:
NSString *pkeyXml = [pkey GetXml];

CkoRsa *rsa = [[CkoRsa alloc] init];

// Import the private key into the RSA component:
success = [rsa ImportPrivateKey: pkeyXml];
if (success != YES) {
    NSLog(@"%@",rsa.LastErrorText);

    return;
}

// Encode the signature as a hex string
rsa.EncodingMode = @"hex";

NSString *strData = @"This is the string to be signed.";

// Sign the string using the sha-1 hash algorithm.
// Other valid choices are "sha-256", "md2" and "md5".
NSString *hexSig = [rsa SignStringENC: strData hashAlg: @"sha-1"];

NSLog(@"%@",hexSig);

NSLog(@"%@",@"Success!");