RSA Signature with Certificate's Private Key from PFX

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

Download: Chilkat Cocoa Objective-C Libraries

NSMutableString *strOutput = [NSMutableString stringWithCapacity:1000];

BOOL success;

//  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] autorelease];

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

CkoCert *cert;
cert = [certStore FindCertBySubject: @"Chilkat Software, Inc."];
if (cert == nil ) {
    [strOutput appendString: certStore.LastErrorText];
    [strOutput appendString: @"\n"];
    self.mainTextField.stringValue = strOutput;
    return;
}

CkoPrivateKey *pkey;
pkey = [cert ExportPrivateKey];
if (pkey == nil ) {
    [strOutput appendString: cert.LastErrorText];
    [strOutput appendString: @"\n"];
    self.mainTextField.stringValue = strOutput;
    return;
}

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

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

//  Any string argument automatically begins the 30-day trial.

success = [rsa UnlockComponent: @"30-day trial"];
if (success != YES) {
    [strOutput appendString: @"RSA component unlock failed"];
    [strOutput appendString: @"\n"];
    self.mainTextField.stringValue = strOutput;
    return;
}

//  Import the private key into the RSA component:
success = [rsa ImportPrivateKey: pkeyXml];
if (success != YES) {
    [strOutput appendString: rsa.LastErrorText];
    [strOutput appendString: @"\n"];
    self.mainTextField.stringValue = strOutput;
    return;
}

//  This example will sign a string, and receive the signature
//  in a hex-encoded string.  Therefore, set the encoding mode
//  to "hex":
rsa.EncodingMode = @"hex";

//  If some other non-Chilkat application or web service is going to be verifying
//  the signature, it is important to match the byte-ordering.
//  The LittleEndian property may be set to YES
//  for little-endian byte ordering,
//  or NO  for big-endian byte ordering.
//  Microsoft apps typically use little-endian, while
//  OpenSSL and other services (such as Amazon CloudFront)
//  use big-endian.
rsa.LittleEndian = NO;

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

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

[strOutput appendString: hexSig];
[strOutput appendString: @"\n"];

[strOutput appendString: @"Success!"];
[strOutput appendString: @"\n"];

self.mainTextField.stringValue = strOutput;