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(Objective-C) RSA Sign with PKCS8 Encrypted KeyDemonstrates how to load a private key from an encrypted PKCS8 file and create an RSA digital signature (and then verify it). Note: This example requires Chilkat v11.0.0 or greater.
#import <CkoPrivateKey.h> #import <CkoRsa.h> #import <NSString.h> #import <CkoCert.h> #import <CkoPublicKey.h> BOOL success = NO; // This example assumes the Chilkat API to have been previously unlocked. // See Global Unlock Sample for sample code. CkoPrivateKey *privKey = [[CkoPrivateKey alloc] init]; // Load the private key from an RSA PEM file: success = [privKey LoadAnyFormatFile: @"raul_privateKey.key" password: @"a0123456789"]; if (success == NO) { NSLog(@"%@",privKey.LastErrorText); return; } CkoRsa *rsa = [[CkoRsa alloc] init]; // Import the private key into the RSA component: success = [rsa UsePrivateKey: privKey]; if (success == NO) { NSLog(@"%@",rsa.LastErrorText); 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"; NSString *strData = @"This is the string to be signed."; // Sign the string using the sha256 hash algorithm. // Other valid choices are sha1, sha384, sha512 and others. NSString *hexSig = [rsa SignStringENC: strData hashAlg: @"sha256"]; if (rsa.LastMethodSuccess == NO) { NSLog(@"%@",rsa.LastErrorText); return; } NSLog(@"%@",hexSig); // Now verify with the public key. // This example shows how to use the public key from // a digital certificate (.cer file) CkoCert *cert = [[CkoCert alloc] init]; success = [cert LoadFromFile: @"raul_publicKey.cer"]; if (success == NO) { NSLog(@"%@",cert.LastErrorText); return; } CkoPublicKey *pubKey = [[CkoPublicKey alloc] init]; [cert GetPublicKey: pubKey]; CkoRsa *rsa2 = [[CkoRsa alloc] init]; success = [rsa2 UsePublicKey: pubKey]; if (success == NO) { NSLog(@"%@",rsa2.LastErrorText); return; } // Verify the signature against the original data: rsa2.EncodingMode = @"hex"; success = [rsa2 VerifyStringENC: strData hashAlg: @"sha256" sig: hexSig]; if (success == NO) { NSLog(@"%@",rsa2.LastErrorText); return; } NSLog(@"%@",@"Signature verified!"); // Verify with incorrect data: success = [rsa2 VerifyStringENC: @"something else" hashAlg: @"sha256" sig: hexSig]; if (success != YES) { NSLog(@"%@",@"Signature not verified! (which was expected in this case)"); } else { NSLog(@"%@",@"Hmmm... that's not right..."); } |
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