(Objective-C) Generate RSA Key and Export to PKCS1 / PKCS8

Objective-C example code showing how to generate an RSA public/private key and save to PKCS1 and PKCS8 format files. In a PKCS1 or PKCS8 formatted file, the key is stored in binary ASN.1 format (and ASN.1 is itself written according to DER -- Distinguished Encoding Rules). A PEM file simply contains the binary ASN.1 base64 encoded and delimited by BEGIN/END lines. PKCS1 format files are never encrypted. PKCS8 can be encrypted or unencrypted. Public keys are never encrypted (there is no need). Private keys *should* always be encrypted - unless perhaps the unencrypted private key is obtained and itself stored in some sort of secure place.

Chilkat Objective-C Library Downloads MAC OS X (Cocoa) Libs iOS Libs

#import <CkoRsa.h>
#import <CkoPublicKey.h>
#import <CkoPrivateKey.h>
#import <NSString.h>

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

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

// Generate a 2048-bit key.  Chilkat RSA supports
// key sizes ranging from 512 bits to 8192 bits.
BOOL success = [rsa GenerateKey: [NSNumber numberWithInt: 2048]];
if (success != YES) {
    NSLog(@"%@",rsa.LastErrorText);
    return;
}

// Get the public and private key parts:
CkoPublicKey *pubKey = [rsa ExportPublicKeyObj];
CkoPrivateKey *privKey = [rsa ExportPrivateKeyObj];

// Get the public key as a PKCS8 PEM string
NSString *pubKeyPem = [pubKey GetPem: NO];
NSLog(@"%@",pubKeyPem);

// Get the public key in PKCS8 format, in a Base64 encoded string.
NSString *pubKeyPkcs8Base64 = [pubKey GetEncoded: NO encoding: @"base64"];
NSLog(@"%@",pubKeyPkcs8Base64);

// Get the public key in PKCS1 format, in a Base64 encoded string.
NSString *pubKeyPkcs1Base64 = [pubKey GetEncoded: YES encoding: @"base64"];
NSLog(@"%@",pubKeyPkcs1Base64);

// Get the private key in a PKCS8 PEM string.
NSString *privKeyPem = [privKey GetPkcs8Pem];
NSLog(@"%@",privKeyPem);

// Get the private key in a PKCS8 encrypted PEM string.
NSString *privKeyEncPem = [privKey GetPkcs8EncryptedPem: @"myPassword"];
NSLog(@"%@",privKeyEncPem);

// Get the private key in PKCS1 Base64 format
NSString *privKeyPkcs1Base64 = [privKey GetPkcs1ENC: @"base64"];
NSLog(@"%@",privKeyPkcs1Base64);

// Get the private key in PKCS8 Base64 format
NSString *privKeyPkcs8Base64 = [privKey GetPkcs8ENC: @"base64"];
NSLog(@"%@",privKeyPkcs8Base64);

// Save to PKCS1 / PKCS8 / PEM files...

// Save the public key to PKCS8 binary DER
success = [pubKey SaveDerFile: NO path: @"pubKey_pkcs8.der"];

// Save the public key to PKCS1 binary DER
success = [pubKey SaveDerFile: @"pubKey_pkcs1.der"];

// Save the private key to unencrypted binary PKCS1 DER.
// Note: PKCS1 is never found in an encrypted format. 
success = [privKey SavePkcs1File: @"privKey_pkcs1.der"];

// Save the private key to unencrypted binary PKCS8
success = [privKey SavePkcs8File: @"privKey_pkcs8.der"];

// Save the private key to encrypted binary PKCS8
success = [privKey SavePkcs8EncryptedFile: @"myPassword" path: @"privKey_enc_pkcs8.der"];

// Save the private key to unencrypted PKCS8 PEM
success = [privKey SavePkcs8PemFile: @"privKey.pem"];

// Save the private key to encrypted PKCS8 PEM
success = [privKey SavePkcs8EncryptedPemFile: @"myPassword" path: @"privKey_enc.pem"];