Objective-C

Duplicate openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

See more RSA Examples

Demonstrates how to duplicate the creation of an RSA signature produced by this OpenSSL command:

openssl dgst -md5 -sign myKey.pem something.txt | openssl enc -base64 -A

Objective-C

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

BOOL success = NO;

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

CkoPrivateKey *pkey = [[CkoPrivateKey alloc] init];

// Load the private key from an RSA PEM file:
success = [pkey LoadPemFile: @"myKey.pem"];

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

// Import the private key into the RSA component:
success = [rsa UsePrivateKey: pkey];
if (success == NO) {
    NSLog(@"%@",rsa.LastErrorText);
    return;
}

// OpenSSL uses BigEndian byte ordering:
rsa.LittleEndian = NO;

// The resulting signature will be a Base64 string:
rsa.EncodingMode = @"base64";

// For simplicity, we're not loading
// the data to be signed from a file.  We are instead simply
// using a literal string value.  
NSString *strData = @"This is the text to be signed.";

// Hash the input using MD5, and then sign the hash:
// Other valid hash algorithm choices are "md2" and "sha-1".
NSString *base64Sig = [rsa SignStringENC: strData hashAlg: @"md5"];

NSLog(@"%@",base64Sig);

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