Objective-C

Generating Repeatable Random Data for Testing/Debugging

See more PRNG Examples

Demonstrates how to use the Fortuna PRNG to generate random-looking but repeatable non-random data for the purpose of testing and debugging. Objective-C

#import <CkoPrng.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.

success = NO;

CkoPrng *fortuna = [[CkoPrng alloc] init];

//  Normally an application would seed the PRNG with entropy from
//  some real random source.  However, sometimes we want the same
//  random sequence of bytes for testing and debugging purposes.
//  This a reason why GetEntropy and AddEntropy are two different methods.
//  An application could omit the call to GetEntropy, and instead pass
//  non-random data to AddEntropy. For example:

//  Seed the PRNG with non-entropy, so we get a repeatable sequence.
//  Note: AddEntropy can be called any number of times.
success = [fortuna AddEntropy: @"01020304" encoding: @"hex"];
success = [fortuna AddEntropy: @"hello world" encoding: @"ascii"];

//  Generate some random data:
NSString *strRandHex = [fortuna GenRandom: [NSNumber numberWithInt: 16] encoding: @"hex"];
NSString *strRandBase64 = [fortuna GenRandom: [NSNumber numberWithInt: 22] encoding: @"base64"];
NSString *strRandBase58 = [fortuna GenRandom: [NSNumber numberWithInt: 32] encoding: @"base58"];

NSLog(@"%@%@",@"hex random bytes: ",strRandHex);
NSLog(@"%@%@",@"base64 random bytes: ",strRandBase64);
NSLog(@"%@%@",@"base58 random bytes: ",strRandBase58);

//  Try it again with a different object to verify that the same results are obtained:
CkoPrng *fortuna2 = [[CkoPrng alloc] init];

success = [fortuna2 AddEntropy: @"01020304" encoding: @"hex"];
success = [fortuna2 AddEntropy: @"hello world" encoding: @"ascii"];

strRandHex = [fortuna2 GenRandom: [NSNumber numberWithInt: 16] encoding: @"hex"];
strRandBase64 = [fortuna2 GenRandom: [NSNumber numberWithInt: 22] encoding: @"base64"];
strRandBase58 = [fortuna2 GenRandom: [NSNumber numberWithInt: 32] encoding: @"base58"];

NSLog(@"%@%@",@"hex random bytes: ",strRandHex);
NSLog(@"%@%@",@"base64 random bytes: ",strRandBase64);
NSLog(@"%@%@",@"base58 random bytes: ",strRandBase58);