(MFC) Generating Repeatable Random Data for Testing/Debugging

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

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkGlobal.h>
#include <CkPrng.h>

void ChilkatSample(void)
    {
    CkString strOut;

    // All Chilkat classes can be unlocked at once at the beginning of a program
    // by calling UnlockBundle.  It requires a Bundle unlock code.
    CkGlobal chilkatGlob;
    bool success = chilkatGlob.UnlockBundle("Anything for 30-day trial.");
    if (success != true) {
        strOut.append(chilkatGlob.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    CkPrng fortuna;

    // 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","hex");
    success = fortuna.AddEntropy("hello world","ascii");

    // Generate some random data:
    const char *strRandHex = fortuna.genRandom(16,"hex");
    const char *strRandBase64 = fortuna.genRandom(22,"base64");
    const char *strRandBase58 = fortuna.genRandom(32,"base58");

    strOut.append("hex random bytes: ");
    strOut.append(strRandHex);
    strOut.append("\r\n");
    strOut.append("base64 random bytes: ");
    strOut.append(strRandBase64);
    strOut.append("\r\n");
    strOut.append("base58 random bytes: ");
    strOut.append(strRandBase58);
    strOut.append("\r\n");

    // Try it again with a different object to verify that the same results are obtained:
    CkPrng fortuna2;

    success = fortuna2.AddEntropy("01020304","hex");
    success = fortuna2.AddEntropy("hello world","ascii");

    strRandHex = fortuna2.genRandom(16,"hex");
    strRandBase64 = fortuna2.genRandom(22,"base64");
    strRandBase58 = fortuna2.genRandom(32,"base58");

    strOut.append("hex random bytes: ");
    strOut.append(strRandHex);
    strOut.append("\r\n");
    strOut.append("base64 random bytes: ");
    strOut.append(strRandBase64);
    strOut.append("\r\n");
    strOut.append("base58 random bytes: ");
    strOut.append(strRandBase58);
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }