DI Management Cryptography

This page contains useful free cryptographic software code that David Ireland has written or adapted in Visual Basic and ANSI C. It's updated frequently, so keep checking.

http://www.di-mgt.com.au/crypto.html

Generating RSA Key Pair Programmatically using OpenSSL

#include "stdafx.h"
#include <conio.h>
#include <openssl/rsa.h>
#include <openssl/bio.h>
#include <openssl/x509.h>
#include <stdlib.h>
#include <stdio.h>
 

int _tmain(int argc, _TCHAR* argv[])
{
    RSA *myrsa;
    unsigned long e = RSA_3;
    BIO* out = NULL
    FILE* fp;
    myrsa = RSA_generate_key(2048,e,NULL,NULL);

    out=BIO_new(BIO_s_file());
    

    if(myrsa==NULL){
        printf("error in generating keypair..");
        printf("press any key to exit..");
        _getch();
    }
    
    fp=fopen("rsakeypair.txt","wb");
    out = BIO_new_fp(fp,BIO_CLOSE);
    BIO_printf(out,"\n");
    RSA_print(out,myrsa,0);
    fclose(fp); _getch(); return(0);
}

The above example program generates a 2048 bit RSA Key pair. It also generates the p,q,n,e and d sections into the text file. In order to build this sample using Visual C++, you will need to build OpenSSL first. After you build OpenSSL, you can then include the generated headers to your VC/Include folder. You will also need to include the the lib files generated by OpenSSL onto VC/Lib. The above example program is written in VS05. OpenSSL simply rocks!

Code + Demo + ReadmeFile : Here

Hashing - Using C# and .Net Framework

A Cryptographic one-way hash function is used to generate a fixed length hash value as a transformation from a specific input. It should be computationally feasible in that it should

• Not have the Avalanche Effect in producing the hash value
• Given h it should be hard to find any m such that h = hash(m)
• It should be collision resistant, i.e given an input m₁, It should be hard to find another input, m₂ (not equal to m₁) such that  hash(m₁) = hash(m₂)
• Resistant to Birthday attacks

.Net Framework BCL provides solid support to some cryptographic hash functions like MD5,SHA1,SHA128,SHA384 and SHA512. I've written a small demo program to compute hash and verify them using the listed cryptographic hash algorithms.

Class Diagram

 

 

 

 

 

 

 

 

  

 

Output

System.Security.Cryptography

Complete .Net Cryptography Classes,Interfaces and Enumerations listing from MSDN. Wanted to keep this live on my blog for future references.. Also Check out this article on MSDN [Protecting Private Data with Cryptography Namespaces of the .Net Framework]