From Forum Nokia Wiki

ID	CS000944	Creation date	May 8, 2008
Platform	S60 3rd Edition, FP1	Tested on devices	Nokia N93
Category	Open C	Subcategory	Files/Data

Keywords (APIs, classes, methods, functions): RC4_KEY, MD5(), RC4_set_key(), RC4()

Overview

This snippet shows how the OpenSSL crypto library can be used to encrypt and decrypt descriptor content using a pass phrase. The example functions openc_encrypt() encrypts and openc_decrypt() decrypts a string of characters using Open C libcrypt.

Note: In order to use this code, you need to install Open C plug-in.

This snippet can be self-signed.

MMP file

The following libraries are required:

LIBRARY libc.lib
LIBRARY euser.lib
LIBRARY libcrypto.lib

Source file

#include <stddef.h>
#include <openssl/rc4.h>
#include <openssl/md5.h>
 
//#include<filelogger.h>
 
void openc_encrypt(int len, unsigned char* in, unsigned char* crypted, unsigned char*
password, int passlen)
{
   unsigned char digest[MD5_DIGEST_LENGTH];
   RC4_KEY key;
 
   MD5(password, passlen, digest);
 
   RC4_set_key(&key, MD5_DIGEST_LENGTH, digest);
   RC4(&key, len, in, crypted);
}
 
void openc_decrypt(int len, unsigned char* in, unsigned char* decrypted, unsigned
char* password, int passlen)
{
   unsigned char digest[MD5_DIGEST_LENGTH];
   RC4_KEY key;
 
   MD5(password, passlen, digest);
 
   RC4_set_key(&key, MD5_DIGEST_LENGTH, digest);
   RC4(&key, len, in, decrypted);
}
 
/////////////////////////////////////////////////////////////////////////////////////
 
const TInt KMaxTextLen = 100;
 
_LIT8(KExampleText, "Encrypt this text!");
_LIT8(KPassWord, "secret");
 
void doExampleL()
    {    
    TBuf8<KMaxTextLen> buffer(KExampleText);
 
    HBufC8* password = KPassWord().AllocLC();    
    HBufC8* crypted = HBufC8::NewLC(buffer.Size());
 
    TPtr8 cryptedPtr = crypted->Des();
    cryptedPtr.SetLength(buffer.Size());
 
    openc_encrypt(buffer.Size(),
              (unsigned char*)buffer.Ptr(),
              (unsigned char*)cryptedPtr.Ptr(),
              (unsigned char*)password->Ptr(),
              password->Size()); 
 
  //LOGDES16(buffer); //Encrypt this text!
  //LOGDES8(*crypted) ; //Ór›­Â Û¦	}ÖŠ4 b q 
 
    HBufC8* decrypted = HBufC8::NewLC(buffer.Size());
    TPtr8 decryptedPtr = decrypted->Des();
 
    buffer.Copy(cryptedPtr);
    decryptedPtr.SetLength(buffer.Size());
 
    openc_decrypt(buffer.Size(),         
    		    (unsigned char*)buffer.Ptr(),
                (unsigned char*)decryptedPtr.Ptr(),
                (unsigned char*)password->Ptr(),
                password->Size());
 
  //LOGDES16(buffer);		//Ór›­Â Û¦	}ÖŠ4 b q 
  //LOGDES8(*decrypted) ; //Encrypt this text!
 
    CleanupStack::PopAndDestroy(3);  //decrypted, crypted, password                   
}

Postconditions

The example text has been encrypted with the pass phrase and after that decrypted with the same pass phrase using the example functions openc_encrypt() and openc_decrypt().