ECC (ECIES) Sample

[Jeffrey Walton]

Hi All,

Based on Jason Smethers code, with additions of buffer management
(using CiphertextLength() and MaxPlaintextLength() from base class
PK_CryptoSystem ).

Wei - would it be possible to add to the FAQ (for a convenient place
to find without searching the archives)?

// Runtime Includes
#include <iostream>
#include <string>

// Crypto++ Includes
#include "cryptlib.h"
#include "oids.h"
#include "osrng.h"
#include "eccrypto.h"
#include "asn.h"
#include "ecp.h"

#include "simple.h"

int main(int argc, char* argv[])
{

try {

CryptoPP::ECIES< CryptoPP::ECP >::PrivateKey PrivateKey;
CryptoPP::ECIES< CryptoPP::ECP >::PublicKey PublicKey;
CryptoPP::AutoSeededRandomPool rng;

// Key Generation (160 bit curve)
// See Jason Smethers post at the following for a copy/paste
of other curves:
// http://www.mail-archive.com/crypto...@eskimo.com/msg02770.html
PrivateKey.Initialize( rng, CryptoPP::ASN1::secp160r2() );
PrivateKey.MakePublicKey( PublicKey );

// Key Validation
if( false == PrivateKey.Validate( rng, 6 ) ) { throw
std::string( "Private Key Validation" ); }
if( false == PublicKey.Validate( rng, 6 ) ) { throw
std::string( "Public Key Validation" ); }

// Encryptor and Decryptor
CryptoPP::ECIES< CryptoPP::ECP >::Encryptor Encryptor( PublicKey );
CryptoPP::ECIES< CryptoPP::ECP >::Decryptor Decryptor( PrivateKey );

// Message
// std::string PlainText = "ECC Test";
std::string PlainText = "Now is the time for all good men to
come to the aid of their country";

// Runtime Sizes...
unsigned int PlainTextLength = PlainText.length() + 1;
unsigned int CipherTextLength = Encryptor.CiphertextLength(
PlainText.length() + 1 );
if( 0 == CipherTextLength ) { throw
std::string("plaintextLength is not valid (too long)"); }

// Diagnostics
std::cout << "The plain text is '" << PlainText << "'" << std::endl;
std::cout << "The plain text length is " << PlainTextLength <<
" (including the trailing '\\0')" << std::endl;
std::cout << "The cipher text length for this message is " <<
CipherTextLength << std::endl;

// Scratch for Encryption
byte* CipherText = new byte[ CipherTextLength ];
if( NULL == CipherText ) { throw std::string( "CipherText
Allocation Failure" ); }
::memset( CipherText, 0xFB, Encryptor.CiphertextLength(
PlainTextLength ) );

// Encryption
Encryptor.Encrypt( rng, reinterpret_cast<const byte*>(
PlainText.c_str() ), PlainTextLength, CipherText );

//
// Take a break...
//
std::cout << std::endl;

// Scratch for Decryption
unsigned int RecoveredTextLength =
Decryptor.MaxPlaintextLength( CipherTextLength );
if( 0 == RecoveredTextLength ) { throw
std::string("ciphertextLength is not valid (too long or too short)");
}

byte* RecoveredText = new byte[ RecoveredTextLength ];
if( NULL == RecoveredText ) { throw std::string(
"RecoveredText CipherText Allocation Failure" ); }
::memset( RecoveredText, 0xFB, PlainTextLength );

// Decryption
Decryptor.Decrypt( rng, CipherText, CipherTextLength, RecoveredText );

// Diagnostics
std::cout << "The recovered text length for this curve is " <<
RecoveredTextLength << std::endl;
std::cout << "The recovered text for this curve is '" <<
reinterpret_cast<char*>( RecoveredText ) << "'" << std::endl;

// Cleanup
if( NULL != CipherText ) { delete[] CipherText; }
if( NULL != RecoveredText ) { delete[] RecoveredText; }

}

catch( CryptoPP::Exception& e ) {

std::cerr << "Crypto++ Error: " << e.what() << std::endl;

return -3;
}

catch( std::string& s ) {

std::cerr << "Error: " << s << std::endl;

return -2;
}

catch (...) {

std::cerr << "Unknown Error" << std::endl;

return -1;
}

return 0;
}