Aaron Polley

// BasicCryptoPPWrap.h
// By: Michael R. Rich, 2009
// This code is placed into the public domain by its author
// No warranty or guarantee of applicability or function is granted.

// This is a wrapper designed to allow rapid use of the Crypto++ cryptographic library in a multitude of applications.
// It permits a developer with a nominal understanding of C++ to rapidly field apps that use cryptography to provide basic confidentiality.
// I wrote it so that a developer need not use any other variable types than string to encrypt and decrypt at will.
// Encrypting a string is as simple as:
//        string plainText = "I don't want anyone seeing this without my permission!"
//        string key = BasicCryptoPPWrap::BitGen(256);        // Better not lose this key!!
//        bool err;
//        string errMsg;
//        string cipherText = BasicCryptoPPWrap::MREncryptStringAES(plainText, key, &err, &errMsg);
// The returned string is not directly viewable.  In this case the string class is used as a handy data buffer for the crypto work.  If you want to see the
// string, simply do this:
//        cout << BasicCryptoPPWrap::HexEncode(cipherText) << "\n";
// To see the text again:
//        string recoveredText = BasicCryptoPPWrap::MRDecryptStringAES(cipherText, key, &err, &errMsg);
//        cout << recoveredText << "\n";
// A more comprehensive example can be seen in the sample code provided with this header

// To use the wrapper, you first need to successfully build and test the Crypto++ library.
// Visit the Crypto++ hompage (www.cryptopp.com) for the latest code, build, and test instructions.
// Then, add the Crypto++ directory to your include directories, link to the cryptopp library and include this header in your code.

// The Crypto++ library is a very powerful set of cryptographic tools, but I found the learning curve to get my first apps running with
// it to be very high.  I examined all the sample code I could find, worked through the API documentation, and examined the
// validation and test code before I finally started catching on.  Then I had to "grep" my way through the files to identify which headers I
// needed to include for a given function.  All of this brainache is undoubtedly due to my own lack of skill and formal training.

// Nonetheless, once I got the pattern figured out, I didn't want to repeat it all over the place in my code, so I wrote this wrapper.
// I don't want you to go through the same thing, so I'm offering this wrapper to those who can use it.

// This simplification comes at a cost of flexibility and performance.  I hope you outgrow this wrapper.  But, until you do, use it well!

// WARNINGS!!
// Data encrypted with methods starting with "MREncrypt" implement a custom initialization vector protocol.  Essentially the iv is either prepended to
// the string or the file you are using.  The "MRDecrypt" methods should be used to decrypt them.  Methods without the "MR" prefix are
// designed to work with a separately supplied iv.
//
// The binary "strings" returned by this wrapper do not play well with the formatted input and output functions and operators (i.e. <<, >>, getLine, etc..)
// You should use binary, unformatted functions to move them around.  See the MREncryptFileAES and MRDecryptFileAES methods for examples.
//
// This wrapper currently only uses one mode of AES encryption.  See flexibility and performance warning above!
//
// I am not a Crypto anything.  The word novice hardly even applies to me.  I am using the Crypto++ library in it's most basic form.
// As a result, I wouldn't use this wrapper in anything serious like financial or medical records, or access to critical infrastructure control
// routines.  I'm just saying.

// If you get a weird link error like "variable not in vtable" or "virtual thunk", add -DCRYPTOPP_DISABLE_ASM to the build options.
// This apparently happens on Mac OS X from time to time (it happened to me)


#ifndef __MRCRYPTOWRAP_H
#define __MRCRYPTOWRAP_H

#include <iostream>
#include <string>
#include <cstdio>
#include "config.h"
#include "hex.h"
#include "files.h"
#include "cryptlib.h"
#include "modes.h"
#include "osrng.h"
#include "filters.h"
#include "aes.h"

using namespace std;
using namespace CryptoPP;

class BasicCryptoPPWrap {
public:

    static bool isHex(string checkForHex) {
        size_t found;
        found = checkForHex.find_first_not_of("0123456789ABCDEF");
        if (found!=string::npos) {
            // This string has non-hex characters in it
            return false;
        } else {
            // only hex characters
            return true;
        }
    }

    static string HexEncode(string binaryString) {

        if (isHex(binaryString)) {
            // This string is already hex, don't convert it!
            return binaryString;
        } else {
            string hexString;
            StringSource(binaryString, true, new HexEncoder(new StringSink(hexString)));
            return hexString;
        }
    }

    static string HexDecode(string hexString) {
        if (isHex(hexString)) {
            string binaryString;
            StringSource(hexString, true, new HexDecoder(new StringSink(binaryString)));
            return binaryString;
        } else {
            // it's already binary!
            return hexString;
        }
    }

    static string MREncryptStringAES(string plainText, string key, bool &err, string &errMsg) {
        // returns an encypted string in binary
        // This version will generate a random 16 byte initialization vector (iv) and prepend it to the actual encrypted text
        // Use MRDecryptStringAES to decrypt this string
        // use EncryptStringAES(plainText, key, iv, err) if you have already have an iv you want to use.
        // key can be sent as a true binary "string" or a hex encoded string
        try {
            // get a random iv
            string iv = ByteGen(AES::BLOCKSIZE);    // BLOCKSIZE is in bytes

            // convert the key if it is sent in hex
            key = HexDecode(key);


            string cipherText = EncryptStringAES(plainText, key, iv, err, errMsg);
            if (err) return "ERROR";

            return iv+cipherText;

        } catch (Exception& e) {
            string errText = "Bad encrypt";
            errMsg = e.GetWhat();
            err = true;
            return errText;
        }
    }

    static string EncryptStringAES(string plainText, string key, string iv, bool &err, string &errMsg) {
        // returns an encypted string in binary
        // This version uses the given iv and returns only the cipherText with no prepend
        // use EncryptStringAES(plainText, key, err) if you want a random iv
        // key and iv can be sent as a true binary "string" or a hex encoded string
        try {
            // convert the iv if it is sent in hex
            iv = HexDecode(iv);

            // convert the key if it is sent in hex
            key = HexDecode(key);

            // setup the encyptor
            CBC_Mode< Rijndael >::Encryption e1( (byte *)key.c_str(), key.length(), (byte *)iv.c_str() );
            // Encryption
            string cipherText;
            StringSource( plainText, true,
                         new StreamTransformationFilter( e1, new CryptoPP::StringSink( cipherText )));

            // return the concatated iv and cipherText
            err = false;
            return cipherText;
        } catch (Exception& e) {
            string errText = "Bad encrypt";
            errMsg = e.GetWhat();
            err = true;
            return errText;
        }

    }

    static string MRDecryptStringAES(string ivAndCipherText, string key, bool &err, string &errMsg){
        // returns the decrypted string
        // This version expects a 16-byte initialization vector prepended to the cipherText
        // This is the output generated by MREncryptStringAES
        // ivAndCipherText & key can be given as hex or binary
        try {
            // convert ivAndCipherText as neccessary
            ivAndCipherText = HexDecode(ivAndCipherText);

            // convert key if necessary
            key = HexDecode(key);

            // recover the bits of the message
            string iv;
            iv.assign(ivAndCipherText, 0, 16);
            string cipherText;
            cipherText.assign(ivAndCipherText, 16, string::npos);

            string plainText = DecryptStringAES(cipherText, key, iv, err, errMsg);
            if (err) return "ERROR";

            err = false;
            return plainText;
        } catch (Exception& e) {
            string errText = "Bad decrypt";
            errMsg = e.GetWhat();
            err = true;
            return errText;
        }
    }

    static string DecryptStringAES(string cipherText, string key, string iv, bool &err, string &errMsg){
        // returns the decrypted string
        // This version uses the given iv
        // use DecryptStringAES(cipherText, key, err) if the iv is prepended to the cipherText
        // cipherText, key, and iv can be given as hex or binary
        try {
            // convert ivAndCipherText as neccessary
            cipherText = HexDecode(cipherText);

            // convert key if necessary
            key = HexDecode(key);

            // convert iv if necessary
            if (isHex(iv)) {
                iv = HexDecode(iv);
            }

            // set up decrypter
            CBC_Mode< Rijndael >::Decryption d((byte *)key.c_str(), key.length(), (byte *)iv.c_str());
            // decrypt
            string plainText;
            StringSource( cipherText, true, new StreamTransformationFilter( d, new StringSink( plainText)));
            err = false;
            return plainText;
        } catch (Exception& e) {
            string errText = "Bad decrypt";
            errMsg = e.GetWhat();
            err = true;
            return errText;
        }
    }

    static void EncryptFileAES(istream& inFile, ostream& outFile, string key, string iv, bool &err, string &errMsg) {
        // will encrypt the file at filenameIn to filenameOut using AES
        // WARNING: The iv must be known and retained for decryption!!
        // key and iv can be hex or binary


        // convert the key and iv
        key = HexDecode(key);
        iv = HexDecode(iv);
        try {
            // Set up the encrypter
            CBC_Mode< Rijndael >::Encryption e1( (byte *)key.c_str(), key.length(), (byte *)iv.c_str() );
            // encrypt
            //if (filenameOut == "cout")
            //  FileSource( filenameIn.c_str(), true, new StreamTransformationFilter( e1, new FileSink(cout)));
            //else
                FileSource( inFile, true, new StreamTransformationFilter( e1, new FileSink(outFile)));
            err= false;
            return;
        } catch (Exception& e) {
            errMsg = e.GetWhat();
            err = true;
            return;
        }
    }


    static void MREncryptFileAES(istream& inFile, ostream& outFile, string key, bool &err, string &errMsg) {
        // will encrypt the file at inFile to outFile using AES
        // but, adds a random iv to the beginning of the newly encrypted file which is recovered and used to decrypt it later.
        // Use MRDecryptFileAES to decrypt this file
        // key can be hex or binary
        // programmers job to open and close the istream and ostream correctly!

        string iv = ByteGen(AES::BLOCKSIZE);

        // encrypt the file to temp
        // generate a random file name that is unlikely to conflict with any existing names.
        string tempName = HexEncode(ByteGen(8));
        ofstream tempFile(tempName.c_str(), ios::binary);
        EncryptFileAES(inFile, tempFile, key, iv, err, errMsg);
        if (err) return;
        tempFile.close();

        try {
            // Now open a new file and put the iv in it

            if (!outFile.good()) {
                err = true;
                errMsg = "Couldn't open desired output file";
                return;
            }

            //write the iv to it
            outFile.write(iv.c_str(), iv.length());

            // open the temp file and load into memory..
            ifstream::pos_type size;
            char * memblock;

            ifstream file(tempName.c_str(), ios::binary | ios::ate);
            if (file.is_open()) {
                size = file.tellg();
                memblock = new char [size];
                file.seekg (0, ios::beg);
                file.read (memblock, size);
                file.close();
            } else {
                err = true;
                errMsg = "Couldn't open encrypted temp file";
                return;
            }

            // write the data to the finished file
            outFile.write(memblock, size);

            delete[] memblock;

            // delete the temp file
            remove(tempName.c_str());
            err = false;
            return;

        } catch (std::exception &e) {
            errMsg = e.what();
            err = true;
            return;
        }
    }


    static void DecryptFileAES(istream& inFile, ostream& outFile, string key, string iv, bool &err, string &errMsg) {
        // will encrypt the file at filenameIn to filenameOut using AES
        // WARNING: The correct iv MUST be provided
        // key and iv can be hex or binary

        // convert the key and iv
        key = HexDecode(key);
        iv = HexDecode(iv);

        try {
            // Set up the encrypter
            CBC_Mode< Rijndael >::Decryption d ( (byte *)key.c_str(), key.length(), (byte *)iv.c_str() );
            // encrypt
            //if (filenameOut == "cout")
            //  FileSource( filenameIn.c_str(), true, new StreamTransformationFilter( d, new FileSink(cout)));
            //else
                FileSource( inFile, true, new StreamTransformationFilter( d, new FileSink(outFile)));
            err= false;
            return;
        } catch (Exception& e) {
            errMsg = e.GetWhat();
            err = true;
            return;
        }
    }

    static void MRDecryptFileAES(istream& inFile, ostream& outFile, string key, bool &err, string &errMsg) {
        // Decrypts a file with a iv stored as the initial 16 bytes;
        // This type of file is generated by MREncryptFileAES

        // first, open the file and load into memory..
        ifstream::pos_type size;
        int datasize;
        char * ivblock;
        char * datablock;

        if (inFile.good()) {
            inFile.seekg(0, ios::end);
            size = inFile.tellg();
            inFile.seekg(0, ios::beg);
            datasize = (int)size-16;
            ivblock = new char[16];
            datablock = new char[datasize];
            inFile.read (ivblock, 16);
            inFile.read(datablock, datasize);

        } else {
            err = true;
            errMsg = "Couldn't open encrypted input file";
            return;
        }

        // Make the iv
        string iv;
        iv.assign(ivblock, 16);
        delete[] ivblock;

        //save the rest of the data as a temp file
        // generate a random file name that is unlikely to conflict with any existing names.
        string tempFile = HexEncode(ByteGen(8));
        ofstream tempOut(tempFile.c_str(), ios::binary);
        if (tempOut.is_open()) {
            // save the data here.
            tempOut.write(datablock, (datasize));
            tempOut.close();
            delete[] datablock;
        } else {
            err = true;
            errMsg = "Couldn't create encrypted temporary file";
            delete[] datablock;
            return;
        }

        ifstream tempIn(tempFile.c_str(), ios::binary);
        // Now decrypt the temp file
        DecryptFileAES(tempIn, outFile, key, iv, err, errMsg);

        tempIn.close();
        remove(tempFile.c_str());
        if (err) return;

        err = false;
        return;
    }

    static string BitGen(int howManyBits) {
        // returns a new random key in binary of the given bit length
        int byteLength = howManyBits/8; // bitLengths always better be div 8!!
        return ByteGen(byteLength);
    }

    static string ByteGen(int howManyBytes) {
        // returns a new random key of the given byte length
        AutoSeededRandomPool rnd;
        byte* block = new byte[howManyBytes]; //Correction for VC++ (Will not compile in VC++ without it)
        rnd.GenerateBlock(block, howManyBytes);
        string blockString;
        blockString.assign((char *)block, sizeof(block));
        return blockString;
    }


    static string hashSHA256(string inputString) {
        // returns a SHA-256 encoded hash of the inputString in binary
        // always returns 256 bits
        SHA256 hash;
        byte digest [ SHA256::DIGESTSIZE ];

        hash.CalculateDigest( digest, (byte *)inputString.c_str(), inputString.length() );
        string hashString;
        hashString.assign((char *)digest, sizeof(digest));

        return hashString;
    }

};

#endif