CODEWITHSUNDEEP
c++encryption
Rocket
Rocket

Reputation: 1093

Storing encrypted string in variable

I'm trying to obscure some code so when complied casual users can't see the plain text strings if they cat the file.

I've found this and it does do what I want.

string encryptDecrypt(string toEncrypt) {
    char key = 'Q';
    string output = toEncrypt;

    for (int i = 0; i < toEncrypt.size(); i++)
        output[i] = toEncrypt[i] ^ key;

    return output;
}

It's run like:

    foo[0] = encryptDecrypt("/path/jon/files");
    cout << "Encrypted:" << foo[0] << "\n";

    string decrypted = encryptDecrypt(foo[0]);
    cout << "Decrypted:" << decrypted << "\n";

Which results in:

Encrypted:~!0%9~;>?~78=4"
Decrypted:/path/jon/files

My plan(!) was to create a new app that just produced the encrypted strings and then in my my app store all the encrypted strings in an array and decrypt then as needed.

From the above output I know the string /path/jon/files is encrypted to ~!0%9~;>?~78=4" but how do I write that into an array?

I had thought:

string foo[2];
foo[0] = "~!0%9~;>?~78=4"";
foo[1] = "XXXXXXX";

But I can't see that working becuase the string contains quotes.

Any way to do this?

UPDATE

I seem to have an issue when I have capital letters in my initial string.

string encrypted = encryptDecrypt("/Path/Jon/Files");
cout << "Encrypted:" << encrypted << "\n";

string decrypted = encryptDecrypt(encrypted);
cout << "Decrypted:" << decrypted << "\n";

string test = "~0%9~?~8=4\"";
decrypted = encryptDecrypt(test);
cout << "Decrypted:" << decrypted << "\n";

Results in:

Encrypted:~0%9~?~8=4"
Decrypted:/Path/Jon/Files
Decrypted:/ath/n/iles

Any idea how to get around that?

Upvotes: 1

Views: 4146

Answers (3)

Persixty
Persixty

Reputation: 8579

You're 'losing' your capitals because you're xoring them with 'Q' and so losing most of their significant bits and they come back as control codes.

Here's a program that encrypts a string as a std::vector<char> for inclusion in your source-code. The problem with your plan to use std::string is some of the values might be invalid characters (e.g. out of place pieces of a UTF-8 multi-byte encoding). The behaviour of std::string containing invalid characters is unspecified. However an `std::vector can contain the full range of byte values.

#include <iostream>
#include <sstream>
#include <vector>

std::vector<char> encrypt(const std::string& toEncrypt) {
    char key = 'Q';
    std::vector<char> output;
    output.reserve(toEncrypt.size());

    for (const auto chr : toEncrypt){
        output.push_back(chr ^ key);
    }
    return output;
}

std::string sourcify(const std::vector<char>& toSource,const std::string& comment){
    
    std::stringstream buffer;
    buffer<<"const std::vector<char> code={";
    bool first=true;
    for(const auto chr : toSource){
        if(!first){
            buffer<<',';
        }else{
            first=false;
        }
        buffer<<static_cast<int>(chr);
    }
    buffer<<"}; /* "<<comment<<" */";
    return buffer.str();
}

std::string decrypt(const std::vector<char>& toDecrypt) {
    char key = 'Q';
    std::string decrypted;
    decrypted.reserve(toDecrypt.size());
    for(const auto chr:toDecrypt){
        decrypted.push_back(chr ^ key);
    }
    return decrypted;
}

int main() {
    
    std::string original="Hello World";
    std::vector<char> encrypted=encrypt(original);
    std::string sourced=sourcify(encrypted,original);
    std::string decrypted=decrypt(encrypted);
    
    std::cout<<original<<std::endl;
    std::cout<<sourced<<std::endl;
    std::cout<<decrypted<<std::endl;
    
    return 0;
}

Upvotes: 1

Tomek Gutkowski
Tomek Gutkowski

Reputation: 3

I have automated my string encryption with:

https://github.com/PELock/StringEncrypt-WebAPI

and it looks like this right now (I took your string so you can see the result)

// encrypted with https://www.stringencrypt.com (v1.3.0) [C/C++]
// foo = "/path/jon/files"
wchar_t foo[16];

foo[8] = 0x29F5; foo[15] = 0x591E; foo[14] = 0x10DF; foo[6] = 0x28D7;
foo[2] = 0x538B; foo[12] = 0x5691; foo[7] = 0x2996; foo[1] = 0x240C;
foo[4] = 0x29D9; foo[13] = 0x5890; foo[10] = 0x5553; foo[3] = 0x2B2A;
foo[0] = 0x518D; foo[9] = 0x54F4; foo[5] = 0x57B8; foo[11] = 0x5472;

for (unsigned int vHlTZ = 0, WgRam = 0; vHlTZ < 16; vHlTZ++)
{
        WgRam = foo[vHlTZ];
        WgRam += vHlTZ;
        WgRam ^= 0x4EE7;
        WgRam = (((WgRam & 0xFFFF) >> 6) | (WgRam << 10)) & 0xFFFF;
        WgRam ^= 0xF4F6;
        WgRam += vHlTZ;
        WgRam ^= vHlTZ;
        WgRam = ~WgRam;
        WgRam = ((WgRam << 14) | ( (WgRam & 0xFFFF) >> 2)) & 0xFFFF;
        WgRam += vHlTZ;
        WgRam = ((WgRam << 4) | ( (WgRam & 0xFFFF) >> 12)) & 0xFFFF;
        WgRam -= 0x184C;
        WgRam ^= 0xDE4A;
        WgRam += 0x5463;
        WgRam += vHlTZ;
        foo[vHlTZ] = WgRam;
}

wprintf(foo);

It works like this:

  1. Provide string label
  2. Set string / file to encrypt
  3. String is encrypted with random algorithm
  4. Decryption code is generated in C/C++

Upvotes: 0

oklas
oklas

Reputation: 8220

escape it

foo[0] = "~!0%9~;>?~78=4\"";

need to be carfully with this, charachter encoding and code pages may joke with you.

UPD: possible will be actual links base64 encode-decode How do I base64 encode (decode) in C? and base64 decode snippet in c++

Upvotes: 2

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