Encryption

// aes.d
// Grabbed these bindings from Deimos
module aes;

enum AES_ENCRYPT = 1;
enum AES_DECRYPT = 0;

enum AES_MAXNR = 14;
enum AES_BLOCK_SIZE = 16;

extern (C):

struct aes_key_st
{
    version (AES_LONG)
    {
        c_ulong[4* (AES_MAXNR + 1)] rd_key;
    }
    else
    {
        uint[4* (AES_MAXNR + 1)] rd_key;
    }
    int rounds;
};
alias aes_key_st AES_KEY;

int AES_set_encrypt_key(const(ubyte)* userKey, const int bits, AES_KEY* key);
int AES_set_decrypt_key(const(ubyte)* userKey, const int bits, AES_KEY* key);
void AES_ecb_encrypt(const(ubyte)* in_, ubyte* out_, const(AES_KEY)* key, const int enc);

// encrypt.d
// compile with dmd -ofencrypt -L-lssl -L-lcrypto encrypt.d aes.d
import std.stdio;

void usage()
{
    writeln("Usage: encrypt [options] string");
    writeln("Options:");
    writeln("-e, --encrypt Encrypt string");
    writeln("-d, --decrypt Decrypt string");
    writeln("-h, --help    Display this help");
    writeln("\nEither --encrypt or --decrypt must be specified, but not both");
}

// Kill the program
void end()
{
    import core.runtime: Runtime;
    import core.stdc.stdlib: exit;
    Runtime.terminate();
    exit(1);
}

void main(string[] args)
{
    import std.getopt;
    import std.string;
    import std.digest.sha;
    import std.conv;
    import std.base64;
    import aes;

    bool encrypt, decrypt, help;

    getopt(args, config.passThrough, "e|encrypt", &encrypt, "d|decrypt", &decrypt, "h|help", &help);

    // Check command line options
    if(args.length != 2 || help || !(encrypt ^ decrypt))
    {
        usage();
        end();
    }

    // The string to be encrypted needs to be converted to an array of ubytes
    ubyte[] inputStr = cast(ubyte[]) args[1];

    // Get password, which is used as the 128-bit key
    write("Password: ");
    ubyte[16] aesKey = readln.chomp.sha256Of.halve();

    if(encrypt)
    {
        AES_KEY encKey;
        auto encOut = new ubyte[inputStr.length];

        // Encrypt and convert to base64
        AES_set_encrypt_key(aesKey.ptr, aesKey.sizeof * 8, &encKey);
        AES_ecb_encrypt(inputStr.ptr, encOut.ptr, &encKey, AES_ENCRYPT);
        writeln(Base64.encode(encOut));
    }
    else
    {
        auto decLength = Base64.decodeLength(inputStr.length);
        AES_KEY decKey;
        auto decB64 = new ubyte[decLength], decOut = new ubyte[decLength];

        // convert back from base64 and decrypt
        decB64 = Base64.decode(inputStr);
        AES_set_decrypt_key(aesKey.ptr, aesKey.sizeof * 8, &decKey);
        AES_ecb_encrypt(decB64.ptr, decOut.ptr, &decKey, AES_DECRYPT);
        writeln(cast(char[]) decOut);
    }
}