Strange Bug

[Timothee Cour via Digitalmars-d-learn]

This and some other recent posts (`Is this a bug?`, `Hopefully a simple
question...`). If you want help (and help other ppl who search for similar
issues), could you please make the subject more descriptive?



On Fri, Jan 20, 2017 at 12:19 AM, Chris M. via Digitalmars-d-learn <
digitalmars-d-learn at puremagic.com> wrote:

> I have no idea if this is an issue with D, or OpenSSL, or if I'm just
> doing something completely wrong. I'm writing a program that will either
> encrypt or decrypt a string using AES in ECB mode (for a school assignment)
> and it's giving me a very strange bug.
>
> encrypt and decrypt are both bools, either one or the other is set based
> on command-line arguments passed to the program. aesKey is a 128-bit value
> hashed from user input, and is (obviously) used as the key for encryption.
> inputStr is either the string to be encrypted or decrypted (also passed in
> as a command-line argument). I grabbed the OpenSSL bindings from Deimos to
> do this.
>
> 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 if(decrypt) // I'd leave this as else, but it's here for explanation
> purposes
> {
>     AES_KEY decKey;
>     auto decLength = Base64.decodeLength(inputStr.length);
>     auto decB64 = new ubyte[decLength], decOut = new ubyte[decLength];
>
>     // convert back from base64 and decrypt
>     decB64 = Base64.decode(inputStr); // Yes I checked, and decB64 has
> exact the same contents as encOut from the if block
>     AES_set_decrypt_key(aesKey.ptr, aesKey.sizeof * 8, &decKey);
>     AES_ecb_encrypt(decB64.ptr, decOut.ptr, &decKey, AES_DECRYPT);
>     writeln(cast(char[]) decOut);
> }
>
> However, this isn't working for a very strange reason (spits back garbage
> instead of the string I originally encrypted).
>
> Here's the problem. I tried running this without the if-else statements
> (i.e. encrypting and decrypting all in one run of the program, code below).
> If I leave in the base64 encoding and decoding, and use decB64 as the input
> to decrypt, it still doesn't work. However, if I decrypt with encOut
> directly, or assign encOut to decB64, it somehow works.
>
> 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);
>
> auto decLength = Base64.decodeLength(Base64.encode(encOut).length);
> AES_KEY decKey;
> auto decB64 = new ubyte[decLength], decOut = new ubyte[decLength];
>
> // convert back from base64 and decrypt
> decB64 = Base64.decode(Base64.encode(encOut));
> // doesn't work unless I uncomment out the following line, or just use
> encOut directly
> //decB64 = encOut;
> AES_set_decrypt_key(aesKey.ptr, aesKey.sizeof * 8, &decKey);
> AES_ecb_encrypt(decB64.ptr, decOut.ptr, &decKey, AES_DECRYPT);
> writeln(cast(char[]) decOut);
>
> tl;dr The decryption doesn't work unless I pass it the exact same buffer
> (including not only contents, but apparently the exact same memory address)
> that I used to receive output from encryption
>
> Does anyone have any idea where the issue may lie, or how I could fix this?
>
> Here's the full program if you want to take a look
> http://pastebin.com/KyY103Ac
>
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