GCHQ | quality reverb built with the JUCE libraries | Audio Utils library

As your key and ciphertext are in hex encoding you need to convert them back to binary data before you can feed them to the decryption function.

The following code gives this output:

Just remove line breaks and it should work.

RC2 is described in RFC2268. It's a block cipher with variable key length and has an additional parameter called effective key length in bits, see RFC2268, Section 2. In the two codes and on the website, a different effective key length in bits is used, causing the different results.

In the Python code, when using PyCryptodome, the effective key length in bits is specified with the parameter effective_keylen upon creation of the ARC2-cipher instance, which may have values between 40 and 1024, where 1024 is the default value. Since the parameter isn't explicitly specified in the posted Python code, the default value is used. Note that this parameter is described in the PyCrypto documentation, but not in the PyCryptodome documentation.

The ciphertext of the website results for effective_keylen = 128. On the website there seems to be no possibility to change the effective key length in bits.

The ciphertext of the C# code can't be reproduced, probably because the IV isn't set in GetRc2Provider (so that the randomly generated IV is used). If this is fixed, it turns out that the effective key length in bits (RC2CryptoServiceProvider#EffectiveKeySize) is implicitly set to the actual key length. If the parameter is explicitly switched to a another value, a System.Security.Cryptography.CryptographicUnexpectedOperationException: EffectiveKeySize must be the same as KeySize in this implementation. is thrown.

Your hmac step is correct, does have the right output bytes (as commented). The conversion problem you have is caused by non-display chars in the temporary string (the raw bytes were not correctly copied pasted from first webpage to second).

To reproduce the exact output at each stage, you can use these commands below.

In terms of C++, you should try to operate on the raw bytes, rather than on the hex string. Take the raw bytes and run them through a base64 URL-safe encoder. Or, as in the example below, take the raw bytes, run them through a plain base64 encoder, and then fix the generated base64 string to be URL safe.

1. Construct the header

You need to use buffer or utf8 strings as parameters for createCipheriv

This works:

Based on comments, your decompresser is fine. The issue is that you're examining the tree object that refers to subtrees and blobs.

All objects start with a header giving the object's type, and the overall size in bytes but expressed as an ASCII string. So tree 36 indicates that this is a tree, and the tree is 36 bytes long. That's followed by an ASCII NUL, 0x00, or CTRL-@. After that come the tree entries.

Each entry has the form mode space name CTRL-@ hash. The hash is binary, and always exactly 20 bytes long (at least until Git switches to a new hash; how this will be indicated, and encoded, is not yet decided). Your mode is 100644 and your name is main.txt, so you have 6+1+8+1+20 = 36 bytes, which is the length in the header, so that's the entire tree.

With BeautifulSoup & urllib you should be able to collect the images in a webpage, iterate and download them.

Your regex contains 3 groupings, the (..). You can get the middle one either by accessing the index 2 of your results (0 being all, 1 the first grouping etc.), or by using ( ) only around the middle part.

E.g. like:

Use response.text instead of response.content – as noted in the Requests documentation quoted below, this will decode the response content to a Unicode string, using the encoding information provided by the HTTP response:

content

Content of the response, in bytes.

text

Content of the response, in unicode.

If Response.encoding is None, encoding will be guessed using chardet.

The encoding of the response content is determined based solely on HTTP headers, following RFC 2616 to the letter. If you can take advantage of non-HTTP knowledge to make a better guess at the encoding, you should set r.encoding appropriately before accessing this property.

Example: