Can't decrypt using CryptoJS (works in Java, Python)

Question

I have a file that I encrypt using AES. Historically, I've had a set of tools (Java, Python) each of which is capable to both encrypt and decrypt these files. However, I've been having problems decrypting these files using CryptoJS.

The encrypted file has IV stored in the first 16 bytes, the rest is payload. During encryption key is formed by using hashing the password string via SHA-1 and using first 32 characters from the hex digest. I've gotten to the point where I can confirm that both IV and key used by CryptoJS is byte-wise identical to the ones used by other tools yet AES.decrypt() produces a buffer that I can't convert back to text.

Here's the decryption code. content and iv are binary strings read directly from file. password is a string with textual password. The code fails trying to convert the result to UTF8 (which I assume is due to the fact that decryption did not succeed).

function string2bytes(s) {
    var bytes = [];

    for (var i = 0; i < s.length; i++) {
        bytes.push(s.charCodeAt(i));
    }

    return bytes;
}


function decryptData(content, ivx, password) {
    // build a key out of text password
    var key = CryptoJS.SHA1(password).toString(CryptoJS.enc.Hex).substring(0, 32);
    console.log("key0: ", key);

    key = string2bytes(key)
    console.log(key);

    // Convert IV from binary string to WordArray
    var iv = CryptoJS.enc.Latin1.parse(ivx);
    console.log("IV: ", iv.toString(CryptoJS.enc.Hex));


    var decrypted = CryptoJS.AES.decrypt(content, key, { iv: iv });

    console.log("raw decrypted: ", decrypted);
    console.log("decrypted: ", iv.toString(CryptoJS.enc.Latin1));
    console.log("decrypted: ", iv.toString(CryptoJS.enc.Utf8));
}

Any help would be appreciated.

Have you tried CryptoJS.AES.decrypt({ciphertext: content}, key, { iv: iv });. Also, did you already parse content and key to the native CryptoJS representation? Both Java and Python have a million different way of encryption something. Saying "(works in Java, Python)" isn't really saying anything. — Artjom B.
Tried it - getting back an array of 52 words, which converts to an empty string. Data is passed to decrypt as follows: content is a binary string (read from file, basically all file content starting at offset 16), key is a JavaScript array of ints, constructed the following way: password -> SHA-1 digest -> first 32 hex chars -> array of bytes, one for each char. IV is a WordArray built from binary IV string read from file (first 16 chars). — Alexander L. Belikoff

Alexander L. Belikoff Alexander L. Belikoff · Accepted Answer · 2016-03-23T21:21:15

Found a solution by sticking to WordArrays (even for the arguments where a binary string is ostensibly OK): The following function does work. The arguments are as follows:

data is a base64 string with encrypted text
password is a regular string with password
iv is a base64 string with an IV.

so

 function decryptData(data, password, iv) {
    var data = CryptoJS.enc.Base64.parse(data);
    var key = CryptoJS.SHA1(password).toString(CryptoJS.enc.Hex).substring(0, 32);
    key = CryptoJS.enc.Base64.parse(btoa(key));

    var iv  = CryptoJS.enc.Base64.parse(iv);
    var decrypted = CryptoJS.AES.decrypt({ciphertext: data}, key, {iv: iv});
    return decrypted.toString(CryptoJS.enc.Utf8);
}

Can't decrypt using CryptoJS (works in Java, Python)

1 Answers