NodeJS Crypto randomBytes to string hex doubling size

Question

I'm experiencing an odd issue using NodeJS crypto and the crypto.randomBtyes function. I've detected strange behaviorthat seems to have only recently appeared in my NodeJS / Typescript 3.2 application.

The error makes sense in its own right: Invalid key length at Cipheriv.createCipherBase (internal/crypto/cipher.js:79:18)

Upon inspecting the key length returned, it is doubling the requested number of bytes. I stated this as "odd" in that it was working previously (as of Thursday/Friday last week (3/7/2019 - 3/8/2019) but as of this morning the new behavior was detected. However, I haven't run any updates since so hopefully I'm missing something obvious. I could change my key size to be half of what I want, however, I wanted to see if I'm overlooking something simple before I implement a hack.

Here is a fairly basic example of my crypto implementation.

import crypto = require('crypto');

export class Encryption {
    static GenerateRandomBytesToHex(size: number): string {
        return crypto.randomBytes(size).toString('hex');
    }
}

However when calling:

let cipherKey = Encryption.GenerateRandomBytesToHex(32);

It is returning a 64 character string rather than a 32 character string.

Example: c8a8437677fcfab679f92c8470ffc34b932f5aaa3296c09f652d2becfe1db8b2 (64 characters in length)

This is an implementation of the concepts outlined in this article: http://vancelucas.com/blog/stronger-encryption-and-decryption-in-node-js/

Any help would be greatly appreciated.

Answer 1

GenerateRandomBytesToHex function returns you a hash that is X Byte long inside of a String where each Byte is displayed in hexadecimal value.

The hexidecimal value of the number 42 is 0x2A. You can see that one Byte (from 0 to 254) is displayed using 2 character in hexadecimal. So it's normal that 32 Byte get displayed as 64 character.

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Exemple : https://codebeautify.org/string-hex-converter