dograma/gramjs/crypto/words.ts

NodeJS/Browser MTProto API Telegram client library,

/*
 * Imported from https://github.com/spalt08/cryptography/blob/master/packages/aes/src/utils/words.ts
 */

export function s2i(str: string, pos: number) {
    return (
        (str.charCodeAt(pos) << 24) ^
        (str.charCodeAt(pos + 1) << 16) ^
        (str.charCodeAt(pos + 2) << 8) ^
        str.charCodeAt(pos + 3)
    );
}

/**
 * Helper function for transforming string key to Uint32Array
 */
export function getWords(key: string | Uint8Array | Uint32Array) {
    if (key instanceof Uint32Array) {
        return key;
    }

    if (typeof key === "string") {
        if (key.length % 4 !== 0)
            for (let i = key.length % 4; i <= 4; i++) key += "\0x00";

        const buf = new Uint32Array(key.length / 4);
        for (let i = 0; i < key.length; i += 4) buf[i / 4] = s2i(key, i);

        return buf;
    }

    if (key instanceof Uint8Array) {
        const buf = new Uint32Array(key.length / 4);

        for (let i = 0; i < key.length; i += 4) {
            buf[i / 4] =
                (key[i] << 24) ^
                (key[i + 1] << 16) ^
                (key[i + 2] << 8) ^
                key[i + 3];
        }

        return buf;
    }

    throw new Error("Unable to create 32-bit words");
}

export function xor(left: Uint32Array, right: Uint32Array, to = left) {
    for (let i = 0; i < left.length; i++) to[i] = left[i] ^ right[i];
}