@li0ard/kalyna/dist/padding.js

Kalyna (DSTU 7624:2014) cipher implementation in pure TypeScript

export const pad = (data, blockSize) => {
    const remainder = data.length % blockSize;
    if (remainder === 0)
        return data;
    const padLength = blockSize - remainder;
    const padded = new Uint8Array(data.length + padLength);
    padded.set(data);
    padded[data.length] = 0x80;
    return padded;
};
export const unpad = (paddedData, blockSize) => {
    if (paddedData.length % blockSize !== 0)
        throw new Error("Padded data length must be multiple of block size");
    let i = paddedData.length - 1;
    while (i >= 0 && paddedData[i] === 0)
        i--;
    if (i < 0)
        throw new Error("Padding error: all bytes are zero");
    if (i === paddedData.length - 1)
        throw new Error("Padding error: no padding bytes found");
    return paddedData.slice(0, i + 1);
};