discrepency between zlib and pako functions

Hello I have in my back end a simple system for encrypting and compressing data.

Backend NodeJS

export const aesEncrypt = (text: string, key: string = ENCRYPTION_KEY) => {
    let iv = randomBytes(IV_LENGTH);
    let cipher = createCipheriv('aes-256-cbc', Buffer.from(key), iv);
    let encrypted = cipher.update(text);
    encrypted = Buffer.concat([encrypted, cipher.final()]);
    return iv.toString('hex') + ':' + encrypted.toString('hex');
}

export const textCompressToBase64Url = (text: string) => {
    return deflateSync(text).toString('base64url')
}

export const packDataForUrl = (data: string, key: string = ENCRYPTION_KEY) => {
    return textCompressToBase64Url(aesEncrypt(data, key))
}

Result string:

eJwVU8cRxDAIbIkowXUjUv8lHP55BoM2Bp_W59hmGWH0DrxKpMlumMlfgAKD2DBKEx0gJs9j2ll-D7Gfl2PAgn1dPN696eDor3dWdR4iHH3hGQRKqKVy790Dneo7VZMEelNVag-n4rKAjhn4NNCiMmqwQ7QHMjgfkk0Rd3GlyviJuxz2zJWh6-_oAd4z9WHQPMhXgQ7P3LkegZHMt9-8h_IA-qSfm5LVIxn3PMJ0DEZSefcNW4CVKMluHkfhqjdIyXSPPWdeJGeJUWjInVq4E3tCClEQq2NSDFfA1QjSi71twSRRoMMk7GtceDIzTCHm9iqjFcB3D0U-N6tTIdnnkpnf_VpHDBJ5VnVZas7DQMVUrUu5TWXZV81j378DjVsYsGhdI7j7my6mFT6HH5dxxusT6_CiKpISF-u3A8U4O-aguJbnMapTBa0R8qEf6iK_GsZoZ89ZuTkBNoCazYWwUR8nQ0jBq9xu6Vr70nMKwAHeXWSNhI4qOS6QjSvtDg_iLoQVRmfAy_RVv3yN7buUFS6MiKCf0yVsgqr8KqYYXf0zR56utsdzXLFGauMhJ7QggHSphe0bwH1DyuQJT-DGAyfgUltmP4JcPUJ0akPPB0NTW6bV-61OIGcSV7N1zcik1_67QIH1c6i3An5X41WgZZfugnkWRxYF-2LxMuskueL8dNV_z7Ub5StKPVmZ2e52Y5M3I905SlaVdG2rF9X5dFg307uxiak2vgYSruvggU07bhP5wV273c6-Z65Zd_mjb0HXXs7pe-mrA-lsHzQZNvp8z2jt4rrID89spGGlyLdsagOyWd-eX13TX1DmNhnRdkMzt0NRHivqORe3nH_9zDtg

I then try to use Pako in the frontend to deflate before doing a AES decrypt however i keep getting various errors: Below is how I convert the base64url to base64 (this works fine)

export const textDecompressFromBase64Url = (text: string) => {
    //@ts-ignore
    const sanitizedbase64 = text.replace(/_/g, '/').replace(/-/g, '+')
    const compressData = sanitizedbase64.split('').map((e) => {
        return e.charCodeAt(0);
    });
    const binData = new Uint8Array(compressData);
    const inflated = inflate(binData, { raw: true }).toString()
    return inflated
}

If I don’t use { raw: true } I get the following error in the inflate method:

incorrect header check

If I pass the {raw: true} I get the following:

invalid code lengths set

In the backend however i’m able to inflate with zlib with no issue:

export const textDecompressFromBase64Url = (text: string) => {
    return inflateSync(Buffer.from(text, 'base64')).toString()
}

[101arrowz]

FWIW I tested this and it works fine equally with fflate.unzlibSync(data) and pako.inflate(data).

const src = `eJwVU8cRxDAIbIkowXUjUv8lHP55BoM2Bp_W59hmGWH0DrxKpMlumMlfgAKD2DBKEx0gJs9j2ll-D7Gfl2PAgn1dPN696eDor3dWdR4iHH3hGQRKqKVy790Dneo7VZMEelNVag-n4rKAjhn4NNCiMmqwQ7QHMjgfkk0Rd3GlyviJuxz2zJWh6-_oAd4z9WHQPMhXgQ7P3LkegZHMt9-8h_IA-qSfm5LVIxn3PMJ0DEZSefcNW4CVKMluHkfhqjdIyXSPPWdeJGeJUWjInVq4E3tCClEQq2NSDFfA1QjSi71twSRRoMMk7GtceDIzTCHm9iqjFcB3D0U-N6tTIdnnkpnf_VpHDBJ5VnVZas7DQMVUrUu5TWXZV81j378DjVsYsGhdI7j7my6mFT6HH5dxxusT6_CiKpISF-u3A8U4O-aguJbnMapTBa0R8qEf6iK_GsZoZ89ZuTkBNoCazYWwUR8nQ0jBq9xu6Vr70nMKwAHeXWSNhI4qOS6QjSvtDg_iLoQVRmfAy_RVv3yN7buUFS6MiKCf0yVsgqr8KqYYXf0zR56utsdzXLFGauMhJ7QggHSphe0bwH1DyuQJT-DGAyfgUltmP4JcPUJ0akPPB0NTW6bV-61OIGcSV7N1zcik1_67QIH1c6i3An5X41WgZZfugnkWRxYF-2LxMuskueL8dNV_z7Ub5StKPVmZ2e52Y5M3I905SlaVdG2rF9X5dFg307uxiak2vgYSruvggU07bhP5wV273c6-Z65Zd_mjb0HXXs7pe-mrA-lsHzQZNvp8z2jt4rrID89spGGlyLdsagOyWd-eX13TX1DmNhnRdkMzt0NRHivqORe3nH_9zDtg`

const decodedbstr = atob(src.replace(/_/g, '/').replace(/-/g, '+'));
const decoded = new Uint8Array(decodedbstr.split('').map(c => c.charCodeAt(0)));

// pako.inflate(decoded) and fflate.unzlibSync(decoded) both work

[puzrin]

See https://github.com/nodeca/pako/blob/master/support/build_fixtures.js#L8-L10 (node should be < v12.17.0). This repo really has appropriate tests. You can just add your fixture, and if problem exists - this will be easy proof of no code mistake at your side.