node.js zlib returning 'Check Headers' error when gunzipping stream - node.js

Question

So I am working on the nodeschool.io stream-adventure tutorial track and I'm having trouble with the last problem. The instructions say:
An encrypted, gzipped tar file will be piped in on process.stdin. To beat this
challenge, for each file in the tar input, print a hex-encoded md5 hash of the
file contents followed by a single space followed by the filename, then a
newline.
You will receive the cipher name as process.argv[2] and the cipher passphrase as
process.argv[3]. You can pass these arguments directly through to
`crypto.createDecipher()`.
The built-in zlib library you get when you `require('zlib')` has a
`zlib.createGunzip()` that returns a stream for gunzipping.
The `tar` module from npm has a `tar.Parse()` function that emits `'entry'`
events for each file in the tar input. Each `entry` object is a readable stream
of the file contents from the archive and:
`entry.type` is the kind of file ('File', 'Directory', etc)
`entry.path` is the file path
Using the tar module looks like:
var tar = require('tar');
var parser = tar.Parse();
parser.on('entry', function (e) {
console.dir(e);
});
var fs = require('fs');
fs.createReadStream('file.tar').pipe(parser);
Use `crypto.createHash('md5', { encoding: 'hex' })` to generate a stream that
outputs a hex md5 hash for the content written to it.
This is my attempt so far to work on it:
var tar = require('tar');
var crypto = require('crypto');
var zlib = require('zlib');
var map = require('through2-map');
var cipherAlg = process.argv[2];
var passphrase = process.argv[3];
var cryptoStream = crypto.createDecipher(cipherAlg, passphrase);
var parser = tar.Parse(); //emits 'entry' events per file in tar input
var gunzip = zlib.createGunzip();
parser.on('entry', function(e) {
e.pipe(cryptoStream).pipe(map(function(chunk) {
console.log(chunk.toString());
}));
});
process.stdin
.pipe(gunzip)
.pipe(parser);
I know it's not complete yet, but my issue is that when I try to run this, the input never gets piped to the tar file parsing part. It seems to hang up on the piping to gunzip. This is my exact error:
events.js:72
throw er; // Unhandled 'error' event
^
Error: incorrect header check
at Zlib._binding.onerror (zlib.js:295:17)
I'm totally stumped because the node documentation for Zlib has no mention of headers except for when it has examples with the http/request modules. There are a number of other questions regarding this error with node, but most use buffers rather than streams, so I couldn't find a relevant answer to my problem. All help is greatly appreciated

Answer 1

I actually figured it out, I was supposed to decrypt the stream before unzipping it.
So instead of:
process.stdin
.pipe(gunzip)
.pipe(parser);
it should be:
process.stdin
.pipe(cryptoStream)
.pipe(gunzip)
.pipe(parser);