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Ahoy there! My first posting, be gentle!

Windows 7 SrvPck 1, node v0.12.3, npm 2.9.1, aes256 cipher

This is throwing me... it's also throwing a very basic error when I retrieve sample data from a client using TCP. My test configuration is on Windows 7 SrvPck 1 with node v0.12.3 and npm 2.9.1. My client/server are on the same Windows machine with port 5000 as the server.

This inquiry is based on this posting which I found very informative - I'm new to node.js and crypto! Unfortunately I've been unable to decrypt any message from the client without the encountering the following error:

crypto.js:202 var ret = this._handle.final(); ^ Error: error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt at Error (native) at Decipher.Cipher.final (crypto.js:202:26) at decrypt (C:\Users\ChromaBurst\decryptserver.js:26:27) at Socket. (C:\Users\ChromaBurst\decryptserver.js:71:23) at Socket.emit (events.js:107:17) at readableAddChunk (_stream_readable.js:163:16) at Socket.Readable.push (_stream_readable.js:126:10) at TCP.onread (net.js:538:20)

To illustrate the problem, I've included a paired down version of the client/server example. I can only get the server-side to decrypt correctly when I encrypt and then decrypt twice the received buffer from the client! Yes, this doesn't make sense!

I'm using the following on the client side:

client.connect(PORT, HOST, function() { . . client.write(encryptedText);
. . });

Can someone shed some light on this basic example... so I can preserve my sanity?

-ChromaBurst

decryptserver.js

// Load the TCP Library net = require('net'); // Load the Crypto Module var crypto = require("crypto"); //var encString=req.query.d; //console.log(encString); var msg = '{"resTemp":"82.19","roomTemp":98,"ph":58,"ec":700}>'; var key = new Buffer('85CE6CCF67FBBAA8BB13479C3A6E084D', 'hex'); function encrypt(key, data) { var cipher = crypto.createCipher('aes256', key); var crypted = cipher.update(data, 'utf-8', 'hex'); crypted += cipher.final('hex'); return crypted; } function decrypt(key, data) { var decipher = crypto.createDecipher('aes256', key); var decrypted = decipher.update(data, 'hex', 'utf-8'); decrypted += decipher.final('utf-8'); return decrypted; } // Keep track of the chat clients var clients = []; // Start a TCP Server net.createServer(function (socket) { // Identify this client socket.name = socket.remoteAddress + ":" + socket.remotePort //socket.setEncoding('hex'); DEBUG // Put this new client in the list clients.push(socket); // Send a nice welcome message and announce socket.write("Welcome " + socket.name + "\n"); broadcast(socket.name + " joined the chat\n", socket); console.log("\r\n"); /*********************************************************************************************/ // Handle incoming messages from clients. socket.on('data', function (data) { //console.log(data); //console.log("recv encrypted msg: " + data); //console.log("\r\n"); // Attempt to decrypt data with the above key var decryptedText = decrypt(key, data); // <---- bad decrypt if <data> is decryted here // By commenting out the decrypt function call above and uncommenting the next block works correctly! /* var test1=encrypt(key, data); // we have received the client msg, encrypt! console.log(test1+"\r\n"); var test2=decrypt(key, test1); console.log(test2+"\r\n"); var test3=decrypt(key, test2); // decrypt twice, yields original client msg! Correct! console.log("check decrypt: "+test3+"\r\n"); */ console.log(decryptedText); broadcast(socket.name + "> " + decryptedText, socket); }); /*********************************************************************************************/ // Remove the client from the list when it leaves socket.on('end', function () { clients.splice(clients.indexOf(socket), 1); broadcast(socket.name + " left the chat.\n"); console.log(socket.name + " left the chat.\n"); }); // Send a message to all clients function broadcast(message, sender) { clients.forEach(function (client) { // Don't want to send it to sender if (client === sender) return; client.write(message); }); // Log it to the server output too process.stdout.write(message) } }).listen(5000); // Put a friendly message on the terminal of the server. console.log("Chat server running at port 5000\n");

encryptclient.js

 // JSON test string - {"resTemp":"82.19","roomTemp":98,"ph":58,"ec":700}> // Load the TCP Library net = require('net'); // Load the Crypto Module var crypto = require("crypto"); //var ciphers = crypto.getCiphers(); //console.log(ciphers); // ['AES-128-CBC', 'AES-128-CBC-HMAC-SHA1', ...] //var HOST = '192.168.0.39'; var HOST = 'localhost'; var PORT = 5000; /*********************************************************************************************/ function encrypt(key, data) { var cipher = crypto.createCipher('aes256', key); var crypted = cipher.update(data, 'utf-8', 'hex'); crypted += cipher.final('hex'); return crypted; } function decrypt(key, data) { var decipher = crypto.createDecipher('aes256', key); var decrypted = decipher.update(data, 'hex', 'utf-8'); decrypted += decipher.final('utf-8'); return decrypted; } /*********************************************************************************************/ var client = new net.Socket(); client.connect(PORT, HOST, function() { console.log('CONNECTED TO: ' + HOST + ':' + PORT); // Write a message to the socket as soon as the client is connected, the server will receive it as message from the client console.log("########################################################"); var msg = '{"resTemp":"82.19","roomTemp":98,"ph":58,"ec":700}>' var key = new Buffer('85CE6CCF67FBBAA8BB13479C3A6E084D', 'hex'); console.log("msg: " + msg); console.log(key); console.log("########################################################\r\n"); // Attempt to encrypt data with the above key var encryptedText = encrypt(key, msg); console.log("sent encrypted msg: " + encryptedText); console.log("\r\n"); //console.log(encryptedText); DEBUG //console.log("\r\n"); // client.write(msg); DEBUG client.write(encryptedText); console.log("########################################################"); console.log("check decrypted msg: " + decrypt(key, encryptedText)); }); /*********************************************************************************************/ // Add a 'data' event handler for the client socket // data is what the server sent to this socket client.on('data', function(data) { console.log("\r\n"); console.log('Server Response: ' + data); // Close the client socket completely client.destroy(); }); /*********************************************************************************************/ // Add a 'close' event handler for the client socket client.on('close', function() { console.log('Connection closed'); });

Server Output - NOT WORKING!

C:\Users\ChromaBurst>node decryptserver_minimal.js Chat server running at port 5000 ::ffff:127.0.0.1:2617 joined the chat crypto.js:202 var ret = this._handle.final(); ^ Error: error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decrypt at Error (native) at Decipher.Cipher.final (crypto.js:202:26) at decrypt (C:\Users\ChromaBurst\decryptserver_minimal.js:24:27) at Socket.<anonymous> (C:\Users\ChromaBurst\decryptserver_minimal.js:58:21) at Socket.emit (events.js:107:17) at readableAddChunk (_stream_readable.js:163:16) at Socket.Readable.push (_stream_readable.js:126:10) at TCP.onread (net.js:538:20) C:\Users\ChromaBurst>

Server Output - CORRECT

C:\Users\ChromaBurst>node decryptserver_minimal_working.js Chat server running at port 5000 ::ffff:127.0.0.1:2648 joined the chat 794795812eb088f315ad9896c07930cb70db6f56a00e712a7df6ead5574b9ce98b39de0a5d25637e 8203b94e2592104e0c4429a4e322c703b0c3cf8fdd3b8d45d13d8459bb38ac224fd05f6961c7a4e1 eab0567a7330db46e43e088f1873d031d7c114056f019b4e4c575c4ffb7931d2313b0c7db6eef61b 39ce0de5614d81deca51480c497ba564fce5d3c8683806cd 21a9de41435c9e497a9775985cfd9bf2cdef139f692a62391171ed445e93dc7481e5b1ea4595e09d 042ea4b84a6a8657f9e401ec9109973fb02cc3403926ff27 check decrypt: {"resTemp":"82.19","roomTemp":98,"ph":58,"ec":700}> ::ffff:127.0.0.1:2648> {"resTemp":"82.19","roomTemp":98,"ph":58,"ec":700}>::ffff :127.0.0.1:2648 left the chat. ::ffff:127.0.0.1:2648 left the chat.

Client Output

C:\Users\ChromaBurst>node encryptclient.js CONNECTED TO: localhost:5000 ######################################################## msg: {"resTemp":"82.19","roomTemp":98,"ph":58,"ec":700}> <Buffer 85 ce 6c cf 67 fb ba a8 bb 13 47 9c 3a 6e 08 4d> ######################################################## sent encrypted msg: 21a9de41435c9e497a9775985cfd9bf2cdef139f692a62391171ed445e93 dc7481e5b1ea4595e09d042ea4b84a6a8657f9e401ec9109973fb02cc3403926ff27 ######################################################## check decrypted msg: {"resTemp":"82.19","roomTemp":98,"ph":58,"ec":700}> Server Response: Welcome ::ffff:127.0.0.1:20809 Connection closed
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1 Answer 1

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The problem appears to be the fact that data being passed to the decrypt method is a Buffer, not a hex string.

Try replacing:

var decryptedText = decrypt(key, data);

With:

var decryptedText = decrypt(key, data.toString('utf-8'));

And it seems to work fine.

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4 Comments

Thanks. Yes, my mistake! var out = decrypt(key, encrypted); should read... console.log("decrypt: " + decryptedText); broadcast(socket.name + "> " + decryptedText, socket); I checked the scope, I think it's okay but it still yields the same "Error: error:06065064:digital envelope routines:EVP_DecryptFinal_ex:bad decryperror" error unfortunately:
@ChromaBurst I've had another look at the issue and believe I've determined the problem (it now works on my machine when I test it after making the change suggested in my (new) answer!)
@chromaburst did you see my updated answer? It should resolve your problem if you make the change it now describes.
Yes, it did! I didn't realize it required a buffer. Thanks for your help.

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