Develop Reference

JSEncrypt into Python

I'm reverse engineering a website. In website's code,
C = n("720d")
w = new C["JSEncrypt"];
w.setPublicKey(k.privateKey);
k = {
privateKey: "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",
encrypt: function() {
var e = arguments.length > 0 && void 0 !== arguments[0] ? arguments[0] : "";
return w.encrypt(e)
}
They defined w and k as above, and encrypt string with it like below.
k.encrypt("text goes here")
And encrypted output is below.
zrvsLtC+A+Ix8Dq/BoRqwRLaI72zOK0TgpJ7KdXEF6spBMYyv6boOzN0yhxA1cKCAImWsaFT7/JRTbBNj40b+qREkE7aNo9gymM4kHH/+u4oFm+2+vLZXBAWGApt9g585tpVLbwOa6ANE2CBLOt8MeZl4smteJq5rKMddRtDosodfdZWTTt8aTbJrgCgkFPzNyYmN+koxwsbZ1VW2MmLtCnIlEIZfDkOkU0WWzcOylLlpG6/Gs0LkRzsY8HoG4ttY0prb8JDlFcuSi+tdLptoSMABJlXZ0mZOAmcElye47QWlq3RlaxF8saJAjthJpsZABiwIRaVUt/X7i6Uunen9A==
I'm pretty sure that w is just JSEncrypt. Seems like when a string is given, It just encrypt string with JSEncrypt which has k.privateKey as public key.
I want to achieve the same thing with Python 3.
from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_v1_5 as Cipher_PKCS1_v1_5
from base64 import b64decode,b64encode
pubkey = "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"
msg = "text goes here"
keyDER = b64decode(pubkey)
keyPub = RSA.importKey(keyDER)
cipher = Cipher_PKCS1_v1_5.new(keyPub)
cipher_text = cipher.encrypt(msg.encode())
emsg = b64encode(cipher_text)
print(emsg)
I'm trying with PyCrypto library, but since the public key looks different from others, error occurs.
Traceback (most recent call last):
File "/Users/pi/Desktop/test/app.py", line 13, in <module>
keyPub = RSA.importKey(keyDER)
File "/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/site-packages/Crypto/PublicKey/RSA.py", line 682, in importKey
raise ValueError("RSA key format is not supported")
ValueError: RSA key format is not supported
How can I achieve the same thing what JSEncrypt does with Python?

TripleDES Java Encryprion to Javascript Decryption

I am using Java to encrypt a text payload with Triple DES. First I create an ephemeral key that I will use for encrypting the payload:
private byte[] createEphemeralKey() throws Exception {
KeyGenerator keygen = KeyGenerator.getInstance("DESede");
keygen.init(168);
return keygen.generateKey().getEncoded();
}
Then I encrypt my payload with said key:
private String encryptTripleDES(byte[] ephemeralKey, String payload) throws Exception {
Cipher cipher = Cipher.getInstance("DESede/ECB/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(ephemeralKey, "DESede"));
byte[] plainTextBytes = payload.getBytes();
byte[] cipherText = cipher.doFinal(plainTextBytes);
return Base64.getEncoder().encodeToString(cipherText);
}
Also need a padding function to ensure the data length is divisable by 8:
private String adjustPadding(String input, int blockSize) {
int len = input.length() % blockSize;
int paddingLength = (len == 0) ? 0 : (blockSize - len);
while (paddingLength > 0) {
input += "F";
paddingLength--;
}
return input;
}
And here is my process end to end:
String data = "Marnus"
byte[] = ephemeralKey = createEphemeralKey();
String adjustedData = adjustPadding (data,8);
String encryptedPayload = encryptTripleDES(ephemeralKey, adjustedData);
String encodedKey = Base64.getEncoder().encodeToString(ephemeralKey)
So I take the 2 variables encryptedPayload and encodedKey, that are both Base64 encoded string, and send it off via HTTP to node express app.
In the Javascript side of things, I use node-forge - Here is the part of my express app that does the decryption:
let nodeBuffer = Buffer.from(data, 'base64')
let input = forge.util.createBuffer(nodeBuffer.toString('binary'))
// 3DES key and IV sizes
let keySize = 24;
let ivSize = 8;
let derivedBytes = forge.pbe.opensslDeriveBytes(ephemeralKey, null, keySize + ivSize);
let buffer = forge.util.createBuffer(derivedBytes);
let key = buffer.getBytes(keySize)
let iv = buffer.getBytes(ivSize)
let decipher = forge.cipher.createDecipher('3DES-ECB', key)
decipher.start({iv: iv})
decipher.update(input)
console.log('decipher result', decipher.finish())
let decryptedResult = decipher.output.data;
Here is an Triples DES example in the node-forge docs:
A few notes:
I create a node-forge buffer from a regular buffer since I don't have a input file like the examples gives. Here is how the docs states one should create one buffer from the other:
*I use base64 as that is what I used in the java side to encode the data that was sent.
Then, I dont have a salt so I left the 2'nd param null in opensslDeriveBytes as specified in the docs I should do.
Thirdly, I am also not sure if my keysize of 24 is correct?
My results
So doing an end to end test yields the following:
In my Java app, the test data was "Marnus", the encryptedPayload was ez+RweSAd+4= and the encodedKey was vCD9mBnWHPEBiQ0BGv7gc6GUCOoBgLCu.
Then in my javascript code data was obviously ez+RweSAd+4=(encryptedPayload) and the ephemeralKey was vCD9mBnWHPEBiQ0BGv7gc6GUCOoBgLCu(encodedKey).
After the decryption ran, the value of decryptedResult was ©ýÕ?µ{', which is obviously just garbage since it was not encoded yet, but I cant figure out which encoding to use?
I tried using forge.util.encode64(decipher.output.data), but that just gave me qf3VP7UYeyc=, which is not right.
For what it's worth, here is the type that decipher.output

With a lot more tweaking and testing different options, I got it working - and the good news is I managed to get it all working with the built in crypto library in nodejs (v12.18.4).
First things first, the JAVA side just needs a change to the key size (from 168 to 112), the rest remains the same - see below example as one single method (should be split up in final implementation of course for testability and usability):
//Some data:
String payload = "{\"data\":\"somedata\"}";
// Create Key
KeyGenerator keygen = KeyGenerator.getInstance("DESede");
keygen.init(112);
byte[] ephemeralKey = keygen.generateKey().getEncoded();
// Adjust the data, see adjustPadding method in the question for details.
String data = adjustPadding (payload,8);
// Wil now be "{"data":"somedata"}FFFFF", can just chop off extra in JS if need be. When sending JSON one knows the end of the object will always be "}"
// Do Encrypt
Cipher cipher = Cipher.getInstance("DESede/ECB/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(ephemeralKey, "DESede"));
byte[] plainTextBytes = data.getBytes();
byte[] cipherText = cipher.doFinal(plainTextBytes);
String encryptedPayload = Base64.getEncoder().encodeToString(cipherText);
//Lastly, Base64 the key so you can transport it too
String encodedKey = Base64.getEncoder().encodeToString(ephemeralKey)
on the Javascript side of things we keep it simple:
// I'm using TS, so change the import if you do plain JS
import crypto = require('crypto')
//need bytes from the base64 payload
let buff = Buffer.from(ephemeralKey, 'base64')
const decipher = crypto.createDecipheriv('des-ede3', buff, null)
decipher.setAutoPadding(false)
let decrypted = decipher.update(data, 'base64', 'utf8')
decrypted += decipher.final('utf8')
console.log(decrypted)
//{"data":"somedata"}FFFFF"

Using CryptoJS to encrypt and Aes Manager to decrypt

I am using CryptoJS to encrypt a message and send it to the server, and decrypting it on the other end in C# using Aes Manager. I get a response back when I send it to the server, but it isn't correct.
Javascript:
this.CryptoJS=require("crypto-js");
var temp=this.CryptoJS.AES.encrypt("hello","yyyyyyyyyyyyyyyyyyyyyyyyyyyyykey",{
keySize:128/8,
iv:this.CryptoJS.enc.Utf8.parse("helllooohelllooo"),
mode:this.CryptoJS.mode.CBC,
padding:this.CryptoJS.pad.ZeroPadding
});
data.text=temp.toString(); // This is how I send it to the server
C#:
byte[] Key = UTF8Encoding.UTF8.GetBytes("yyyyyyyyyyyyyyyyyyyyyyyyyyyyykey");
byte[] toBytes = UTF8Encoding.UTF8.GetBytes("helllooohelllooo");
AesManaged aes = new AesManaged();
aes.Key = Key;
aes.IV = toBytes;
aes.Padding = PaddingMode.Zeros;
aes.Mode = CipherMode.CBC;
aes.KeySize = 128;
aes.BlockSize = 128;
byte[] bytes = Convert.FromBase64String(data.text);
UTF8Encoding utf8 = new UTF8Encoding();
using (ICryptoTransform decryptor = aes.CreateDecryptor(aes.Key, aes.IV))
{
MemoryStream MS = new MemoryStream(bytes);
CryptoStream CS = new CryptoStream(MS, decryptor, CryptoStreamMode.Write);
CS.Write(bytes, 0, bytes.Length);
CS.FlushFinalBlock();
MS.Position = 0;
bytes = new byte[MS.Length];
MS.Read(bytes, 0, bytes.Length);
Plaintext = utf8.GetString(bytes);
var temp = 5;
}
This is what I get as a result from the Plaintext variable: t�k�\a``\u007f������\f^,F~\u0017�\u001fp��#5�\u007f\\

You should explicitly pass the key, plaintext and IV as binary data rather than strings:
let iv = CryptoJS.enc.Utf8.parse("helllooohelllooo");
let pt = CryptoJS.enc.Utf8.parse("hello");
let key = CryptoJS.enc.Utf8.parse("yyyyyyyyyyyyyyyyyyyyyyyyyyyyykey");
Then use in the code like so:
CryptoJS.AES.encrypt(pt, key, ...);
Note that your use of zero padding, fixed IV, and no HMAC or AEAD mode makes the code you have completely insecure. You definitely should not use it. Consult this GitHub repository for examples of secure encryption between JavaScript and C#.

I was able to fix my problem i was not converting the original key to utf8 and once i did that it fixed itself
Resource

Encrypt in VB.NET Rijndael Managed and Decrypt in Javascript CryptoJS

I'm making an app that has to decrypt QRs and well... It doesn't, because i get the QR string but i cannot decrypt it.
I'm using this encryption method in VB.NET, and it works perfectly when i read an decrypt from VB.NET:
Private Function GetCodedQR(ByVal str As String) As String
Dim sToEncrypt As String = str
Dim encrypted() As Byte
' Create an Rijndael object
' with the specified key and IV.
Using rijAlg = Rijndael.Create()
rijAlg.Padding = PaddingMode.Zeros
rijAlg.Mode = CipherMode.CBC
rijAlg.KeySize = 256
rijAlg.BlockSize = 256
rijAlg.Key = System.Text.Encoding.ASCII.GetBytes("12345678912345678912345678912345")
rijAlg.IV = System.Text.Encoding.ASCII.GetBytes("123452hheeyy66#cs!9hjv887mxx7#8y")
' Create an encryptor to perform the stream transform.
Dim encryptor As ICryptoTransform = rijAlg.CreateEncryptor(rijAlg.Key, rijAlg.IV)
' Create the streams used for encryption.
Using msEncrypt As New MemoryStream()
Using csEncrypt As New CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write)
Using swEncrypt As New StreamWriter(csEncrypt)
'Write all data to the stream.
swEncrypt.Write(sToEncrypt)
End Using
encrypted = msEncrypt.ToArray()
End Using
End Using
End Using
sToEncrypt = Convert.ToBase64String(encrypted)
Return sToEncrypt
End Function
But when im using JS (CryptoJS) to decrypt the message it just dont work!
var iv = CryptoJS.enc.Utf8.parse('123452hheeyy66#cs!9hjv887mxx7#8y');
var decrypted = CryptoJS.AES.decrypt(encrypted, '12345678912345678912345678912345', { iv: iv, mode: CryptoJS.mode.CBC, padding: CryptoJS.pad.ZeroPadding });
Please help me I'm doing my best but JS is not my thing.

python decrypt a text encrypted in jsencrypt

In a web form the answers (packed in a jsonstring) are encrypted in several steps. First a random key is generated. Second the random key is used for AES encryption of the jsonstring. The random key is encrypted as well. Both are send in the body of a mail.
// Generate Random key
var rand_key = ('0000' + Math.random().toString(36).replace('.', '')).substr(-10);
console.log('rand_key', rand_key)
//var pubkey = "MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBALDjeFwFNhMCjMwcRVVKG1VvfsntEVPR3lNTujJnNk1+iSqZ4Tl5Lwq9GbwO+qlYVwXHNmeqG7rkEhL9uyDIZVECAwEAAQ=="
// rsa_key_public07012016.bin
//var pubkey = "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCv8FVei4Q2ehmYsSCv/uODSojIOGHwfQe686S1cEH5i/1mGME5ZzNqyy0d+lhMRD0tr7Sje7JoCEC/XRIZaiKJjpl1+3RXotf/Cx3bd9H7WtitshZB1m38ZZFsrX4oigMpUPFbCefMeBS4hvvNnmtl08lQGhfIXdXeflZsgWRHtQIDAQAB";
// my_pub_key.pem
var pubkey ="MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA38gtENP9/hpirSCIsPh6CAVm0UmME4XBlPyK8yhwk079EUJpNzlEhu9HKcA/B7Fxo2lNoY9Tb9e+PYtJ6+VOB4+Y6zgGMX7cchYmumKRTbbQ6FNfBE5Q8XnOAUlgC7gNrs0e5lW7JH1kWlK+eTT4TANT7F3US09aXmym+fZaRInbXmJujGnDIbRIIbzr5FE82EeMpw2TqRWV466wz5EeFWSSQ8EqV1pSox8B1ywb6cnB/Vofs2qR9Zf2efi9TMcSGm/ij/p9IZcbLeep9qfGsv29lbLNMfwNwQyH0JU27eAM4tPdirceZPxfD6iiILmKzN253BMoAeQCp6us53CnGQIDAQAB"
// Make form_data a JSON string
var jsonstring = JSON.stringify(form_data);
// Create AES encrypted object
var aes_encrypted_json = CryptoJS.AES.encrypt(jsonstring, rand_key);
// Encrypt rand_key
var encrypt = new JSEncrypt();
//console.log('encrypt obj', encrypt);
encrypt.setPublicKey(pubkey);
var encrypted_rand_key = encrypt.encrypt(rand_key);
//var encrypted = encrypt.encrypt(jsonstring);
console.log('encypted', encrypted_rand_key);
var mail_body = encrypted_rand_key + aes_encrypted_json
console.log('body', mail_body)
var mailto_string = "mailto:info#xyz.com?subject=FORM&body=" + encodeURIComponent(mail_body);
$('#mailtosend').attr('href', mailto_string);
At the recipient mail server side I want to decrypt the random generated key and the jsonstring using a private key using the pycryptodome package.
from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_v1_5
from base64 import *
def decrypt(key, text):
if type(key) == str:
key = key.encode()
if type(text) == str:
text = text.encode()
rsakey = RSA.importKey(key)
rsakey = PKCS1_v1_5.new(rsakey)
d = rsakey.decrypt(text, 'bolloux')
return d
# rand_key am2mhiwwmi
text = "ZvcrluUmZLY3lRRw01W9mQnhMn7zzpIWn1Bo3csM/ZZ0pWY/8H2dCB9fZDi9/cmp0UtIqDXhLd7SIwyxqrFgPcHUuEHlZl0WQcjSty8PjadG2Abulk1XqEQV4u0Gb/bFGDBMcf5tV1G0d4FFcBPE8r8inrxUjSj2CSffVL8gIGq3ZfY5g7t5FOZV8npBCEONgOLKYnzIiHrHUuXWsOaMAqxMFOLd5DTDLKAkyMybDClsLW9ka+CvWd5fnZBCvO2ziehFp7b9PG4QPSnQpdC8jNLGZB2h0FI8YQD6IyUwmVluUbAlPMqwd6A2CBdGCbfbMChaA5R7bJgKkYhPOQTjaQ=="
text = b64decode(text.encode())
with open('my_priv_key.pem', 'rb') as f:
key = f.read()
decrypt(key, text)
I run into a encoding problem. "UnicodeDecodeError: 'ascii' codec can't decode byte 0xf7 in position 1: ordinal not in range(128)" The encoding is complicating the issue beyond my capabilities.
My questions:
1. How can I resolve the encoding problem ?
2. How can I make the decryption work ?
Thanks

The issue is more than likely caused by b64decode(text) returning a str that contains values such as \xf7 and then attempting to .encode() those values within your decrypt function. encode will use the default encoding which in this case is ascii. I would personally remove the calls to encode unless you specifically have a reason you are doing so.