How do I get last 32 bytes in Java - javascript

How do I get last 32 bytes in Java?
I tried this but the result is not same with javascript output.
byte[] privateKeyBytes32 = Arrays.copyOfRange(privateKeyBytes, privateKeyBytes.length - 32, privateKeyBytes.length);
byte[] publicKeyBytes32 = Arrays.copyOfRange(publicKeyBytes, publicKeyBytes.length - 32, publicKeyBytes.length);
Here is the code in reference code achieved inJavascript:
const computeSecretX25519 = (privKey, PubKey) => {
let privateKey = Buffer.from(privKey,'base64');
let publicKey = Buffer.from(PubKey, 'base64');
// real value is at last 32 bytes
const KEY_LENGTH = 32;
privateKey = privateKey.slice(privateKey.length - KEY_LENGTH);
publicKey = publicKey.slice(publicKey.length - KEY_LENGTH);
return sharedKey(privateKey, publicKey);
};

Related

Invalid Key Length in NodeJS, but Valid Key Length in C#

I'm converting Rijndael decryption from C# to NodeJS.
The Key (or Passphrase) used is 13 characters long. The IV used is 17 characters long.
Note: I have no control over the length choice
Below is the Rijndael decryption in C#
using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
public class Program
{
public class CryptoProvider
{
private ICryptoTransform encryptor = (ICryptoTransform)null;
private ICryptoTransform decryptor = (ICryptoTransform)null;
private int minSaltLen = -1;
private int maxSaltLen = -1;
public CryptoProvider(string passPhrase, string initVector)
: this(passPhrase, initVector, -1, -1, -1, (string)null, (string)null, 3)
{
}
public CryptoProvider(
string passPhrase,
string initVector,
int minSaltLen,
int maxSaltLen,
int keySize,
string hashAlgorithm,
string saltValue,
int passwordIterations)
{
this.minSaltLen = 4;
this.maxSaltLen = 8;
keySize = 256;
hashAlgorithm = "SHA512";
byte[] rgbIV = Encoding.ASCII.GetBytes(initVector);
byte[] rgbSalt = new byte[0];
byte[] bytes = new PasswordDeriveBytes(passPhrase, rgbSalt, hashAlgorithm, passwordIterations).GetBytes(keySize / 8);
RijndaelManaged rijndaelManaged = new RijndaelManaged();
if (rgbIV.Length == 0)
rijndaelManaged.Mode = CipherMode.ECB;
else
rijndaelManaged.Mode = CipherMode.CBC;
this.encryptor = rijndaelManaged.CreateEncryptor(bytes, rgbIV);
this.decryptor = rijndaelManaged.CreateDecryptor(bytes, rgbIV);
}
public string Decrypt(string cipherText) {
return this.Decrypt(Convert.FromBase64String(cipherText));
}
public string Decrypt(byte[] cipherTextBytes) {
return Encoding.UTF8.GetString(this.DecryptToBytes(cipherTextBytes));
}
public byte[] DecryptToBytes(string cipherText) {
return this.DecryptToBytes(Convert.FromBase64String(cipherText));
}
public byte[] DecryptToBytes(byte[] cipherTextBytes)
{
int num = 0;
int sourceIndex = 0;
MemoryStream memoryStream = new MemoryStream(cipherTextBytes);
byte[] numArray = new byte[cipherTextBytes.Length];
lock (this)
{
CryptoStream cryptoStream = new CryptoStream((Stream)memoryStream, this.decryptor, CryptoStreamMode.Read);
num = cryptoStream.Read(numArray, 0, numArray.Length);
memoryStream.Close();
cryptoStream.Close();
}
if (this.maxSaltLen > 0 && this.maxSaltLen >= this.minSaltLen)
sourceIndex = (int)numArray[0] & 3 | (int)numArray[1] & 12 | (int)numArray[2] & 48 | (int)numArray[3] & 192;
byte[] destinationArray = new byte[num - sourceIndex];
Array.Copy((Array)numArray, sourceIndex, (Array)destinationArray, 0, num - sourceIndex);
return destinationArray;
}
}
public static void Main()
{
string Key = "";
string IV = "";
string encryptedUserData = "u7uENpFfpQhMXiTThL/ajA==";
string decryptedUserData;
CryptoProvider crypto = new CryptoProvider(Key, IV);
decryptedUserData = crypto.Decrypt(encryptedUserData.Trim());
Console.WriteLine(decryptedUserData);
}
}
which for some reason, I can decrypt the string in dotnetfiddle, but not in Visual Studio (because it returns an error of 'Specified initialization vector (IV) does not match the block size for this algorithm. (Parameter 'rgbIV')'
Below is my attempt to convert in NodeJS using the rijndael-js library:
const Rijndael = require("rijndael-js");
const key = "";
const iv = "";
const cipher = new Rijndael(key, "cbc");
const ciphertext = "u7uENpFfpQhMXiTThL/ajA==";
const plaintext = Buffer.from(cipher.decrypt(ciphertext, 256, iv));
which returns an error of Unsupported key size: 104 bit
All errors point to the same thing: Invalid Key/IV lengths.
Would there be a work-around where I can force NodeJS to accept the Key and IV as valid lengths? Is there something I am missing, doing incorrectly, or misconfigured?
Edit:
I was able to find a PasswordDeriveBytes implementation for NodeJS and compared the results from C# and they are equal.
I updated my NodeJS implementation (see sandbox) and noticed a few things:
All resulting ciphertexts are the same. I am guessing this stems from salts.
I tried decrypting a ciphertext generated from C#, but there seems to be a few characters to the left of the resulting value.
Example: C# Encrypted String: zAqv5w/gwT0sFYXZEx+Awg==, NodeJS Decrypted String: ���&��4423
When I try to decrypt a ciphertext generated in NodeJS in C#, the C# compiler returns an error of System.Security.Cryptography.CryptographicException: Padding is invalid and cannot be removed.
Edit:
C# code (executable with .NET Framework 4.7.2):
using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
namespace ProgramEncrypt
{
public class CryptoProvider
{
private ICryptoTransform encryptor = (ICryptoTransform)null;
private ICryptoTransform decryptor = (ICryptoTransform)null;
private int minSaltLen = -1;
private int maxSaltLen = -1;
public CryptoProvider(string passPhrase, string initVector) : this(passPhrase, initVector, -1, -1, -1, (string)null, (string)null, 3) { }
public CryptoProvider(
string passPhrase,
string initVector,
int minSaltLen,
int maxSaltLen,
int keySize,
string hashAlgorithm,
string saltValue,
int passwordIterations)
{
this.minSaltLen = 4;
this.maxSaltLen = 8;
keySize = 256;
hashAlgorithm = "SHA512";
byte[] rgbIV = Encoding.ASCII.GetBytes(initVector);
byte[] rgbSalt = new byte[0];
byte[] bytes = new PasswordDeriveBytes(passPhrase, rgbSalt, hashAlgorithm, passwordIterations).GetBytes(keySize / 8);
RijndaelManaged rijndaelManaged = new RijndaelManaged();
if (rgbIV.Length == 0)
rijndaelManaged.Mode = CipherMode.ECB;
else
rijndaelManaged.Mode = CipherMode.CBC;
this.encryptor = rijndaelManaged.CreateEncryptor(bytes, rgbIV);
this.decryptor = rijndaelManaged.CreateDecryptor(bytes, rgbIV);
}
public string Encrypt(string plainText) => this.Encrypt(Encoding.UTF8.GetBytes(plainText));
public string Encrypt(byte[] plainTextBytes) => Convert.ToBase64String(this.EncryptToBytes(plainTextBytes));
public byte[] EncryptToBytes(string plainText) => this.EncryptToBytes(Encoding.UTF8.GetBytes(plainText));
public byte[] EncryptToBytes(byte[] plainTextBytes)
{
byte[] buffer = this.AddSalt(plainTextBytes);
MemoryStream memoryStream = new MemoryStream();
lock (this)
{
CryptoStream cryptoStream = new CryptoStream((Stream)memoryStream, this.encryptor, CryptoStreamMode.Write);
cryptoStream.Write(buffer, 0, buffer.Length);
cryptoStream.FlushFinalBlock();
byte[] array = memoryStream.ToArray();
memoryStream.Close();
cryptoStream.Close();
return array;
}
}
public string Decrypt(string cipherText) => this.Decrypt(Convert.FromBase64String(cipherText));
public string Decrypt(byte[] cipherTextBytes) => Encoding.UTF8.GetString(this.DecryptToBytes(cipherTextBytes));
public byte[] DecryptToBytes(string cipherText) => this.DecryptToBytes(Convert.FromBase64String(cipherText));
public byte[] DecryptToBytes(byte[] cipherTextBytes)
{
int num = 0;
int sourceIndex = 0;
MemoryStream memoryStream = new MemoryStream(cipherTextBytes);
byte[] numArray = new byte[cipherTextBytes.Length];
lock (this)
{
CryptoStream cryptoStream = new CryptoStream((Stream)memoryStream, this.decryptor, CryptoStreamMode.Read);
num = cryptoStream.Read(numArray, 0, numArray.Length);
memoryStream.Close();
cryptoStream.Close();
}
if (this.maxSaltLen > 0 && this.maxSaltLen >= this.minSaltLen)
sourceIndex = (int)numArray[0] & 3 | (int)numArray[1] & 12 | (int)numArray[2] & 48 | (int)numArray[3] & 192;
byte[] destinationArray = new byte[num - sourceIndex];
Array.Copy((Array)numArray, sourceIndex, (Array)destinationArray, 0, num - sourceIndex);
return destinationArray;
}
private byte[] AddSalt(byte[] plainTextBytes)
{
if (this.maxSaltLen == 0 || this.maxSaltLen < this.minSaltLen)
return plainTextBytes;
byte[] salt = this.GenerateSalt();
byte[] destinationArray = new byte[plainTextBytes.Length + salt.Length];
Array.Copy((Array)salt, (Array)destinationArray, salt.Length);
Array.Copy((Array)plainTextBytes, 0, (Array)destinationArray, salt.Length, plainTextBytes.Length);
return destinationArray;
}
private byte[] GenerateSalt()
{
int length = this.minSaltLen != this.maxSaltLen ? this.GenerateRandomNumber(this.minSaltLen, this.maxSaltLen) : this.minSaltLen;
byte[] data = new byte[length];
new RNGCryptoServiceProvider().GetNonZeroBytes(data);
data[0] = (byte)((int)data[0] & 252 | length & 3);
data[1] = (byte)((int)data[1] & 243 | length & 12);
data[2] = (byte)((int)data[2] & 207 | length & 48);
data[3] = (byte)((int)data[3] & 63 | length & 192);
return data;
}
private int GenerateRandomNumber(int minValue, int maxValue)
{
byte[] data = new byte[4];
new RNGCryptoServiceProvider().GetBytes(data);
return new Random(((int)data[0] & (int)sbyte.MaxValue) << 24 | (int)data[1] << 16 | (int)data[2] << 8 | (int)data[3]).Next(minValue, maxValue + 1);
}
public static void Main()
{
string Key = "HelL!oWoRL3ds";
string IV = "HElL!o#wOrld!##%$";
string toEncrypt = "1234";
string encryptedData, decryptedData;
CryptoProvider crypto = new CryptoProvider(Key, IV);
encryptedData = crypto.Encrypt(toEncrypt.Trim());
decryptedData = crypto.Decrypt(encryptedData.Trim());
Console.WriteLine("ENCRYPTED: " + encryptedData);
Console.WriteLine("DECRYPTED: " + decryptedData);
}
}
}
NodeJS code (codesandbox.io):
import { deriveBytesFromPassword } from "./deriveBytesFromPassword";
const Rijndael = require("rijndael-js");
const dataToEncrypt = "1234";
const SECRET_KEY = "HelL!oWoRL3ds"; // 13 chars
const SECRET_IV = "HElL!o#wOrld!##%$"; // 17 chars
const keySize = 256;
const hashAlgorithm = "SHA512";
// Use only the first 16 bytes of the IV
const rgbIV = Buffer.from(SECRET_IV, "ascii").slice(0, 16); // #ref https://stackoverflow.com/a/57147116/12278028
const rgbSalt = Buffer.from([]);
const derivedPasswordBytes = deriveBytesFromPassword(
SECRET_KEY,
rgbSalt,
3,
hashAlgorithm,
keySize / 8
);
const dataToEncryptInBytes = Buffer.from(dataToEncrypt, "utf8");
const cipher = new Rijndael(derivedPasswordBytes, "cbc");
const encrypted = Buffer.from(cipher.encrypt(dataToEncryptInBytes, 16, rgbIV));
console.log(encrypted.toString("base64"));
// Use this if you only have the Base64 string
// Note: The Base64 string in Line 34 is from C#
// const decrypted = Buffer.from(
// cipher.decrypt(Buffer.from("zAqv5w/gwT0sFYXZEx+Awg==", "base64"), 16, rgbIV)
// );
const decrypted = Buffer.from(cipher.decrypt(encrypted, 16, rgbIV));
console.log(decrypted.toString());
A possible NodeJS implementation based on your sandbox code that is compatible with the C# code is:
const crypto = require("crypto");
const Rijndael = require("rijndael-js");
const pkcs7 = require('pkcs7-padding');
const SECRET_KEY = "HelL!oWoRL3ds"; // 13 chars
const SECRET_IV = "HElL!o#wOrld!##%$"; // 17 chars
const rgbIV = Buffer.from(SECRET_IV, "ascii").slice(0, 16);
const rgbSalt = Buffer.from([]);
const keySize = 256;
const hashAlgorithm = "SHA512";
const minSaltLen = 4;
const maxSaltLen = 8;
function encrypt(plaintextStr) {
var derivedPasswordBytes = deriveBytesFromPassword(SECRET_KEY, rgbSalt, 3, hashAlgorithm, keySize/8);
var cipher = new Rijndael(derivedPasswordBytes, "cbc");
var plaintext = Buffer.from(plaintextStr, "utf8");
var salt = generateSalt();
var saltPlaintext = Buffer.concat([salt, plaintext])
var saltPlaintextPadded = pkcs7.pad(saltPlaintext, 16)
var ciphertext = Buffer.from(cipher.encrypt(saltPlaintextPadded, 128, rgbIV));
return ciphertext.toString("base64");
}
function decrypt(ciphertextB64) {
var derivedPasswordBytes = deriveBytesFromPassword(SECRET_KEY, rgbSalt, 3, hashAlgorithm, keySize/8);
var cipher = new Rijndael(derivedPasswordBytes, "cbc");
var ciphertext = Buffer.from(ciphertextB64, 'base64');
var saltPlaintextPadded = Buffer.from(cipher.decrypt(ciphertext, 128, rgbIV));
var sourceIndex = saltPlaintextPadded[0] & 3 | saltPlaintextPadded[1] & 12 | saltPlaintextPadded[2] & 48 | saltPlaintextPadded[3] & 192
var plaintextPadded = saltPlaintextPadded.subarray(sourceIndex)
var plaintext = pkcs7.unpad(plaintextPadded)
return plaintext;
}
function generateSalt() {
var length = minSaltLen != maxSaltLen ? crypto.randomInt(minSaltLen, maxSaltLen + 1) : minSaltLen;
var data = crypto.randomBytes(length);
data[0] = data[0] & 252 | length & 3;
data[1] = data[1] & 243 | length & 12;
data[2] = data[2] & 207 | length & 48;
data[3] = data[3] & 63 | length & 192;
return data;
}
var plaintext = "1234";
var ciphertextB64 = encrypt(plaintext);
var plaintext = decrypt(ciphertextB64);
console.log(ciphertextB64);
console.log(plaintext.toString('hex'))
using the key derivation from the linked post.
Ciphertexts generated with this code can be decrypted with the C# code, and vice versa, ciphertexts generated with the C# code can be decrypted with this code.
Explanation:
The linked C# code can process a 17 bytes IV under .NET Framework (tested for 4.7.2). However, only the first 16 bytes are taken into account. With the addition rijndaelManaged.IV = rgbIV (as in the MS examples) an exception is thrown. Under .NET Core (tested for 3.0+) an exception is always thrown. This indicates that processing an IV in the .NET Framework that is too large, is more likely a bug. Anyway, in the NodeJS code also only the first 16 bytes of the IV have to be considered.
The C# code uses the proprietary key derivation PasswordDeriveBytes. The same key derivation must be applied in the NodeJS code. In the code above, the implementation linked by the OP is used.
The library involved rijndael-js applies Zero padding, but the C# code uses PKCS#7 padding. Therefore, in the NodeJS code, the plaintext (or concatenation of salt and plaintext) must be padded with PKCS#7 before encryption (this satisfies the length criterion and Zero padding is no longer applied). Accordingly, the padding must be removed after decryption. A possible library is pkcs7-padding. Alternatively, instead of rijndael-js, another library could be used which applies PKCS#7 padding by default.
The C# code uses two salts: One is the empty (!) rgbSalt, which is applied in the key derivation. The other is a second salt, which is randomly generated with respect to both length and content during encryption, is prepended to the plaintext, and contains the information about the salt length, which is determined during decryption. This logic must be implemented in the NodeJS code for both codes to be compatible.
The GenerateRandomNumber() method cannot be ported because its result depends on the internal details of the Random() implementation (which, by the way, is not a CSPRNG). The method is supposed to generate a random integer. For this purpose crypto.randomInt() is used. For RNGCryptoServiceProvider#GetNonZeroBytes() create.RandomBytes() is applied. This NodeJS function also allows 0x00 bytes, which could be optimized if needed.
Security:
The proprietary key derivation PasswordDeriveBytes is deprecated and insecure. Instead, Rfc2898DeriveBytes should be used in the C# code and PBKDF2 in the NodeJS code.
The missing salt in the key derivation is insecure and allows attacks e.g. via rainbow tables. Instead, a salt of sufficient size (at least 8 bytes) should be randomly generated for each encryption. This salt is not secret and is therefore usually concatenated with the ciphertext.
The C# implementation uses a static IV, which is insecure as well. Although the random second salt provides a different ciphertext for identical plaintexts and identical IVs, a best practice should be applied instead of a user defined construct. A proven way is a randomly generated IV, analogous to the salt used for key derivation (randomly generated for each encryption, concatenated with the ciphertext).

jsrsasign with ECDSA verifying issue

I could verify an ECDSA / SHA256 signature using the standard library of Javascript (window.crypto.subtle.verify) but cannot using the jsrsasign library (KJUR.crypto). I have also tried 'KJUR.crypto.ECDSA' class directly but no luck neither.
See below both script methods which dont provide same result. Could someone advise the issue(s) ?
//function to convert HEX to Decimal - return Arraybuffer
function hexStringToUint8Array(hexString) {
if (hexString.length % 2 != 0)
throw "Invalid hexString";
var arrayBuffer = new Uint8Array(hexString.length / 2);
for (var i = 0; i < hexString.length; i += 2) {
var byteValue = parseInt(hexString.substr(i, 2), 16);
if (byteValue == NaN)
throw "Invalid hexString";
arrayBuffer[i / 2] = byteValue;
}
return arrayBuffer;
}
//function to convert Base64 to hex (8 bits formats)
function base64ToHex(str) {
const raw = atob(str);
let result = '';
for (let i = 0; i < raw.length; i++) {
const hex = raw.charCodeAt(i).toString(16);
result += (hex.length === 2 ? hex : '0' + hex);
}
return result;
}
//convert Base64 URL to Base64
function base64urlToBase64(base64url) {
base64url = base64url.toString();
return base64url
.replace(/\-/g, "+")
.replace(/_/g, "/");
}
//Define values
Base64URL_coordX = '2uYQAsY-bvzz7r7SL-tK2C0eySfYEf1blv91cnd_1G4';
Base64URL_coordY = 'S3j1vy2sbkExAYXumb3w1HMVH-4ztoHclVTwQd45Reg';
signature = 'ed0c2b2e56731511ce2cea1d7320cdbc39dbabca7f525ec5d646b7c11cb35d5846a1cb70c2a1d8480f5ef88b46d401ca78b18ccae9ae4e3934a6b8fe412f7b11';
dataHex = '48656c6c6f20386777696669'; // ='Hello 8gwifi'
////////////Verifying Method using standard javascript
var dataToVerify = hexStringToUint8Array(dataHex);
var SignatureToVerify = hexStringToUint8Array(signature);
window.crypto.subtle.importKey(
"jwk", //can be "jwk" (public or private), "spki" (public only), or "pkcs8" (private only)
{ //this is an example jwk key, other key types are Uint8Array objects
kty: "EC",
crv: "P-256",
x: Base64URL_coordX, // expects x and y to be «base64url» encoded
y: Base64URL_coordY,
ext: true,
},
{ //these are the algorithm options
name: "ECDSA",
namedCurve: "P-256", //can be "P-256", "P-384", or "P-521"
},
false, //whether the key is extractable (i.e. can be used in exportKey)
["verify"] //"verify" for public key import, "sign" for private key imports
)
.then(function(publicKey){
window.crypto.subtle.verify(
{
name: "ECDSA",
hash: {name: "SHA-256"}, //can be "SHA-1", "SHA-256", "SHA-384", or "SHA-512"
},
publicKey, //from generateKey or importKey above
SignatureToVerify, //ArrayBuffer of the signature
dataToVerify //ArrayBuffer of the data
)
.then(function(isvalid){
console.log('Signature valid1: ', isvalid);
})
.catch(function(err){
console.error(err);
});
});
////////////Verifying Method using KJUR
Hex_coordX = base64ToHex(base64urlToBase64(Base64URL_coordX));
Hex_coordY = base64ToHex(base64urlToBase64(Base64URL_coordY));
var XY = Hex_coordX.toString(16) + Hex_coordY.toString(16);
var sig = new KJUR.crypto.Signature({"alg": "SHA256withECDSA", "prov": "cryptojs/jsrsa"});
sig.init({xy: XY, curve: "secp256r1"});
sig.updateHex(dataHex);
var result = sig.verify(signature);
//Printing Verification
console.log('Signature valid2: ', result);
It says in the description of the library that it is JCA style. This probably means that the signature generation / verification functions have a ASN.1 / DER encoded input / output.
This consist of an ASN.1 SEQUENCE (tag 0x30), the length of the two integers inside. These two INTEGER's have tag 0x02 and a length of the size of the integer value of the r and s components of the signature. These are big endian, signed integers (which means stripping bytes if they are 0x00 or adding a 0x00 if the top byte is 0x80 or higher).
In your case that would be:
r = ed0c2b2e56731511ce2cea1d7320cdbc39dbabca7f525ec5d646b7c11cb35d58
s = 46a1cb70c2a1d8480f5ef88b46d401ca78b18ccae9ae4e3934a6b8fe412f7b11
Now converting these to DER ASN.1:
ri = 02 21 00 ed0c2b2e56731511ce2cea1d7320cdbc39dbabca7f525ec5d646b7c11cb35d58
si = 02 20 46a1cb70c2a1d8480f5ef88b46d401ca78b18ccae9ae4e3934a6b8fe412f7b11
and finally adding the sequence and adding the concatenation of above:
sig = 30 45 02 21 00 ed0c2b2e56731511ce2cea1d7320cdbc39dbabca7f525ec5d646b7c11cb35d58
02 20 46a1cb70c2a1d8480f5ef88b46d401ca78b18ccae9ae4e3934a6b8fe412f7b11
and checking the result e.g. here.
But I guess in your case just calling the function concatSigToASN1Sig would be faster :P

How Can replicate this cryptojs encrypt with PHP?

I have this encrypt function in Typescript.
encrypt( text, password) {
let response = '';
let text= btoa(text);
const keyBytes = CryptoJS.PBKDF2(password, this.KEY_COMPLEMENTARY, { keySize: 48 / 4, iterations: 1000 });
const key = new CryptoJS.lib.WordArray.init(keyBytes.words, 32);
const iV = new CryptoJS.lib.WordArray.init(keyBytes.words.splice(32 / 4), 16);
const data = CryptoJS.enc.Utf16LE.parse(text);
const encrypted = CryptoJS.AES.encrypt(data, key, { iv: iV });
response = encrypted.toString();
return response;}
Is it possible to program this encryption in PHP?

CryptoJS - Decrypt an encrypted file

I'm trying to write an application to do end-to-end encryption for files with JS in browser. However I don't seem to be able to get all files decrypted correctly.
TL;DR As it's impractical to encrypt files bigger than 1MB as a whole, I'm trying to encrypt them chunk by chunk. After doing so I try to write the encrypted words (resulted from CryptoJS's WordArray) into a blob. As for decryption I read the files and split them to chunks according to map generated while encrypting the chunks and try to decrypt them. The problem is decrypted result is 0 bits!
I guess I'm not reading the chunks while decrypting correctly. Please take a look at the code below for the function getBlob (writing data to the blob) and the last part of decryptFile for reading chunks.
More explanation
I'm using CryptoJS AES with default settings.
Right now my code looks like this:
function encryptFile (file, options, resolve, reject) {
if (!options.encrypt) {
return resolve(file)
}
if (!options.processor || !options.context) {
return reject('No encryption method.')
}
function encryptBlob (file, optStart, optEnd) {
const start = optStart || 0
let stop = optEnd || CHUNK_SIZE
if (stop > file.size - 1) {
stop = file.size
}
const blob = file.slice(start, stop)
const fileReader = new FileReader()
fileReader.onloadend = function () {
if (this.readyState !== FileReader.DONE) return
const index = Math.ceil(optStart / CHUNK_SIZE)
const result = CryptoJS.lib.WordArray.create(this.result)
encryptedFile[index] = encrypt(result)
chunksResolved++
if (chunksResolved === count) {
const {sigBytes, sigBytesMap, words} = getCipherInfo(encryptedFile)
const blob = getBlob(sigBytes, words)
resolve(blob, Object.keys(sigBytesMap))
}
}
fileReader.readAsArrayBuffer(blob)
}
let chunksResolved = 0
const encryptedFile = []
const CHUNK_SIZE = 1024*1024
const count = Math.ceil(file.size / CHUNK_SIZE)
const encrypt = value => options.processor.call(
options.context, value, 'file',
(v, k) => CryptoJS.AES.encrypt(v, k))
for (let start = 0; (start + CHUNK_SIZE) / CHUNK_SIZE <= count; start+= CHUNK_SIZE) {
encryptBlob(file, start, start + CHUNK_SIZE - 1)
}
}
As you can see I'm trying to read the file chunk by chunk (each chunk is 1MB or fileSize % 1MB) as ArrayBuffer, converting it to WordArray for CryptoJS to understand and encrypt it.
After encrypting all the chunks I try to write each word they have to a blob (using a code I found in CryptoJS's issues in Google Code, mentioned below) and I guess here is what goes wrong. I also generated a map for where encrypted chunks end so I can later use it to get the chunks out of the binary file for decryption.
And here's how I decrypt the files:
function decryptFile (file, sigBytesMap, filename, options, resolve, reject) {
if (!options.decrypt) {
return resolve(file)
}
if (!options.processor || !options.context) {
return reject('No decryption method.')
}
function decryptBlob (file, index, start, stop) {
const blob = file.slice(start, stop)
const fileReader = new FileReader()
fileReader.onloadend = function () {
if (this.readyState !== FileReader.DONE) return
const result = CryptoJS.lib.WordArray.create(this.result)
decryptedFile[index] = decrypt(result)
chunksResolved++
if (chunksResolved === count) {
const {sigBytes, words} = getCipherInfo(decryptedFile)
const finalFile = getBlob(sigBytes, words)
resolve(finalFile, filename)
}
}
fileReader.readAsArrayBuffer(blob)
}
let chunksResolved = 0
const count = sigBytesMap.length
const decryptedFile = []
const decrypt = value => options.processor.call(
options.context, value, 'file',
(v, k) => CryptoJS.AES.decrypt(v, k))
for (let i = 0; i < count; i++) {
decryptBlob(file, i, parseInt(sigBytesMap[i - 1]) || 0, parseInt(sigBytesMap[i]) - 1)
}
}
Decryption is exactly like the encryption but doesn't work. Although chunks are not 1MB anymore, they are limited to sigBytes mentioned in the map. There is no result for the decryption! sigBytes: 0.
Here's the code for generating a blob and getting sigbytesMap:
function getCipherInfo (ciphers) {
const sigBytesMap = []
const sigBytes = ciphers.reduce((tmp, cipher) => {
tmp += cipher.sigBytes || cipher.ciphertext.sigBytes
sigBytesMap.push(tmp)
return tmp
}, 0)
const words = ciphers.reduce((tmp, cipher) => {
return tmp.concat(cipher.words || cipher.ciphertext.words)
}, [])
return {sigBytes, sigBytesMap, words}
}
function getBlob (sigBytes, words) {
const bytes = new Uint8Array(sigBytes)
for (var i = 0; i < sigBytes; i++) {
const byte = (words[i >>> 2] >>> (24 - (i % 4) * 8)) & 0xff
bytes[i] = byte
}
return new Blob([ new Uint8Array(bytes) ])
}
I'm guessing the issue is the method I'm using to read the encrypted chunks. Or maybe writing them!
I should also mention that previously I was doing something different for encryption. I was stringifying each WordArray I got as the result for CryptoJS.AES.encrypt using the toString method with the default encoding (which I believe is CryptoJS.enc.Hex) but some files didn't decrypt correctly. It didn't have anything to do with the size of the original file, rather than their types. Again, I'm guessing!
Turns out the problem was the WordArray returned by CryptoJS.AES.decrypt(value, key) has 4 extra words as padding which should not be included in the final result. CryptoJS tries unpadding the result but only changes sigBytes accordingly and doesn't change words. So when decrypting, before writing chunks to file pop those extra words. 4 words for full chunks and 3 for smaller ones (last chunk).
check this issue
import CryptoJS from "crypto-js";
async function encryptBlobToBlob(blob: Blob, secret: string): Promise<Blob> {
const wordArray = CryptoJS.lib.WordArray.create(await blob.arrayBuffer());
const result = CryptoJS.AES.encrypt(wordArray, secret);
return new Blob([result.toString()]);
}
export async function decryptBlobToBlob(blob: Blob, secret: string): Promise<Blob> {
const decryptedRaw = CryptoJS.AES.decrypt(await blob.text(), secret);
return new Blob([wordArrayToByteArray(decryptedRaw)]);
}
function wordToByteArray(word, length) {
const ba = [];
const xFF = 0xff;
if (length > 0) ba.push(word >>> 24);
if (length > 1) ba.push((word >>> 16) & xFF);
if (length > 2) ba.push((word >>> 8) & xFF);
if (length > 3) ba.push(word & xFF);
return ba;
}
function wordArrayToByteArray({ words, sigBytes }: { sigBytes: number; words: number[] }) {
const result = [];
let bytes;
let i = 0;
while (sigBytes > 0) {
bytes = wordToByteArray(words[i], Math.min(4, sigBytes));
sigBytes -= bytes.length;
result.push(bytes);
i++;
}
return new Uint8Array(result.flat());
}
async function main() {
const secret = "bbbb";
const blob = new Blob(["1".repeat(1e3)]);
const encryptedBlob = await encryptBlobToBlob(blob, secret);
console.log("enrypted blob size", encryptedBlob.size);
const decryptedBlob = await decryptBlobToBlob(encryptedBlob, secret);
console.log("decryptedBlob", decryptedBlob);
console.log(await decryptedBlob.text());
}
main();

"Invalid AES Block Size" SJCL Decryption

Trying to decrypt AES using RNCryptor-js which uses SJCL. After logging all the steps on each end, (other end is RNCryptor-python) the keys, salts, HMAC hashes, everything matches up. But when I get to the final step:
var aes = new sjcl.cipher.aes(encryption_key);
sjcl.beware["CBC mode is dangerous because it doesn't protect message integrity."]()
var decrypted = aes.decrypt(ciphertext, iv);
I get the error:
sjcl.exception.invalid {toString: function, message: "invalid aes block size"}
Here is the full code:
PBKDF2:
this.KeyForPassword = function(password, salt) {
var hmacSHA256 = function (password) {
var hasher = new sjcl.misc.hmac(password, sjcl.hash.sha256);
this.encrypt = function () {
return hasher.encrypt.apply(hasher, arguments);
};
};
return sjcl.misc.pbkdf2(password, salt, 10000, 32 * 8, hmacSHA256);
};
Decryption (takes a hex input):
this.decrypt = function(password, message, options) {
message = sjcl.codec.hex.toBits(message);
options = options || {};
var version = sjcl.bitArray.extract(message, 0 * 8, 8);
var options = sjcl.bitArray.extract(message, 1 * 8, 8);
var encryption_salt = sjcl.bitArray.bitSlice(message, 2 * 8, 10 * 8);
var encryption_key = _this.KeyForPassword(password, encryption_salt, "decryption");
var hmac_salt = sjcl.bitArray.bitSlice(message, 10 * 8, 18 * 8);
var hmac_key = _this.KeyForPassword(password, hmac_salt, "decryption");
var iv = sjcl.bitArray.bitSlice(message, 18 * 8, 34 * 8);
var ciphertext_end = sjcl.bitArray.bitLength(message) - (32 * 8);
var ciphertext = sjcl.bitArray.bitSlice(message, 34 * 8, ciphertext_end);
var hmac = sjcl.bitArray.bitSlice(message, ciphertext_end);
var expected_hmac = new sjcl.misc.hmac(hmac_key).encrypt(sjcl.bitArray.bitSlice(message, 0, ciphertext_end));
if (! sjcl.bitArray.equal(hmac, expected_hmac)) {
throw new sjcl.exception.corrupt("HMAC mismatch or bad password.");
}
var aes = new sjcl.cipher.aes(encryption_key);
sjcl.beware["CBC mode is dangerous because it doesn't protect message integrity."]()
var decrypted = aes.decrypt(ciphertext, iv);
return decrypted;
}
The error is thrown on the second to last statement where decrypted is defined.
I looked at the sjcl exception and it looks like it's looking for an input of length 4, which I'm guessing is a WordArray. I'm just lost as to how to get a valid input. Like I said, the ciphertext, iv, hmac tag, salts are all being sliced properly on the javascript end. Might just be an encoding problem.
This error also seems to only be happening on json (format: '{"key":"value"}'), when I tried something like "Hello, world" I got back a 4 word array with no errors.
Any suggestions?
var decrypted = aes.decrypt(ciphertext, iv);
should be
var decrypted = sjcl.mode.cbc.decrypt(aes, ciphertext, iv);
I was also having trouble with padding happening in cbc.js (link to source) and it turned out that I hadn't included bitArray.js (link) which includes an important xor function (not to confused with the simple ^ operator).
So: include bitArray.js
The output should also be encoded:
return sjcl.codec.utf8String.fromBits(decrypted);

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