I have gone through many posts here but did not find the right solution. I want to decrypt a value encrypted in c# .net from Android.
I have successfully decrypted in .net platform using the following code snippet
public static void Main()
{
string _privateKey = Base64Decode("myprivatekey");
var rsa = new RSACryptoServiceProvider();
string data = "198,47,144,175,154,47,194,175,242,41,212,150,220,177,198,161,236,36,197,62,18,111,21,244,232,245,90,234,195,169,141,195,139,199,131,163,26,124,246,50,102,229,73,148,18,110,170,145,112,237,23,123,226,135,158,206,71,116,9,219,56,96,140,19,180,192,80,29,63,160,43,127,204,135,155,67,46,160,225,12,85,161,107,214,104,218,6,220,252,73,252,92,152,235,214,126,245,126,129,150,49,68,162,120,237,246,27,25,45,225,106,201,251,128,243,213,250,172,26,28,176,219,198,194,7,202,34,210";
var dataArray = data.Split(new char[] { ',' });
byte[] dataByte = new byte[dataArray.Length];
for (int i = 0; i < dataArray.Length; i++)
{
dataByte[i] = Convert.ToByte(dataArray[i]);
}
rsa.FromXmlString(_privateKey);
var decryptedByte = rsa.Decrypt(dataByte, false);
Console.WriteLine(_encoder.GetString(decryptedByte));
}
Now I want to do the same process in Android app. Please can somebody guide me through this?
I have tried the following code but its throwing javax.crypto.IllegalBlockSizeException: input must be under 128 bytes exception
String modulusString = "hm2oRCtP6usJKYpq7o1K20uUuL11j5xRrbV4FCQhn/JeXLT21laKK9901P69YUS3bLo64x8G1PkCfRtjbbZCIaa1Ci/BCQX8nF2kZVfrPyzcmeAkq4wsDthuZ+jPInknzUI3TQPAzdj6gim97E731i6WP0MHFqW6ODeQ6Dsp8pc=";
String publicExponentString = "AQAB";
byte[] modulusBytes = Base64.decode(modulusString, DEFAULT);
byte[] exponentBytes = Base64.decode(publicExponentString, DEFAULT);
BigInteger modulus = new BigInteger(1, modulusBytes);
BigInteger publicExponent = new BigInteger(1, exponentBytes);
RSAPrivateKeySpec rsaPubKey = new RSAPrivateKeySpec(modulus, publicExponent);
KeyFactory fact = KeyFactory.getInstance("RSA");
PrivateKey pubKey = fact.generatePrivate(rsaPubKey);
Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1PADDING");
cipher.init(Cipher.ENCRYPT_MODE, pubKey);
byte[] plainBytes = result.getBytes("UTF-16LE");
byte[] cipherData = cipher.doFinal(plainBytes);
String encryptedStringBase64 = Base64.decode(cipherData, DEFAULT).toString();
i want to encrypt a json data
{
"urc": "7718313198",
"umc": "101871",
"ak": "asdfgh123456",
"fname": "Biswajit",
"lname": "Dolui",
"email": "retailer001#giblvirtualmail.com",
"phno": "7718313198",
"pin": "712410"
}
i could not encrypt long string in asp.net using rsa algorithm 2048
var csp = new RSACryptoServiceProvider(2048);
//how to get the private key
var privKey = csp.ExportParameters(true);
//and the public key ...
var pubKey = csp.ExportParameters(false);
//converting the public key into a string representation
string pubKeyString;
{
//we need some buffer
var sw = new System.IO.StringWriter();
//we need a serializer
var xs = new System.Xml.Serialization.XmlSerializer(typeof(RSAParameters));
//serialize the key into the stream
xs.Serialize(sw, pubKey);
//get the string from the stream
pubKeyString = sw.ToString();
}
//converting it back
{
//get a stream from the string
var sr = new System.IO.StringReader(pubKeyString);
//we need a deserializer
var xs = new System.Xml.Serialization.XmlSerializer(typeof(RSAParameters));
//get the object back from the stream
pubKey = (RSAParameters)xs.Deserialize(sr);
}
//conversion for the private key is no black magic either ... omitted
//we have a public key ... let's get a new csp and load that key
csp = new RSACryptoServiceProvider();
csp.ImportParameters(pubKey);
//we need some data to encrypt
var plainTextData = "{urc: 7718313198,umc: 101871,ak: asdfgh123456,fname: Biswajit,lname: Dolui,email: biswajitdoluicse#gmail.com,phno: 7718313198}";
//for encryption, always handle bytes...
var bytesPlainTextData = System.Text.Encoding.Unicode.GetBytes(plainTextData);
//apply pkcs#1.5 padding and encrypt our data
var bytesCypherText = csp.Encrypt(bytesPlainTextData, false);
//we might want a string representation of our cypher text... base64 will do
var cypherText = Convert.ToBase64String(bytesCypherText);
I have to write a code in Node js using crypto module (as I am not allowed to use any module apart from MIT licensed). I need to generate a key pair and encrypt some message with the pulic key and decrypt it with private key. The first part i.e generation of key pair is done. I am not getting any clue how to use crypto modue to encrypt and decrypt some message using the same key pair.
This should do what you want:
const { generateKeyPairSync, publicEncrypt, privateDecrypt } = require('crypto');
//generate a key pair RSA type encryption with a .pem format
const { publicKey, privateKey } = generateKeyPairSync('rsa', {
modulusLength: 4096,
publicKeyEncoding: {
type: 'spki',
format: 'pem'
},
privateKeyEncoding: {
type: 'pkcs8',
format: 'pem',
}
});
// print out the generated keys
console.log(`PublicKey: ${publicKey}`);
console.log(`PrivateKey: ${privateKey}`);
//message to be encrypted
var toEncrypt = "my secret text to be encrypted";
var encryptBuffer = Buffer.from(toEncrypt);
//encrypt using public key
var encrypted = publicEncrypt(publicKey,encryptBuffer);
//print out the text and cyphertext
console.log("Text to be encrypted:");
console.log(toEncrypt);
console.log("cipherText:");
console.log(encrypted.toString());
//decrypt the cyphertext using the private key
var decryptBuffer = Buffer.from(encrypted.toString("base64"), "base64");
var decrypted = privateDecrypt(privateKey,decryptBuffer);
//print out the decrypted text
console.log("decripted Text:");
console.log(decrypted.toString());
It generates a key pair that can be used to encrypt and decrypt a message.
In the Node Documentation for the Crypto lib is the following example:
var crypto = require('crypto');
var alice = crypto.getDiffieHellman('modp5');
var bob = crypto.getDiffieHellman('modp5');
alice.generateKeys();
bob.generateKeys();
var alice_secret = alice.computeSecret(bob.getPublicKey(), null, 'hex');
var bob_secret = bob.computeSecret(alice.getPublicKey(), null, 'hex');
/* alice_secret and bob_secret should be the same */
console.log(alice_secret == bob_secret);
This example shows how to compute a shared secret which can then be used with .createCipher() and .createDecipher() as shown below:
var encrypt64 = function(aMsg, aSecret) {
var cipher, tRet;
cipher = crypto.createCipher('aes-256-cbc', aSecret);
tRet = cipher.update(aMsg, 'utf8', 'base64');
tRet += cipher.final('base64');
return tRet;
};
var decrypt64 = function(aMsg, aSecret) {
var decipher, tRet;
decipher = crypto.createDecipher('aes-256-cbc', aSecret);
tRet = decipher.update(aMsg.replace(/\s/g, "+"), 'base64', 'utf8');
tRet += decipher.final('utf8');
return tRet;
};
I am learning about encryption and using crypto-js I have made a Js & c# version.
What I am trying to accomplish is that the JS or c# version will be able to decode each other messages.
For testing I have kept the IV and KEY , paddding and mode the same in both the JS and C# instance.
I have them both decrypting and encrypting data respectivly but what I have yet to accomplish is providing an encrypted from JS be able to decode using c#.
JS
var key = CryptoJS.enc.Base64.parse('7061737323313233');
var iv = CryptoJS.enc.Base64.parse('7061737323313233');
var encrypted = CryptoJS.AES.encrypt("It works", key,
{ keySize: 128 / 8, iv: iv, mode: CryptoJS.mode.CBC,padding: CryptoJS.pad.Pkcs7 });
var decrypted = CryptoJS.AES.decrypt(encrypted, key, {
keySize: 128 / 8, iv: iv, mode: CryptoJS.mode.CBC, padding: CryptoJS.pad.Pkcs7 });
document.write('Encrypted :' + encrypted + '<br>');
document.write('Key :' + encrypted.key + '<br>');
document.write('Salt :' + encrypted.salt + '<br>');
document.write('iv :' + encrypted.iv + '<br>');
document.write('Decrypted : ' + decrypted + '<br>');
document.write('utf8 = ' + decrypted.toString(CryptoJS.enc.Utf8) + '<br>');
C#
public void startEncryption(string original )
{
using (RijndaelManaged myRijndael = new RijndaelManaged())
{
//Settings
myRijndael.Mode = CipherMode.CBC;
myRijndael.Padding = PaddingMode.PKCS7;
myRijndael.FeedbackSize = 128;
keybytes = Encoding.UTF8.GetBytes("7061737323313233");
//Should be made unique for each message!. TODO
iv = Encoding.UTF8.GetBytes("7061737323313233");
// Encrypt the string to an array of bytes.
encrypted = EncryptStringToBytes(original, keybytes, iv);
//Show Encrypted data
txt_Output.Text = Convert.ToBase64String(encrypted);
// Decrypt the bytes to a string.
string roundtrip = DecryptStringFromBytes(encrypted, keybytes, iv);
//Display the original data and the decrypted data.
Console.WriteLine("Original: {0}", original);
Console.WriteLine("Round Trip: {0}", roundtrip);
}
}
Where the problem arises in decryption.
private void btn_Decrypt_Click(object sender, EventArgs e)
{
Console.WriteLine("Decrypting..");
using (RijndaelManaged myRijndael = new RijndaelManaged())
{
//Settings
myRijndael.Mode = CipherMode.CBC;
myRijndael.Padding = PaddingMode.PKCS7;
myRijndael.FeedbackSize = 128;
keybytes = Encoding.UTF8.GetBytes("7061737323313233");
//Should be made unique for each message!. TODO
iv = Encoding.UTF8.GetBytes("7061737323313233");
// Decrypt the bytes to a string.
string roundtrip = DecryptToString(txt_Output.Text);
txt_Output.Text = roundtrip;
//Display the original data and the decrypted data.
}
}
public string DecryptToString(string TextValue)
{
return DecryptStringFromBytes(Convert.FromBase64String(TextValue), keybytes, iv);
}
static string DecryptStringFromBytes(byte[] cipherText, byte[] Key, byte[] IV)
{
// Check arguments.
if (cipherText == null || cipherText.Length <= 0)
throw new ArgumentNullException("cipherText");
if (Key == null || Key.Length <= 0)
throw new ArgumentNullException("Key");
if (IV == null || IV.Length <= 0)
throw new ArgumentNullException("Key");
// Declare the string used to hold
// the decrypted text.
string plaintext = null;
// Create an RijndaelManaged object
// with the specified key and IV.
using (RijndaelManaged rijAlg = new RijndaelManaged())
{
rijAlg.Key = Key;
rijAlg.IV = IV;
rijAlg.Padding = PaddingMode.PKCS7;
rijAlg.Mode = CipherMode.CBC;
// Create a decrytor to perform the stream transform.
ICryptoTransform decryptor = rijAlg.CreateDecryptor(rijAlg.Key, rijAlg.IV);
// Create the streams used for decryption.
using (MemoryStream msDecrypt = new MemoryStream(cipherText))
{
using (CryptoStream csDecrypt =
new CryptoStream(msDecrypt,decryptor,CryptoStreamMode.Read))
{
using (StreamReader srDecrypt = new StreamReader(csDecrypt))
{
// Read the decrypted bytes from the decrypting stream
// and place them in a string.
plaintext = srDecrypt.ReadToEnd();
}
}
}
}
return plaintext;
}
I am producing different encrypted size strings:
JS:MhAP11fHa+fUfRzSw2UHVQ==
C#:+Ijpt1GDVgM4MqMAQUwf0Q==
I get Padding is invalid and cannot be removed, when trying to decrypt the JS string in c#
Where have I got wrong?.
Basically you run into encoding issues. First of all, you parse your IV using Base64 decoding in one implementation and one using direct character encoding in the other. Your Base64 strings don't look like Base64 strings either.
Furthermore, many libraries (incorrectly) allow that incorrect key and IV sizes are used. This is however confusing as there is no generic way for key or IV expansion. So you should make sure that the binary representations of the key and IV are correct for the specific algorithm.
For AES you should use a key size of 128, 192 or 256 bits and an IV size identical to the block size, 128 bits. The IV should be randomly generated and communicated to the other side, e.g. by prefixing the IV to the ciphertext.
I have given a task in which I need to encrypt an user's ID using AES encryption, what they want is I need to pass in a parameter in a website just like this.
URL : http://www.site.com/event/sample.jce
Parameter : ?param= encrypted text
aside from that there was an attched php sample that they want me to follow to encrypt but I don't have an idea on how to convert this one in .NET
function getEncrypt($sStr, $sKey, $sIV){
$sCipher = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $sKey, $sStr, MCRYPT_MODE_CFB, $sIV);
return bin2hex($sCipher);
}
$sStr = "13410##13";
$sKey = "mediaservice1234";
$sKey = "kjcemsdev3jangho"; // Do not change
$sIV = "fs0tjwkdgh0akstp"; // Do not change
$tmp= getEncrypt($sStr, $sKey, $sIV);
Could somebody help me to understand this codes? or better if they could help me to convert this one on .NEt code? Thanks. :)
Try this, you need to set the FeedbackSize and Padding:
public static string Encrypt(string plaintext)
{
RijndaelManaged rijndaelCipher = new RijndaelManaged();
//RijndaelManaged rijndaelCipher = new RijndaelManaged();
rijndaelCipher.FeedbackSize = 8;
rijndaelCipher.Mode = CipherMode.CFB;
rijndaelCipher.KeySize = 128;
// rijndaelCipher.BlockSize = 128;
rijndaelCipher.BlockSize = 128;
rijndaelCipher.Padding = PaddingMode.Zeros;
byte[] plaintextByte = System.Text.Encoding.ASCII.GetBytes(plaintext);
//Rfc2898DeriveBytes
ASCIIEncoding textConverter = new ASCIIEncoding();
rijndaelCipher.Key = textConverter.GetBytes(PRIVATEKEY); ;
rijndaelCipher.IV = Convert.FromBase64String(PRIVATEIV);
ICryptoTransform encryptor = rijndaelCipher.CreateEncryptor();
//http://msdn.microsoft.com/en-us/library/system.security.cryptography.rijndaelmanaged(VS.80).aspx
//Encrypt the data.
MemoryStream msEncrypt = new MemoryStream();
CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write);
//Convert the data to a byte array.
byte[] toEncrypt = textConverter.GetBytes(plaintext);
//Write all data to the crypto stream and flush it.
csEncrypt.Write(toEncrypt, 0, toEncrypt.Length);
csEncrypt.FlushFinalBlock();
byte[] encrypted = new byte[16];
//Get encrypted array of bytes.
encrypted = msEncrypt.ToArray();
return Convert.ToBase64String(encrypted);
}
Here you can find some more information about using the AES encryption in .net:
http://msdn.microsoft.com/en-us/library/system.security.cryptography.rijndaelmanaged%28VS.80%29.aspx
The code is pretty straight forward.