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Bouncy Castle Encrypt and Decrypt Password - Org.BouncyCastle.Crypto.InvalidCipherTextException: 'block incorrect'

NOTE: This is NOT for encrypting user passwords. Use a Hash to store user passwords. You can also throw some salt on those passwords similarly to salt bae.
I need to store one of my passwords to log into a program. I can encrypt the password but when I decrypt I get the error:
Org.BouncyCastle.Crypto.InvalidCipherTextException: 'block incorrect'
I am going to use a different private key so I'm not worried about posting this one here.
Program Class:
var input = "TestPassword123!";
Encryption EC = new Encryption();
var Key = "-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----";
var encrypted = EC.RsaEncrypt(input, Key);
string password = EC.RsaDecrypt(encrypted, Key);
Encryption Class
using System;
using System.IO;
using System.Text;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.Crypto.Encodings;
using Org.BouncyCastle.Crypto.Engines;
using Org.BouncyCastle.OpenSsl;
namespace TemarkNamespace
{
internal class Encryption
{
public string RsaEncrypt(string clearText, string Key)
{
var bytesToEncrypt = Encoding.UTF8.GetBytes(clearText);
var encryptEngine = new Pkcs1Encoding(new RsaEngine());
using (var txtreader = new StringReader(Key))
{
var keyPair = (AsymmetricCipherKeyPair)new PemReader(txtreader).ReadObject();
encryptEngine.Init(true, keyPair.Private);
}
var encrypted = Convert.ToBase64String(encryptEngine.ProcessBlock(bytesToEncrypt, 0, bytesToEncrypt.Length));
return encrypted;
}
// Decryption:
public string RsaDecrypt(string pass, string Key)
{
var bytesToDecrypt = Convert.FromBase64String(pass);
AsymmetricCipherKeyPair keyPair;
var decryptEngine = new Pkcs1Encoding(new RsaEngine());
using (var txtreader = new StringReader(Key))
{
keyPair = (AsymmetricCipherKeyPair)new PemReader(txtreader).ReadObject();
decryptEngine.Init(false, keyPair.Private);
}
var decrypted = Encoding.UTF8.GetString(decryptEngine.ProcessBlock(bytesToDecrypt, 0, bytesToDecrypt.Length));
return decrypted;
}
}
}

I found this code and it seems to work fine
using System.Security.Cryptography;
public string Encrypt(string s)
{
if (String.IsNullOrEmpty(s))
{
return s;
}
else
{
var encoding = new UTF8Encoding();
byte[] plain = encoding.GetBytes(s);
byte[] secret = ProtectedData.Protect(plain, null, DataProtectionScope.CurrentUser);
return Convert.ToBase64String(secret);
}
}
public string Decrypt(string s)
{
if (String.IsNullOrEmpty(s))
{
return s;
}
else
{
byte[] secret = Convert.FromBase64String(s);
byte[] plain = ProtectedData.Unprotect(secret, null, DataProtectionScope.CurrentUser);
var encoding = new UTF8Encoding();
return encoding.GetString(plain);
}
}

Trying to decrypt a string with public key(not private) using bouncycastle in .net

As a sample app, I encrypted a string using an rsa public key(supplied by a 3rd party api) using BouncyCastle library in .NET. When I send this encrypted string to the said 3rd party api endpoint, it is able to decrypt it(using its private key). I don't have their private key, but, is it possible to decrypt the string on my end using just the public key that I have?
From my understanding of RSA public/private key pair, when decrypting, you use the private key stored with you to decrypt a string and use the public key to confirm that you are receiving data from a said source.
public string RsaEncryptWithPublic(string clearText
, string publicKey)
{
var bytesToEncrypt = Encoding.UTF8.GetBytes(clearText);
var encryptEngine = new Pkcs1Encoding(new RsaEngine());
using (var txtreader = new StringReader(publicKey))
{
var keyParameter = (AsymmetricKeyParameter)new PemReader(txtreader).ReadObject();
encryptEngine.Init(true, keyParameter);
}
var encrypted = Convert.ToBase64String(encryptEngine.ProcessBlock(bytesToEncrypt, 0, bytesToEncrypt.Length));
return encrypted;
}
public string RsaDecrypt(string base64Input
, string privateKey)
{
var bytesToDecrypt = Convert.FromBase64String(base64Input);
//get a stream from the string
AsymmetricCipherKeyPair keyPair;
var decryptEngine = new Pkcs1Encoding(new RsaEngine());
using (var txtreader = new StringReader(privateKey))
{
keyPair = (AsymmetricCipherKeyPair)new PemReader(txtreader).ReadObject();
//decryptEngine.Init(false, keyPair.Private);
decryptEngine.Init(false, keyPair.Public);
}
var decrypted = Encoding.UTF8.GetString(decryptEngine.ProcessBlock(bytesToDecrypt, 0, bytesToDecrypt.Length));
return decrypted;
}
static void Main(string[] args)
{
string _creditCardNumber = "5454545454545454";
string publicKey = System.IO.File.ReadAllText(#"C:\ThirdPartyKeys\RSAPublicKey_01.txt");
var enc = new EncryptionClass();
var encryptedWithPublic = enc.RsaEncryptWithPublic(_creditCardNumber, publicKey);
Console.WriteLine("String: " + _creditCardNumber);
Console.WriteLine("Encrypted String: " + encryptedWithPublic);
// Decrypt
var outputWithPublic = enc.RsaDecrypt(encryptedWithPublic, publicKey);
//var outputWithPrivate = enc.RsaDecrypt(encryptedWithPrivate, _privateKey);
Console.WriteLine("Decrypted String: " + outputWithPublic);
}
The encryption works, but when I try to decrypt with the same public key, it complains of
Invalid Cast Exception:
Unable to cast object of type 'Org.BouncyCastle.Crypto.Parameters.RsaKeyParameters' to type 'Org.BouncyCastle.Crypto.AsymmetricCipherKeyPair'.
at line in RsaDecrypt function:
keyPair = (AsymmetricCipherKeyPair)new PemReader(txtreader).ReadObject();

No. It's Asymmetric Encryption which means you can't decrypt it with the public key. If you could, it would defeat the purpose and anyone with the public key would be able to decrypt your secret message

RSA Public and Private keys in string format

How to use Public and Private RSA keys provided as string for encryption and decryption. as i'm using RSACryptoServiceProvider, it requires XML format, so is there any possibility to use string as provided. Thanks.

You have to parse the initial string to get all vectors, public keys, exponents separately. Then convert this strings to byte and use this piece of code as an example:
RSAParameters parameters = new RSAParameters();
//here you have to set all provided exponents, vectors
parameters.Exponent = myExponent; //...and other properties
//then - create new RSA cryptoservise provider and import parameters
RSACryptoServiceProvider RSA = new RSACryptoServiceProvider();
RSA.ImportParameters(parameters);
To convert string to byte use this expression - it's already tested:
public static byte[] String2ByteArray(string Hex, int j = -2) =>
(Hex.StartsWith("0x") ? Hex = Hex.Substring(2) : Hex).Where((x, i) => i % 2 == 0)
.Select(x => byte.Parse(Hex.Substring(j += 2, 2), NumberStyles.HexNumber)).ToArray();
public static Action<string> writeOutput = (x) => Debug.WriteLine(x);
And if you're given XML like so:
<RSAKeyValue>
<Modulus>…</Modulus>
<Exponent>…</Exponent>
<P>…</P>
<Q>…</Q>
<DP>…</DP>
<DQ>…</DQ>
<InverseQ>…</InverseQ>
<D>…</D>
</RSAKeyValue>
You can parse this XML to retrieve all the parameters. So assign them to
parameters.Modulus
parameters.Exponent
parameters.P
parameters.D
parameters.DP
parameters.DQ
parameters.InverseQ

Having used Bouncy castle dll, pasting key info into text file and using below code i've solved the problem:
public string RSABouncyEncrypt(string content)
{
var bytesToEncrypt = Encoding.UTF8.GetBytes(content);
AsymmetricKeyParameter keyPair;
using (var reader = File.OpenText(#"E:\......\public.pem"))
{
keyPair = (AsymmetricKeyParameter)new Org.BouncyCastle.OpenSsl.PemReader(reader).ReadObject();
}
var engine = new RsaEngine();
engine.Init(true, keyPair);
var encrypted = engine.ProcessBlock(bytesToEncrypt, 0, bytesToEncrypt.Length);
var cryptMessage = Convert.ToBase64String(encrypted);
//Logs.Log.LogMessage("encrypted: " + cryptMessage);
//Console.WriteLine(cryptMessage);
//Decrypt before return statement to check that it has been encrypted correctly
//RSADecrypt(cryptMessage);
return cryptMessage;
}
public string RSADecrypt(string string64)
{
var bytesToDecrypt = Convert.FromBase64String(string64); // string to decrypt, base64 encoded
AsymmetricCipherKeyPair keyPair;
using (var reader = File.OpenText(#"E:\.....\private.pem"))
keyPair = (AsymmetricCipherKeyPair)new Org.BouncyCastle.OpenSsl.PemReader(reader).ReadObject();
var decryptEngine = new RsaEngine();
decryptEngine.Init(false, keyPair.Private);
var decrypted = Encoding.UTF8.GetString(decryptEngine.ProcessBlock(bytesToDecrypt, 0, bytesToDecrypt.Length));
//Logs.Log.LogMessage("decrypted: " + decrypted);
//Console.WriteLine(decrypted);
return decrypted;
}

how to encrypt and decrypt with only public key with rsa c#

I want to encrypt and decrypt the RSA using only the public key, but I get an error on the decryption side. Error: "unknown block type"
Can you help?
BigInteger rsaPubMod = new BigInteger(Base64.Decode("ALGZqqOFBDh6qULIV0hf5g+Zg5uQqTYWhrw9fzUJwWL8dW7V6kd+9kO8yD+1/f8NVmSDAWGfmVImsPNZp/8x/tF/DycPi5vfRuzHfFcT0mSgD7VW2CfuKM0Gh2WOpgXct6IMC7UsWTkPf8VBSgHobbkr+Ex5pm09mooe2KXTtXN3"));
BigInteger rsaPubExp = new BigInteger(Base64.Decode("AQAB"));
Org.BouncyCastle.Crypto.AsymmetricCipherKeyPair keyPair = new AsymmetricCipherKeyPair(new RsaKeyParameters(false, rsaPubMod, rsaPubExp), new RsaKeyParameters(true, rsaPubMod,rsaPubExp));
RsaKeyParameters pubParameters = new RsaKeyParameters(false, rsaPubMod, rsaPubExp);
IAsymmetricBlockCipher eng = new Pkcs1Encoding(new RsaEngine());
eng.Init(true, pubParameters);
byte[] encdata = Convert.FromBase64String("test");
var encdataResult = eng.ProcessBlock(encdata, 0, encdata.Length);
string result = Convert.ToBase64String(encdataResult);
IAsymmetricBlockCipher deng = new Pkcs1Encoding(new RsaEngine());
deng.Init(false, pubParameters);
byte[] decdata = Convert.FromBase64String(result);
var dencdataResult = deng.ProcessBlock(decdata, 0, decdata.Length);
string result2 = Encoding.UTF8.GetString(dencdataResult);

RSA is an asymmetric algorithm. With a public key you can encrypt, or perform signature verification. With a private key you can decrypt, perform signature creation, or create a public key.

Read RSA PrivateKey in C# and Bouncy Castle

I have successfully written to public and private key files with OpenSSL format.
Files:
-----BEGIN PUBLIC KEY-----
MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCpHCHYgawzNlxVebSKXL7vfc/i
hP+dQgMxlaPEi7/vpQtV2szHjIP34MnUKelXFuIETJjOgjWAjTTJoj38MQUWc3u7
SRXaGVggqQEKH+cRi5+UcEObIfpi+cIyAm9MJqKabfJK2e5X/OS7FgAwPjgtDbZO
ZxamOrWWL8KGB+lH+QIDAQAB
-----END PUBLIC KEY-----
-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
And public key contains just the public key portion of course.
After encrypting my message using the public key. I want to read the private key file
and decrypt it but it's not working. I'm getting exceptions trying to read the private key saying can't cast object to asymmetriccipherkey.
Here is my code:
public static AsymmetricKeyParameter ReadAsymmetricKeyParameter(string pemFilename)
{
var fileStream = System.IO.File.OpenText(pemFilename);
var pemReader = new Org.BouncyCastle.OpenSsl.PemReader(fileStream);
var KeyParameter = (Org.BouncyCastle.Crypto.AsymmetricKeyParameter)pemReader.ReadObject();
return KeyParameter;
}
static void Encrypt2(string publicKeyFileName, string inputMessage, string encryptedFileName)
{
UTF8Encoding utf8enc = new UTF8Encoding();
FileStream encryptedFile = null;
try
{
// Converting the string message to byte array
byte[] inputBytes = utf8enc.GetBytes(inputMessage);
// RSAKeyPairGenerator generates the RSA Key pair based on the random number and strength of key required
/*RsaKeyPairGenerator rsaKeyPairGnr = new RsaKeyPairGenerator();
rsaKeyPairGnr.Init(new Org.BouncyCastle.Crypto.KeyGenerationParameters(new SecureRandom(), 512));
Org.BouncyCastle.Crypto.AsymmetricCipherKeyPair keyPair = rsaKeyPairGnr.GenerateKeyPair();
*/
AsymmetricKeyParameter publicKey = ReadAsymmetricKeyParameter(publicKeyFileName);
// Creating the RSA algorithm object
IAsymmetricBlockCipher cipher = new RsaEngine();
// Initializing the RSA object for Encryption with RSA public key. Remember, for encryption, public key is needed
cipher.Init(true, publicKey);
//Encrypting the input bytes
byte[] cipheredBytes = cipher.ProcessBlock(inputBytes, 0, inputMessage.Length);
//Write the encrypted message to file
// Write encrypted text to file
encryptedFile = File.Create(encryptedFileName);
encryptedFile.Write(cipheredBytes, 0, cipheredBytes.Length);
}
catch (Exception ex)
{
// Any errors? Show them
Console.WriteLine("Exception encrypting file! More info:");
Console.WriteLine(ex.Message);
}
finally
{
// Do some clean up if needed
if (encryptedFile != null)
{
encryptedFile.Close();
}
}
}
Here is the decrypt function. 2nd one is without using Bouncy Castle, however, I'd rather use Bouncy Castle since later I'll be also encrypting and decrypting in Java.
static void Decrypt2(string privateKeyFileName, string encryptedFileName, string plainTextFileName)
{
UTF8Encoding utf8enc = new UTF8Encoding();
FileStream encryptedFile = null;
StreamWriter plainFile = null;
byte[] encryptedBytes = null;
string plainText = "";
try
{
// Converting the string message to byte array
//byte[] inputBytes = utf8enc.GetBytes(inputMessage);
// RSAKeyPairGenerator generates the RSA Key pair based on the random number and strength of key required
/*RsaKeyPairGenerator rsaKeyPairGnr = new RsaKeyPairGenerator();
rsaKeyPairGnr.Init(new Org.BouncyCastle.Crypto.KeyGenerationParameters(new SecureRandom(), 512));
Org.BouncyCastle.Crypto.AsymmetricCipherKeyPair keyPair = rsaKeyPairGnr.GenerateKeyPair();
*/
StreamReader sr = File.OpenText(privateKeyFileName);
PemReader pr = new PemReader(sr);
PemReader pemReader = new PemReader(new StringReader(privateKeyFileName));
AsymmetricCipherKeyPair keyPair = (AsymmetricCipherKeyPair)pemReader.ReadObject();
Console.WriteLine(keyPair.ToString());
AsymmetricKeyParameter privatekey = keyPair.Private;
Console.WriteLine(pr.ReadPemObject());
AsymmetricCipherKeyPair KeyPair = (AsymmetricCipherKeyPair)pr.ReadObject();
AsymmetricKeyParameter privateKey = ReadAsymmetricKeyParameter(privateKeyFileName);
// Creating the RSA algorithm object
IAsymmetricBlockCipher cipher = new RsaEngine();
Console.WriteLine("privateKey: " + privateKey.ToString());
// Initializing the RSA object for Decryption with RSA private key. Remember, for decryption, private key is needed
//cipher.Init(false, KeyPair.Private);
//cipher.Init(false, KeyPair.Private);
cipher.Init(false, keyPair.Private);
// Read encrypted text from file
encryptedFile = File.OpenRead(encryptedFileName);
encryptedBytes = new byte[encryptedFile.Length];
encryptedFile.Read(encryptedBytes, 0, (int)encryptedFile.Length);
//Encrypting the input bytes
//byte[] cipheredBytes = cipher.ProcessBlock(inputBytes, 0, inputMessage.Length);
byte[] cipheredBytes = cipher.ProcessBlock(encryptedBytes, 0, encryptedBytes.Length);
//Write the encrypted message to file
// Write encrypted text to file
plainFile = File.CreateText(plainTextFileName);
plainText = Encoding.Unicode.GetString(cipheredBytes);
plainFile.Write(plainText);
}
catch (Exception ex)
{
// Any errors? Show them
Console.WriteLine("Exception encrypting file! More info:");
Console.WriteLine(ex.Message);
}
finally
{
// Do some clean up if needed
if (plainFile != null)
{
plainFile.Close();
}
if (encryptedFile != null)
{
encryptedFile.Close();
}
}
}
// Decrypt a file
static void Decrypt(string privateKeyFileName, string encryptedFileName, string plainFileName)
{
// Variables
CspParameters cspParams = null;
RSACryptoServiceProvider rsaProvider = null;
StreamReader privateKeyFile = null;
FileStream encryptedFile = null;
StreamWriter plainFile = null;
string privateKeyText = "";
string plainText = "";
byte[] encryptedBytes = null;
byte[] plainBytes = null;
try
{
// Select target CSP
cspParams = new CspParameters();
cspParams.ProviderType = 1; // PROV_RSA_FULL
//cspParams.ProviderName; // CSP name
rsaProvider = new RSACryptoServiceProvider(cspParams);
// Read private/public key pair from file
privateKeyFile = File.OpenText(privateKeyFileName);
privateKeyText = privateKeyFile.ReadToEnd();
// Import private/public key pair
rsaProvider.FromXmlString(privateKeyText);
// Read encrypted text from file
encryptedFile = File.OpenRead(encryptedFileName);
encryptedBytes = new byte[encryptedFile.Length];
encryptedFile.Read(encryptedBytes, 0, (int)encryptedFile.Length);
// Decrypt text
plainBytes = rsaProvider.Decrypt(encryptedBytes, false);
// Write decrypted text to file
plainFile = File.CreateText(plainFileName);
plainText = Encoding.Unicode.GetString(plainBytes);
plainFile.Write(plainText);
}
catch (Exception ex)
{
// Any errors? Show them
Console.WriteLine("Exception decrypting file! More info:");
Console.WriteLine(ex.Message);
}
finally
{
// Do some clean up if needed
if (privateKeyFile != null)
{
privateKeyFile.Close();
}
if (encryptedFile != null)
{
encryptedFile.Close();
}
if (plainFile != null)
{
plainFile.Close();
}
}
} // Decrypt

I figured this out. Basically to read a private openssl key using BouncyCastle and C# is like this:
static AsymmetricKeyParameter readPrivateKey(string privateKeyFileName)
{
AsymmetricCipherKeyPair keyPair;
using (var reader = File.OpenText(privateKeyFileName))
keyPair = (AsymmetricCipherKeyPair)new PemReader(reader).ReadObject();
return keyPair.Private;
}
Then this key can be used to decrypt data such as below:
AsymmetricKeyParameter key = readPrivateKey(pemFilename);
RsaEngine e = new RsaEngine();
e.Init(false, key);
byte[] decipheredBytes = e.ProcessBlock(cipheredData, 0, cipheredData.Length);