I am trying to sign and verify the singed data in C# using Bouncy Castle. I went through almost everything I found on google but it does not seem to solve my problem. Please have a look at my approach.
public class Crypto2
{
private static RsaKeyParameters MakeKey(String modulusHexString, String exponentHexString, bool isPrivateKey)
{
var modulus = new Org.BouncyCastle.Math.BigInteger(modulusHexString);
var exponent = new Org.BouncyCastle.Math.BigInteger(exponentHexString);
return new RsaKeyParameters(isPrivateKey, modulus, exponent);
}
public static string Sign(string data, string privateModulusHexString, string privateExponentHexString)
{
/* Make the key */
RsaKeyParameters key = MakeKey(privateModulusHexString, privateExponentHexString, true);
/* Init alg */
ISigner sig = SignerUtilities.GetSigner("SHA1withRSA");
/* Populate key */
sig.Init(true, key);
/* Get the bytes to be signed from the string */
var bytes = Encoding.UTF8.GetBytes(data);
/* Calc the signature */
sig.BlockUpdate(bytes, 0, bytes.Length);
byte[] signature = sig.GenerateSignature();
/* Base 64 encode the sig so its 8-bit clean */
var signedString = Convert.ToBase64String(signature);
return signedString;
}
public static bool Verify(string data, string expectedSignature, string publicModulusHexString, string publicExponentHexString)
{
/* Make the key */
RsaKeyParameters key = MakeKey(publicModulusHexString, publicExponentHexString, false);
/* Init alg */
ISigner signer = SignerUtilities.GetSigner("SHA1withRSA");
/* Populate key */
signer.Init(false, key);
/* Get the signature into bytes */
var expectedSig = Convert.FromBase64String(expectedSignature);
/* Get the bytes to be signed from the string */
var msgBytes = Encoding.UTF8.GetBytes(data);
/* Calculate the signature and see if it matches */
signer.BlockUpdate(msgBytes, 0, msgBytes.Length);
return signer.VerifySignature(expectedSig);
}
protected void Page_Load(object sender, EventArgs e)
{
string data = "Hello World";
string privateKeyPath = System.Web.HttpContext.Current.Server.MapPath("~/App_Data/e-MOne-i.key");
string publicKeyPath = System.Web.HttpContext.Current.Server.MapPath("~/App_Data/m1pay-fpx.cer");
var key = readPrivateKey(privateKeyPath);
var publicKey = ReadCertificate(publicKeyPath);
var SignedData = Crypto2.Sign(data, ((RsaKeyParameters)key.Private).Modulus.ToString(), ((RsaKeyParameters)key.Private).Exponent.ToString());
bool result = Crypto2.Verify(data, SignedData, ((RsaKeyParameters)publicKey.GetPublicKey()).Modulus.ToString(), ((RsaKeyParameters)publicKey.GetPublicKey()).Exponent.ToString());
}
static AsymmetricCipherKeyPair readPrivateKey(string privateKeyFileName)
{
AsymmetricCipherKeyPair keyPair;
using (var reader = File.OpenText(privateKeyFileName))
keyPair = (AsymmetricCipherKeyPair)new PemReader(reader).ReadObject();
return keyPair;
}
static X509Certificate ReadCertificate(string filename)
{
X509CertificateParser certParser = new X509CertificateParser();
Stream stream = new FileStream(filename, FileMode.Open);
X509Certificate cert = certParser.ReadCertificate(stream);
stream.Close();
return cert;
}
}
Related
I am trying to decrypt and validate the hash but at times of decrypting, it throws me the error 'Key does not exist' and at the time of validating the hash return False
https://payvyne.readme.io/docs/webhooks
Signature:
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
Public key:
pA6ULfXWrIMq-qvxn_0CykoStq0ZMYm63lHsuXTsE4q4tgekLJDW2Lnf35ilbFU_vybBdyeJAphpsYc4P0eJBt_z2T62HAV3gnwp_GU6hWIo8faK31TSXIrLmGjZlAVynAxjFYZoNxMeZuwEXpxG4bRGs58P7XSx1fAzedX6oGIlcSLljKH4I1BHt6gJhPIHYNXQzq_a0hX54C1m1VDVP_kot8ui1YKZil_riROK_Xk4ktnOTAqXo9z4uNBqzzH2k0J2YNiCb8VOdbp7kjmH9sPLI-jb-ociy0wSkGZc1e8saGIkkSm4eUASvX_M_TTDD99OrgoIS2Vx07Tw4lK5yd28EMVBUzy2OypuPVf9PyoDGv_4241x5PpJsA9IKocD7AgwxJ3E7FBFhvuSP8c5wspkbQxBwv5nnk2zAxuZsiJeK0o3JSxjkZJEkeVY4mA3VV9SvSXEKAFg2h9J3CR9PTwrZoVBruycVtWJ4it5jroXff-aGlLoRAO0g3gtfjkJb3tw6SJTFOA49iJci76Mj8Adz3eeEEGxTxfDzh_lq0jXxTk7cQSaR2_ChYLHaoorrrFmAvWgDH_lSvlISIgey-SzUoJM9RAy4gVFdmg-XCQQlpMh_d1-IACO3EfBvYKWE-6uGIqx1nZhn9WIDdSqMp6940xRxl0vQy8vYCQ5q8U
Data for Sign in string:
{"type":"PAYMENT_STATUS_CHANGE","paymentId":"1c6e834f074ec941","status":"FAILED","timestamp":1652688286662,"amount":"164.69","currency":"GBP","description":"This is test payment","paymentType":"ONE_OFF","bankName":"Diamond bank","destinationAccount":"GBP2","createdAt":"2022-05-16T08:04:32.994","updatedAt":"2022-05-16T08:04:46.662","customerReference":"1199","refundedAmount":"0.00"}
Expo (exponent):
AQAB
Below is the code to Decrypt the signature using public key.
public static void DecryptUsingPublicKey(string publicKey, string expo, string signature)
{
var modulus = ConvertToBase64(publicKey);
var exponent = Convert.FromBase64String(expo);
RSACryptoServiceProvider csp = new RSACryptoServiceProvider(2048);
var _publicKey = csp.ExportParameters(false);
_publicKey.Modulus = modulus;
_publicKey.Exponent = exponent;
csp.ImportParameters(_publicKey);
var dataBytes = ConvertToBase64(signature);
var plainText = csp.Decrypt(dataBytes, false);
var returnData = Encoding.Unicode.GetString(plainText);
Console.WriteLine($"value: {returnData}");
}
Below is the code for Verify signature using public key
public static void VerifySignature(string signature, string pKey, string dataForSign)
{
string pKeyNew = pKey;
pKeyNew = pKeyNew.Replace("_", "/").Replace("-", "+");
string publicKey = $"<RSAKeyValue><Modulus>{pKeyNew}==</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";
var encoder = new UTF8Encoding();
byte[] dataForSignAsBytes = encoder.GetBytes(dataForSign);
byte[] signatureAsBytes = ConvertToBase64(signature);
RSACryptoServiceProvider rsaCryptoServiceProvider = new RSACryptoServiceProvider();
rsaCryptoServiceProvider.FromXmlString(publicKey);
var hashData = SHA256.Create().ComputeHash(dataForSignAsBytes);
var result1 = rsaCryptoServiceProvider.VerifyData(dataForSignAsBytes, CryptoConfig.MapNameToOID("SHA256"), signatureAsBytes);
var result2 = rsaCryptoServiceProvider.VerifyHash(hashData, CryptoConfig.MapNameToOID("SHA256"), signatureAsBytes);
var result3 = rsaCryptoServiceProvider.VerifyHash(hashData, signatureAsBytes, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
var result4 = rsaCryptoServiceProvider.VerifyData(dataForSignAsBytes, signatureAsBytes, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
Console.WriteLine(result1);
Console.WriteLine(result2);
Console.WriteLine(result3);
Console.WriteLine(result4);
}
ConvertToBase64 function
public static byte[] ConvertToBase64(string data)
{
byte[] cyperBuffer;
string dataNew = data;
dataNew = dataNew.Replace("_", "/").Replace("-", "+");
try
{
if (dataNew.Substring(dataNew.Length - 1) != "=")
{
dataNew += "=";
}
cyperBuffer = Convert.FromBase64String(dataNew);
}
catch
{
dataNew += "=";
try
{
cyperBuffer = Convert.FromBase64String(dataNew);
}
catch
{
//If any error occured while convert to base64 then append '=' at the end.
dataNew += "=";
cyperBuffer = Convert.FromBase64String(dataNew);
}
}
return cyperBuffer;
}
This is a conversion mistake; you need to decode the base 64 signature, not encode the signature, so the following line is wrong:
byte[] signatureAsBytes = ConvertToBase64(signature);
it should be something like:
byte[] signatureAsBytes = ConvertFromBase64(signature);
Decryption is modular exponentiation with a private key. Furthermore, encryption normally uses a different padding scheme than signature generation, so you'd expect that the unpadding would fail if you try and decrypt. Only verification is possible.
I've seen plenty of encryption/decryption tutorials and examples on the net in C# that use the System.Security.Cryptography.RSACryptoServiceProvider, but what I'm hoping to be able to do is:
Create an RSA public/private keypair
Transmit the public key (or for proof of concept, just move it in a string variable)
Create a new RSA crypto provider and encrypt a string with the public key
Transmit the encrypted string (or data) back to the original crypto provider and decrypt the string
Could anyone point me to a useful resource for this?
well there are really enough examples for this, but anyway, here you go
using System;
using System.Security.Cryptography;
namespace RsaCryptoExample
{
static class Program
{
static void Main()
{
//lets take a new CSP with a new 2048 bit rsa key pair
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 = "foobar";
//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);
/*
* some transmission / storage / retrieval
*
* and we want to decrypt our cypherText
*/
//first, get our bytes back from the base64 string ...
bytesCypherText = Convert.FromBase64String(cypherText);
//we want to decrypt, therefore we need a csp and load our private key
csp = new RSACryptoServiceProvider();
csp.ImportParameters(privKey);
//decrypt and strip pkcs#1.5 padding
bytesPlainTextData = csp.Decrypt(bytesCypherText, false);
//get our original plainText back...
plainTextData = System.Text.Encoding.Unicode.GetString(bytesPlainTextData);
}
}
}
as a side note: the calls to Encrypt() and Decrypt() have a bool parameter that switches between OAEP and PKCS#1.5 padding ... you might want to choose OAEP if it's available in your situation
public static string Encryption(string strText)
{
var publicKey = "<RSAKeyValue><Modulus>21wEnTU+mcD2w0Lfo1Gv4rtcSWsQJQTNa6gio05AOkV/Er9w3Y13Ddo5wGtjJ19402S71HUeN0vbKILLJdRSES5MHSdJPSVrOqdrll/vLXxDxWs/U0UT1c8u6k/Ogx9hTtZxYwoeYqdhDblof3E75d9n2F0Zvf6iTb4cI7j6fMs=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";
var testData = Encoding.UTF8.GetBytes(strText);
using (var rsa = new RSACryptoServiceProvider(1024))
{
try
{
// client encrypting data with public key issued by server
rsa.FromXmlString(publicKey.ToString());
var encryptedData = rsa.Encrypt(testData, true);
var base64Encrypted = Convert.ToBase64String(encryptedData);
return base64Encrypted;
}
finally
{
rsa.PersistKeyInCsp = false;
}
}
}
public static string Decryption(string strText)
{
var privateKey = "<RSAKeyValue><Modulus>21wEnTU+mcD2w0Lfo1Gv4rtcSWsQJQTNa6gio05AOkV/Er9w3Y13Ddo5wGtjJ19402S71HUeN0vbKILLJdRSES5MHSdJPSVrOqdrll/vLXxDxWs/U0UT1c8u6k/Ogx9hTtZxYwoeYqdhDblof3E75d9n2F0Zvf6iTb4cI7j6fMs=</Modulus><Exponent>AQAB</Exponent><P>/aULPE6jd5IkwtWXmReyMUhmI/nfwfkQSyl7tsg2PKdpcxk4mpPZUdEQhHQLvE84w2DhTyYkPHCtq/mMKE3MHw==</P><Q>3WV46X9Arg2l9cxb67KVlNVXyCqc/w+LWt/tbhLJvV2xCF/0rWKPsBJ9MC6cquaqNPxWWEav8RAVbmmGrJt51Q==</Q><DP>8TuZFgBMpBoQcGUoS2goB4st6aVq1FcG0hVgHhUI0GMAfYFNPmbDV3cY2IBt8Oj/uYJYhyhlaj5YTqmGTYbATQ==</DP><DQ>FIoVbZQgrAUYIHWVEYi/187zFd7eMct/Yi7kGBImJStMATrluDAspGkStCWe4zwDDmdam1XzfKnBUzz3AYxrAQ==</DQ><InverseQ>QPU3Tmt8nznSgYZ+5jUo9E0SfjiTu435ihANiHqqjasaUNvOHKumqzuBZ8NRtkUhS6dsOEb8A2ODvy7KswUxyA==</InverseQ><D>cgoRoAUpSVfHMdYXW9nA3dfX75dIamZnwPtFHq80ttagbIe4ToYYCcyUz5NElhiNQSESgS5uCgNWqWXt5PnPu4XmCXx6utco1UVH8HGLahzbAnSy6Cj3iUIQ7Gj+9gQ7PkC434HTtHazmxVgIR5l56ZjoQ8yGNCPZnsdYEmhJWk=</D></RSAKeyValue>";
var testData = Encoding.UTF8.GetBytes(strText);
using (var rsa = new RSACryptoServiceProvider(1024))
{
try
{
var base64Encrypted = strText;
// server decrypting data with private key
rsa.FromXmlString(privateKey);
var resultBytes = Convert.FromBase64String(base64Encrypted);
var decryptedBytes = rsa.Decrypt(resultBytes, true);
var decryptedData = Encoding.UTF8.GetString(decryptedBytes);
return decryptedData.ToString();
}
finally
{
rsa.PersistKeyInCsp = false;
}
}
}
Honestly, I have difficulty implementing it because there's barely any tutorials I've searched that displays writing the keys into the files. The accepted answer was "fine". But for me I had to improve it so that both keys gets saved into two separate files. I've written a helper class so y'all just gotta copy and paste it. Hope this helps lol.
using Microsoft.Win32;
using System;
using System.IO;
using System.Security.Cryptography;
namespace RsaCryptoExample
{
class RSAFileHelper
{
readonly string pubKeyPath = "public.key";//change as needed
readonly string priKeyPath = "private.key";//change as needed
public void MakeKey()
{
//lets take a new CSP with a new 2048 bit rsa key pair
RSACryptoServiceProvider csp = new RSACryptoServiceProvider(2048);
//how to get the private key
RSAParameters privKey = csp.ExportParameters(true);
//and the public key ...
RSAParameters pubKey = csp.ExportParameters(false);
//converting the public key into a string representation
string pubKeyString;
{
//we need some buffer
var sw = new 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();
File.WriteAllText(pubKeyPath, pubKeyString);
}
string privKeyString;
{
//we need some buffer
var sw = new StringWriter();
//we need a serializer
var xs = new System.Xml.Serialization.XmlSerializer(typeof(RSAParameters));
//serialize the key into the stream
xs.Serialize(sw, privKey);
//get the string from the stream
privKeyString = sw.ToString();
File.WriteAllText(priKeyPath, privKeyString);
}
}
public void EncryptFile(string filePath)
{
//converting the public key into a string representation
string pubKeyString;
{
using (StreamReader reader = new StreamReader(pubKeyPath)){pubKeyString = reader.ReadToEnd();}
}
//get a stream from the string
var sr = new StringReader(pubKeyString);
//we need a deserializer
var xs = new System.Xml.Serialization.XmlSerializer(typeof(RSAParameters));
//get the object back from the stream
RSACryptoServiceProvider csp = new RSACryptoServiceProvider();
csp.ImportParameters((RSAParameters)xs.Deserialize(sr));
byte[] bytesPlainTextData = File.ReadAllBytes(filePath);
//apply pkcs#1.5 padding and encrypt our data
var bytesCipherText = csp.Encrypt(bytesPlainTextData, false);
//we might want a string representation of our cypher text... base64 will do
string encryptedText = Convert.ToBase64String(bytesCipherText);
File.WriteAllText(filePath,encryptedText);
}
public void DecryptFile(string filePath)
{
//we want to decrypt, therefore we need a csp and load our private key
RSACryptoServiceProvider csp = new RSACryptoServiceProvider();
string privKeyString;
{
privKeyString = File.ReadAllText(priKeyPath);
//get a stream from the string
var sr = new StringReader(privKeyString);
//we need a deserializer
var xs = new System.Xml.Serialization.XmlSerializer(typeof(RSAParameters));
//get the object back from the stream
RSAParameters privKey = (RSAParameters)xs.Deserialize(sr);
csp.ImportParameters(privKey);
}
string encryptedText;
using (StreamReader reader = new StreamReader(filePath)) { encryptedText = reader.ReadToEnd(); }
byte[] bytesCipherText = Convert.FromBase64String(encryptedText);
//decrypt and strip pkcs#1.5 padding
byte[] bytesPlainTextData = csp.Decrypt(bytesCipherText, false);
//get our original plainText back...
File.WriteAllBytes(filePath, bytesPlainTextData);
}
}
}
I'll share my very simple code for sample purpose. Hope it will help someone like me searching for quick code reference.
My goal was to receive rsa signature from backend, then validate against input string using public key and store locally for future periodic verifications.
Here is main part used for signature verification:
...
var signature = Get(url); // base64_encoded signature received from server
var inputtext= "inputtext"; // this is main text signature was created for
bool result = VerifySignature(inputtext, signature);
...
private bool VerifySignature(string input, string signature)
{
var result = false;
using (var cps=new RSACryptoServiceProvider())
{
// converting input and signature to Bytes Arrays to pass to VerifyData rsa method to verify inputtext was signed using privatekey corresponding to public key we have below
byte[] inputtextBytes = Encoding.UTF8.GetBytes(input);
byte[] signatureBytes = Convert.FromBase64String(signature);
cps.FromXmlString("<RSAKeyValue><Modulus>....</Modulus><Exponent>....</Exponent></RSAKeyValue>"); // xml formatted publickey
result = cps.VerifyData(inputtextBytes , new SHA1CryptoServiceProvider(), signatureBytes );
}
return result;
}
for big data
public class RsaService : System.IDisposable
{
public delegate int TransformBlockCall(System.ReadOnlySpan<byte> data, System.Span<byte> destination);
private readonly RSA _encoder;
private readonly RSAEncryptionPadding _padding;
private readonly TransformBlockCall _encryptBlockCall;
private readonly TransformBlockCall _decryptBlockCall;
private int _encrypt_InputBlockSize;
private int _encrypt_OutputBlockSize;
private int _decrypt_InputBlockSize;
private int _decrypt_OutputBlockSize;
public RsaService(RSA encoder) {
if(encoder == null)
throw new System.ArgumentNullException(nameof(encoder));
_encoder = encoder;
_padding = RSAEncryptionPadding.Pkcs1;
_encryptBlockCall = new TransformBlockCall(EncryptBlock);
_decryptBlockCall = new TransformBlockCall(DecryptBlock);
OnEndSetParameters();
}
private void OnEndSetParameters() {
_encrypt_InputBlockSize = GetSizeOutputEncryptOfKeySize(_encoder.KeySize);
_encrypt_OutputBlockSize = _encoder.KeySize / 8;
_decrypt_InputBlockSize = _encrypt_OutputBlockSize;
_decrypt_OutputBlockSize = _encrypt_OutputBlockSize;
}
public void ImportParameters(RSAParameters parameters) {
_encoder.ImportParameters(parameters);
OnEndSetParameters();
}
public byte[] Encrypt(byte[] data) {
if(data == null) throw new System.ArgumentNullException(nameof(data));
if(data.Length == 0) return data;
int outputLength = GetEncryptOutputMaxByteCount(data.Length);
byte[] outputData = new byte[outputLength];
Encrypt(data, outputData);
return outputData;
}
public byte[] Decrypt(byte[] data) {
if(data == null) throw new System.ArgumentNullException(nameof(data));
if(data.Length == 0) return data;
int maxOutputLength = GetDecryptOutputMaxByteCount(data.Length);
byte[] outputData = new byte[maxOutputLength];
int actual_OutputLength = Decrypt(data, outputData);
if(maxOutputLength > actual_OutputLength)
System.Array.Resize(ref outputData, actual_OutputLength);
return outputData;
}
public int Encrypt(System.ReadOnlySpan<byte> data, System.Span<byte> destination) {
#if DEBUG
int inputBlockSize = _encrypt_InputBlockSize;
int outputBlockSize = _encoder.KeySize / 8;
int blockCount = (data.Length / inputBlockSize);
if(data.Length % inputBlockSize != 0)
blockCount++;
System.Diagnostics.Debug.Assert((blockCount * outputBlockSize) <= destination.Length);
#endif
if(data.Length > _encrypt_InputBlockSize)
return TransformFinal(_encryptBlockCall, data, destination, _encrypt_InputBlockSize);
else
return _encryptBlockCall(data, destination);
}
public int Decrypt(System.ReadOnlySpan<byte> data, System.Span<byte> destination) {
if(data.Length > _decrypt_InputBlockSize)
return TransformFinal(_decryptBlockCall, data, destination, _decrypt_InputBlockSize);
else
return _decryptBlockCall(data, destination);
}
private int EncryptBlock(System.ReadOnlySpan<byte> data, System.Span<byte> destination) => _encoder.Encrypt(data, destination, _padding);
private int DecryptBlock(System.ReadOnlySpan<byte> data, System.Span<byte> destination) => _encoder.Decrypt(data, destination, _padding);
public int GetEncryptOutputMaxByteCount(int inputCount) => GetBlockCount(inputCount, _encrypt_InputBlockSize) * _encrypt_OutputBlockSize;
public int GetDecryptOutputMaxByteCount(int inputCount) => GetBlockCount(inputCount, _decrypt_InputBlockSize) * _decrypt_OutputBlockSize;
public void Dispose() {
_encoder.Dispose();
System.GC.SuppressFinalize(this);
}
#region Methods_Helper
public static RsaService Create(RSAParameters parameters) => new RsaService(RSA.Create(parameters));
public static RsaService Create() => new RsaService(RSA.Create());
// [keySize] ÷ 8 - [11 bytes for padding] = Result
// Exsimple: [2048 key size] ÷ 8 - [11 bytes for padding] = 245
public static int GetSizeOutputEncryptOfKeySize(int keySize) => (keySize / 8) - 11;
private static int GetBlockCount(int dataLength,int inputBlockSize) {
int blockCount = (dataLength / inputBlockSize);
if(dataLength % inputBlockSize != 0)
blockCount++;
return blockCount;
}
public static int TransformFinal(TransformBlockCall transformBlockCall, System.ReadOnlySpan<byte> data, System.Span<byte> destination, int inputBlockSize) {
int blockCount = GetBlockCount(data.Length, inputBlockSize);
int data_writtenCount = 0;
int destination_writtenCount = 0;
while(blockCount-- > 0) {
if(blockCount == 0) {
inputBlockSize = data.Length - data_writtenCount;
if(inputBlockSize == 0) break;
}
destination_writtenCount += transformBlockCall(data: data.Slice(data_writtenCount, inputBlockSize)
, destination: destination.Slice(destination_writtenCount));
data_writtenCount += inputBlockSize;
}
return destination_writtenCount;
}
public static (RSAParameters keyPublic, RSAParameters keyPrivate) GenerateKeyPair(int keySize = 2048) {
RSAParameters keyPriv;
RSAParameters keyPub;
using(var rsa = RSA.Create(keySize)) {
keyPriv = rsa.ExportParameters(true);
keyPub = rsa.ExportParameters(false);
}
return (keyPub, keyPriv);
}
#endregion Methods_Helper
}
public static class Program
{
static void Main() {
var (keyPublic, keyPrivate) = RsaService.GenerateKeyPair();
var encryptor = RsaService.Create(keyPublic);
var decryptor = RsaService.Create(keyPrivate);
string originalText = "";
for(int i = 0; i < 1000; i++) {
originalText += "ABC123456789";
}
byte[] inputData = Encoding.UTF8.GetBytes(originalText); // data random for test
System.Console.WriteLine("inputData.Length: {0}", inputData.Length);
var encryptedData = encryptor.Encrypt(inputData);
System.Console.WriteLine("encryptedData.Length: {0}", encryptedData.Length);
byte[] decryptedData = decryptor.Decrypt(encryptedData);
string decryptedText = Encoding.UTF8.GetString(decryptedData);
System.Console.WriteLine("status: {0}", decryptedText == originalText);
}
}
I've seen plenty of encryption/decryption tutorials and examples on the net in C# that use the System.Security.Cryptography.RSACryptoServiceProvider, but what I'm hoping to be able to do is:
Create an RSA public/private keypair
Transmit the public key (or for proof of concept, just move it in a string variable)
Create a new RSA crypto provider and encrypt a string with the public key
Transmit the encrypted string (or data) back to the original crypto provider and decrypt the string
Could anyone point me to a useful resource for this?
well there are really enough examples for this, but anyway, here you go
using System;
using System.Security.Cryptography;
namespace RsaCryptoExample
{
static class Program
{
static void Main()
{
//lets take a new CSP with a new 2048 bit rsa key pair
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 = "foobar";
//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);
/*
* some transmission / storage / retrieval
*
* and we want to decrypt our cypherText
*/
//first, get our bytes back from the base64 string ...
bytesCypherText = Convert.FromBase64String(cypherText);
//we want to decrypt, therefore we need a csp and load our private key
csp = new RSACryptoServiceProvider();
csp.ImportParameters(privKey);
//decrypt and strip pkcs#1.5 padding
bytesPlainTextData = csp.Decrypt(bytesCypherText, false);
//get our original plainText back...
plainTextData = System.Text.Encoding.Unicode.GetString(bytesPlainTextData);
}
}
}
as a side note: the calls to Encrypt() and Decrypt() have a bool parameter that switches between OAEP and PKCS#1.5 padding ... you might want to choose OAEP if it's available in your situation
public static string Encryption(string strText)
{
var publicKey = "<RSAKeyValue><Modulus>21wEnTU+mcD2w0Lfo1Gv4rtcSWsQJQTNa6gio05AOkV/Er9w3Y13Ddo5wGtjJ19402S71HUeN0vbKILLJdRSES5MHSdJPSVrOqdrll/vLXxDxWs/U0UT1c8u6k/Ogx9hTtZxYwoeYqdhDblof3E75d9n2F0Zvf6iTb4cI7j6fMs=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";
var testData = Encoding.UTF8.GetBytes(strText);
using (var rsa = new RSACryptoServiceProvider(1024))
{
try
{
// client encrypting data with public key issued by server
rsa.FromXmlString(publicKey.ToString());
var encryptedData = rsa.Encrypt(testData, true);
var base64Encrypted = Convert.ToBase64String(encryptedData);
return base64Encrypted;
}
finally
{
rsa.PersistKeyInCsp = false;
}
}
}
public static string Decryption(string strText)
{
var privateKey = "<RSAKeyValue><Modulus>21wEnTU+mcD2w0Lfo1Gv4rtcSWsQJQTNa6gio05AOkV/Er9w3Y13Ddo5wGtjJ19402S71HUeN0vbKILLJdRSES5MHSdJPSVrOqdrll/vLXxDxWs/U0UT1c8u6k/Ogx9hTtZxYwoeYqdhDblof3E75d9n2F0Zvf6iTb4cI7j6fMs=</Modulus><Exponent>AQAB</Exponent><P>/aULPE6jd5IkwtWXmReyMUhmI/nfwfkQSyl7tsg2PKdpcxk4mpPZUdEQhHQLvE84w2DhTyYkPHCtq/mMKE3MHw==</P><Q>3WV46X9Arg2l9cxb67KVlNVXyCqc/w+LWt/tbhLJvV2xCF/0rWKPsBJ9MC6cquaqNPxWWEav8RAVbmmGrJt51Q==</Q><DP>8TuZFgBMpBoQcGUoS2goB4st6aVq1FcG0hVgHhUI0GMAfYFNPmbDV3cY2IBt8Oj/uYJYhyhlaj5YTqmGTYbATQ==</DP><DQ>FIoVbZQgrAUYIHWVEYi/187zFd7eMct/Yi7kGBImJStMATrluDAspGkStCWe4zwDDmdam1XzfKnBUzz3AYxrAQ==</DQ><InverseQ>QPU3Tmt8nznSgYZ+5jUo9E0SfjiTu435ihANiHqqjasaUNvOHKumqzuBZ8NRtkUhS6dsOEb8A2ODvy7KswUxyA==</InverseQ><D>cgoRoAUpSVfHMdYXW9nA3dfX75dIamZnwPtFHq80ttagbIe4ToYYCcyUz5NElhiNQSESgS5uCgNWqWXt5PnPu4XmCXx6utco1UVH8HGLahzbAnSy6Cj3iUIQ7Gj+9gQ7PkC434HTtHazmxVgIR5l56ZjoQ8yGNCPZnsdYEmhJWk=</D></RSAKeyValue>";
var testData = Encoding.UTF8.GetBytes(strText);
using (var rsa = new RSACryptoServiceProvider(1024))
{
try
{
var base64Encrypted = strText;
// server decrypting data with private key
rsa.FromXmlString(privateKey);
var resultBytes = Convert.FromBase64String(base64Encrypted);
var decryptedBytes = rsa.Decrypt(resultBytes, true);
var decryptedData = Encoding.UTF8.GetString(decryptedBytes);
return decryptedData.ToString();
}
finally
{
rsa.PersistKeyInCsp = false;
}
}
}
Honestly, I have difficulty implementing it because there's barely any tutorials I've searched that displays writing the keys into the files. The accepted answer was "fine". But for me I had to improve it so that both keys gets saved into two separate files. I've written a helper class so y'all just gotta copy and paste it. Hope this helps lol.
using Microsoft.Win32;
using System;
using System.IO;
using System.Security.Cryptography;
namespace RsaCryptoExample
{
class RSAFileHelper
{
readonly string pubKeyPath = "public.key";//change as needed
readonly string priKeyPath = "private.key";//change as needed
public void MakeKey()
{
//lets take a new CSP with a new 2048 bit rsa key pair
RSACryptoServiceProvider csp = new RSACryptoServiceProvider(2048);
//how to get the private key
RSAParameters privKey = csp.ExportParameters(true);
//and the public key ...
RSAParameters pubKey = csp.ExportParameters(false);
//converting the public key into a string representation
string pubKeyString;
{
//we need some buffer
var sw = new 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();
File.WriteAllText(pubKeyPath, pubKeyString);
}
string privKeyString;
{
//we need some buffer
var sw = new StringWriter();
//we need a serializer
var xs = new System.Xml.Serialization.XmlSerializer(typeof(RSAParameters));
//serialize the key into the stream
xs.Serialize(sw, privKey);
//get the string from the stream
privKeyString = sw.ToString();
File.WriteAllText(priKeyPath, privKeyString);
}
}
public void EncryptFile(string filePath)
{
//converting the public key into a string representation
string pubKeyString;
{
using (StreamReader reader = new StreamReader(pubKeyPath)){pubKeyString = reader.ReadToEnd();}
}
//get a stream from the string
var sr = new StringReader(pubKeyString);
//we need a deserializer
var xs = new System.Xml.Serialization.XmlSerializer(typeof(RSAParameters));
//get the object back from the stream
RSACryptoServiceProvider csp = new RSACryptoServiceProvider();
csp.ImportParameters((RSAParameters)xs.Deserialize(sr));
byte[] bytesPlainTextData = File.ReadAllBytes(filePath);
//apply pkcs#1.5 padding and encrypt our data
var bytesCipherText = csp.Encrypt(bytesPlainTextData, false);
//we might want a string representation of our cypher text... base64 will do
string encryptedText = Convert.ToBase64String(bytesCipherText);
File.WriteAllText(filePath,encryptedText);
}
public void DecryptFile(string filePath)
{
//we want to decrypt, therefore we need a csp and load our private key
RSACryptoServiceProvider csp = new RSACryptoServiceProvider();
string privKeyString;
{
privKeyString = File.ReadAllText(priKeyPath);
//get a stream from the string
var sr = new StringReader(privKeyString);
//we need a deserializer
var xs = new System.Xml.Serialization.XmlSerializer(typeof(RSAParameters));
//get the object back from the stream
RSAParameters privKey = (RSAParameters)xs.Deserialize(sr);
csp.ImportParameters(privKey);
}
string encryptedText;
using (StreamReader reader = new StreamReader(filePath)) { encryptedText = reader.ReadToEnd(); }
byte[] bytesCipherText = Convert.FromBase64String(encryptedText);
//decrypt and strip pkcs#1.5 padding
byte[] bytesPlainTextData = csp.Decrypt(bytesCipherText, false);
//get our original plainText back...
File.WriteAllBytes(filePath, bytesPlainTextData);
}
}
}
I'll share my very simple code for sample purpose. Hope it will help someone like me searching for quick code reference.
My goal was to receive rsa signature from backend, then validate against input string using public key and store locally for future periodic verifications.
Here is main part used for signature verification:
...
var signature = Get(url); // base64_encoded signature received from server
var inputtext= "inputtext"; // this is main text signature was created for
bool result = VerifySignature(inputtext, signature);
...
private bool VerifySignature(string input, string signature)
{
var result = false;
using (var cps=new RSACryptoServiceProvider())
{
// converting input and signature to Bytes Arrays to pass to VerifyData rsa method to verify inputtext was signed using privatekey corresponding to public key we have below
byte[] inputtextBytes = Encoding.UTF8.GetBytes(input);
byte[] signatureBytes = Convert.FromBase64String(signature);
cps.FromXmlString("<RSAKeyValue><Modulus>....</Modulus><Exponent>....</Exponent></RSAKeyValue>"); // xml formatted publickey
result = cps.VerifyData(inputtextBytes , new SHA1CryptoServiceProvider(), signatureBytes );
}
return result;
}
for big data
public class RsaService : System.IDisposable
{
public delegate int TransformBlockCall(System.ReadOnlySpan<byte> data, System.Span<byte> destination);
private readonly RSA _encoder;
private readonly RSAEncryptionPadding _padding;
private readonly TransformBlockCall _encryptBlockCall;
private readonly TransformBlockCall _decryptBlockCall;
private int _encrypt_InputBlockSize;
private int _encrypt_OutputBlockSize;
private int _decrypt_InputBlockSize;
private int _decrypt_OutputBlockSize;
public RsaService(RSA encoder) {
if(encoder == null)
throw new System.ArgumentNullException(nameof(encoder));
_encoder = encoder;
_padding = RSAEncryptionPadding.Pkcs1;
_encryptBlockCall = new TransformBlockCall(EncryptBlock);
_decryptBlockCall = new TransformBlockCall(DecryptBlock);
OnEndSetParameters();
}
private void OnEndSetParameters() {
_encrypt_InputBlockSize = GetSizeOutputEncryptOfKeySize(_encoder.KeySize);
_encrypt_OutputBlockSize = _encoder.KeySize / 8;
_decrypt_InputBlockSize = _encrypt_OutputBlockSize;
_decrypt_OutputBlockSize = _encrypt_OutputBlockSize;
}
public void ImportParameters(RSAParameters parameters) {
_encoder.ImportParameters(parameters);
OnEndSetParameters();
}
public byte[] Encrypt(byte[] data) {
if(data == null) throw new System.ArgumentNullException(nameof(data));
if(data.Length == 0) return data;
int outputLength = GetEncryptOutputMaxByteCount(data.Length);
byte[] outputData = new byte[outputLength];
Encrypt(data, outputData);
return outputData;
}
public byte[] Decrypt(byte[] data) {
if(data == null) throw new System.ArgumentNullException(nameof(data));
if(data.Length == 0) return data;
int maxOutputLength = GetDecryptOutputMaxByteCount(data.Length);
byte[] outputData = new byte[maxOutputLength];
int actual_OutputLength = Decrypt(data, outputData);
if(maxOutputLength > actual_OutputLength)
System.Array.Resize(ref outputData, actual_OutputLength);
return outputData;
}
public int Encrypt(System.ReadOnlySpan<byte> data, System.Span<byte> destination) {
#if DEBUG
int inputBlockSize = _encrypt_InputBlockSize;
int outputBlockSize = _encoder.KeySize / 8;
int blockCount = (data.Length / inputBlockSize);
if(data.Length % inputBlockSize != 0)
blockCount++;
System.Diagnostics.Debug.Assert((blockCount * outputBlockSize) <= destination.Length);
#endif
if(data.Length > _encrypt_InputBlockSize)
return TransformFinal(_encryptBlockCall, data, destination, _encrypt_InputBlockSize);
else
return _encryptBlockCall(data, destination);
}
public int Decrypt(System.ReadOnlySpan<byte> data, System.Span<byte> destination) {
if(data.Length > _decrypt_InputBlockSize)
return TransformFinal(_decryptBlockCall, data, destination, _decrypt_InputBlockSize);
else
return _decryptBlockCall(data, destination);
}
private int EncryptBlock(System.ReadOnlySpan<byte> data, System.Span<byte> destination) => _encoder.Encrypt(data, destination, _padding);
private int DecryptBlock(System.ReadOnlySpan<byte> data, System.Span<byte> destination) => _encoder.Decrypt(data, destination, _padding);
public int GetEncryptOutputMaxByteCount(int inputCount) => GetBlockCount(inputCount, _encrypt_InputBlockSize) * _encrypt_OutputBlockSize;
public int GetDecryptOutputMaxByteCount(int inputCount) => GetBlockCount(inputCount, _decrypt_InputBlockSize) * _decrypt_OutputBlockSize;
public void Dispose() {
_encoder.Dispose();
System.GC.SuppressFinalize(this);
}
#region Methods_Helper
public static RsaService Create(RSAParameters parameters) => new RsaService(RSA.Create(parameters));
public static RsaService Create() => new RsaService(RSA.Create());
// [keySize] ÷ 8 - [11 bytes for padding] = Result
// Exsimple: [2048 key size] ÷ 8 - [11 bytes for padding] = 245
public static int GetSizeOutputEncryptOfKeySize(int keySize) => (keySize / 8) - 11;
private static int GetBlockCount(int dataLength,int inputBlockSize) {
int blockCount = (dataLength / inputBlockSize);
if(dataLength % inputBlockSize != 0)
blockCount++;
return blockCount;
}
public static int TransformFinal(TransformBlockCall transformBlockCall, System.ReadOnlySpan<byte> data, System.Span<byte> destination, int inputBlockSize) {
int blockCount = GetBlockCount(data.Length, inputBlockSize);
int data_writtenCount = 0;
int destination_writtenCount = 0;
while(blockCount-- > 0) {
if(blockCount == 0) {
inputBlockSize = data.Length - data_writtenCount;
if(inputBlockSize == 0) break;
}
destination_writtenCount += transformBlockCall(data: data.Slice(data_writtenCount, inputBlockSize)
, destination: destination.Slice(destination_writtenCount));
data_writtenCount += inputBlockSize;
}
return destination_writtenCount;
}
public static (RSAParameters keyPublic, RSAParameters keyPrivate) GenerateKeyPair(int keySize = 2048) {
RSAParameters keyPriv;
RSAParameters keyPub;
using(var rsa = RSA.Create(keySize)) {
keyPriv = rsa.ExportParameters(true);
keyPub = rsa.ExportParameters(false);
}
return (keyPub, keyPriv);
}
#endregion Methods_Helper
}
public static class Program
{
static void Main() {
var (keyPublic, keyPrivate) = RsaService.GenerateKeyPair();
var encryptor = RsaService.Create(keyPublic);
var decryptor = RsaService.Create(keyPrivate);
string originalText = "";
for(int i = 0; i < 1000; i++) {
originalText += "ABC123456789";
}
byte[] inputData = Encoding.UTF8.GetBytes(originalText); // data random for test
System.Console.WriteLine("inputData.Length: {0}", inputData.Length);
var encryptedData = encryptor.Encrypt(inputData);
System.Console.WriteLine("encryptedData.Length: {0}", encryptedData.Length);
byte[] decryptedData = decryptor.Decrypt(encryptedData);
string decryptedText = Encoding.UTF8.GetString(decryptedData);
System.Console.WriteLine("status: {0}", decryptedText == originalText);
}
}
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);
I recently posted about issues with encrypting large data with RSA, I am finally done with that and now I am moving on to implementing signing with a user's private key and verifying with the corresponding public key. However, whenever I compare the signed data and the original message I basically just get false returned. I am hoping some of your could see what I am doing wrong.
Here is the code:
public static string SignData(string message, RSAParameters privateKey)
{
//// The array to store the signed message in bytes
byte[] signedBytes;
using (var rsa = new RSACryptoServiceProvider())
{
//// Write the message to a byte array using UTF8 as the encoding.
var encoder = new UTF8Encoding();
byte[] originalData = encoder.GetBytes(message);
try
{
//// Import the private key used for signing the message
rsa.ImportParameters(privateKey);
//// Sign the data, using SHA512 as the hashing algorithm
signedBytes = rsa.SignData(originalData, CryptoConfig.MapNameToOID("SHA512"));
}
catch (CryptographicException e)
{
Console.WriteLine(e.Message);
return null;
}
finally
{
//// Set the keycontainer to be cleared when rsa is garbage collected.
rsa.PersistKeyInCsp = false;
}
}
//// Convert the a base64 string before returning
return Convert.ToBase64String(signedBytes);
}
So that is the first step, to sign the data, next I move on to verifying the data:
public static bool VerifyData(string originalMessage, string signedMessage, RSAParameters publicKey)
{
bool success = false;
using (var rsa = new RSACryptoServiceProvider())
{
byte[] bytesToVerify = Convert.FromBase64String(originalMessage);
byte[] signedBytes = Convert.FromBase64String(signedMessage);
try
{
rsa.ImportParameters(publicKey);
SHA512Managed Hash = new SHA512Managed();
byte[] hashedData = Hash.ComputeHash(signedBytes);
success = rsa.VerifyData(bytesToVerify, CryptoConfig.MapNameToOID("SHA512"), signedBytes);
}
catch (CryptographicException e)
{
Console.WriteLine(e.Message);
}
finally
{
rsa.PersistKeyInCsp = false;
}
}
return success;
}
And here is the test client:
public static void Main(string[] args)
{
PublicKeyInfrastructure pki = new PublicKeyInfrastructure();
Cryptograph crypto = new Cryptograph();
RSAParameters privateKey = crypto.GenerateKeys("email#email.com");
const string PlainText = "This is really sent by me, really!";
RSAParameters publicKey = crypto.GetPublicKey("email#email.com");
string encryptedText = Cryptograph.Encrypt(PlainText, publicKey);
Console.WriteLine("This is the encrypted Text:" + "\n " + encryptedText);
string decryptedText = Cryptograph.Decrypt(encryptedText, privateKey);
Console.WriteLine("This is the decrypted text: " + decryptedText);
string messageToSign = encryptedText;
string signedMessage = Cryptograph.SignData(messageToSign, privateKey);
//// Is this message really, really, REALLY sent by me?
bool success = Cryptograph.VerifyData(messageToSign, signedMessage, publicKey);
Console.WriteLine("Is this message really, really, REALLY sent by me? " + success);
}
Am I missing a step here? According to the Cryptography API and the examples there, I shouldn't manually compute any hashes, since I supply the algorithm within the method call itself.
Any help will be greatly appreciated.
Your problem is at the beginning of the VerifyData method:
public static bool VerifyData(string originalMessage, string signedMessage, RSAParameters publicKey)
{
bool success = false;
using (var rsa = new RSACryptoServiceProvider())
{
//Don't do this, do the same as you did in SignData:
//byte[] bytesToVerify = Convert.FromBase64String(originalMessage);
var encoder = new UTF8Encoding();
byte[] bytesToVerify = encoder.GetBytes(originalMessage);
byte[] signedBytes = Convert.FromBase64String(signedMessage);
try
...
For some reason you switched to FromBase64String instead of UTF8Encoding.GetBytes.