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"Bad data .\r\n" Error for RSA signing data

This question might be duplicate but other solutions seem to be not working for me. I am working on RSA for the first time, so little confusing. I have public and private keys and want to sign the text using these. Below is my code:
public void RSA()
{
var publickey = "***";
var privatekey = "***";
using (var RSA = new RSACryptoServiceProvider())
{
UnicodeEncoding ByteConverter = new UnicodeEncoding();
RSAParameters myRSAParameters = RSA.ExportParameters(true);
myRSAParameters.Modulus = ByteConverter.GetBytes(publickey);
myRSAParameters.D = ByteConverter.GetBytes(privatekey);
myRSAParameters.Exponent = ByteConverter.GetBytes("5");
string signedmessage = SignData("ABC", myRSAParameters);
}
}
public static String SignData(string message, RSAParameters privatekey)
{
byte[] signedBytes;
using (var rsa = new RSACryptoServiceProvider())
{
var encoder = new UTF8Encoding();
byte[] originalData = encoder.GetBytes(message);
try
{
rsa.ImportParameters(privatekey);
signedBytes = rsa.SignData(originalData, CryptoConfig.MapNameToOID("SHA512"));
}
catch (CryptographicException e)
{
Console.WriteLine(e.Message);
return null;
}
finally
{
rsa.PersistKeyInCsp = false;
}
}
return Convert.ToBase64String(signedBytes);
}
Actually I am not sure about RSAParameters they are given correctly or not. After running this code this throws an exception as
"Bad data .\r\n"
Any help would be appreciated.

How to verify digital signature in C#

I am new here.
I am learning the digital signature in C#. The certificates are generated followed by this document. Other documents I read: RSACng,
X509Certificate2.
I am working on Windows 10 Pro 1809, .Net Core 2.1, VSCode.
class Program
{
static void Main(string[] args)
{
var passwd = "password";
// Get client certificate.
var clientCertPath = #"./Certificates/test.pfx";
var clientCert = new X509Certificate2(clientCertPath, passwd);
// Get server certificate.
var serverCertPath = #"./Certificates/test.cer";
var serverCert = new X509Certificate2(serverCertPath);
// Generate data.
var translateResultData = BuildData();
var content = String.Join('&', translateResultData.Select(p => String.Join('=', p.Key, p.Value)));
// Sign
var sign = SignatureUtil.Sign(data: content, clientCert: clientCert);
// translateResultData.TryAdd(key: "sign", value : sign);
// Copy content ONLY for test.
var checkSign = sign;
var checkContent = content;
// Verify
var valid = SignatureUtil.Verify(data: checkContent, signature: checkSign, serverCert: serverCert);
System.Console.WriteLine(valid);
}
}
public class SignatureUtil
{
public static string Sign(string data, X509Certificate2 clientCert)
{
using(var privateKey = clientCert.GetRSAPrivateKey())
{
var dataByteArray = Encoding.UTF8.GetBytes(data);
var signatureByteArray = privateKey.SignData(
data: dataByteArray,
hashAlgorithm: HashAlgorithmName.SHA256,
padding: RSASignaturePadding.Pkcs1);
return Convert.ToBase64String(signatureByteArray);
}
}
public static bool Verify(string data, string signature, X509Certificate2 serverCert)
{
try
{
using(var publicKey = serverCert.GetRSAPublicKey())
{
var dataByteArray = Encoding.UTF8.GetBytes(data);
var signatureByteArray = Convert.FromBase64String(signature);
return publicKey.VerifyData(
data: dataByteArray,
signature: signatureByteArray,
hashAlgorithm: HashAlgorithmName.SHA256,
padding: RSASignaturePadding.Pkcs1);
}
}
catch (System.Exception)
{
return false;
}
}
}
Expected result: valid should be true because I am checking the original data.
Fact: The Verify method always returns false even the original data are passed.
Can you tell me what I did wrong?

I cannot tell you what is going wrong in your code since I cannot reproduce it. Here is a very detailed answer how you can sign using RSA and SHA256. Your approach and the one described in this answer are conceptually the same, but maybe there is a difference in your code compared to this answer.
And here is a example how in my company certificates associated with smart cards are used for signing and verifying signatures. One big difference is that we do not store the signature as a string but rather keep it as an array of bytes.
public byte[] SignData(byte[] data)
{
using (var sha256 = SHA256.Create())
{
using (var rsa = Certificate.GetRSAPrivateKey())
{
return rsa.SignData(data, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1)
}
}
}
public bool VerifySignature(byte[] data, byte[] signature)
{
using (var sha256 = SHA256.Create())
{
using (var rsa = Certificate.GetRSAPublicKey())
{
return rsa.VerifyData(data, signature, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1)
}
}
}

How can I create a SHA1WithRSA signature

I have a signature generator in Java:
private static String getPvtKeyFromConfig = "merchantPvtKey";
private static String getPubKeyFromConfig = "merchantPubKey";
private static String getSaltFromConfig = "merchant_salt";
public static void main(String[] args) throws Exception {
// Generate Signature
String uniqueId="ab123";
byte[] data = Base64.decodeBase64(uniqueId);
java.security.Signature sig =java.security.Signature.getInstance("SHA1WithRSA");
sig.initSign(getPrivateFromSpec(getPvtKeyFromConfig));
sig.update(data);
byte[] signatureBytes = sig.sign();
System.out.println("Signature for uniqueId - "+uniqueId+": "+ Base64.encodeBase64String(signatureBytes));
}
How can I do it in C#?

I think this is what you are looking for:
static byte[] Sign(string text, string certSubject)
{
// Access a store
using (X509Store store = new X509Store(StoreName.My, StoreLocation.CurrentUser))
{
store.Open(OpenFlags.ReadOnly);
// Find the certificate used to sign
RSACryptoServiceProvider provider = null;
foreach (X509Certificate2 cert in store.Certificates)
{
if (cert.Subject.Contains(certSubject))
{
// Get its associated CSP and private key
provider = (RSACryptoServiceProvider)cert.PrivateKey;
break;
}
}
if (provider == null)
throw new Exception("Certificate not found.");
// Hash the data
var hash = HashText(text);
// Sign the hash
var signature = provider.SignHash(hash, CryptoConfig.MapNameToOID("SHA1"));
return signature;
}
}
static bool Verify(string text, byte[] signature, string certPath)
{
// Load the certificate used to verify the signature
X509Certificate2 certificate = new X509Certificate2(certPath);
// Get its associated provider and public key
RSACryptoServiceProvider provider = (RSACryptoServiceProvider)certificate.PublicKey.Key;
// Hash the data
var hash = HashText(text);
// Verify the signature with the hash
var result = provider.VerifyHash(hash, CryptoConfig.MapNameToOID("SHA1"), signature);
return result;
}
static byte[] HashText(string text)
{
SHA1Managed sha1Hasher = new SHA1Managed();
UnicodeEncoding encoding = new UnicodeEncoding();
byte[] data = encoding.GetBytes(text);
byte[] hash = sha1Hasher.ComputeHash(data);
return hash;
}
Sample usage:
var signature = Sign("To be or not to be, that is the question.", "CN=some_cert");
var result = Verify("To be or not to be, that is the question.", signature, "C:\\temp\\some_cert.cer");
Console.WriteLine("Verified: {0}", result);

Below C# code works for me for the exact java code mentioned in the question.
Few Notes :
.) Your project should have Target frameworks as 4.8
.) You should have existing private key
.) Using this Private key we can generate the .pfx certificate by using the OpenSSL commands.( we will have to generate the .crt first and then .pfx)
static string GenerateSignatureUsingCert(string dataToSign)
{
X509Certificate2 certificate = new X509Certificate2(#"C:\PFX\MyCertificate.pfx", "****", X509KeyStorageFlags.Exportable);
RSA privateKey1 = certificate.GetRSAPrivateKey();
Encoding unicode = Encoding.UTF8;
byte[] bytesInUni = unicode.GetBytes(dataToSign);
return Convert.ToBase64String(privateKey1.SignData(bytesInUni, HashAlgorithmName.SHA256,RSASignaturePadding.Pkcs1));
}
Usage
string canonicalizeData = CanonicalizeHeaders(headers);
String data = null;
try
{
data = GenerateSignatureUsingCert(canonicalizeData);
}
catch(Exception ex)
{
Console.WriteLine(ex.Message);
}
Console.WriteLine("Signature: " + data);

Cryptographic operation error with MachineKey.Unprotect

I am getting a Cryptographic operation error using the Protection function shown below, but it doesn't indicate what is going wrong.
The error is occurring on MachineKey.Unprotect() when I'm parsing in the bytes.
When the purpose is "username" the parse text value is ??;?W???Qzz<&???Sc??]7\\??\u001d???=?0\u007fN??g&\u001a?p?w?jJ?q?O&~c??!w???;\bv which is converted to byte[64]
I have also tried UTF8 conversion from string/bytes bytes/string with the same result.
What could be causing this?
Test Method:
var username = PasswordStorage.Protection("wheels", "username", true);
var password = PasswordStorage.Protection("legman", "password", true);
var decodeUN = PasswordStorage.Protection(username, "username", false);
var decodePass = PasswordStorage.Protection(password, "password", false);
Protection Method:
public static string Protection(string text, string purpose, bool protect)
{
try
{
if (string.IsNullOrEmpty(text))
return null;
byte[] stream = Encoding.ASCII.GetBytes(text);
var encodedBytes = new Byte[] { };
encodedBytes = protect ? MachineKey.Protect(stream, purpose) : MachineKey.Unprotect(stream, purpose);
return Encoding.ASCII.GetString(encodedBytes);
}
catch (Exception e)
{
// error logging omitted
}
return null;
}

Signing Data Using C#

I have file which I am signing using RSA algorithm using two methods:
bouncycastle
openssl
both results in two different output and openssl results in valid file. I don't know why my c# code is giving wrong output.
Here is my code for bouncy castle in c#
private void GenerateSignatureFile(string sourceFile)
{
try
{
var stringToSign = ReadText(sourceFile).ToString();
var sig = Sign(stringToSign);
var fileContent = Encoding.UTF8.GetString(sig);
using (var sw = File.CreateText(Path.Combine(_projectLocation, _sigFileName)))
{
sw.WriteLine(fileContent);
}
}
catch (Exception ex)
{
LoggingService.Log(ex.Message);
}
}
public byte[] Sign(String data)
{
var key = readPrivateKey();
/* Make the key */
var keyParameter = new RsaKeyParameters(key.IsPrivate, ((RsaPrivateCrtKeyParameters)key).Modulus, ((RsaPrivateCrtKeyParameters)key).Exponent);
/* Init alg */
ISigner sig = SignerUtilities.GetSigner("SHA256withRSA");
/* 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);
return sig.GenerateSignature();
}
public static IEnumerable<string> ReadText(string scriptPath)
{
var buffer = new StringBuilder();
foreach (var line in File.ReadLines(scriptPath))
{
if (line == "GO")
{
yield return buffer.ToString();
buffer.Clear();
}
else
{
buffer.AppendLine(line);
}
}
}
private AsymmetricKeyParameter readPrivateKey()
{
AsymmetricCipherKeyPair keyPair;
using (var reader = new StringReader(_privateKey))
keyPair = (AsymmetricCipherKeyPair)new PemReader(reader).ReadObject();
return keyPair.Private;
}
and in openssl I use following command to sign data
openssl dgst -sha256 -sign content_private_key.pem -out content.zip.sig content.zip
I don't know why my c# code is resulting in different output.

I don't think that ReadText will always return the text identical to the binary text that openssl processes. To be sure, just write the bytes variable to file after the following line was executed:
var bytes = Encoding.UTF8.GetBytes(data);
For instance you could compare the two files using sha256sum.
If this is indeed the culprit then simply read in the file as binary and sign that.