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Read ECC private key PEM into AsymmetricCipherKeyPair c# bouncy castle

I generate an ECC key pair in PEM format using Bouncy Castle using:
var curve = ECNamedCurveTable.GetByName("secp256k1");
var domainParams = new ECDomainParameters(curve.Curve, curve.G, curve.N, curve.H, curve.GetSeed());
var secureRandom = new SecureRandom();
var keyParams = new ECKeyGenerationParameters(domainParams, secureRandom);
var generator = new ECKeyPairGenerator("ECDSA");
generator.Init(keyParams);
AsymmetricCipherKeyPair keyPair = generator.GenerateKeyPair();
TextWriter textWriter = new StringWriter();
PemWriter pemWriter = new PemWriter(textWriter);
pemWriter.WriteObject(keyPair.Private);
pemWriter.Writer.Flush();
string pem_privatekey = textWriter.ToString();
My current ECC private key is:
-----BEGIN EC PRIVATE KEY-----MIIBUQIBAQQgyDHBaj30dcIsS4otdOXR8ue+rZDwHcGEjxwle3H24W6ggeMwgeACAQEwLAYHKoZIzj0BAQIhAP////////////////////////////////////7///wvMEQEIAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABCAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABwRBBHm+Zn753LusVaBilc6HCwcCm/zbLc4o2VnygVsW+BeYSDradyajxGVdpPv8DhEIqP0XtEimhVQZnEfQj/sQ1LgCIQD////////////////////+uq7c5q9IoDu/0l6M0DZBQQIBAaFEA0IABHxw0PK0uEvnF1lwhkLmHUlVtQVUrLp/1EcKzfAm6xOL/I6LtQ9nXPxDNhaxf/rPtk3DkZ5CaO0hLr1trCRrJz8=-----END EC PRIVATE KEY-----
I want to read this pem format private in a bouncy castle ECPrivateKeyParameters or AsymmetricCipherKeyPair format.
I am trying the following code.
pem is the above private key string.
PemReader pr = new PemReader(new StringReader(pem));
ECPrivateKeyParameters KeyPair = (ECPrivateKeyParameters)pr.ReadObject();
Why this returns null? Please correct me.

pr.ReadObject() returns an AsymmetricCipherKeyPair instance here. This has the properties Private and Public which here returns an ECPrivateKeyParameters and ECPublicKeyParameters instance respectively, i.e. the code should be:
PemReader pr = new PemReader(new StringReader(pem));
AsymmetricCipherKeyPair keyPair = (AsymmetricCipherKeyPair)pr.ReadObject();
ECPrivateKeyParameters privateKeyParams = (ECPrivateKeyParameters)keyPair.Private;
ECPublicKeyParameters publicKeyParams = (ECPublicKeyParameters)keyPair.Public; // for completeness

Generate key/Encryption/Decryption for RSACryptoProvider and BouncyCastle

Key generated through RSACryptoProvider is work for BouncyCastle Encryption (using publickey) / Decryption (using privatekey) ?
using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider())
{
var pu = rsa.ToXmlString(false);
var pr = rsa.ToXmlString(true);
}
Also, how to generate key using BouncyCastle ?

Answer to first question, yes, RSA is a standard and it doesn't depends on the libraries used.
Second, try this:
public static void GetRsaKeyPair(out string privateXml, out string publicXml)
{
CryptoApiRandomGenerator randomGenerator = new CryptoApiRandomGenerator();
SecureRandom secureRandom = new SecureRandom(randomGenerator);
var keyGenerationParameters = new KeyGenerationParameters(secureRandom, 1024);
var rsaKeyPairGenerator = new RsaKeyPairGenerator();
rsaKeyPairGenerator.Init(keyGenerationParameters);
AsymmetricCipherKeyPair rsaKeyPair = rsaKeyPairGenerator.GenerateKeyPair();
var privateRsaParameters = DotNetUtilities.ToRSAParameters((RsaPrivateCrtKeyParameters)rsaKeyPair.Private);
using (RSACryptoServiceProvider rsaProvider = new RSACryptoServiceProvider())
{
rsaProvider.ImportParameters(privateRsaParameters);
privateXml = rsaProvider.ToXmlString(true);
publicXml = rsaProvider.ToXmlString(false);
}
}

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.

RSA Decryption using BouncyCastle with private PEM file not working

I'm doing some tests with BouncyCastle in C# and I want to encrypt some data and decrypt it later with a pair of keys that I have in my computer stored as PEM files.
public static string RSABouncyEncrypt(string content)
{
var bytesToEncrypt = Encoding.UTF8.GetBytes(content);
AsymmetricKeyParameter keyPair;
using (var reader = File.OpenText(#"C:\Users\Diego\Documents\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);
System.Windows.MessageBox.Show(cryptMessage);
//Decrypt before return statement to check that it has been encrypted correctly
RSADecrypt(cryptMessage);
return cryptMessage;
}
public static void RSADecrypt(string string64)
{
var bytesToDecrypt = Convert.FromBase64String(string64); // string to decrypt, base64 encoded
AsymmetricCipherKeyPair keyPair;
using (var reader = File.OpenText(#"C:\Users\Diego\Documents\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);
System.Windows.MessageBox.Show(decrypted);
}
The RSADecrypt function shows an error. when I show the message box after decrypting I get this:
���Z��8o>>���;;�/�Z�ב?���#�F��(͌5���o1I�,���4� S�W��)��w��x�4p�$-|А���&��Rv}�G��V�c ��&wU?
�D�� }E���O����7�n��!(e��E��$y�g9ςOأ��P�� �t�d�T�nN��K$�bQ��!�v���-�Hb���1���?����#B�y� r��Le�h=*Yr�w
�l�W|�嘟��|g��EV��#�[��M
which is definitely not what I encrypted. What am I doing wrong?

Actually the answer why it is not working is that there is no information about padding. Correct way how to instantiate RsaEngine is sth. like this
var decryptEngine = new Pkcs1Encoding(RsaEngine())
var bytesToDecrypt = Convert.FromBase64String(string64); // string to decrypt, base64 encoded
AsymmetricCipherKeyPair keyPair;
using (var reader = File.OpenText(#"C:\Users\Diego\Documents\private.pem"))
keyPair = (AsymmetricCipherKeyPair)new Org.BouncyCastle.OpenSsl.PemReader(reader).ReadObject();
var decryptEngine = new Pkcs1Encoding(RsaEngine());
decryptEngine.Init(false, keyPair.Private);
var decrypted = Encoding.UTF8.GetString(decryptEngine.ProcessBlock(bytesToDecrypt, 0, bytesToDecrypt.Length));
Logs.Log.LogMessage("decrypted: " + decrypted);
System.Windows.MessageBox.Show(decrypted);

I reproduced this problem and it happened because you used a private key and a public key that don't match. In other words the message was encrypted with a private key (let's call it private_key_1) that came from one pair (private_key_1/public_key_1) but you tried to decrypt it with a public key (let's call it publick_key_2) that came from a different pair (private_key_2/public_key_2). Try to generate a new key pair and use it in your example e.g.:
var kpgen = new RsaKeyPairGenerator();
kpgen.Init(new KeyGenerationParameters(new SecureRandom(new CryptoApiRandomGenerator()), 1024));
var keyPair = kpgen.GenerateKeyPair();
using (var writer = new StreamWriter(File.OpenWrite(#"C:\Users\Diego\Documents\private2.pem")))
{
new PemWriter(writer).WriteObject(keyPair.Private);
}
using (var writer = new StreamWriter(File.OpenWrite(#"C:\Users\Diego\Documents\public2.pem")))
{
new PemWriter(writer).WriteObject(keyPair.Public);
}