I am trying to sign some data using the private key from the smart card. The key algorithm is ECDSA. when I try to get the private key object it occurs system not supported exception.
Then after some research, I get to know that X509Certificate2 is not supporting EC Keys.
sysSec.X509Certificate2 cert = CertHelper.GetSignCertificate(serialNumber); //Get Certificate from Store var
key = cert.PrivateKey;
Then i try to use Bouncy Castle library. But in here i couldn't get ECPrivateKeyParameters after parsing X509Certificate2 . There is a code :
byte[] pkcs12Bytes = cert.Export(sysSec.X509ContentType.Pkcs12,"test");
Pkcs12Store pkcs12 = new Pkcs12StoreBuilder().Build();
pkcs12.Load(new MemoryStream(pkcs12Bytes, false), "test".ToCharArray());
ECPrivateKeyParameters privKey = null;
foreach (string alias in pkcs12.Aliases)
{
if (pkcs12.IsKeyEntry(alias))
{
privKey = (ECPrivateKeyParameters)pkcs12.GetKey(alias).Key;
break;
}
}
It also not works. But strange things happen when I create CMS file. It works.
public byte[] Sign(byte[] data , X509Certificate2 certificate ,bool detached )
{
if (data == null)
throw new ArgumentNullException("data");
if (certificate == null)
throw new ArgumentNullException("certificate");
// setup the data to sign
// ContentInfo content = new ContentInfo( new Oid("1.3.14.3.2.26"), data);
ContentInfo content = new ContentInfo( data);
SignedCms signedCms = new SignedCms(content, detached);
CmsSigner signer = new CmsSigner(SubjectIdentifierType.IssuerAndSerialNumber, certificate);
signer.SignedAttributes.Add(new Pkcs9DocumentName("testname"));
signer.SignedAttributes.Add(new Pkcs9SigningTime());
//signer.;
// CmsRecipientCollection recipest =new CmsRecipientCollection ()
// create the signature
signedCms.ComputeSignature(signer);
// signedCms.ComputeSignature()
byte[] res = signedCms.Encode();
foreach (SignerInfo info in signedCms.SignerInfos)
{
foreach (var item in info.SignedAttributes)
{
string frname = item.Oid.FriendlyName ?? "null";
Console.WriteLine(string.Format(" OID {0} : Value {1}", frname, item.Oid.Value.ToString()));
}
foreach (var item in info.UnsignedAttributes)
{
string frname = item.Oid.FriendlyName ?? "null";
Console.WriteLine(string.Format(" OID {0} : Value {1}", frname, item.Oid.Value.ToString()));
}
}
Console.WriteLine("Signed !");
return res;
}
So do anyone knows how to handle it?
Also how to sign from smartCard using Bouncy Castle?
According to my understanding BouncyCastle is a cryptographic library. It can sign something, if you provide the key. Smart cards however don't typically export private keys (so I have some doubts, whether your certificate contains the one from the smart card) but expect commands to sign something, e. g. by receiving the respective hash value and returning the signature (after ensuring appropriate user authentication).
This is typically accomplished using a PKCS#11 interface (assumed you have a driver for it matching the command set of your card) or by sending the appropriate command APDUs directly to the card (quite complicated) from your application. I found nothing on the bouncy castle website, suggesting that there is some support for addressing smart cards. (It may be hidden in the OpenPGP functionality, if your card is compliant to that standard.)
So without being acquainted with BouncyCastle it seems to me, that it won't match your expectations.
Related
I am creating signed & encrypted pkcs 7 data.
The certificates that I use to generate signatures are issued by an external party (goverment agency).
The 'other-side' only supports signatures based on a SHA256 digest, computed using RSASSA-PSS, but CmsSigner (internally used by SignedCms) automatically chooses 'plain RSA'.
Creating an RSASSA-PSS (or RsaPss) signature would not be problem. The issue at hand is that CmsSigner seems to choose the signature algorithm, based on the certificate's key pair algorithm.
Code snippet:
public static byte[] EncryptDotNet(P12Keystore p12KeyStore, byte[] secret, params Etk[] etks)
{
if (etks == null || etks?.Any() == false)
{
throw new ArgumentNullException(nameof(etks));
}
var authenticationCertificate = p12KeyStore.AuthenticationCert;
var cmsSigner = new CmsSigner(SubjectIdentifierType.IssuerAndSerialNumber, authenticationCertificate)
{
IncludeOption = X509IncludeOption.EndCertOnly,
DigestAlgorithm = new Oid(oidDigestAlgoSHA256)
};
var content = new ContentInfo(secret);
var innerSignedCms = new SignedCms(content);
innerSignedCms.ComputeSignature(cmsSigner, true);
if (innerSignedCms.SignerInfos[0].SignatureAlgorithm.Value != signatureAlgorithmRSASSAPSS)
{
//---> does not comply with expectation.
}
I have tried using reflection to setting the the algorithm oid for RSASSA-PSS to the public/private key of the certificate, didn't seem to have an impact.
Now I am wondering if I can take the RSA output and do the PSS padding myself?
Anyhow, I am open to all suggestions...
I am trying to sign some data using a certificate private key. The issue I'm finding is that the signature is different depending on if I'm executing it locally or on a server.
I'm using the following code as a test, running under the same user both locally and on the server:
using System;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Text;
namespace TestSignature
{
class Program
{
static void Main(string[] args)
{
var key = SigningKeyFromCertificate(StoreName.My, StoreLocation.LocalMachine, X509FindType.FindByThumbprint, "thumbprint");
var alg = CryptoConfig.MapNameToOID("SHA256");
var data = Encoding.UTF8.GetBytes("test");
var sig = key.SignData(data, alg);
Console.WriteLine(Convert.ToBase64String(sig));
}
private static RSACryptoServiceProvider SigningKeyFromCertificate(StoreName storeName, StoreLocation storeLocation, X509FindType findType, string findValue)
{
X509Store store = new X509Store(storeName, storeLocation);
store.Open(OpenFlags.ReadOnly);
var certs = store.Certificates.Find(findType, findValue, false);
if (certs?.Count > 0)
{
var cert = certs[0];
if (cert.HasPrivateKey)
{
// Force use of Enhanced RSA and AES Cryptographic Provider to allow use of SHA256.
var key = cert.PrivateKey as RSACryptoServiceProvider;
var enhanced = new RSACryptoServiceProvider().CspKeyContainerInfo;
var parameters = new CspParameters(enhanced.ProviderType, enhanced.ProviderName, key.CspKeyContainerInfo.UniqueKeyContainerName);
return new RSACryptoServiceProvider(parameters);
}
else
{
throw new Exception($"No private key access to cert '{findValue}.'");
}
}
else
{
throw new Exception($"Cert '{findValue}' not found!");
}
}
}
}
Locally, I get the following signature:
YUjspKhLl7v3u5VQkh1PfHytMTpEtbAftxOA5v4lmph3B4ssVlZp7KedO5NW9K5L222Kz9Ik9/55NirS0cNCz/cDhEFRtD4daJ9qLRuM8oD5hCj6Jt9Vc6WeS2he+Cqfoylnv4V9plfi1xw8y7EyAf4C77BGkXOdyP5wyz2Xubo=
On the server, I get this one instead:
u1RUDwbBlUpOgNNkAjXhYEWfVLGpMOa0vEfm6PUkB4y9PYBk1lDmCAp+488ta+ipbTdSDLM9btRqsQfZ7JlIn/dIBw9t5K63Y7dcDcc7gDLE1+umLJ7EincMcdwUv3YQ0zCvzc9RrP0jKJManV1ptQNnODpMktGYAq1KmJb9aTY=
Any idea of what could be different? I would think, with the same certificate, the same code, and the same data, the signature should be the same.
(The example is written in C# 4.5.2.)
You have some code to reopen the CAPI key handle under PROV_RSA_AES:
// Force use of Enhanced RSA and AES Cryptographic Provider to allow use of SHA256.
var key = cert.PrivateKey as RSACryptoServiceProvider;
var enhanced = new RSACryptoServiceProvider().CspKeyContainerInfo;
var parameters = new CspParameters(
enhanced.ProviderType,
enhanced.ProviderName,
key.CspKeyContainerInfo.UniqueKeyContainerName);
return new RSACryptoServiceProvider(parameters);
But key.CspKeyContainerInfo.UniqueKeyContainerName isn't the name of the key (it's the name of the file on disk where the key lives), so you're opening a brand new key (you're also generating a new ephemeral key just to ask what the default provider is). Since it's a named key it persists, and subsequent application executions resolve to the same key -- but a different "same" key on each computer.
A more stable way of reopening the key is
var cspParameters = new CspParameters
{
KeyContainerName = foo.CspKeyContainerInfo.KeyContainerName,
Flags = CspProviderFlags.UseExistingKey,
};
(since the provider type and name aren't specified they will use the defaults, and by saying UseExistingKey you get an exception if you reference a key that doesn't exist).
That said, the easiest fix is to stop using RSACryptoServiceProvider. .NET Framework 4.6 (and .NET Core 1.0) have a(n extension) method on X509Certificate2, GetRSAPrivateKey(), it returns an RSA (which you should avoid casting) which is usually RSACng (on Windows), but may be RSACryptoServiceProvider if only CAPI had a driver required for a HSM, and may be some other RSA in the future. Since RSACng handles SHA-2 better there's almost never a need to "reopen" the return object (even if it's RSACryptoServiceProvider, and even if the type isn't PROV_RSA_AES (24), that doesn't mean the HSM will fail to do SHA-2).
I need to create "Client" ECDSA certificate signed by "Root" certificate (self-signed, ECDSA).
"Root" certificate was created as described in Translating Elliptic Curve parameters (BC to MS).
To create "Client" certificate (signed by "Root") slightly modified algorithm can be used.
The difference is that the private key (used to sign public key from keypair generated for "Client" certificate) must be supplied from the "outside" - it is a private-key of "Root" certificate.
But this is the issue. I cannot find a way how to get and translate private key to type Org.BouncyCastle.Crypto.Parameters.ECPrivateKeyParameters that could be passed to signature-factory.
// 1. get private-key of "Root" certificate from existing certificate:
byte[] msRootCertData = File.ReadAllBytes(#"c:\root_ecdsa_cert.pfx");
X509Certificate2 msRootCert = new X509Certificate2(msRootCertData);
ECDsaCng msRootPrivateKey = msRootCert.GetECDsaPrivateKey() as ECDsaCng;
ECParameters msRootPrivateKeyParameters = msRootPrivateKey.ExportParameters(true);
// here comes the issue:
ECPrivateKeyParameters bcRootPrivateKeysParameters = TranslateMSKeysToBouncy(msRootPrivateKeyParameters);
// 2. generate "Client" key-pair:
AsymmetricCipherKeyPair bcClientKeyPair = bcKeyGen.GenerateKeyPair();
ECPrivateKeyParameters bcClientPrivKey = (ECPrivateKeyParameters)bcClientKeyPair.Private;
ECPrivateKeyParameters bcClientPublKey = (ECPublicKeyParameters)bcClientKeyPair.Public;
// 3. create X509 certificate:
X509V3CertificateGenerator bcCertGen = new X509V3CertificateGenerator();
bcCertGen.SetPublicKey(bcClientPublKey);
// .. set subject, validity period etc
ISignatureFactory sigFac = new Asn1SignatureFactory("Sha256WithECDSA", bcRootPrivateKeysParameters);
Org.BouncyCastle.X509.X509Certificate bcClientX509Cert = bcCertGen.Generate(sigFac);
byte[] x509CertEncoded = bcClientX509Cert.GetEncoded();
// the rest is the same as in the mentioned example.
Any hints?
Or is there other way? (for example: passing instance of X509Certificate2 directly to BouncyCastle library (avoid to translate private-keys to Cng), or generating "Client" certificate without BouncyCastle)
Thanks.
If you can take a dependency on .NET Framework 4.7.2 (or .NET Core 2.0) you can do it without BouncyCastle, via the new CertificateRequest class:
X509Certificate2 publicPrivate;
using (ECDsa clientPrivateKey = ECDsa.Create())
{
var request = new CertificateRequest(
"CN=Et. Cetera",
clientPrivateKey,
HashAlgorithmName.SHA256);
// Assuming this isn't another CA cert:
request.CertificateExtensions.Add(
new X509BasicConstraintsExtension(false, false, 0, false));
// other CertificateExtensions as you desire.
// Assign, or derive, a serial number.
// RFC 3280 recommends that it have no more than 20 bytes encoded.
// 12 random bytes seems long enough.
byte[] serial = new byte[12];
using (RandomNumberGenerator rng = RandomNumberGenerator.Create())
{
rng.GetBytes(serial);
}
DateTimeOffset notBefore = DateTimeOffset.UtcNow;
DateTimeOffset notAfter = notBefore.AddMonths(15);
using (X509Certificate2 publicOnly = request.Create(
msRootCert,
notBefore,
notAfter,
serial))
{
publicPrivate = publicOnly.CopyWithPrivateKey(clientPrivateKey);
}
}
// The original key object was disposed,
// but publicPrivate.GetECDsaPrivateKey() still works.
If you want to add publicPrivate to an X509Store you need to either 1) export it to a PFX and re-import it, or 2) change the key creation to use a named key. Otherwise, only the public portion will be saved (on Windows).
I have X509 certificates that are stored on the network. I can read the chain from remote windows certificate store. I need to sign some data and include chain to the signature to make it possible to validate it later.
The problem is that I can't find a way to put certificate chain to the CsmSigner. I have read that it takes certificate from constructor parameter and tries to build a chain with X509Chain.Build. It ignores Certificates list values and fails (obviously) because no certificate can be found in the local Windows cert store.
Please find below my test code (that works only if certificates were saved locally to the windows cert store)
protected byte[] SignWithSystem(byte[] data, X509Certificate2 cert, X509Certificate[] chain)
{
ContentInfo contentInfo = new ContentInfo(data);
SignedCms signedCms = new SignedCms(contentInfo, true);
CmsSigner cmsSigner = new CmsSigner(cert);
cmsSigner.DigestAlgorithm = new Oid("2.16.840.1.101.3.4.2.1"); //sha256
cmsSigner.IncludeOption = X509IncludeOption.WholeChain;
if (chain != null)
{
//adding cert chain to signer
cmsSigner.Certificates.AddRange(chain);
signedCms.Certificates.AddRange(chain);
}
signedCms.ComputeSignature(cmsSigner); //fails here with System.Security.Cryptography.CryptographicException : A certificate chain could not be built to a trusted root authority.
byte[] signedPkcs = signedCms.Encode();
return signedPkcs;
}
Is there any way to make it work without uploading certificates to the local store? Should I use any alternative signer?
I can try to upload certificates to the store but the problems are that
I have to add and remove certificates (permissions have to be granted)
There are several processes that applies signature so cross-process synchronization have to be added.
This is not that I'd like to do.
Example CMS Signing with BouncyCastle for .NET
You could use the BouncyCastle crypto library for .NET, which contains its own X509 certificate and CMS signing machinery. A lot of the examples and documentation on the web are for Java, as BouncyCastle was a Java library first. I've used the answer to this Stackoverflow question as a starting point for the certificate and key loading, and added the CMS signing. You may have to tweak parameters to produce the results you want for your use case.
I've made the signing function look approximately like yours, but note the private key is a separate parameter now.
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Org.BouncyCastle.Cms;
using Org.BouncyCastle.Pkcs;
using Org.BouncyCastle.X509;
using Org.BouncyCastle.Crypto;
using Org.BouncyCastle.X509.Store;
class Program
{
protected static byte[] SignWithSystem(byte[] data, AsymmetricKeyParameter key, X509Certificate cert, X509Certificate[] chain)
{
var generator = new CmsSignedDataGenerator();
// Add signing key
generator.AddSigner(
key,
cert,
"2.16.840.1.101.3.4.2.1"); // SHA256 digest ID
var storeCerts = new List<X509Certificate>();
storeCerts.Add(cert); // NOTE: Adding end certificate too
storeCerts.AddRange(chain); // I'm assuming the chain collection doesn't contain the end certificate already
// Construct a store from the collection of certificates and add to generator
var storeParams = new X509CollectionStoreParameters(storeCerts);
var certStore = X509StoreFactory.Create("CERTIFICATE/COLLECTION", storeParams);
generator.AddCertificates(certStore);
// Generate the signature
var signedData = generator.Generate(
new CmsProcessableByteArray(data),
false); // encapsulate = false for detached signature
return signedData.GetEncoded();
}
static void Main(string[] args)
{
try
{
// Load end certificate and signing key
AsymmetricKeyParameter key;
var signerCert = ReadCertFromFile(#"C:\Temp\David.p12", "pin", out key);
// Read CA cert
var caCert = ReadCertFromFile(#"C:\Temp\CA.cer");
var certChain = new X509Certificate[] { caCert };
var result = SignWithSystem(
Guid.NewGuid().ToByteArray(), // Any old data for sake of example
key,
signerCert,
certChain);
File.WriteAllBytes(#"C:\Temp\Signature.data", result);
}
catch (Exception ex)
{
Console.WriteLine("Failed : " + ex.ToString());
Console.ReadKey();
}
}
public static X509Certificate ReadCertFromFile(string strCertificatePath)
{
// Create file stream object to read certificate
using (var keyStream = new FileStream(strCertificatePath, FileMode.Open, FileAccess.Read))
{
var parser = new X509CertificateParser();
return parser.ReadCertificate(keyStream);
}
}
// This reads a certificate from a file.
// Thanks to: http://blog.softwarecodehelp.com/2009/06/23/CodeForRetrievePublicKeyFromCertificateAndEncryptUsingCertificatePublicKeyForBothJavaC.aspx
public static X509Certificate ReadCertFromFile(string strCertificatePath, string strCertificatePassword, out AsymmetricKeyParameter key)
{
key = null;
// Create file stream object to read certificate
using (var keyStream = new FileStream(strCertificatePath, FileMode.Open, FileAccess.Read))
{
// Read certificate using BouncyCastle component
var inputKeyStore = new Pkcs12Store();
inputKeyStore.Load(keyStream, strCertificatePassword.ToCharArray());
var keyAlias = inputKeyStore.Aliases.Cast<string>().FirstOrDefault(n => inputKeyStore.IsKeyEntry(n));
// Read Key from Aliases
if (keyAlias == null)
throw new NotImplementedException("Alias");
key = inputKeyStore.GetKey(keyAlias).Key;
//Read certificate into 509 format
return (X509Certificate)inputKeyStore.GetCertificate(keyAlias).Certificate;
}
}
}
.NET CMS (Quick-fix with rest of chain omitted from signature)
I can reproduce your problem with a certificate whose root is not in the trusted certificate store, and confirm that adding the certificate chain to the cmsSigner/signedCms Certificates collection does not avoid the A certificate chain could not be built to a trusted root authority error.
You can sign successfully by setting cmsSigner.IncludeOption = X509IncludeOption.EndCertOnly;
However, if you do this, you will not get the rest of the chain in the signature. This probably isn't what you want.
As an aside, in your example you are using X509Certificate for the array of certificates in the chain, but passing them to an X509Certificate2Collection (note the "2" in there). X509Certificate2 derives from X509Certificate, but if its not actually an X509Certificate2 that you put in one of those collections, you'll get a cast error if something iterates over the collection (you don't get an error when adding a certificate of the wrong type unfortunately, because X509Certificate2Collection also derives from X509CertificateCollection and inherits its add methods).
Adding sample code that creates detached PKCS7 signature using BouncyCastle (thanks to softwariness) without Certificate store.
It uses .net X509Certificate2 instances as input parameter. First certificate in collection have to be linked with private key to sign data.
Also I'd like to note that it is not possible to read private key associated with certificate from remote Windows cert store using .net X509Certificate2.PrivateKey property. By default private key is not loaded with certificate using X509Store(#"\\remotemachine\MY", StoreLocation.LocalMachine) and when X509Certificate2.PrivateKey property is accessed on local machine it fails with error "Keyset does not exist".
public void SignWithBouncyCastle(Collection<X509Certificate2> netCertificates)
{
// first cert have to be linked with private key
var signCert = netCertificates[0];
var Cert = Org.BouncyCastle.Security.DotNetUtilities.FromX509Certificate(signCert);
var data = Encoding.ASCII.GetBytes(Cert.SubjectDN.ToString());
var bcCertificates = netCertificates.Select(_ => Org.BouncyCastle.Security.DotNetUtilities.FromX509Certificate(_)).ToList();
var x509Certs = X509StoreFactory.Create("Certificate/Collection", new X509CollectionStoreParameters(bcCertificates));
var msg = new CmsProcessableByteArray(data);
var gen = new CmsSignedDataGenerator();
var privateKey = Org.BouncyCastle.Security.DotNetUtilities.GetKeyPair(signCert.PrivateKey).Private;
gen.AddSigner(privateKey, Cert, CmsSignedDataGenerator.DigestSha256);
gen.AddCertificates(x509Certs);
var signature = gen.Generate(msg, false).GetEncoded();
Trace.TraceInformation("signed");
CheckSignature(data, signature);
Trace.TraceInformation("checked");
try
{
CheckSignature(new byte[100], signature);
}
catch (CryptographicException cex)
{
Trace.TraceInformation("signature was checked for modified data '{0}'", cex.Message);
}
}
void CheckSignature(byte[] data, byte[] signature)
{
var ci = new ContentInfo(data);
SignedCms signedCms = new SignedCms(ci, true);
signedCms.Decode(signature);
foreach (X509Certificate cert in signedCms.Certificates)
Trace.TraceInformation("certificate found {0}", cert.Subject);
signedCms.CheckSignature(true);
}
To be clear, I am no security or cryptography expert.. but per my knowledge, for receiver to be able to validate the signature, the root certificate in the certificate chain you used for signing, must already be a trusted root for the receiver.
If the receiver does not have the root certificate already in their store, and marked as a trusted root... then doesn't matter how you sign the data.. it will fail validation on receiver end. And this is by design.
See more at Chain of trust
Hence the only real solution to your problem I see is to ensure that the root certificate is provisioned as trusted root on both ends... Typically done by a Certificate Authority.
Enterprise application scenario - Typically in an enterprise some group in IT department (who have access to all machines in the domain - like domain admins) would enable this scenario by ensuring that every computer in the domain has root certificate owned by this group, present on every machine as trusted root, and an application developer in the enterprise typically requests a new certificate for use with their application, which has the chain of trust going back to the root certificate already distributed to all machines in the domain.
Found out contact person for this group in your company, and have them issue a certificate you can use for signature.
Internet application scenario - There are established Certificate Authorities, who own their root certificates, and work with OS vendors to ensure that their root certificates are in trusted store, as the OS vendor ships the OS to it's customers. (One reason why using pirated OS can be harmful. It's not just about viruses / malware..). And that is why when you use a certificate issued by VeriSign to sign the data, the signature can be validated by most other machines in the world.
I am working on a project where I need to use a "public key" to encrypt a message using RSA algorithm. I was provided with a certificate and my first thought was to use Public Key from that certificate and after investigation I learned I need to use RSACryptoServiceProvider for encryption.
I have checked msdn and only method I thought I should use is RSACryptoServiceProvider.ImportCspBlob(byte[] keyBlob).
When I tried to use public key exported from certificate I was getting an error that the header data for certificate is invalid.
I know I can cast X509certificate2.PublicKey.Key to RSACryptoServiceProvider but from what I understood from my client is that going forward I will be given only a public key and not the certificate. This key will have to be saved in .xml configuration file.
So to summarize: Is there a way to generate an RSACryptoServiceProvider given only a certificate's public key?
You can try to look at this example: RSA public key encryption in C#
var publicKey = "<RSAKeyValue><Modulus>21wEnTU+mcD2w0Lfo1Gv4rtcSWsQJQTNa6gio05AOkV/Er9w3Y13Ddo5wGtjJ19402S71HUeN0vbKILLJdRSES5MHSdJPSVrOqdrll/vLXxDxWs/U0UT1c8u6k/Ogx9hTtZxYwoeYqdhDblof3E75d9n2F0Zvf6iTb4cI7j6fMs=</Modulus><Exponent>AQAB</Exponent></RSAKeyValue>";
var testData = Encoding.UTF8.GetBytes("testing");
using ( var rsa = new RSACryptoServiceProvider(1024))
{
try
{
// client encrypting data with public key issued by server
//
rsa.FromXmlString(publicKey);
var encryptedData = rsa.Encrypt(testData, true);
var base64Encrypted = Convert.ToBase64String(encryptedData);
}
finally
{
rsa.PersistKeyInCsp = false;
}
}
You are OK and following a good typical pattern. The Sender of the data does not need the private key.
The following may confirm some of the code you already have figured out.
The one line where I set the private key for the receiver/decoder I left out.
I took this from a test case I have in my build deploy stuff.
byte[] certBytAr; // This is the certificate as bianry in a .cer file (no private key in it - public only)
X509Certificate2 cert2 = new X509Certificate2(certBytAr);
string strToEncrypt = "Public To Private Test StackOverFlow PsudeoCode. Surfs Up at Secret Beach.";
byte[] bytArToEncrypt = Encoding.UTF8.GetBytes(strToEncrypt);
RSACryptoServiceProvider rsaEncryptor = (RSACryptoServiceProvider)cert2.PublicKey.Key;
byte[] dataNowEncryptedArray = rsaEncryptor.Encrypt(bytArToEncrypt, true);
// done - you now have encrypted bytes
//
// somewhere elxe ...
// this should decrpyt it - simulate the destination which will decrypt the data with the private key
RSACryptoServiceProvider pk = // how this is set is complicated
// set the private key in the x509 oobject we created way above
cert2.PrivateKey = pk;
RSACryptoServiceProvider rsaDecryptor = (RSACryptoServiceProvider)cert2.PrivateKey;
byte[] dataDecrypted = rsaDecryptor.Decrypt(dataNowEncryptedArray, true);
Console.WriteLine(" encrypt 1 Way Intermediate " + BitConverter.ToString(dataDecrypted));
string strDecodedFinal = Encoding.UTF8.GetString(dataDecrypted);
if (strDecodedFinal == strToEncrypt)
{
}
else
{
Console.WriteLine(" FAILURE OF ENCRYPTION ROUND TRIP IN SIMPLE TEST (Direction: Public to Private). No Surfing For You ");
}