From a legacy program:
bye[] rsaPrivateKeyExport = RSACryptoProvider.ExportCspBlob(true);
These keys are stored in a file.
As part of a legacy refresh, I need to use CNG RSA keys.
So something like reading the old blob and then converting:
CngKey cngPrv = CngKey.Import(rsaPrvKeyExport,
CngKeyBlobFormat.GenericPrivateBlob);
But I cannot get this to work?
How do I convert the old blob type to the new one? Do I only use parts of the old blob?
The key length is 2048.
GenericPrivateBlob is a CNG-specific format, it doesn't mean "try any private thing".
CNG is capable of opening CAPI key blobs, using the formats identified at https://learn.microsoft.com/en-us/windows/desktop/api/Bcrypt/nf-bcrypt-bcryptexportkey.
private static readonly CngKeyBlobFormat s_legacyRsaPrivateBlobFormat =
new CngKeyBlobFormat("CAPIPRIVATEBLOB");
...
byte[] exported;
using (RSACryptoServiceProvider a = new RSACryptoServiceProvider(2048))
{
exported = a.ExportCspBlob(true);
}
RSA b;
using (CngKey key = CngKey.Import(exported, s_legacyRsaPrivateBlob))
{
b = new RSACng(key);
}
// This using is broken out here just to show that the constructed object can safely outlive
// the CngKey object that it was created from.
using (b)
{
...
}
I am looking for the same solution that was found in this question:
How can I import an RSA private key into an RSACryptoServiceProvider?
Unfortunately the actual method of the solution is not provided and I'm having trouble with the last steps. The overview:
I have an existing private key that was creating with CAPI using these steps:
// Abbreviated for clarity.
CryptAcquireContext(..., MS_ENHANCED_PROV, ...);
// Generate public/private key pair
CryptCreateHash(..., CALG_SHA1, ...);
CryptHashData(hash, password, ...);
CryptDeriveKey(..., CALG_3DES, hash, CRYPT_EXPORTABLE, ...);
CyrptExportKey(..., derivedKey, PRIVATEKEYBLOB, ...);
I need to import this key into a C# RSACryptoService provider.
Based on the other question, I know that I have to derive the key using PasswordDerivedBytes and then decrypt the key using the derived key, but I do not know how to perform those steps.
I've got something like the following to get started:
var parameters = new CspParameters
{
ProviderName = "Microsoft Enhanced Cryptographic Provider v1.0",
ProviderType = 1,
Flags = CspProviderFlags.UseMachineKeyStore,
KeyContainerName = "KeyContainer"
};
var csp = new RSACryptoServiceProvider(parameters);
byte[] pwd = Encoding.ASCII.GetBytes("Password");
PasswordDeriveBytes pdb = new PasswordDeriveBytes(pwd, new byte[0], parameters);
// This line throws a CryptographicException with "Invalid flags specified."
byte[] symKey = pdb.CryptDeriveKey("TripleDES", "SHA1", 192, new byte[8]);
If I remove the KeyContainerName from the CspParamaters then I can generate a key, but I was under the impression that I had to use the same Csp to derive the same key.
And once I've got the key out, I don't know what I'm supposed to do with it to decrypt the key.
I am trying to read an RSA private key into .Net using BouncyCastle to test data I have previously encrypted. The encrypted data is working fine using the public key and Bouncy Castle and I have also used the same private key as below (which is DER format) to successfully decrypt my data in a PHP application but I don't know why I can't create the private key in .Net to do the same thing:
byte[] privatekey = File.ReadAllBytes(#"C:\Users\Luke\privkey.der");
var rsaKeyParameters = (RsaKeyParameters)PrivateKeyFactory.CreateKey(privatekey);
The second line throws an exception:
"unknown object in factory: DerInteger\r\nParameter name: obj"
I also tried using a stream instead of a byte array and the same error occurs. The key pair was created using OpenSSL and as mentioned, decryption works in PHP using openssl_private_decrypt() and the same key as in the .Net code. I also tried a PEM format of the same key and that also didn't work (but I don't think BC supports PEM directly anyway)
Has anyone done this before? Thanks
The problem was that I had assumed PublicKeyFactory and PrivateKeyFactory were complimentary since they are in the same namespace. They are not!
To decode the private key, I needed the following alternative code:
var privKeyObj = Asn1Object.FromStream(privatekey);
var privStruct = new RsaPrivateKeyStructure((Asn1Sequence)privKeyObj);
// Conversion from BouncyCastle to .Net framework types
var rsaParameters = new RSAParameters();
rsaParameters.Modulus = privStruct.Modulus.ToByteArrayUnsigned();
rsaParameters.Exponent = privStruct.PublicExponent.ToByteArrayUnsigned();
rsaParameters.D = privStruct.PrivateExponent.ToByteArrayUnsigned();
rsaParameters.P = privStruct.Prime1.ToByteArrayUnsigned();
rsaParameters.Q = privStruct.Prime2.ToByteArrayUnsigned();
rsaParameters.DP = privStruct.Exponent1.ToByteArrayUnsigned();
rsaParameters.DQ = privStruct.Exponent2.ToByteArrayUnsigned();
rsaParameters.InverseQ = privStruct.Coefficient.ToByteArrayUnsigned();
var rsa = new RSACryptoServiceProvider();
rsa.ImportParameters(rsaParameters);
return Encoding.UTF8.GetString(rsa.Decrypt(Convert.FromBase64String(ciphertext), true));
A BIG thankyou to owlstead for their help.
My application will take a set of files and sign them. (I'm not trying to sign an assembly.) There is a .p12 file that I get the private key from.
This is the code I was trying to use, but I get a System.Security.Cryptography.CryptographicException "Invalid algorithm specified.".
X509Certificate pXCert = new X509Certificate2(#"keyStore.p12", "password");
RSACryptoServiceProvider csp = (RSACryptoServiceProvider)pXCert.PrivateKey;
string id = CryptoConfig.MapNameToOID("SHA256");
return csp.SignData(File.ReadAllBytes(filePath), id);
According to this answer it can't be done (the RSACryptoServiceProvider does not support SHA-256), but I was hoping that it might be possible using a different library, like Bouncy Castle.
I'm new to this stuff and I'm finding Bouncy Castle to be very confusing. I'm porting a Java app to C# and I have to use the same type of encryption to sign the files, so I am stuck with RSA + SHA256.
How can I do this using Bouncy Castle, OpenSSL.NET, Security.Cryptography, or another 3rd party library I haven't heard of? I'm assuming, if it can be done in Java then it can be done in C#.
UPDATE:
this is what I got from the link in poupou's anwser
X509Certificate2 cert = new X509Certificate2(KeyStoreFile, password");
RSACryptoServiceProvider rsacsp = (RSACryptoServiceProvider)cert.PrivateKey;
CspParameters cspParam = new CspParameters();
cspParam.KeyContainerName = rsacsp.CspKeyContainerInfo.KeyContainerName;
cspParam.KeyNumber = rsacsp.CspKeyContainerInfo.KeyNumber == KeyNumber.Exchange ? 1 : 2;
RSACryptoServiceProvider aescsp = new RSACryptoServiceProvider(cspParam);
aescsp.PersistKeyInCsp = false;
byte[] signed = aescsp.SignData(File.ReadAllBytes(file), "SHA256");
bool isValid = aescsp.VerifyData(File.ReadAllBytes(file), "SHA256", signed);
The problem is that I'm not getting the same results as I got with the original tool. As far as I can tell from reading the code the CryptoServiceProvider that does the actual signing is not using the PrivateKey from key store file. Is that Correct?
RSA + SHA256 can and will work...
Your later example may not work all the time, it should use the hash algorithm's OID, rather than it's name. As per your first example, this is obtained from a call to CryptoConfig.MapNameToOID(AlgorithmName) where AlgorithmName is what you are providing (i.e. "SHA256").
First you are going to need is the certificate with the private key. I normally read mine from the LocalMachine or CurrentUser store by using a public key file (.cer) to identify the private key, and then enumerate the certificates and match on the hash...
X509Certificate2 publicCert = new X509Certificate2(#"C:\mycertificate.cer");
//Fetch private key from the local machine store
X509Certificate2 privateCert = null;
X509Store store = new X509Store(StoreLocation.LocalMachine);
store.Open(OpenFlags.ReadOnly);
foreach( X509Certificate2 cert in store.Certificates)
{
if (cert.GetCertHashString() == publicCert.GetCertHashString())
privateCert = cert;
}
However you get there, once you've obtained a certificate with a private key we need to reconstruct it. This may be required due to the way the certificate creates it's private key, but I'm not really sure why. Anyway, we do this by first exporting the key and then re-importing it using whatever intermediate format you like, the easiest is xml:
//Round-trip the key to XML and back, there might be a better way but this works
RSACryptoServiceProvider key = new RSACryptoServiceProvider();
key.FromXmlString(privateCert.PrivateKey.ToXmlString(true));
Once that is done we can now sign a piece of data as follows:
//Create some data to sign
byte[] data = new byte[1024];
//Sign the data
byte[] sig = key.SignData(data, CryptoConfig.MapNameToOID("SHA256"));
Lastly, the verification can be done directly with the certificate's public key without need for the reconstruction as we did with the private key:
key = (RSACryptoServiceProvider)publicCert.PublicKey.Key;
if (!key.VerifyData(data, CryptoConfig.MapNameToOID("SHA256"), sig))
throw new CryptographicException();
The use of privateKey.toXMLString(true) or privateKey.exportParameters(true) aren't usable in a secure environment, since they require your private key to be exportable, which is NOT a good practice.
A better solution is to explicitly load the "Enhanced" crypto provider as such:
// Find my openssl-generated cert from the registry
var store = new X509Store(StoreLocation.LocalMachine);
store.Open(OpenFlags.ReadOnly);
var certificates = store.Certificates.Find(X509FindType.FindBySubjectName, "myapp.com", true);
var certificate = certificates[0];
store.Close();
// Note that this will return a Basic crypto provider, with only SHA-1 support
var privKey = (RSACryptoServiceProvider)certificate.PrivateKey;
// Force use of the Enhanced RSA and AES Cryptographic Provider with openssl-generated SHA256 keys
var enhCsp = new RSACryptoServiceProvider().CspKeyContainerInfo;
var cspparams = new CspParameters(enhCsp.ProviderType, enhCsp.ProviderName, privKey.CspKeyContainerInfo.KeyContainerName);
privKey = new RSACryptoServiceProvider(cspparams);
This is how I dealt with that problem:
X509Certificate2 privateCert = new X509Certificate2("certificate.pfx", password, X509KeyStorageFlags.Exportable);
// This instance can not sign and verify with SHA256:
RSACryptoServiceProvider privateKey = (RSACryptoServiceProvider)privateCert.PrivateKey;
// This one can:
RSACryptoServiceProvider privateKey1 = new RSACryptoServiceProvider();
privateKey1.ImportParameters(privateKey.ExportParameters(true));
byte[] data = Encoding.UTF8.GetBytes("Data to be signed");
byte[] signature = privateKey1.SignData(data, "SHA256");
bool isValid = privateKey1.VerifyData(data, "SHA256", signature);
I settled on changing the key file to specify the appropriate Crypto Service Provider, avoiding the issue in .NET altogether.
So when I create a PFX file out of a PEM private key and a CRT public certificate, I do it as follows:
openssl pkcs12 -export -aes256 -CSP "Microsoft Enhanced RSA and AES Cryptographic Provider" -inkey priv.pem -in pub.crt -out priv.pfx
The key part being -CSP "Microsoft Enhanced RSA and AES Cryptographic Provider".
(-inkey specifies the private key file and -in specifies the public certificate to incorporate.)
You may need to tweak this for the file formats you have on hand. The command line examples on this page can help with that:
https://www.sslshopper.com/ssl-converter.html
I found this solution here:
http://hintdesk.com/c-how-to-fix-invalid-algorithm-specified-when-signing-with-sha256/
Use can use this on more recent frameworks.
public byte[] GetSignature(byte[] inputData)
{
using (var rsa = this.signingCertificate.GetRSAPrivateKey())
{
return rsa.SignData(inputData, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
}
}
public bool ValidateSignature(byte[] inputData, byte[] signature)
{
using (var rsa = this.signingCertificate.GetRSAPublicKey())
{
return rsa.VerifyData(inputData, signature, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);
}
}
The signingCertificate above is a X509Certificate2 with a private key. This method does not require you to import any existing keys and works in a secure environment.
When you use a certificate to get your RSACryptoServiceProvider it really matters what's the underlying CryptoAPI provider. By default, when you create a certificate with 'makecert', it's "RSA-FULL" which only supports SHA1 hashes for signature. You need the new "RSA-AES" one that supports SHA2.
So, you can create your certificate with an additional option: -sp "Microsoft Enhanced RSA and AES Cryptographic Provider" (or an equivalent -sy 24) and then your code would work without the key juggling stuff.
Here is how I signed a string without having to modify the certificate (to a Microsoft Enhanced RSA and AES Cryptographic provider).
byte[] certificate = File.ReadAllBytes(#"C:\Users\AwesomeUser\Desktop\Test\ServerCertificate.pfx");
X509Certificate2 cert2 = new X509Certificate2(certificate, string.Empty, X509KeyStorageFlags.Exportable);
string stringToBeSigned = "This is a string to be signed";
SHA256Managed shHash = new SHA256Managed();
byte[] computedHash = shHash.ComputeHash(Encoding.Default.GetBytes(stringToBeSigned));
var certifiedRSACryptoServiceProvider = cert2.PrivateKey as RSACryptoServiceProvider;
RSACryptoServiceProvider defaultRSACryptoServiceProvider = new RSACryptoServiceProvider();
defaultRSACryptoServiceProvider.ImportParameters(certifiedRSACryptoServiceProvider.ExportParameters(true));
byte[] signedHashValue = defaultRSACryptoServiceProvider.SignData(computedHash, "SHA256");
string signature = Convert.ToBase64String(signedHashValue);
Console.WriteLine("Signature : {0}", signature);
RSACryptoServiceProvider publicCertifiedRSACryptoServiceProvider = cert2.PublicKey.Key as RSACryptoServiceProvider;
bool verify = publicCertifiedRSACryptoServiceProvider.VerifyData(computedHash, "SHA256", signedHashValue);
Console.WriteLine("Verification result : {0}", verify);
According to this blog it should work with FX 3.5 (see note below). However it's important to recall that most of .NET cryptography is based on CryptoAPI (even if CNG is being more and more exposed in recent FX releases).
The key point is that CryptoAPI algorithm support depends on the Crypto Service Provider (CSP) being used and that varies a bit between Windows versions (i.e. what's working on Windows 7 might not work on Windows 2000).
Read the comments (from the blog entry) to see a possible workaround where you specify the AES CSP (instead of the default one) when creating your RSACCryptoServiceProvider instance. That seems to work for some people, YMMV.
Note: this is confusing to many people because all the released .NET frameworks includes a managed implementation of SHA256 which cannot be used by CryptoAPI. FWIW Mono does not suffer from such issues ;-)
I know this is an old thread but for those still stuck in the past and looking for an answer, the following worked for me based off #BKibler's answer. The comments stated it's not using the correct key and it's because the solution is missing a couple key settings.
// Find my openssl-generated cert from the registry
var store = new X509Store(StoreLocation.LocalMachine);
store.Open(OpenFlags.ReadOnly);
var certificates = store.Certificates.Find(X509FindType.FindBySubjectName, "myapp.com", true);
var certificate = certificates[0];
store.Close();
// Note that this will return a Basic crypto provider, with only SHA-1 support
var privKey = (RSACryptoServiceProvider)certificate.PrivateKey;
// Force use of the Enhanced RSA and AES Cryptographic Provider with openssl-generated SHA256 keys
var enhCsp = new RSACryptoServiceProvider().CspKeyContainerInfo;
if (!Enum.TryParse<KeyNumber>(privKey.CspKeyContainerInfo.KeyNumber.ToString(), out var keyNumber))
throw new Exception($"Unknown key number {privKey.CspKeyContainerInfo.KeyNumber}");
var cspparams = new CspParameters(enhCsp.ProviderType, enhCsp.ProviderName, privKey.CspKeyContainerInfo.KeyContainerName)
{
KeyNumber = (int)keyNumber,
Flags = CspProviderFlags.UseExistingKey
};
privKey = new RSACryptoServiceProvider(cspparams);
You need to set both "KeyNumber" and "Flags" so the existing (non-exportable) key is used and you can use the public key from the certificate to verify.
I have noticed similar issues in .NET with the wrong private key being used (or was it flat-out errors? I do not recall) when the certificate I am working with is not in the user/computer certificate store. Installing it into the stored fixed the problem for my scenario and things started working as expected - perhaps you can try that.
I can decrypt a password protected PKCS8 DER key with the following code:
MemoryStream ms = new MemoryStream(privateKey);
AsymmetricKeyParameter keyparams = Org.BouncyCastle.Security.PrivateKeyFactory.DecryptKey(password.ToCharArray(), ms);
RSAParameters rsaparams = DotNetUtilities.ToRSAParameters((RsaPrivateCrtKeyParameters)keyparams);
RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
rsa.ImportParameters(rsaparams);
return rsa;
Now, I have to recreate the same type of key when it is given to me in a different format (in this example it was given to me as a PFX file). So I have to create a password protected PKCS8 DER key from the PFX private key. After reading the Bouncy Castle source code, I managed to find the PrivateKeyFactory.EncryptKey function, but I can't get it to work. The code I have is the following:
X509Certificate2 cert = new X509Certificate2(pfx_bytes, password,X509KeyStorageFlags.Exportable);
var pkey = cert.PrivateKey;
var bcCert = DotNetUtilities.FromX509Certificate(cert);
var bcPkey = DotNetUtilities.GetKeyPair(pkey).Private;
return PrivateKeyFactory.EncryptKey(Org.BouncyCastle.Asn1.DerObjectIdentifier.Der, password.ToCharArray(), Encoding.UTF8.GetBytes(Guid.NewGuid().ToString()), 10, bcPkey);
When I run the previous code, I get the exception "System.ArgumentException: attempt to use non-PBE algorithm with PBE EncryptedPrivateKeyInfo generation".
Google searches reveal nothing except the source code for the function, and though I've tried to follow it to find the solution I haven't been able to.
Can someone please point me in the right direction as to how I could use the function to create a password protected PKCS8 DER key from a standard .net Private key?
The first argument to PrivateKeyFactory.EncryptKey is supposed to identify an algorithm to encrypt with. The simplest way is to give the ObjectIdentifier (OID) of a standard PBE algorithm e.g. PKCSObjectIdentifiers.PbeWithShaAnd3KeyTripleDesCbc instead of DerObjectIdentifier.Der . You could take a look at PbeUtilities class if you want to see what other algorithms are available.
PBE algorithms supported by PBEUtil:
PBEwithMD2andDES-CBC, PBEwithMD2andRC2-CBC, PBEwithMD5andDES-CBC, PBEwithMD5andRC2-CBC, PBEwithSHA1andDES-CBC, PBEwithSHA1andRC2-CBC, PBEwithSHA-1and128bitRC4, PBEwithSHA-1and40bitRC4, PBEwithSHA-1and3-keyDESEDE-CBC, PBEwithSHA-1and2-keyDESEDE-CBC, PBEwithSHA-1and128bitRC2-CBC, PBEwithSHA-1and40bitRC2-CBC, PBEwithHmacSHA-1, PBEwithHmacSHA-224, PBEwithHmacSHA-256, PBEwithHmacRIPEMD128, PBEwithHmacRIPEMD160, and PBEwithHmacRIPEMD256.
Example:
private static string EncryptPrivateKey(AsymmetricKeyParameter privateKey)
{
var encKey = PrivateKeyFactory.EncryptKey("PBEwithSHA1andDES-CBC", "test".ToCharArray(),
new byte[256], 1, privateKey);
return Convert.ToBase64String(encKey);
}