RSACryptoServiceProvider.SignHash Method
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Computes the signature for the specified hash value.
Overloads
| SignHash(Byte[], String) |
Computes the signature for the specified hash value. |
| SignHash(Byte[], HashAlgorithmName, RSASignaturePadding) |
Computes the signature for the specified hash value using the specified padding. |
SignHash(Byte[], String)
Computes the signature for the specified hash value.
public:
cli::array <System::Byte> ^ SignHash(cli::array <System::Byte> ^ rgbHash, System::String ^ str);public byte[] SignHash (byte[] rgbHash, string? str);public byte[] SignHash (byte[] rgbHash, string str);override this.SignHash : byte[] * string -> byte[]member this.SignHash : byte[] * string -> byte[]Public Function SignHash (rgbHash As Byte(), str As String) As Byte()Parameters
- rgbHash
- Byte[]
The hash value of the data to be signed.
- str
- String
The hash algorithm identifier (OID) used to create the hash value of the data.
Returns
Byte[]
The RSA signature for the specified hash value.
Exceptions
The rgbHash parameter is null.
The cryptographic service provider (CSP) cannot be acquired.
-or-
There is no private key.
Examples
The following code example encrypts some data, creates a hash of the encrypted data, and then signs hash with a digital signature.
// This example uses the SHA1 algorithm.
// Due to collision problems with SHA1, Microsoft recommends SHA256 or better.
#using <System.dll>
using namespace System;
using namespace System::Text;
using namespace System::Security::Cryptography;
ref class Sender
{
private:
RSAParameters rsaPubParams;
RSAParameters rsaPrivateParams;
public:
Sender()
{
RSACryptoServiceProvider^ rsaCSP = gcnew RSACryptoServiceProvider;
//Generate public and private key data.
rsaPrivateParams = rsaCSP->ExportParameters( true );
rsaPubParams = rsaCSP->ExportParameters( false );
}
property RSAParameters PublicParameters
{
RSAParameters get()
{
return rsaPubParams;
}
}
//Manually performs hash and then signs hashed value.
array<Byte>^ HashAndSign( array<Byte>^encrypted )
{
RSACryptoServiceProvider^ rsaCSP = gcnew RSACryptoServiceProvider;
SHA1Managed^ hash = gcnew SHA1Managed;
array<Byte>^hashedData;
rsaCSP->ImportParameters( rsaPrivateParams );
hashedData = hash->ComputeHash( encrypted );
return rsaCSP->SignHash( hashedData, CryptoConfig::MapNameToOID( "SHA1" ) );
}
//Encrypts using only the public key data.
array<Byte>^ EncryptData( RSAParameters rsaParams, array<Byte>^toEncrypt )
{
RSACryptoServiceProvider^ rsaCSP = gcnew RSACryptoServiceProvider;
rsaCSP->ImportParameters( rsaParams );
return rsaCSP->Encrypt( toEncrypt, false );
}
};
ref class Receiver
{
private:
RSAParameters rsaPubParams;
RSAParameters rsaPrivateParams;
public:
Receiver()
{
RSACryptoServiceProvider^ rsaCSP = gcnew RSACryptoServiceProvider;
//Generate public and private key data.
rsaPrivateParams = rsaCSP->ExportParameters( true );
rsaPubParams = rsaCSP->ExportParameters( false );
}
property RSAParameters PublicParameters
{
RSAParameters get()
{
return rsaPubParams;
}
}
//Manually performs hash and then verifies hashed value.
bool VerifyHash( RSAParameters rsaParams, array<Byte>^signedData, array<Byte>^signature )
{
RSACryptoServiceProvider^ rsaCSP = gcnew RSACryptoServiceProvider;
SHA1Managed^ hash = gcnew SHA1Managed;
array<Byte>^hashedData;
rsaCSP->ImportParameters( rsaParams );
bool dataOK = rsaCSP->VerifyData(signedData, CryptoConfig::MapNameToOID("SHA1"), signature);
hashedData = hash->ComputeHash( signedData );
return rsaCSP->VerifyHash( hashedData, CryptoConfig::MapNameToOID( "SHA1" ), signature );
}
//Decrypt using the private key data.
void DecryptData( array<Byte>^encrypted )
{
array<Byte>^fromEncrypt;
String^ roundTrip;
ASCIIEncoding^ myAscii = gcnew ASCIIEncoding;
RSACryptoServiceProvider^ rsaCSP = gcnew RSACryptoServiceProvider;
rsaCSP->ImportParameters( rsaPrivateParams );
fromEncrypt = rsaCSP->Decrypt( encrypted, false );
roundTrip = myAscii->GetString( fromEncrypt );
Console::WriteLine( "RoundTrip: {0}", roundTrip );
}
};
int main()
{
array<Byte>^toEncrypt;
array<Byte>^encrypted;
array<Byte>^signature;
//Choose a small amount of data to encrypt.
String^ original = "Hello";
ASCIIEncoding^ myAscii = gcnew ASCIIEncoding;
//Create a sender and receiver.
Sender^ mySender = gcnew Sender;
Receiver^ myReceiver = gcnew Receiver;
//Convert the data string to a byte array.
toEncrypt = myAscii->GetBytes( original );
//Encrypt data using receiver's public key.
encrypted = mySender->EncryptData( myReceiver->PublicParameters, toEncrypt );
//Hash the encrypted data and generate a signature on the hash
// using the sender's private key.
signature = mySender->HashAndSign( encrypted );
Console::WriteLine( "Original: {0}", original );
//Verify the signature is authentic using the sender's public key.
if ( myReceiver->VerifyHash( mySender->PublicParameters, encrypted, signature ) )
{
//Decrypt the data using the receiver's private key.
myReceiver->DecryptData( encrypted );
}
else
{
Console::WriteLine( "Invalid signature" );
}
}
// This example uses the SHA1 algorithm.
// Due to collision problems with SHA1, Microsoft recommends SHA256 or better.
using System;
using System.Text;
using System.Security.Cryptography;
namespace RSACryptoServiceProvider_Examples
{
class MyMainClass
{
static void Main()
{
byte[] toEncrypt;
byte[] encrypted;
byte[] signature;
//Choose a small amount of data to encrypt.
string original = "Hello";
ASCIIEncoding myAscii = new ASCIIEncoding();
//Create a sender and receiver.
Sender mySender = new Sender();
Receiver myReceiver = new Receiver();
//Convert the data string to a byte array.
toEncrypt = myAscii.GetBytes(original);
//Encrypt data using receiver's public key.
encrypted = mySender.EncryptData(myReceiver.PublicParameters, toEncrypt);
//Hash the encrypted data and generate a signature on the hash
// using the sender's private key.
signature = mySender.HashAndSign(encrypted);
Console.WriteLine("Original: {0}", original);
//Verify the signature is authentic using the sender's public key.
if (myReceiver.VerifyHash(mySender.PublicParameters, encrypted, signature))
{
//Decrypt the data using the receiver's private key.
myReceiver.DecryptData(encrypted);
}
else
{
Console.WriteLine("Invalid signature");
}
}
}
class Sender
{
RSAParameters rsaPubParams;
RSAParameters rsaPrivateParams;
public Sender()
{
RSACryptoServiceProvider rsaCSP = new RSACryptoServiceProvider();
//Generate public and private key data.
rsaPrivateParams = rsaCSP.ExportParameters(true);
rsaPubParams = rsaCSP.ExportParameters(false);
}
public RSAParameters PublicParameters
{
get
{
return rsaPubParams;
}
}
//Manually performs hash and then signs hashed value.
public byte[] HashAndSign(byte[] encrypted)
{
RSACryptoServiceProvider rsaCSP = new RSACryptoServiceProvider();
SHA1Managed hash = new SHA1Managed();
byte[] hashedData;
rsaCSP.ImportParameters(rsaPrivateParams);
hashedData = hash.ComputeHash(encrypted);
return rsaCSP.SignHash(hashedData, CryptoConfig.MapNameToOID("SHA1"));
}
//Encrypts using only the public key data.
public byte[] EncryptData(RSAParameters rsaParams, byte[] toEncrypt)
{
RSACryptoServiceProvider rsaCSP = new RSACryptoServiceProvider();
rsaCSP.ImportParameters(rsaParams);
return rsaCSP.Encrypt(toEncrypt, false);
}
}
class Receiver
{
RSAParameters rsaPubParams;
RSAParameters rsaPrivateParams;
public Receiver()
{
RSACryptoServiceProvider rsaCSP = new RSACryptoServiceProvider();
//Generate public and private key data.
rsaPrivateParams = rsaCSP.ExportParameters(true);
rsaPubParams = rsaCSP.ExportParameters(false);
}
public RSAParameters PublicParameters
{
get
{
return rsaPubParams;
}
}
//Manually performs hash and then verifies hashed value.
public bool VerifyHash(RSAParameters rsaParams, byte[] signedData, byte[] signature)
{
RSACryptoServiceProvider rsaCSP = new RSACryptoServiceProvider();
SHA1Managed hash = new SHA1Managed();
byte[] hashedData;
rsaCSP.ImportParameters(rsaParams);
bool dataOK = rsaCSP.VerifyData(signedData, CryptoConfig.MapNameToOID("SHA1"), signature);
hashedData = hash.ComputeHash(signedData);
return rsaCSP.VerifyHash(hashedData, CryptoConfig.MapNameToOID("SHA1"), signature);
}
//Decrypt using the private key data.
public void DecryptData(byte[] encrypted)
{
byte[] fromEncrypt;
string roundTrip;
ASCIIEncoding myAscii = new ASCIIEncoding();
RSACryptoServiceProvider rsaCSP = new RSACryptoServiceProvider();
rsaCSP.ImportParameters(rsaPrivateParams);
fromEncrypt = rsaCSP.Decrypt(encrypted, false);
roundTrip = myAscii.GetString(fromEncrypt);
Console.WriteLine("RoundTrip: {0}", roundTrip);
}
}
}
' This example uses the SHA1 algorithm.
' Due to collision problems with SHA1, Microsoft recommends SHA256 or better.
Imports System.Text
Imports System.Security.Cryptography
Namespace RSACryptoServiceProvider_Examples
Class MyMainClass
Shared Sub Main()
Dim toEncrypt() As Byte
Dim encrypted() As Byte
Dim signature() As Byte
'Choose a small amount of data to encrypt.
Dim original As String = "Hello"
Dim myAscii As New ASCIIEncoding()
'Create a sender and receiver.
Dim mySender As New Sender()
Dim myReceiver As New Receiver()
'Convert the data string to a byte array.
toEncrypt = myAscii.GetBytes(original)
'Encrypt data using receiver's public key.
encrypted = mySender.EncryptData(myReceiver.PublicParameters, toEncrypt)
'Hash the encrypted data and generate a signature on the hash
' using the sender's private key.
signature = mySender.HashAndSign(encrypted)
Console.WriteLine("Original: {0}", original)
'Verify the signature is authentic using the sender's public key.
If myReceiver.VerifyHash(mySender.PublicParameters, encrypted, signature) Then
'Decrypt the data using the receiver's private key.
myReceiver.DecryptData(encrypted)
Else
Console.WriteLine("Invalid signature")
End If
End Sub
End Class
Class Sender
Private rsaPubParams As RSAParameters
Private rsaPrivateParams As RSAParameters
Public Sub New()
Dim rsaCSP As New RSACryptoServiceProvider()
'Generate public and private key data.
rsaPrivateParams = rsaCSP.ExportParameters(True)
rsaPubParams = rsaCSP.ExportParameters(False)
End Sub
Public ReadOnly Property PublicParameters() As RSAParameters
Get
Return rsaPubParams
End Get
End Property
'Manually performs hash and then signs hashed value.
Public Function HashAndSign(ByVal encrypted() As Byte) As Byte()
Dim rsaCSP As New RSACryptoServiceProvider()
Dim hash As New SHA1Managed()
Dim hashedData() As Byte
rsaCSP.ImportParameters(rsaPrivateParams)
hashedData = hash.ComputeHash(encrypted)
Return rsaCSP.SignHash(hashedData, CryptoConfig.MapNameToOID("SHA1"))
End Function 'HashAndSign
'Encrypts using only the public key data.
Public Function EncryptData(ByVal rsaParams As RSAParameters, ByVal toEncrypt() As Byte) As Byte()
Dim rsaCSP As New RSACryptoServiceProvider()
rsaCSP.ImportParameters(rsaParams)
Return rsaCSP.Encrypt(toEncrypt, False)
End Function 'EncryptData
End Class
Class Receiver
Private rsaPubParams As RSAParameters
Private rsaPrivateParams As RSAParameters
Public Sub New()
Dim rsaCSP As New RSACryptoServiceProvider()
'Generate public and private key data.
rsaPrivateParams = rsaCSP.ExportParameters(True)
rsaPubParams = rsaCSP.ExportParameters(False)
End Sub
Public ReadOnly Property PublicParameters() As RSAParameters
Get
Return rsaPubParams
End Get
End Property
'Manually performs hash and then verifies hashed value.
Public Function VerifyHash(ByVal rsaParams As RSAParameters, ByVal signedData() As Byte, ByVal signature() As Byte) As Boolean
Dim rsaCSP As New RSACryptoServiceProvider()
Dim hash As New SHA1Managed()
Dim hashedData() As Byte
Dim dataOK As Boolean
rsaCSP.ImportParameters(rsaParams)
dataOK = rsaCSP.VerifyData(signedData, CryptoConfig.MapNameToOID("SHA1"), signature)
hashedData = hash.ComputeHash(signedData)
Return rsaCSP.VerifyHash(hashedData, CryptoConfig.MapNameToOID("SHA1"), signature)
End Function 'VerifyHash
'Decrypt using the private key data.
Public Sub DecryptData(ByVal encrypted() As Byte)
Dim fromEncrypt() As Byte
Dim roundTrip As String
Dim myAscii As New ASCIIEncoding()
Dim rsaCSP As New RSACryptoServiceProvider()
rsaCSP.ImportParameters(rsaPrivateParams)
fromEncrypt = rsaCSP.Decrypt(encrypted, False)
roundTrip = myAscii.GetString(fromEncrypt)
Console.WriteLine("RoundTrip: {0}", roundTrip)
End Sub
End Class
End Namespace 'RSACryptoServiceProvider_Examples
Remarks
This method creates a digital signature that is verified using the VerifyHash method.
The valid hash algorithms are SHA1 and MD5. The algorithm identifier can be derived from the hash name by using the MapNameToOID method.
Due to collision problems with SHA1 and MD5, Microsoft recommends a security model based on SHA256 or better.
See also
Applies to
SignHash(Byte[], HashAlgorithmName, RSASignaturePadding)
Computes the signature for the specified hash value using the specified padding.
public:
override cli::array <System::Byte> ^ SignHash(cli::array <System::Byte> ^ hash, System::Security::Cryptography::HashAlgorithmName hashAlgorithm, System::Security::Cryptography::RSASignaturePadding ^ padding);public override byte[] SignHash (byte[] hash, System.Security.Cryptography.HashAlgorithmName hashAlgorithm, System.Security.Cryptography.RSASignaturePadding padding);override this.SignHash : byte[] * System.Security.Cryptography.HashAlgorithmName * System.Security.Cryptography.RSASignaturePadding -> byte[]Public Overrides Function SignHash (hash As Byte(), hashAlgorithm As HashAlgorithmName, padding As RSASignaturePadding) As Byte()Parameters
- hash
- Byte[]
The hash value of the data to be signed.
- hashAlgorithm
- HashAlgorithmName
The hash algorithm name used to create the hash value of the data.
- padding
- RSASignaturePadding
The padding.
Returns
Byte[]
The RSA signature for the specified hash value.
Exceptions
hashAlgorithm is null or Empty.
padding does not equal Pkcs1.
Applies to
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