DSACryptoServiceProvider Class
Assembly: mscorlib (in mscorlib.dll)
'Declaration <ComVisibleAttribute(True)> _ Public NotInheritable Class DSACryptoServiceProvider Inherits DSA Implements ICspAsymmetricAlgorithm 'Usage Dim instance As DSACryptoServiceProvider
/** @attribute ComVisibleAttribute(true) */ public final class DSACryptoServiceProvider extends DSA implements ICspAsymmetricAlgorithm
ComVisibleAttribute(true) public final class DSACryptoServiceProvider extends DSA implements ICspAsymmetricAlgorithm
Not applicable.
You can use the DSACryptoServiceProvider class to create digital signatures and protect the integrity of your data.
To use a public-key system to digitally sign a message, the sender first applies a hash function to the message to create a message digest. The sender then encrypts the message digest with the sender's private key to create the sender's personal signature. Upon receiving the message and signature, the receiver decrypts the signature using the sender's public key to recover the message digest and hashes the message using the same hash algorithm that the sender used. If the message digest that the receiver computes exactly matches the message digest received from the sender, the receiver can be sure that the message was not altered while in transit. Note that a signature can be verified by anyone, because the sender's public key is common knowledge.
This algorithm supports key lengths from 512 bits to 1024 bits in increments of 64 bits.
The following code example creates a digital signature of a hash value using the DSACryptoServiceProvider class and then verifies the signature.
Imports System Imports System.Security.Cryptography _ Class DSACSPSample Shared Sub Main() Try 'Create a new instance of DSACryptoServiceProvider to generate 'a new key pair. Dim DSA As New DSACryptoServiceProvider() 'The hash value to sign. Dim HashValue As Byte() = {59, 4, 248, 102, 77, 97, 142, 201, 210, 12, 224, 93, 25, 41, 100, 197, 213, 134, 130, 135} 'The value to hold the signed value. Dim SignedHashValue As Byte() = DSASignHash(HashValue, DSA.ExportParameters(True), "SHA1") 'Verify the hash and display the results. If DSAVerifyHash(HashValue, SignedHashValue, DSA.ExportParameters(False), "SHA1") Then Console.WriteLine("The hash value was verified.") Else Console.WriteLine("The hash value was not verified.") End If Catch e As ArgumentNullException Console.WriteLine(e.Message) End Try End Sub Public Shared Function DSASignHash(ByVal HashToSign() As Byte, ByVal DSAKeyInfo As DSAParameters, ByVal HashAlg As String) As Byte() Try 'Create a new instance of DSACryptoServiceProvider. Dim DSA As New DSACryptoServiceProvider() 'Import the key information. DSA.ImportParameters(DSAKeyInfo) 'Create an DSASignatureFormatter object and pass it the 'DSACryptoServiceProvider to transfer the private key. Dim DSAFormatter As New DSASignatureFormatter(DSA) 'Set the hash algorithm to the passed value. DSAFormatter.SetHashAlgorithm(HashAlg) 'Create a signature for HashValue and return it. Return DSAFormatter.CreateSignature(HashToSign) Catch e As CryptographicException Console.WriteLine(e.Message) Return Nothing End Try End Function Public Shared Function DSAVerifyHash(ByVal HashValue() As Byte, ByVal SignedHashValue() As Byte, ByVal DSAKeyInfo As DSAParameters, ByVal HashAlg As String) As Boolean Try 'Create a new instance of DSACryptoServiceProvider. Dim DSA As New DSACryptoServiceProvider() 'Import the key information. DSA.ImportParameters(DSAKeyInfo) 'Create an DSASignatureDeformatter object and pass it the 'DSACryptoServiceProvider to transfer the private key. Dim DSADeformatter As New DSASignatureDeformatter(DSA) 'Set the hash algorithm to the passed value. DSADeformatter.SetHashAlgorithm(HashAlg) 'Verify signature and return the result. Return DSADeformatter.VerifySignature(HashValue, SignedHashValue) Catch e As CryptographicException Console.WriteLine(e.Message) Return False End Try End Function End Class
import System.*;
import System.Security.Cryptography.*;
class DSACSPSample
{
public static void main(String[] args)
{
try {
// Create a new instance of DSACryptoServiceProvider to generate
// a new key pair.
DSACryptoServiceProvider dsa = new DSACryptoServiceProvider();
// The hash value to sign.
ubyte hashValue[] = {59, 4, 248, 102, 77, 97, 142, 201,
210, 12, 224, 93, 25, 41, 100, 197, 213, 134, 130, 135};
// The value to hold the signed value.
ubyte signedHashValue[] = DSASignHash(hashValue,
dsa.ExportParameters(true), "SHA1");
// Verify the hash and display the results.
if (DSAVerifyHash(hashValue, signedHashValue,
dsa.ExportParameters(false), "SHA1")) {
Console.WriteLine("The hash value was verified.");
}
else {
Console.WriteLine("The hash value was not verified.");
}
}
catch (ArgumentNullException e) {
Console.WriteLine(e.get_Message());
}
} //main
public static ubyte[] DSASignHash(ubyte hashToSign[],
DSAParameters dsaKeyInfo, String hashAlg)
{
try {
// Create a new instance of DSACryptoServiceProvider.
DSACryptoServiceProvider dsa = new DSACryptoServiceProvider();
// Import the key information.
dsa.ImportParameters(dsaKeyInfo);
// Create an DSASignatureFormatter object and pass it the
// DSACryptoServiceProvider to transfer the private key.
DSASignatureFormatter dsaFormatter = new
DSASignatureFormatter(dsa);
// Set the hash algorithm to the passed value.
dsaFormatter.SetHashAlgorithm(hashAlg);
// Create a signature for HashValue and return it.
return dsaFormatter.CreateSignature(hashToSign) ;
}
catch (CryptographicException e) {
Console.WriteLine(e.get_Message());
return null ;
}
} //DSASignHash
public static boolean DSAVerifyHash(ubyte hashValue[],
ubyte signedHashValue[], DSAParameters dsaKeyInfo, String hashAlg)
{
try {
// Create a new instance of DSACryptoServiceProvider.
DSACryptoServiceProvider dsa = new DSACryptoServiceProvider();
// Import the key information.
dsa.ImportParameters(dsaKeyInfo);
// Create an DSASignatureDeformatter object and pass it the
// DSACryptoServiceProvider to transfer the private key.
DSASignatureDeformatter dsaDeformatter = new
DSASignatureDeformatter(dsa);
// Set the hash algorithm to the passed value.
dsaDeformatter.SetHashAlgorithm(hashAlg);
// Verify signature and return the result.
return dsaDeformatter.VerifySignature(hashValue, signedHashValue);
}
catch (CryptographicException e) {
Console.WriteLine(e.get_Message());
return false ;
}
} //DSAVerifyHash
} //DSACSPSample
System.Security.Cryptography.AsymmetricAlgorithm
System.Security.Cryptography.DSA
System.Security.Cryptography.DSACryptoServiceProvider
Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.