RSAPKCS1SignatureDeformatter.VerifySignature(Byte[], Byte[]) Method

Definition

Namespace:

System.Security.Cryptography

Assembly:

System.Security.Cryptography.dll

Source:

RSAPKCS1SignatureDeformatter.cs

Verifies the RSA PKCS#1 signature for the specified data.

public:
 override bool VerifySignature(cli::array <System::Byte> ^ rgbHash, cli::array <System::Byte> ^ rgbSignature);

public override bool VerifySignature (byte[] rgbHash, byte[] rgbSignature);

override this.VerifySignature : byte[] * byte[] -> bool

Public Overrides Function VerifySignature (rgbHash As Byte(), rgbSignature As Byte()) As Boolean

Parameters

rgbHash

Byte[]

The data signed with rgbSignature.

rgbSignature

Byte[]

The signature to be verified for rgbHash.

Returns

Boolean

true if rgbSignature matches the signature computed using the specified hash algorithm and key on rgbHash; otherwise, false.

Exceptions

CryptographicUnexpectedOperationException

The key is null.

-or-

The hash algorithm is null.

ArgumentNullException

The rgbHash parameter is null.

-or-

The rgbSignature parameter is null.

Examples

The following example demonstrates how to use the VerifySignature method to verify a signature.

using System;
using System.Security.Cryptography;

class RSASample
{

    static void Main()
    {
        try
        {
            //Create a new instance of RSA.
            using (RSA rsa = RSA.Create())
            {
                //The hash to sign.
                byte[] hash;
                using (SHA256 sha256 = SHA256.Create())
                {
                    byte[] data = new byte[] { 59, 4, 248, 102, 77, 97, 142, 201, 210, 12, 224, 93, 25, 41, 100, 197, 213, 134, 130, 135 };
                    hash = sha256.ComputeHash(data);
                }

                //Create an RSASignatureFormatter object and pass it the 
                //RSA instance to transfer the key information.
                RSAPKCS1SignatureFormatter RSAFormatter = new RSAPKCS1SignatureFormatter(rsa);

                //Set the hash algorithm to SHA256.
                RSAFormatter.SetHashAlgorithm("SHA256");

                //Create a signature for HashValue and return it.
                byte[] signedHash = RSAFormatter.CreateSignature(hash);
                //Create an RSAPKCS1SignatureDeformatter object and pass it the  
                //RSA instance to transfer the key information.
                RSAPKCS1SignatureDeformatter RSADeformatter = new RSAPKCS1SignatureDeformatter(rsa);
                RSADeformatter.SetHashAlgorithm("SHA256");
                //Verify the hash and display the results to the console. 
                if (RSADeformatter.VerifySignature(hash, signedHash))
                {
                    Console.WriteLine("The signature was verified.");
                }
                else
                {
                    Console.WriteLine("The signature was not verified.");
                }
            }
        }
        catch (CryptographicException e)
        {
            Console.WriteLine(e.Message);
        }
    }
}

Imports System.Security.Cryptography

Friend Class RSASample

    Shared Sub Main()
        Try
            'Create a new instance of RSA.
            Using rsa As RSA = RSA.Create()
                'The hash to sign.
                Dim hash() As Byte
                Using sha256 As SHA256 = SHA256.Create()
                    Dim data() As Byte = { 59, 4, 248, 102, 77, 97, 142, 201, 210, 12, 224, 93, 25, 41, 100, 197, 213, 134, 130, 135 }
                    hash = sha256.ComputeHash(data)
                End Using

                'Create an RSASignatureFormatter object and pass it the 
                'RSA instance to transfer the key information.
                Dim RSAFormatter As New RSAPKCS1SignatureFormatter(rsa)

                'Set the hash algorithm to SHA256.
                RSAFormatter.SetHashAlgorithm("SHA256")

                'Create a signature for HashValue and return it.
                Dim signedHash() As Byte = RSAFormatter.CreateSignature(hash)
                'Create an RSAPKCS1SignatureDeformatter object and pass it the  
                'RSA instance to transfer the key information.
                Dim RSADeformatter As New RSAPKCS1SignatureDeformatter(rsa)
                RSADeformatter.SetHashAlgorithm("SHA256")
                'Verify the hash and display the results to the console. 
                If RSADeformatter.VerifySignature(hash, signedHash) Then
                    Console.WriteLine("The signature was verified.")
                Else
                    Console.WriteLine("The signature was not verified.")
                End If
            End Using

        Catch e As CryptographicException
            Console.WriteLine(e.Message)
        End Try
    End Sub

End Class

Remarks

You must specify a key and a hash algorithm before calling this method.

See also

• Cryptographic Services