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RSACryptoServiceProvider.SignData Method (Stream, Object)

Computes the hash value of the specified input stream using the specified hash algorithm, and signs the resulting hash value.

Namespace:  System.Security.Cryptography
Assembly:  mscorlib (in mscorlib.dll)

public byte[] SignData(
	Stream inputStream,
	Object halg
)

Parameters

inputStream
Type: System.IO.Stream

The input data for which to compute the hash.

halg
Type: System.Object

The hash algorithm to use to create the hash value.

Return Value

Type: System.Byte[]
The RSA signature for the specified data.

ExceptionCondition
ArgumentNullException

The halg parameter is null.

ArgumentException

The halg parameter is not a valid type.

The halg parameter can accept a String, a HashAlgorithm, or a Type.

The following code example signs and verifies data.

using System;
using System.Security.Cryptography;
using System.Text;
using System.IO;

class RSACSPSample
{
    static void Main()
    {
        try
        {
            ASCIIEncoding ByteConverter = new ASCIIEncoding();

            // Create some bytes to be signed. 
            byte[] dataBytes = ByteConverter.GetBytes("Here is some data to sign!");

            // Create a buffer for the memory stream. 
            byte[] buffer = new byte[dataBytes.Length];

            // Create a MemoryStream.
            MemoryStream mStream = new MemoryStream(buffer);

            // Write the bytes to the stream and flush it.
            mStream.Write(dataBytes, 0, dataBytes.Length);

            mStream.Flush();

            // Create a new instance of the RSACryptoServiceProvider class  
            // and automatically create a new key-pair.
            RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider();

            // Export the key information to an RSAParameters object. 
            // You must pass true to export the private key for signing. 
            // However, you do not need to export the private key 
            // for verification.
            RSAParameters Key = RSAalg.ExportParameters(true);

            // Hash and sign the data. 
            byte[] signedData = HashAndSignBytes(mStream, Key);


            // Verify the data and display the result to the  
            // console. 
            if(VerifySignedHash(dataBytes, signedData, Key))
            {
                Console.WriteLine("The data was verified.");
            }
            else
            {
                Console.WriteLine("The data does not match the signature.");
            } 

            // Close the MemoryStream.
            mStream.Close();

        }
        catch(ArgumentNullException)
        {
            Console.WriteLine("The data was not signed or verified");

        }
    }
    public static byte[] HashAndSignBytes(Stream DataStream, RSAParameters Key)
    {
        try
        { 
            // Reset the current position in the stream to  
            // the beginning of the stream (0). RSACryptoServiceProvider 
            // can't verify the data unless the the stream position 
            // is set to the starting position of the data.
            DataStream.Position = 0;

            // Create a new instance of RSACryptoServiceProvider using the  
            // key from RSAParameters.  
            RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider();

            RSAalg.ImportParameters(Key);

            // Hash and sign the data. Pass a new instance of SHA1CryptoServiceProvider 
            // to specify the use of SHA1 for hashing. 
            return RSAalg.SignData(DataStream, new SHA1CryptoServiceProvider());
        }
        catch(CryptographicException e)
        {
            Console.WriteLine(e.Message);

            return null;
        }
    }

    public static bool VerifySignedHash(byte[] DataToVerify, byte[] SignedData, RSAParameters Key)
    {
        try
        {
            // Create a new instance of RSACryptoServiceProvider using the  
            // key from RSAParameters.
            RSACryptoServiceProvider RSAalg = new RSACryptoServiceProvider();

            RSAalg.ImportParameters(Key);

            // Verify the data using the signature.  Pass a new instance of SHA1CryptoServiceProvider 
            // to specify the use of SHA1 for hashing. 
            return RSAalg.VerifyData(DataToVerify, new SHA1CryptoServiceProvider(), SignedData); 

        }
        catch(CryptographicException e)
        {
            Console.WriteLine(e.Message);

            return false;
        }
    }
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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