SafeRsaProviderHandle.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / WCF / WCF / 3.5.30729.1 / untmp / Orcas / SP / ndp / cdf / src / WCF / infocard / Service / managed / Microsoft / InfoCards / SafeRsaProviderHandle.cs / 1 / SafeRsaProviderHandle.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------

namespace Microsoft.InfoCards 
{
    using System; 
    using System.ComponentModel; 
    using System.Globalization;
    using System.Runtime.InteropServices; 
    using System.Runtime.ConstrainedExecution;
    using System.Security;
    using Microsoft.InfoCards.Diagnostics;
    using IDT=Microsoft.InfoCards.Diagnostics.InfoCardTrace; 

 
 
    //
    // Summary: 
    // Provides a wrapper over a handle retrieved by CryptAcquireContext
    //
    internal class SafeRsaProviderHandle : SafeHandle
    { 
        [DllImport( "advapi32.dll",
                    EntryPoint      ="CryptAcquireContextW", 
                    CharSet         = CharSet.Unicode, 
                    ExactSpelling   = true,
                    SetLastError    = true ) ] 
        [SuppressUnmanagedCodeSecurity]
        private static extern bool CryptAcquireContext(
                            [Out] out SafeRsaProviderHandle hProv,
                            [In] string pszContainer, 
                            [In] string pszProvider,
                            [In] uint dwProvType, 
                            [In] uint dwFlags ); 

        [DllImport( "advapi32.dll", 
                    EntryPoint      = "CryptReleaseContext",
                    CharSet         = CharSet.Unicode,
                    ExactSpelling   = true,
                    SetLastError    = true ) ] 
        [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
        [SuppressUnmanagedCodeSecurity] 
        private static extern bool CryptReleaseContext( 
                          [In] IntPtr hProv,
                          [In] uint dwFlags ); 


        public static SafeRsaProviderHandle Construct()
        { 
            //
            // The native provider we use to do encryption and decryption and associated constants to 
            // set up the Microsoft Enhanced RSA and AES provider 
            //
            const uint CRYPT_VERIFYCONTEXT      = 0xF0000000; 
            const byte PROV_RSA_AES            = 24;

            //
            // We use a null provider and CRYPT_VERIFYCONTEXT as a flag 
            // to force the use of ephemeral keys. See http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B238187
            // for details. 
            // 
            SafeRsaProviderHandle h;
            if( !SafeRsaProviderHandle.CryptAcquireContext( out h, 
                                                            null,
                                                            null,
                                                            PROV_RSA_AES,
                                                            CRYPT_VERIFYCONTEXT ) ) 
            {
                Win32Exception e = new Win32Exception( Marshal.GetLastWin32Error() ); 
                IDT.CloseInvalidOutSafeHandle(h); 
                IDT.TraceAndLogException( e );
                throw IDT.ThrowHelperError( new CommunicationException( e.Message  )  ); 

            }
            return h;
        } 

        private SafeRsaProviderHandle() : base( IntPtr.Zero, true ) 
        { 
        }
 

        public override bool IsInvalid
        {
            get 
            {
                return ( IntPtr.Zero == base.handle ); 
            } 
        }
 

        protected override bool ReleaseHandle()
        {
            #pragma warning suppress 56523 
            return CryptReleaseContext( base.handle, 0 );
        } 
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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