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X509Certificate2 Class

Represents an X.509 certificate.

System.Object
  System.Security.Cryptography.X509Certificates.X509Certificate
    System.Security.Cryptography.X509Certificates.X509Certificate2

Namespace:  System.Security.Cryptography.X509Certificates
Assembly:  System (in System.dll)

'Declaration
<SerializableAttribute> _
Public Class X509Certificate2 _
	Inherits X509Certificate

The X509Certificate2 type exposes the following members.

  NameDescription
Public methodX509Certificate2Initializes a new instance of the X509Certificate2 class.
Public methodX509Certificate2(Byte())Initializes a new instance of the X509Certificate2 class using information from a byte array.
Public methodX509Certificate2(IntPtr)Initializes a new instance of the X509Certificate2 class using an unmanaged handle.
Public methodX509Certificate2(String)Initializes a new instance of the X509Certificate2 class using a certificate file name.
Public methodX509Certificate2(X509Certificate)Initializes a new instance of the X509Certificate2 class using an X509Certificate object.
Public methodX509Certificate2(Byte(), SecureString)Initializes a new instance of the X509Certificate2 class using a byte array and a password.
Public methodX509Certificate2(Byte(), String)Initializes a new instance of the X509Certificate2 class using a byte array and a password.
Protected methodX509Certificate2(SerializationInfo, StreamingContext)Initializes a new instance of the X509Certificate2 class using the specified serialization and stream context information.
Public methodX509Certificate2(String, SecureString)Initializes a new instance of the X509Certificate2 class using a certificate file name and a password.
Public methodX509Certificate2(String, String)Initializes a new instance of the X509Certificate2 class using a certificate file name and a password used to access the certificate.
Public methodX509Certificate2(Byte(), SecureString, X509KeyStorageFlags)Initializes a new instance of the X509Certificate2 class using a byte array, a password, and a key storage flag.
Public methodX509Certificate2(Byte(), String, X509KeyStorageFlags)Initializes a new instance of the X509Certificate2 class using a byte array, a password, and a key storage flag.
Public methodX509Certificate2(String, SecureString, X509KeyStorageFlags)Initializes a new instance of the X509Certificate2 class using a certificate file name, a password, and a key storage flag.
Public methodX509Certificate2(String, String, X509KeyStorageFlags)Initializes a new instance of the X509Certificate2 class using a certificate file name, a password used to access the certificate, and a key storage flag.
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  NameDescription
Public propertyArchivedGets or sets a value indicating that an X.509 certificate is archived.
Public propertyExtensionsGets a collection of X509Extension objects.
Public propertyFriendlyNameGets or sets the associated alias for a certificate.
Public propertyHandleGets a handle to a Microsoft Cryptographic API certificate context described by an unmanaged PCCERT_CONTEXT structure. (Inherited from X509Certificate.)
Public propertyHasPrivateKeyGets a value that indicates whether an X509Certificate2 object contains a private key.
Public propertyIssuerGets the name of the certificate authority that issued the X.509v3 certificate. (Inherited from X509Certificate.)
Public propertyIssuerNameGets the distinguished name of the certificate issuer.
Public propertyNotAfterGets the date in local time after which a certificate is no longer valid.
Public propertyNotBeforeGets the date in local time on which a certificate becomes valid.
Public propertyPrivateKeyGets or sets the AsymmetricAlgorithm object that represents the private key associated with a certificate.
Public propertyPublicKeyGets a PublicKey object associated with a certificate.
Public propertyRawDataGets the raw data of a certificate.
Public propertySerialNumberGets the serial number of a certificate.
Public propertySignatureAlgorithmGets the algorithm used to create the signature of a certificate.
Public propertySubjectGets the subject distinguished name from the certificate. (Inherited from X509Certificate.)
Public propertySubjectNameGets the subject distinguished name from a certificate.
Public propertyThumbprintGets the thumbprint of a certificate.
Public propertyVersionGets the X.509 format version of a certificate.
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  NameDescription
Public methodEquals(Object)Compares two X509Certificate objects for equality. (Inherited from X509Certificate.)
Public methodEquals(X509Certificate)Compares two X509Certificate objects for equality. (Inherited from X509Certificate.)
Public methodExport(X509ContentType)Exports the current X509Certificate object to a byte array in a format described by one of the X509ContentType values. (Inherited from X509Certificate.)
Public methodExport(X509ContentType, SecureString)Exports the current X509Certificate object to a byte array using the specified format and a password. (Inherited from X509Certificate.)
Public methodExport(X509ContentType, String)Exports the current X509Certificate object to a byte array in a format described by one of the X509ContentType values, and using the specified password. (Inherited from X509Certificate.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.)
Public methodStatic memberGetCertContentType(Byte())Indicates the type of certificate contained in a byte array.
Public methodStatic memberGetCertContentType(String)Indicates the type of certificate contained in a file.
Public methodGetCertHashReturns the hash value for the X.509v3 certificate as an array of bytes. (Inherited from X509Certificate.)
Public methodGetCertHashStringReturns the SHA1 hash value for the X.509v3 certificate as a hexadecimal string. (Inherited from X509Certificate.)
Public methodGetEffectiveDateStringReturns the effective date of this X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetExpirationDateStringReturns the expiration date of this X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetFormatReturns the name of the format of this X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetHashCodeReturns the hash code for the X.509v3 certificate as an integer. (Inherited from X509Certificate.)
Public methodGetIssuerName Obsolete. Returns the name of the certification authority that issued the X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetKeyAlgorithmReturns the key algorithm information for this X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetKeyAlgorithmParametersReturns the key algorithm parameters for the X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetKeyAlgorithmParametersStringReturns the key algorithm parameters for the X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetName Obsolete. Returns the name of the principal to which the certificate was issued. (Inherited from X509Certificate.)
Public methodGetNameInfoGets the subject and issuer names from a certificate.
Public methodGetPublicKeyReturns the public key for the X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetPublicKeyStringReturns the public key for the X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetRawCertDataReturns the raw data for the entire X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetRawCertDataStringReturns the raw data for the entire X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetSerialNumberReturns the serial number of the X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetSerialNumberStringReturns the serial number of the X.509v3 certificate. (Inherited from X509Certificate.)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodImport(Byte())Populates an X509Certificate2 object with data from a byte array. (Overrides X509Certificate.Import(Byte()).)
Public methodImport(String)Populates an X509Certificate2 object with information from a certificate file. (Overrides X509Certificate.Import(String).)
Public methodImport(Byte(), SecureString, X509KeyStorageFlags)Populates an X509Certificate2 object using data from a byte array, a password, and a key storage flag. (Overrides X509Certificate.Import(Byte(), SecureString, X509KeyStorageFlags).)
Public methodImport(Byte(), String, X509KeyStorageFlags)Populates an X509Certificate2 object using data from a byte array, a password, and flags for determining how to import the private key. (Overrides X509Certificate.Import(Byte(), String, X509KeyStorageFlags).)
Public methodImport(String, SecureString, X509KeyStorageFlags)Populates an X509Certificate2 object with information from a certificate file, a password, and a key storage flag. (Overrides X509Certificate.Import(String, SecureString, X509KeyStorageFlags).)
Public methodImport(String, String, X509KeyStorageFlags)Populates an X509Certificate2 object with information from a certificate file, a password, and a X509KeyStorageFlags value. (Overrides X509Certificate.Import(String, String, X509KeyStorageFlags).)
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodResetResets the state of an X509Certificate2 object. (Overrides X509Certificate.Reset.)
Public methodToStringDisplays an X.509 certificate in text format. (Overrides X509Certificate.ToString.)
Public methodToString(Boolean)Displays an X.509 certificate in text format. (Overrides X509Certificate.ToString(Boolean).)
Public methodVerifyPerforms a X.509 chain validation using basic validation policy.
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  NameDescription
Explicit interface implemetationPrivate methodIDeserializationCallback.OnDeserializationImplements the ISerializable interface and is called back by the deserialization event when deserialization is complete. (Inherited from X509Certificate.)
Explicit interface implemetationPrivate methodISerializable.GetObjectDataGets serialization information with all the data needed to recreate an instance of the current X509Certificate object. (Inherited from X509Certificate.)
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The X.509 structure originated in the International Organization for Standardization (ISO) working groups. This structure can be used to represent various types of information including identity, entitlement, and holder attributes (permissions, age, sex, location, affiliation, and so forth). Although the ISO specifications are most informative on the structure itself, the X509Certificate2 class is designed to model the usage scenarios defined in specifications issued by the Internet Engineering Task Force (IETF) Public Key Infrastructure, X.509 (PKIX) working group. The most informative of these specifications is RFC 3280, "Certificate and Certificate Revocation List (CRL) Profile."

The following example demonstrates how to use an X509Certificate2 object to encrypt and decrypt a file.


Imports System
Imports System.Security.Cryptography
Imports System.Security.Cryptography.X509Certificates
Imports System.IO
Imports System.Text


' To run this sample use the Certificate Creation Tool (Makecert.exe) to generate a test X.509 certificate and 
' place it in the local user store. 
' To generate an exchange key and make the key exportable run the following command from a Visual Studio command prompt: 
'makecert -r -pe -n "CN=CERT_SIGN_TEST_CERT" -b 01/01/2010 -e 01/01/2012 -sky exchange -ss my

Class Program

    ' Path variables for source, encryption, and
    ' decryption folders. Must end with a backslash.
    Private Shared encrFolder As String = "C:\Encrypt\"
    Private Shared decrFolder As String = "C:\Decrypt\"
    Private Shared originalFile As String = "TestData.txt"
    Private Shared encryptedFile As String = "TestData.enc"


    Shared Sub Main(ByVal args() As String)

        ' Create an input file with test data.
        Dim sw As StreamWriter = File.CreateText(originalFile)
        sw.WriteLine("Test data to be encrypted")
        sw.Close()

        ' Get the certifcate to use to encrypt the key.
        Dim cert As X509Certificate2 = GetCertificateFromStore("CN=CERT_SIGN_TEST_CERT")
        If cert Is Nothing Then
            Console.WriteLine("Certificatge 'CN=CERT_SIGN_TEST_CERT' not found.")
            Console.ReadLine()
        End If


        ' Encrypt the file using the public key from the certificate.
        EncryptFile(originalFile, CType(cert.PublicKey.Key, RSACryptoServiceProvider))

        ' Decrypt the file using the private key from the certificate.
        DecryptFile(encryptedFile, CType(cert.PrivateKey, RSACryptoServiceProvider))

        'Display the original data and the decrypted data.
        Console.WriteLine("Original:   {0}", File.ReadAllText(originalFile))
        Console.WriteLine("Round Trip: {0}", File.ReadAllText(decrFolder + originalFile))
        Console.WriteLine("Press the Enter key to exit.")
        Console.ReadLine()

    End Sub 'Main

    Private Shared Function GetCertificateFromStore(ByVal certName As String) As X509Certificate2
        ' Get the certificate store for the current user.
        Dim store As New X509Store(StoreLocation.CurrentUser)
        Try
            store.Open(OpenFlags.ReadOnly)

            ' Place all certificates in an X509Certificate2Collection object.
            Dim certCollection As X509Certificate2Collection = store.Certificates
            ' If using a certificate with a trusted root you do not need to FindByTimeValid, instead use:
            ' currentCerts.Find(X509FindType.FindBySubjectDistinguishedName, certName, true);
            Dim currentCerts As X509Certificate2Collection = certCollection.Find(X509FindType.FindByTimeValid, DateTime.Now, False)
            Dim signingCert As X509Certificate2Collection = currentCerts.Find(X509FindType.FindBySubjectDistinguishedName, certName, False)
            If signingCert.Count = 0 Then
                Return Nothing
            End If ' Return the first certificate in the collection, has the right name and is current.
            Return signingCert(0)
        Finally
            store.Close()
        End Try


    End Function 'GetCertificateFromStore

    ' Encrypt a file using a public key.
    Private Shared Sub EncryptFile(ByVal inFile As String, ByVal rsaPublicKey As RSACryptoServiceProvider)
        Dim aesManaged As New AesManaged()
        Try
            ' Create instance of AesManaged for
            ' symetric encryption of the data.
            aesManaged.KeySize = 256
            aesManaged.BlockSize = 128
            aesManaged.Mode = CipherMode.CBC
            Dim transform As ICryptoTransform = aesManaged.CreateEncryptor()
            Try
                Dim keyFormatter As New RSAPKCS1KeyExchangeFormatter(rsaPublicKey)
                Dim keyEncrypted As Byte() = keyFormatter.CreateKeyExchange(aesManaged.Key, aesManaged.GetType())

                ' Create byte arrays to contain
                ' the length values of the key and IV.
                Dim LenK(3) As Byte
                Dim LenIV(3) As Byte

                Dim lKey As Integer = keyEncrypted.Length
                LenK = BitConverter.GetBytes(lKey)
                Dim lIV As Integer = aesManaged.IV.Length
                LenIV = BitConverter.GetBytes(lIV)

                ' Write the following to the FileStream
                ' for the encrypted file (outFs):
                ' - length of the key
                ' - length of the IV
                ' - ecrypted key
                ' - the IV
                ' - the encrypted cipher content
                Dim startFileName As Integer = inFile.LastIndexOf("\") + 1
                ' Change the file's extension to ".enc"
                Dim outFile As String = encrFolder + inFile.Substring(startFileName, inFile.LastIndexOf(".") - startFileName) + ".enc"
                Directory.CreateDirectory(encrFolder)

                Dim outFs As New FileStream(outFile, FileMode.Create)
                Try

                    outFs.Write(LenK, 0, 4)
                    outFs.Write(LenIV, 0, 4)
                    outFs.Write(keyEncrypted, 0, lKey)
                    outFs.Write(aesManaged.IV, 0, lIV)

                    ' Now write the cipher text using
                    ' a CryptoStream for encrypting.
                    Dim outStreamEncrypted As New CryptoStream(outFs, transform, CryptoStreamMode.Write)
                    Try

                        ' By encrypting a chunk at
                        ' a time, you can save memory
                        ' and accommodate large files.
                        Dim count As Integer = 0
                        Dim offset As Integer = 0

                        ' blockSizeBytes can be any arbitrary size.
                        Dim blockSizeBytes As Integer = aesManaged.BlockSize / 8
                        Dim data(blockSizeBytes) As Byte
                        Dim bytesRead As Integer = 0

                        Dim inFs As New FileStream(inFile, FileMode.Open)
                        Try
                            Do
                                count = inFs.Read(data, 0, blockSizeBytes)
                                offset += count
                                outStreamEncrypted.Write(data, 0, count)
                                bytesRead += blockSizeBytes
                            Loop While count > 0
                            inFs.Close()
                        Finally
                            inFs.Dispose()
                        End Try
                        outStreamEncrypted.FlushFinalBlock()
                        outStreamEncrypted.Close()
                    Finally
                        outStreamEncrypted.Dispose()
                    End Try
                    outFs.Close()
                Finally
                    outFs.Dispose()
                End Try
            Finally
                transform.Dispose()
            End Try
        Finally
            aesManaged.Dispose()
        End Try

    End Sub 'EncryptFile


    ' Decrypt a file using a private key.
    Private Shared Sub DecryptFile(ByVal inFile As String, ByVal rsaPrivateKey As RSACryptoServiceProvider)

        ' Create instance of AesManaged for
        ' symetric decryption of the data.
        Dim aesManaged As New AesManaged()
        Try
            aesManaged.KeySize = 256
            aesManaged.BlockSize = 128
            aesManaged.Mode = CipherMode.CBC

            ' Create byte arrays to get the length of
            ' the encrypted key and IV.
            ' These values were stored as 4 bytes each
            ' at the beginning of the encrypted package.
            Dim LenK() As Byte = New Byte(4 - 1) {}
            Dim LenIV() As Byte = New Byte(4 - 1) {}

            ' Consruct the file name for the decrypted file.
            Dim outFile As String = decrFolder + inFile.Substring(0, inFile.LastIndexOf(".")) + ".txt"

            ' Use FileStream objects to read the encrypted
            ' file (inFs) and save the decrypted file (outFs).
            Dim inFs As New FileStream(encrFolder + inFile, FileMode.Open)
            Try

                inFs.Seek(0, SeekOrigin.Begin)
                inFs.Seek(0, SeekOrigin.Begin)
                inFs.Read(LenK, 0, 3)
                inFs.Seek(4, SeekOrigin.Begin)
                inFs.Read(LenIV, 0, 3)

                ' Convert the lengths to integer values.
                Dim lengthK As Integer = BitConverter.ToInt32(LenK, 0)
                Dim lengthIV As Integer = BitConverter.ToInt32(LenIV, 0)

                ' Determine the start postition of
                ' the ciphter text (startC)
                ' and its length(lenC).
                Dim startC As Integer = lengthK + lengthIV + 8
                Dim lenC As Integer = (CType(inFs.Length, Integer) - startC)

                ' Create the byte arrays for
                ' the encrypted Rijndael key,
                ' the IV, and the cipher text.
                Dim KeyEncrypted() As Byte = New Byte(lengthK - 1) {}
                Dim IV() As Byte = New Byte(lengthIV - 1) {}

                ' Extract the key and IV
                ' starting from index 8
                ' after the length values.
                inFs.Seek(8, SeekOrigin.Begin)
                inFs.Read(KeyEncrypted, 0, lengthK)
                inFs.Seek(8 + lengthK, SeekOrigin.Begin)
                inFs.Read(IV, 0, lengthIV)
                Directory.CreateDirectory(decrFolder)
                ' Use RSACryptoServiceProvider
                ' to decrypt the Rijndael key.
                Dim KeyDecrypted As Byte() = rsaPrivateKey.Decrypt(KeyEncrypted, False)

                ' Decrypt the key.
                Dim transform As ICryptoTransform = aesManaged.CreateDecryptor(KeyDecrypted, IV)
                ' Decrypt the cipher text from
                ' from the FileSteam of the encrypted
                ' file (inFs) into the FileStream
                ' for the decrypted file (outFs).
                Dim outFs As New FileStream(outFile, FileMode.Create)
                Try
                    ' Decrypt the cipher text from
                    ' from the FileSteam of the encrypted
                    ' file (inFs) into the FileStream
                    ' for the decrypted file (outFs).

                    Dim count As Integer = 0
                    Dim offset As Integer = 0

                    Dim blockSizeBytes As Integer = aesManaged.BlockSize / 8
                    Dim data(blockSizeBytes) As Byte

                    ' By decrypting a chunk a time,
                    ' you can save memory and
                    ' accommodate large files.
                    ' Start at the beginning
                    ' of the cipher text.
                    inFs.Seek(startC, SeekOrigin.Begin)
                    Dim outStreamDecrypted As New CryptoStream(outFs, transform, CryptoStreamMode.Write)
                    Try
                        Do
                            count = inFs.Read(data, 0, blockSizeBytes)
                            offset += count
                            outStreamDecrypted.Write(data, 0, count)
                        Loop While count > 0

                        outStreamDecrypted.FlushFinalBlock()
                        outStreamDecrypted.Close()
                    Finally
                        outStreamDecrypted.Dispose()
                    End Try
                    outFs.Close()
                Finally
                    outFs.Dispose()
                End Try
                inFs.Close()

            Finally
                inFs.Dispose()

            End Try

        Finally
            aesManaged.Dispose()
        End Try


    End Sub 'DecryptFile 
End Class 'Program



The following example creates a command-line executable that takes a certificate file as an argument and prints various certificate properties to the console.


Imports System
Imports System.Security.Cryptography
Imports System.Security.Permissions
Imports System.IO
Imports System.Security.Cryptography.X509Certificates
Imports Microsoft.VisualBasic




Class CertInfo

    'Reads a file.
    Friend Shared Function ReadFile(ByVal fileName As String) As Byte()
        Dim f As New FileStream(fileName, FileMode.Open, FileAccess.Read)
        Dim size As Integer = Fix(f.Length)
        Dim data(size) As Byte
        size = f.Read(data, 0, size)
        f.Close()
        Return data

    End Function 

    <SecurityPermission(SecurityAction.LinkDemand, Unrestricted:=True)> _
    Shared Sub Main(ByVal args() As String)
        'Test for correct number of arguments.
        If args.Length < 1 Then
            Console.WriteLine("Usage: CertInfo <filename>")
            Return
        End If
        Try
            Dim x509 As New X509Certificate2()
            'Create X509Certificate2 object from .cer file.
            Dim rawData As Byte() = ReadFile(args(0))

            x509.Import(rawData)

            'Print to console information contained in the certificate.
            Console.WriteLine("{0}Subject: {1}{0}", Environment.NewLine, x509.Subject)
            Console.WriteLine("{0}Issuer: {1}{0}", Environment.NewLine, x509.Issuer)
            Console.WriteLine("{0}Version: {1}{0}", Environment.NewLine, x509.Version)
            Console.WriteLine("{0}Valid Date: {1}{0}", Environment.NewLine, x509.NotBefore)
            Console.WriteLine("{0}Expiry Date: {1}{0}", Environment.NewLine, x509.NotAfter)
            Console.WriteLine("{0}Thumbprint: {1}{0}", Environment.NewLine, x509.Thumbprint)
            Console.WriteLine("{0}Serial Number: {1}{0}", Environment.NewLine, x509.SerialNumber)
            Console.WriteLine("{0}Friendly Name: {1}{0}", Environment.NewLine, x509.PublicKey.Oid.FriendlyName)
            Console.WriteLine("{0}Public Key Format: {1}{0}", Environment.NewLine, x509.PublicKey.EncodedKeyValue.Format(True))
            Console.WriteLine("{0}Raw Data Length: {1}{0}", Environment.NewLine, x509.RawData.Length)
            Console.WriteLine("{0}Certificate to string: {1}{0}", Environment.NewLine, x509.ToString(True))

            Console.WriteLine("{0}Certificate to XML String: {1}{0}", Environment.NewLine, x509.PublicKey.Key.ToXmlString(False))

            'Add the certificate to a X509Store.
            Dim store As New X509Store()
            store.Open(OpenFlags.MaxAllowed)
            store.Add(x509)
            store.Close()

        Catch dnfExcept As DirectoryNotFoundException
            Console.WriteLine("Error: The directory specified could not be found.")
        Catch ioExpcept As IOException
            Console.WriteLine("Error: A file in the directory could not be accessed.")
        Catch nrExcept As NullReferenceException
            Console.WriteLine("File must be a .cer file. Program does not have access to that type of file.")
        End Try

    End Sub
End Class


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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