类X509Certificate2

X509Certificate2类的初始化。

文章：使用X509Certificate2类操作证书文件

参考：https://docs.microsoft.com/zh-cn/dotnet/api/system.security.cryptography.x509certificates.x509certificate2?redirectedfrom=MSDN&view=netframework-4.8

标题：X509Certificate2 类

下面的示例演示如何使用X509Certificate2对象对文件进行加密和解密。

using System;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.IO;
using 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
namespace X509CertEncrypt
{
    class Program
    {

        // Path variables for source, encryption, and
        // decryption folders. Must end with a backslash.
        private static string encrFolder = @"C:\Encrypt\";
        private static string decrFolder = @"C:\Decrypt\";
        private static string originalFile = "TestData.txt";
        private static string encryptedFile = "TestData.enc";

        static void Main(string[] args)
        {

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

            // Get the certifcate to use to encrypt the key.
            X509Certificate2 cert = GetCertificateFromStore("CN=CERT_SIGN_TEST_CERT");
            if (cert == null)
            {
                Console.WriteLine("Certificate 'CN=CERT_SIGN_TEST_CERT' not found.");
                Console.ReadLine();
            }

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

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

            //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();
        }
        private static X509Certificate2 GetCertificateFromStore(string certName)
        {

            // Get the certificate store for the current user.
            X509Store store = new X509Store(StoreLocation.CurrentUser);
            try
            {
                store.Open(OpenFlags.ReadOnly);

                // Place all certificates in an X509Certificate2Collection object.
                X509Certificate2Collection certCollection = store.Certificates;
                // If using a certificate with a trusted root you do not need to FindByTimeValid, instead:
                // currentCerts.Find(X509FindType.FindBySubjectDistinguishedName, certName, true);
                X509Certificate2Collection currentCerts = certCollection.Find(X509FindType.FindByTimeValid, DateTime.Now, false);
                X509Certificate2Collection signingCert = currentCerts.Find(X509FindType.FindBySubjectDistinguishedName, certName, false);
                if (signingCert.Count == )
                    return null;
                // Return the first certificate in the collection, has the right name and is current.
                return signingCert[];
            }
            finally
            {
                store.Close();
            }

        }

        // Encrypt a file using a public key.
        private static void EncryptFile(string inFile, RSACryptoServiceProvider rsaPublicKey)
        {
            using (AesManaged aesManaged = new AesManaged())
            {
                // Create instance of AesManaged for
                // symetric encryption of the data.
                aesManaged.KeySize = ;
                aesManaged.BlockSize = ;
                aesManaged.Mode = CipherMode.CBC;
                using (ICryptoTransform transform = aesManaged.CreateEncryptor())
                {
                    RSAPKCS1KeyExchangeFormatter keyFormatter = new RSAPKCS1KeyExchangeFormatter(rsaPublicKey);
                    byte[] keyEncrypted = keyFormatter.CreateKeyExchange(aesManaged.Key, aesManaged.GetType());

                    // Create byte arrays to contain
                    // the length values of the key and IV.
                    byte[] LenK = new byte[];
                    byte[] LenIV = new byte[];

                    int lKey = keyEncrypted.Length;
                    LenK = BitConverter.GetBytes(lKey);
                    int lIV = 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

                    int startFileName = inFile.LastIndexOf("\\") + ;
                    // Change the file's extension to ".enc"
                    string outFile = encrFolder + inFile.Substring(startFileName, inFile.LastIndexOf(".") - startFileName) + ".enc";
                    Directory.CreateDirectory(encrFolder);

                    using (FileStream outFs = new FileStream(outFile, FileMode.Create))
                    {

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

                        // Now write the cipher text using
                        // a CryptoStream for encrypting.
                        using (CryptoStream outStreamEncrypted = new CryptoStream(outFs, transform, CryptoStreamMode.Write))
                        {

                            // By encrypting a chunk at
                            // a time, you can save memory
                            // and accommodate large files.
                            int count = ;
                            int offset = ;

                            // blockSizeBytes can be any arbitrary size.
                            int blockSizeBytes = aesManaged.BlockSize / ;
                            byte[] data = new byte[blockSizeBytes];
                            int bytesRead = ;

                            using (FileStream inFs = new FileStream(inFile, FileMode.Open))
                            {
                                do
                                {
                                    count = inFs.Read(data, offset, blockSizeBytes);
                                    offset += count;
                                    outStreamEncrypted.Write(data, , count);
                                    bytesRead += count;
                                }
                                while (count > );
                                inFs.Close();
                            }
                            outStreamEncrypted.FlushFinalBlock();
                            outStreamEncrypted.Close();
                        }
                        outFs.Close();
                    }
                }
            }
        }

        // Decrypt a file using a private key.
        private static void DecryptFile(string inFile, RSACryptoServiceProvider rsaPrivateKey)
        {

            // Create instance of AesManaged for
            // symetric decryption of the data.
            using (AesManaged aesManaged = new AesManaged())
            {
                aesManaged.KeySize = ;
                aesManaged.BlockSize = ;
                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.
                byte[] LenK = new byte[];
                byte[] LenIV = new byte[];

                // Consruct the file name for the decrypted file.
                string outFile = decrFolder + inFile.Substring(, inFile.LastIndexOf(".")) + ".txt";

                // Use FileStream objects to read the encrypted
                // file (inFs) and save the decrypted file (outFs).
                using (FileStream inFs = new FileStream(encrFolder + inFile, FileMode.Open))
                {

                    inFs.Seek(, SeekOrigin.Begin);
                    inFs.Seek(, SeekOrigin.Begin);
                    inFs.Read(LenK, , );
                    inFs.Seek(, SeekOrigin.Begin);
                    inFs.Read(LenIV, , );

                    // Convert the lengths to integer values.
                    int lenK = BitConverter.ToInt32(LenK, );
                    int lenIV = BitConverter.ToInt32(LenIV, );

                    // Determine the start postition of
                    // the ciphter text (startC)
                    // and its length(lenC).
                    int startC = lenK + lenIV + ;
                    int lenC = (int)inFs.Length - startC;

                    // Create the byte arrays for
                    // the encrypted AesManaged key,
                    // the IV, and the cipher text.
                    byte[] KeyEncrypted = new byte[lenK];
                    byte[] IV = new byte[lenIV];

                    // Extract the key and IV
                    // starting from index 8
                    // after the length values.
                    inFs.Seek(, SeekOrigin.Begin);
                    inFs.Read(KeyEncrypted, , lenK);
                    inFs.Seek( + lenK, SeekOrigin.Begin);
                    inFs.Read(IV, , lenIV);
                    Directory.CreateDirectory(decrFolder);
                    // Use RSACryptoServiceProvider
                    // to decrypt the AesManaged key.
                    byte[] KeyDecrypted = rsaPrivateKey.Decrypt(KeyEncrypted, false);

                    // Decrypt the key.
                    using (ICryptoTransform transform = 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).
                        using (FileStream outFs = new FileStream(outFile, FileMode.Create))
                        {

                            int count = ;
                            int offset = ;

                            int blockSizeBytes = aesManaged.BlockSize / ;
                            byte[] data = new byte[blockSizeBytes];

                            // 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);
                            using (CryptoStream outStreamDecrypted = new CryptoStream(outFs, transform, CryptoStreamMode.Write))
                            {
                                do
                                {
                                    count = inFs.Read(data, offset, blockSizeBytes);
                                    offset += count;
                                    outStreamDecrypted.Write(data, , count);
                                }
                                while (count > );

                                outStreamDecrypted.FlushFinalBlock();
                                outStreamDecrypted.Close();
                            }
                            outFs.Close();
                        }
                        inFs.Close();
                    }

                }

            }
        }

    }
}

下面的示例创建一个命令行可执行文件, 该命令行可执行文件将证书文件作为参数, 并将各种证书属性打印到控制台。

using System;
using System.Security.Cryptography;
using System.Security.Permissions;
using System.IO;
using System.Security.Cryptography.X509Certificates;

class CertInfo
{
    //Reads a file.
    internal static byte[] ReadFile (string fileName)
    {
        FileStream f = new FileStream(fileName, FileMode.Open, FileAccess.Read);
        int size = (int)f.Length;
        byte[] data = new byte[size];
        size = f.Read(data, , size);
        f.Close();
        return data;
    }
    //Main method begins here.
    static void Main(string[] args)
    {
        //Test for correct number of arguments.
        if (args.Length < )
        {
            Console.WriteLine("Usage: CertInfo <filename>");
            return;
        }
        try
        {
            X509Certificate2 x509 = new X509Certificate2();
            //Create X509Certificate2 object from .cer file.
            byte[] rawData = ReadFile(args[]);
            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.
            X509Store store = new X509Store();
            store.Open(OpenFlags.MaxAllowed);
            store.Add(x509);
            store.Close();
        }
        catch (DirectoryNotFoundException)
        {
               Console.WriteLine("Error: The directory specified could not be found.");
        }
        catch (IOException)
        {
            Console.WriteLine("Error: A file in the directory could not be accessed.");
        }
        catch (NullReferenceException)
        {
            Console.WriteLine("File must be a .cer file. Program does not have access to that type of file.");
        }
    }
}

X.509 结构源自国际标准化组织 (ISO) 工作组。The X.509 structure originated in the International Organization for Standardization (ISO) working groups. 此结构可用于表示各种类型的信息, 包括标识、权利和持有者属性 (权限、年龄、性别、位置、从属关系, 等等)。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). 尽管 ISO 规范在结构本身上是最丰富的信息, X509Certificate2但类设计用于根据 Internet 工程任务组 (IETF) 公钥基础结构 x.509 (PKIX) 工作组。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. 这些规范的最重要信息是 RFC 3280 "证书和证书吊销列表 (CRL) 配置文件"。

重要

从开始IDisposable , 此类型实现接口。 .NET Framework 4.6.NET Framework 4.6Starting with the .NET Framework 4.6.NET Framework 4.6, this type implements the IDisposable interface. 在使用完类型后，您应直接或间接释放类型。When you have finished using the type, you should dispose of it either directly or indirectly. 若要直接Dispose释放类型, 请try / catch在块中调用其方法。To dispose of the type directly, call its Dispose method in a try/catch block. 若要间接释放类型，请使用 using（在 C# 中）或 Using（在 Visual Basic 中）等语言构造。To dispose of it indirectly, use a language construct such as using (in C#) or Using (in Visual Basic). 有关详细信息, 请参阅IDisposable接口主题中的 "使用实现 IDisposable 的对象" 一节。For more information, see the "Using an Object that Implements IDisposable" section in the IDisposable interface topic.

对于面向.NET Framework 4.5.2.NET Framework 4.5.2和更早版本的应用X509Certificate2 , IDisposable类不实现接口, 因此不具有Dispose方法。