一个cer还需要一个签名的证书本身，这是为了防止cer证书被篡改。
有两种类型的证书：
1. 根证书
2. 由根证书颁发子证书。
特根证书。它是自签名。
而其它子证书的签名公钥都保存在它的上级证书里面。
能够用C#来做一些验证。
首先是根证书的签名验证。
// 验证根证书签名 X509Certificate2 x509Root = new X509Certificate2("C:\\Users\\kevin\\Desktop\\KevinRoot.cer"); Console.WriteLine("Root Certificate Verified? : {0}{1}", x509Root.Verify(), Environment.NewLine); // 根证书是自签名。所以能够通过。
非常easy，由于根证书是自签名的，x509Root.Verify()会返回true。然后是子证书的验证，
X509Certificate2 x509 = new X509Certificate2("C:\\Users\\kevin\\Desktop\\ChildSubject2.cer"); byte[] rawdata = x509.RawData; Console.WriteLine("Content Type: {0}{1}", X509Certificate2.GetCertContentType(rawdata), Environment.NewLine); Console.WriteLine("Friendly Name: {0}{1}", x509.FriendlyName, Environment.NewLine); Console.WriteLine("Certificate Verified?: {0}{1}", x509.Verify(), Environment.NewLine); Console.WriteLine("Simple Name: {0}{1}", x509.GetNameInfo(X509NameType.SimpleName, true), Environment.NewLine); Console.WriteLine("Signature Algorithm: {0}{1}", x509.SignatureAlgorithm.FriendlyName, Environment.NewLine); // Console.WriteLine("Private Key: {0}{1}", x509.PrivateKey.ToXmlString(false), Environment.NewLine); // cer里面并没有私钥信息 Console.WriteLine("Public Key: {0}{1}", x509.PublicKey.Key.ToXmlString(false), Environment.NewLine); Console.WriteLine("Certificate Archived?: {0}{1}", x509.Archived, Environment.NewLine); Console.WriteLine("Length of Raw Data: {0}{1}", x509.RawData.Length, Environment.NewLine); 这里我用自己创建的子证书，x509.Verify()总是返回false，就算我把根证书导入到“trust”里面，还是返回false。不知道为什么。可是假设我用公司的证书（verisign颁发的）。却能够返回true。不知道是不是我自己创建的根证书，子证书有什么配置问题。有空再研究。 反正验证也就这么回事。
以下的代码。用来检查整个证书链。
//Output chain information of the selected certificate. X509Chain ch = new X509Chain(); ch.Build(x509); Console.WriteLine("Chain Information"); ch.ChainPolicy.RevocationMode = X509RevocationMode.Online; Console.WriteLine("Chain revocation flag: {0}", ch.ChainPolicy.RevocationFlag); Console.WriteLine("Chain revocation mode: {0}", ch.ChainPolicy.RevocationMode); Console.WriteLine("Chain verification flag: {0}", ch.ChainPolicy.VerificationFlags); Console.WriteLine("Chain verification time: {0}", ch.ChainPolicy.VerificationTime); Console.WriteLine("Chain status length: {0}", ch.ChainStatus.Length); Console.WriteLine("Chain application policy count: {0}", ch.ChainPolicy.ApplicationPolicy.Count); Console.WriteLine("Chain certificate policy count: {0} {1}", ch.ChainPolicy.CertificatePolicy.Count, Environment.NewLine); //Output chain element information. Console.WriteLine("Chain Element Information"); Console.WriteLine("Number of chain elements: {0}", ch.ChainElements.Count); Console.WriteLine("Chain elements synchronized? {0} {1}", ch.ChainElements.IsSynchronized, Environment.NewLine); // int index = 0; foreach (X509ChainElement element in ch.ChainElements) { Console.WriteLine("Element subject name: {0}", element.Certificate.Subject); Console.WriteLine("Element issuer name: {0}", element.Certificate.Issuer); Console.WriteLine("Element certificate valid until: {0}", element.Certificate.NotAfter); Console.WriteLine("Element certificate is valid: {0}", element.Certificate.Verify()); Console.WriteLine("Element error status length: {0}", element.ChainElementStatus.Length); Console.WriteLine("Element information: {0}", element.Information); Console.WriteLine("Number of element extensions: {0}{1}", element.Certificate.Extensions.Count, Environment.NewLine); string a = element.Certificate.Thumbprint; // string b = ch.ChainPolicy.ExtraStore[0].Thumbprint; //ch.ChainPolicy.ExtraStore[index - 1].Thumbprint; if (ch.ChainStatus.Length > 1) { for (int index = 0; index < element.ChainElementStatus.Length; index++) { Console.WriteLine(element.ChainElementStatus[index].Status); Console.WriteLine(element.ChainElementStatus[index].StatusInformation); } } }上面的代码也非常easy，事实上就是把整个证书链里面的每个证书打印信息一下。详细的函数调用參数msdn。 以下是完整代码。注意里面的几个证书路径是我写死的，假设想測试以下的代码，仅仅须要自己创建几个证书。
using System;using System.Security.Cryptography;using System.Security.Permissions;using System.IO;using System.Security.Cryptography.X509Certificates;class CertSelect{ static void Main() { // 验证根证书签名 X509Certificate2 x509Root = new X509Certificate2("C:\\Users\\kevin\\Desktop\\KevinRoot.cer"); Console.WriteLine("Root Certificate Verified?: {0}{1}", x509Root.Verify(), Environment.NewLine); // 根证书是自签名，所以能够通过。 X509Certificate2 x509 = new X509Certificate2("C:\\Users\\kevin\\Desktop\\ChildSubject2.cer"); byte[] rawdata = x509.RawData; Console.WriteLine("Content Type: {0}{1}", X509Certificate2.GetCertContentType(rawdata), Environment.NewLine); Console.WriteLine("Friendly Name: {0}{1}", x509.FriendlyName, Environment.NewLine); Console.WriteLine("Certificate Verified?: {0}{1}", x509.Verify(), Environment.NewLine); Console.WriteLine("Simple Name: {0}{1}", x509.GetNameInfo(X509NameType.SimpleName, true), Environment.NewLine); Console.WriteLine("Signature Algorithm: {0}{1}", x509.SignatureAlgorithm.FriendlyName, Environment.NewLine); // Console.WriteLine("Private Key: {0}{1}", x509.PrivateKey.ToXmlString(false), Environment.NewLine); // cer里面并没有私钥信息 Console.WriteLine("Public Key: {0}{1}", x509.PublicKey.Key.ToXmlString(false), Environment.NewLine); Console.WriteLine("Certificate Archived?: {0}{1}", x509.Archived, Environment.NewLine); Console.WriteLine("Length of Raw Data: {0}{1}", x509.RawData.Length, Environment.NewLine); //Output chain information of the selected certificate. X509Chain ch = new X509Chain(); ch.Build(x509); Console.WriteLine("Chain Information"); ch.ChainPolicy.RevocationMode = X509RevocationMode.Online; Console.WriteLine("Chain revocation flag: {0}", ch.ChainPolicy.RevocationFlag); Console.WriteLine("Chain revocation mode: {0}", ch.ChainPolicy.RevocationMode); Console.WriteLine("Chain verification flag: {0}", ch.ChainPolicy.VerificationFlags); Console.WriteLine("Chain verification time: {0}", ch.ChainPolicy.VerificationTime); Console.WriteLine("Chain status length: {0}", ch.ChainStatus.Length); Console.WriteLine("Chain application policy count: {0}", ch.ChainPolicy.ApplicationPolicy.Count); Console.WriteLine("Chain certificate policy count: {0} {1}", ch.ChainPolicy.CertificatePolicy.Count, Environment.NewLine); //Output chain element information. Console.WriteLine("Chain Element Information"); Console.WriteLine("Number of chain elements: {0}", ch.ChainElements.Count); Console.WriteLine("Chain elements synchronized? {0} {1}", ch.ChainElements.IsSynchronized, Environment.NewLine); // int index = 0; foreach (X509ChainElement element in ch.ChainElements) { Console.WriteLine("Element subject name: {0}", element.Certificate.Subject); Console.WriteLine("Element issuer name: {0}", element.Certificate.Issuer); Console.WriteLine("Element certificate valid until: {0}", element.Certificate.NotAfter); Console.WriteLine("Element certificate is valid: {0}", element.Certificate.Verify()); Console.WriteLine("Element error status length: {0}", element.ChainElementStatus.Length); Console.WriteLine("Element information: {0}", element.Information); Console.WriteLine("Number of element extensions: {0}{1}", element.Certificate.Extensions.Count, Environment.NewLine); string a = element.Certificate.Thumbprint; // string b = ch.ChainPolicy.ExtraStore[0].Thumbprint; //ch.ChainPolicy.ExtraStore[index - 1].Thumbprint; if (ch.ChainStatus.Length > 1) { for (int index = 0; index < element.ChainElementStatus.Length; index++) { Console.WriteLine(element.ChainElementStatus[index].Status); Console.WriteLine(element.ChainElementStatus[index].StatusInformation); } } } x509.Reset(); } }
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