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随着《电子签名法》的颁布，数字证书应用越来越广泛，在一般的应用中，我们都是在系统中安装pkcs12格式的证书。在访问应用（一般是网页、电子邮件等）时，选择合适的证书。我们也可以使用编程来直接读取证书文件。下面我们就介绍如何使用.net读取数字证书。
要读取pkcs12格式的证书，我们需要调用API，在WIN32类中，我们声明这些API的引用：
1 using System;
2using System.Runtime.InteropServices;
3
4namespace X509Cert
5   {
6
7 public class WIN32
8  {
9 public const uint CRYPT_USER_KEYSET = 0x00001000;
10 public const uint CERT_KEY_PROV_INFO_PROP_ID = 0x00000002;
11 public const uint CRYPT_DELETEKEYSET = 0x00000010;
12
13 [DllImport("crypt32.dll", SetLastError=true)]
14 public static extern IntPtr PFXImportCertStore(ref CRYPT_DATA_BLOB pPfx,[MarshalAs(UnmanagedType.LPWStr)] String szPassword,uint dwFlags);
15
16 [DllImport("CRYPT32.DLL", EntryPoint="CertEnumCertificatesInStore", CharSet=CharSet.Auto, SetLastError=true)]
17 public static extern IntPtr CertEnumCertificatesInStore( IntPtr storeProvider, IntPtr prevCertContext);
18
19 [DllImport("CRYPT32.DLL",CharSet=CharSet.Auto, SetLastError=true)]
20 public static extern bool CertGetCertificateContextProperty(IntPtr pCertContext,uint dwPropId,IntPtr pvData,ref uint pcbData);
21
22 [DllImport("advapi32.dll",EntryPoint="CryptAcquireContext",CharSet=CharSet.Auto, SetLastError=true)]
23 public static extern bool CryptAcquireContext(ref IntPtr phProv,string szContainer,string szProvider,uint dwProvType,uint dwFlags);
24
25 [StructLayout(LayoutKind.Sequential)]
26 public struct CRYPT_DATA_BLOB {
27 public int cbData;
28 public IntPtr pbData;
29 }
30
31 [StructLayout(LayoutKind.Sequential)]
32 public struct CRYPT_KEY_PROV_INFO {
33
34 [MarshalAs(UnmanagedType.LPWStr)]
35 public String ContainerName;
36
37 [MarshalAs(UnmanagedType.LPWStr)]
38 public String ProvName;
39
40 public uint ProvType;
41
42 public uint Flags;
43
44 public uint ProvParam;
45
46 public IntPtr rgProvParam;
47
48 public uint KeySpec;
49
50 }
51
52 public WIN32()
53 {
54 //
55 // TODO: 在此处添加构造函数逻辑
56 //
57 }
58 }
59 }
60
然后在Cert类中写一个Read方法读取其中的证书。注意：pfx文件有可能包含几个证书
1using System;
2using System.IO;
3using System.Runtime.InteropServices;
4using System.Security.Cryptography.X509Certificates;
5
6namespace X509Cert
7{
8 /**//// <summary>
9 /// Cert 的摘要说明。
10 /// </summary>
11 public class Cert
12 {
13 public Cert()
14 {
15 //
16 // TODO: 在此处添加构造函数逻辑
17 //
18 }
19 public static System.Security.Cryptography.X509Certificates.X509Certificate[] Read(string filename,string password) {
20
21 //打开证书文件，并读到一个字节数组中。
22 FileStream stream = new FileStream(filename,FileMode.Open);
23 byte[] buffer = new byte[stream.Length];
24 stream.Read(buffer,0,buffer.Length);
25 stream.Close();
26
27 //声明并实例化WIN32.CRYPT_DATA_BLOB 将读取到的字节数组拷贝到它的pbData属性中。将字节数组长度赋给cbData属性
28 WIN32.CRYPT_DATA_BLOB cryptdata = new WIN32.CRYPT_DATA_BLOB();
29 cryptdata.cbData = buffer.Length;
30 cryptdata.pbData = Marshal.AllocHGlobal(cryptdata.cbData);
31 Marshal.Copy(buffer,0,cryptdata.pbData,buffer.Length);
32 IntPtr hMemStore = WIN32.PFXImportCertStore(ref cryptdata,"1234",WIN32.CRYPT_USER_KEYSET);
33 Marshal.FreeHGlobal(cryptdata.pbData);
34
35 uint provinfosize = 0;
36 WIN32.CRYPT_KEY_PROV_INFO certinfo = new WIN32.CRYPT_KEY_PROV_INFO();
37
38 System.Collections.ArrayList certs = new System.Collections.ArrayList();
39
40 IntPtr certHandle = IntPtr.Zero;
41 while((certHandle = WIN32.CertEnumCertificatesInStore(hMemStore,certHandle)) != IntPtr.Zero) {
42
43 if(WIN32.CertGetCertificateContextProperty(certHandle,WIN32.CERT_KEY_PROV_INFO_PROP_ID,IntPtr.Zero,ref provinfosize)){
44
45 IntPtr info = Marshal.AllocHGlobal((int)provinfosize);
46
47 if(WIN32.CertGetCertificateContextProperty(certHandle,WIN32.CERT_KEY_PROV_INFO_PROP_ID,info,ref provinfosize)) {
48 certinfo = (WIN32.CRYPT_KEY_PROV_INFO)Marshal.PtrToStructure(info,typeof(WIN32.CRYPT_KEY_PROV_INFO));
49
50 certs.Add(new X509Certificate(certHandle));
51 }
52 Marshal.FreeHGlobal(info);
53
54 }
55 }
56
57 Marshal.FreeHGlobal(hMemStore);
58
59 IntPtr hCryptProv = IntPtr.Zero;
60 if(!WIN32.CryptAcquireContext(ref hCryptProv,certinfo.ContainerName,certinfo.ProvName,certinfo.ProvType,WIN32.CRYPT_DELETEKEYSET))
61 throw new Exception("释放内存错误");
62 return (X509Certificate[])certs.ToArray(typeof(X509Certificate));
63
64 }
65 }
66}
67
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