使用c#读取.p7m文件

作为上面发布的非自由/非开源解决方案的替代方案，我可能建议看看我的免费/开源S/MIME库:MimeKit

要处理输入数据，您可以这样做:

var entity = MimeEntity.Load (stream);
if (entity is MultipartSigned) {
    var signed = (MultipartSigned) entity;
    foreach (var signature in signed.Verify ()) {
        try {
            bool valid = signature.Verify ();
            // If valid is true, then it signifies that the signed content has
            // not been modified since this particular signer signed the content.
            //
            // However, if it is false, then it indicates that the signed content
            // has been modified.
        } catch (DigitalSignatureVerifyException) {
            // There was an error verifying the signature.
        }
        // If you'd like to get a copy of the certificate used for signing,
        // you could do this:
        var wrapper = (SecureMimeDigitalCertificate) signature.Certificate;
        var cert = wrapper.Certificate;
        // The cert is a BouncyCastle X509Certificate, so if you want to convert
        // it to a System.Security X509Certificate2, you can do this:
        var x509certificate2 = new X509Certificate2 (cert.GetEncoded ());
    }
}

请这样检查:有关代码的更多信息:http://www.logue.com.ar/blog/2010/03/encryption-and-decryption-with-x-509-certificates/

using System;
using System.Linq;
using System.Text;
using System.Security.Cryptography.X509Certificates;
using System.Security.Cryptography;
using System.Security.Cryptography.Pkcs;
using System.IO;
namespace Logue.Library.Cryptography
{
public static class CryptographyHelper
{
    #region Public methods
    public static string Encrypt(string fullMessage, string certificateName)
    {
        X509Certificate2 certificate = GetCertificate(certificateName);
        string base64DecryptedContent = Convert.ToBase64String(Encoding.UTF8.GetBytes(fullMessage));
        base64DecryptedContent = ChunkContent(base64DecryptedContent, 76);
        base64DecryptedContent = EnvelopeBase64(base64DecryptedContent);
        byte[] contentBytes = Encoding.ASCII.GetBytes(base64DecryptedContent);
        Oid contentOid = new Oid("1.2.840.113549.1.7.1", "PKCS 7 Data");
        Oid algorithmOid = new Oid("1.2.840.113549.3.2", "rc2");
        AlgorithmIdentifier algorithmIdentifier = new AlgorithmIdentifier(algorithmOid);
        ContentInfo content = new ContentInfo(contentOid, contentBytes);
        EnvelopedCms envelope = new EnvelopedCms(SubjectIdentifierType.NoSignature, content, algorithmIdentifier);
        envelope.Encrypt(new CmsRecipient(certificate));
        byte[] encryptedBytes = envelope.Encode();
        string encryptedContent = Convert.ToBase64String(encryptedBytes);
        encryptedContent = ChunkContent(encryptedContent, 76);
        string result = EnvelopEncryptedContent(encryptedContent);
        return result;
    }
    public static string Decrypt(string fullMessage)
    {
        string messageContent = GetContentInBase64(fullMessage);
        // Load envelope and decrypt
        EnvelopedCms envelope = new EnvelopedCms();
        envelope.Decode(Convert.FromBase64String(messageContent));
        envelope.Decrypt();
        // Get original bytes
        byte[] decryptedBytes = envelope.ContentInfo.Content;
        string decryptedText = Encoding.ASCII.GetString(decryptedBytes);
        // Get processed Base64 content
        byte[] decryptedContentBytes = Convert.FromBase64String(GetContentInBase64(decryptedText));
        string decryptedContentText = Encoding.UTF8.GetString(decryptedContentBytes);
        return decryptedContentText;
    }
    #endregion
    #region Private Methods
    private static string ChunkContent(string encryptedContent, int chunkSize)
    {
        StringBuilder sb = new StringBuilder();
        StringReader sr = new StringReader(encryptedContent);
        int position = 0;
        char[] buffer = new char[chunkSize];
        while (position < encryptedContent.Length)
        {
            if (encryptedContent.Length - (position + chunkSize) < 0)
            chunkSize = encryptedContent.Length - position;
            sb.Append(encryptedContent.Substring(position, chunkSize));
            sb.Append("rn");
            position += chunkSize;
        }
        return sb.ToString();
    }
    private static string EnvelopEncryptedContent(string encryptedContent)
    {
        return CryptographyResources.ENCRYPTED_TEMPLATE.Replace("[REPLACE]", encryptedContent);
    }
    private static string EnvelopeBase64(string content)
    {
        return CryptographyResources.BASE64_TEMPLATE.Replace("[REPLACE]", content);
    }
    private static X509Certificate2 GetCertificate(string certificateName)
    {
        X509Store store = new X509Store(StoreName.My, StoreLocation.LocalMachine);
        store.Open(OpenFlags.OpenExistingOnly | OpenFlags.ReadOnly);
        X509Certificate2 certificate = store.Certificates.Cast<X509Certificate2>().Where(cert => cert.Subject.IndexOf(certificateName) >= 0).FirstOrDefault();
        if (certificate == null)
        throw new Exception("Certificate " + certificateName + " not found.");
        return certificate;
    }
    private static string GetContentInBase64(string fullMessage)
    {
        string contentSeparator = Environment.NewLine + Environment.NewLine;
        int startIndex = fullMessage.IndexOf(contentSeparator) + contentSeparator.Length;
        int endIndex = fullMessage.Length - 1;
        StringBuilder sb = new StringBuilder();
        string[] lines = fullMessage.Substring(startIndex, endIndex - startIndex).Split(new string[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
        foreach (string line in lines)
        sb.Append(line);
        return sb.ToString();
    }
    #endregion
}
}

你得到的是一个S/MIME消息。你需要解析S/MIME消息，然后解码附件，. net并没有提供现成的S/MIME解析功能，所以你需要使用一些第三方库——要么是这个答案中提到的，要么是Rebex或我们的SecureBlackbox来解析消息。

与其尝试直接从文件解析BigFix(又名IBM Tivoli Endpoint Manager) Fixlet，还有一种更简单的方法。只需使用BigFix REST API来单独查询Fixlet的组件。您可以在IBM论坛上看到如何做到这一点的示例(以及示例c#代码):https://www.ibm.com/developerworks/community/wikis/home?lang=en !维基/Tivoli % 20端点% 20经理/页面/REST api % 20