在 C# 中使用 PFX 文件加密字符串

Question

我想使用 PFX 文件加密我的字符串。然后将加密的字符串写入数据库。 PFX 文件的密码安全地存储在 app.config 中，并且也被加密。当方法被执行时，它总是抛出 System.NullReferenceException，但我不知道为什么。我看着我的变量，文件的密码被正确解密。这是我的源代码。

public string EncryptString(string text, string certificatePath, string password)
    {
        byte[] data = Encoding.UTF8.GetBytes(text);
        X509Certificate2Collection collection = new X509Certificate2Collection();
        collection.Import(certificatePath, password, X509KeyStorageFlags.PersistKeySet);
        X509Certificate2 certificate = collection[0];
        RSACryptoServiceProvider publickey = certificate.PublicKey.Key as RSACryptoServiceProvider;
        byte[] encrypted = publickey.Decrypt(data, false);

        return Convert.ToBase64String(encrypted);
    }

调试 Visual Studio 后显示“publickey = null”

PFX 作为 Base64：

MIIKPgIBAzCCCggGCSqGSIb3DQEHAaCCCfkEggn1MIIJ8TCCBI8GCSqGSIb3DQEH
BqCCBIAwggR8AgEAMIIEdQYJKoZIhvcNAQcBMBwGCiqGSIb3DQEMAQMwDgQIaRni
rL+ok9YCAggAgIIESA9adfH+bqz+53fdbDfvh/0/KGJzGLR+H/+u/xI1Nxb+LVLd
1pQuunmDO1yaJ8YEltO3SaxjhXdBB8sCohY0PEgloi4c/BpvihTf+FYzpp4+Bm4M
H4T2oSVQ3bwsKNsIXRwmrWEknP6UQMRM+4hEdr+5o9vt54CYoQ2eRS7W9Tpze5Nd
GHihHha+7qyeVsDWp/2MI1lmORcpQc7vrKqKeR2/KzkF5THzsorBNTvnIJMqBkNj
cqxX4jp83JXRAXnCTyYPvPPtQD2H9L+35WT9dPfOrmqgZBKMb7eKsW2dmdTth86T
p9K45kALt/DNCmC+dp3txNLOEgugWflNf3f1K2R/eua6orqQT8ByYNcAr/7nEr7s
Z4s/nOj0fF2Etgrdrzf+ryXaG4A/S1jDVXTzS/UYpk7IHVUbnQpYZtyUbX5tKaxR
HQr01vHK2hYPx/ziJU0xtWXlKrE6CtRaQ5KlfwL+In97wRj+8MStmy15LohBOSt0
pVcEh1+w/yg7bT2Y6l2ehJGf3rj0ah8r3BWWxaGLTeIvG8BbyFAeGN+3hOmjFBCG
0KL1GvvvIOE3NUOQyTIR/OCdu7NPlnAPSWiQQ0QiJ62CHkwCYDIQNnSGXXPGQ9fx
lbyJ8FQz1r6ajMwUNsNujR7ud7yX5g/jIQZy7u6EfvpRjcnR5rFp76s41NLY2jp6
cSItQX+4Ws7309/Ck8MeckeB6mlwOkZ93wg+eLyj8eoTmNt6PczwgrEk8nSz8S27
p54LzCZIZ3SGmLp0wOZjzv09dF3d9E0UBf2nx7yEv+Jph0CxUG2anj/u8NFiMTo5
4t3Bw8ymzGRdyZlgBbw/ZIHuL2x/uMpx+hoDxnWtWCVB9pcC1FEdM2kd8Td9JAoC
/rfctPUrA5xZGG7PPxONvmgnh8RUFKK5axQg/3Od+PhvAR3bA5Tr4iFepGNYIvbB
KU3foBXAyqeHLNmoNFBJRX3DlwsgEU7kXJF7Ov5GE+gSzjj/7Z7KfYREYn1AgDMx
n72dwWMWiegW0Buqix3k8bmv3kgPqsNyLt6/qZyE7G/KSZJOPO4H3hg0LDAqkx3y
fGFgtAYbeCgeHo5aLQEBRuSFjgRsIQuOrtK0csh7CqTtwH7G/+2BL4FArHs262ct
Sk/FV3v/ADEuWAj7rddI3Ks9kJxuT5RQKEm9JdVhoLJ8CwX8coXlCPmPlPbemw3z
B6SgutICCVwjJOdpccjP9u2aPQH/268+aMD20+PLOfibQbh4we40M0y9CKo5Od/i
qR8FAA8Rr5OMsHAYFGYgP9HNKTr3wHpphUrX/VhQ7cVggONhBpG1eQuJlOTvdn7R
OCJ5RESIscEjASMc0IiFvVFVxG2jp5PtDy4dt9B+SMqb3PpDdRez8LRM86PEb7qO
1oWcFmMiZu8anNixzFz3L1NWDVDyAfl4lrUbnfhnb9UhKEANys4Up3EzKcGB5NxT
gK2k82swggVaBgkqhkiG9w0BBwGgggVLBIIFRzCCBUMwggU/BgsqhkiG9w0BDAoB
AqCCBO4wggTqMBwGCiqGSIb3DQEMAQMwDgQILoUgnShgmUsCAggABIIEyJ48PbMu
u2+T+SWEsLVpNwtDXxZDa+403cWxyw4yPFnuibWauMGql/tXCKQ82n3geASXj30B
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Manw+pRcNrFxUIRszecResunmrzpE4HylQq9iy7SQfU17KC7YWZJBMI7pknC/q9c
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IRegMgwm/h17LOrTQPvtPYV/hbmXhBjCwD8771uhqWFw6q8gh42/D/Q6k43WEVNy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（我使用 XCA 创建了我的证书） 密码：test123

有人可以帮我吗？

Answer 1

您不能只使用 pfx 加密数据，您需要指定格式。

Windows 将 .pfx 用于 PKCS #12 文件。该文件可以包含各种加密信息，包括证书、证书链、根授权证书和私钥。可以对其内容进行加密保护（使用密码），以保持私钥的私密性并保持根证书的完整性。

What is the difference between a cer, pvk, and pfx file?

使用 EnvelopedCms，您可以获得一种易于使用并使用 pfx 文件的格式，有关详细信息，请参阅 Cryptographic Message Syntax https://www.rfc-editor.org/rfc/rfc5652。

如果您想保护敏感数据，您应该让专业人士审查您的实施！

代码

一些学生出于学习目的创建，https://github.com/haevg-rz/LearnToCode/blob/master/Examples/EncryptionDemo/EncryptionDemo.Sample/CryptographicMessageSyntax.cs

我对代码做了一些改动，所以它更熟悉你的代码。

using System;
using System.Security.Cryptography;
using System.Security.Cryptography.X509Certificates;
using System.Security.Cryptography.Pkcs;
using System.Text;
using System.IO;
using System.Security;

namespace PfxTest
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Hello to PfxTest!");
            File.WriteAllBytes("test.pfx", Convert.FromBase64String(pfxBase64));
            
            var r = EncryptString("Hello", "test.pfx","test123");
            Console.WriteLine(r);
        }

        static string pfxBase64 = "MIIKPgIBAzCCCggGCSqGSIb3DQEHAaCCCfkEggn1MIIJ8TCCBI8GCSqGSIb3DQEHBqCCBIAwggR8AgEAMIIEdQYJKoZIhvcNAQcBMBwGCiqGSIb3DQEMAQMwDgQIaRnirL+ok9YCAggAgIIESA9adfH+bqz+53fdbDfvh/0/KGJzGLR+H/+u/xI1Nxb+LVLd1pQuunmDO1yaJ8YEltO3SaxjhXdBB8sCohY0PEgloi4c/BpvihTf+FYzpp4+Bm4MH4T2oSVQ3bwsKNsIXRwmrWEknP6UQMRM+4hEdr+5o9vt54CYoQ2eRS7W9Tpze5NdGHihHha+7qyeVsDWp/2MI1lmORcpQc7vrKqKeR2/KzkF5THzsorBNTvnIJMqBkNjcqxX4jp83JXRAXnCTyYPvPPtQD2H9L+35WT9dPfOrmqgZBKMb7eKsW2dmdTth86Tp9K45kALt/DNCmC+dp3txNLOEgugWflNf3f1K2R/eua6orqQT8ByYNcAr/7nEr7sZ4s/nOj0fF2Etgrdrzf+ryXaG4A/S1jDVXTzS/UYpk7IHVUbnQpYZtyUbX5tKaxRHQr01vHK2hYPx/ziJU0xtWXlKrE6CtRaQ5KlfwL+In97wRj+8MStmy15LohBOSt0pVcEh1+w/yg7bT2Y6l2ehJGf3rj0ah8r3BWWxaGLTeIvG8BbyFAeGN+3hOmjFBCG0KL1GvvvIOE3NUOQyTIR/OCdu7NPlnAPSWiQQ0QiJ62CHkwCYDIQNnSGXXPGQ9fxlbyJ8FQz1r6ajMwUNsNujR7ud7yX5g/jIQZy7u6EfvpRjcnR5rFp76s41NLY2jp6cSItQX+4Ws7309/Ck8MeckeB6mlwOkZ93wg+eLyj8eoTmNt6PczwgrEk8nSz8S27p54LzCZIZ3SGmLp0wOZjzv09dF3d9E0UBf2nx7yEv+Jph0CxUG2anj/u8NFiMTo54t3Bw8ymzGRdyZlgBbw/ZIHuL2x/uMpx+hoDxnWtWCVB9pcC1FEdM2kd8Td9JAoC/rfctPUrA5xZGG7PPxONvmgnh8RUFKK5axQg/3Od+PhvAR3bA5Tr4iFepGNYIvbBKU3foBXAyqeHLNmoNFBJRX3DlwsgEU7kXJF7Ov5GE+gSzjj/7Z7KfYREYn1AgDMxn72dwWMWiegW0Buqix3k8bmv3kgPqsNyLt6/qZyE7G/KSZJOPO4H3hg0LDAqkx3yfGFgtAYbeCgeHo5aLQEBRuSFjgRsIQuOrtK0csh7CqTtwH7G/+2BL4FArHs262ctSk/FV3v/ADEuWAj7rddI3Ks9kJxuT5RQKEm9JdVhoLJ8CwX8coXlCPmPlPbemw3zB6SgutICCVwjJOdpccjP9u2aPQH/268+aMD20+PLOfibQbh4we40M0y9CKo5Od/iqR8FAA8Rr5OMsHAYFGYgP9HNKTr3wHpphUrX/VhQ7cVggONhBpG1eQuJlOTvdn7ROCJ5RESIscEjASMc0IiFvVFVxG2jp5PtDy4dt9B+SMqb3PpDdRez8LRM86PEb7qO1oWcFmMiZu8anNixzFz3L1NWDVDyAfl4lrUbnfhnb9UhKEANys4Up3EzKcGB5NxTgK2k82swggVaBgkqhkiG9w0BBwGgggVLBIIFRzCCBUMwggU/BgsqhkiG9w0BDAoBAqCCBO4wggTqMBwGCiqGSIb3DQEMAQMwDgQILoUgnShgmUsCAggABIIEyJ48PbMuu2+T+SWEsLVpNwtDXxZDa+403cWxyw4yPFnuibWauMGql/tXCKQ82n3geASXj30B8SOoEPWoggw1SCGfkd5GFIUIRpMLRuDjDWWgXHNFkiqSyRatbTAXwkM/pRtdtDYvVsdfI8chXkP4M5kOZY761zfhTjIKcJV4X9pDs4VaRiuFJKOL2Qa5qua+YsGeiXjorQIyMB1kNvRJTyMq1XewK9+pa0Dto+Lqo9bkkpgsIQDWAC7CVvfiVUFcBONgoKNCManw+pRcNrFxUIRszecResunmrzpE4HylQq9iy7SQfU17KC7YWZJBMI7pknC/q9cG6pe7pW71zBU5Tgl5TB7lKryOO1Yp9AsIt008yn2qPNGKgSIKvnxdBgYFdyG+SUyU2piSoXEwAfXAoN4vOdHVl46WaiBRtuxwaDfOwgk5W4EafgthZJsfKulHt4A32dzARlYQ9eQe4qLftSOLQToZZ19R4eSV3acU7z6xj9sdF/CrqZEw5meJnu05hj5/sbomF7V+ct8U8p6sTVJeWXk83I2FM/l1qGy/Vu0PQYdCJFEZYuG1tzNlhBFegZuWnTzU3EuP058G+P3SBWzsGddo/p+xVSaKCm6cSpl1tb1iAephXmmSK56qmQwLpy0NqrIIRegMgwm/h17LOrTQPvtPYV/hbmXhBjCwD8771uhqWFw6q8gh42/D/Q6k43WEVNyjMKlaMNlhYhZgiM4Y6ebE8mi9OHGsPcW84aSkY9GDS+Q4s+y7Co0ImLOHtrsWBSpLkmtd3fTxQPCN1xsAKY63VTNlLlgRJtsSDTT7DWsBkTmyPFcpOtPIObh/fASKrY78m/iH+QgFSpZI3jBrenNW7YJ9Zdb6GaVl2ljoPynTqPtdGY3D8N6kGys26zLn5E5xjUrAZkhmIJ3KT0KXXtv8FIl5QvoJziQm35wv4J00ZjiSOHOnHBbDxrHvUkZgipVAbmdCxXvgNN2bm9K4rGfM8C2+fSFMLy1UprMwIv6QDL26RXYAd0lQE2vV8HjCcclnaDh21Nywf7NYBuWF0qOEZ43rBPlhNrtsgeBUCZHnxJTPVJ6agPQU2bomTpgNjx0NEMPUileecQXmGJZs1sNJrlL+j9TWtTdH0gsBQ//XNSj3nxPwCwTerqFE8Nr3M8qX/vQlCSqhExftT6AI/OEjjMsE9maZOjgNt21rAe/pFGnAEnIqQiQYG/kmeyCBscmOktvbxh3kn9NVf2S/oDkkD25fF2I+RKp8vG917B46FjsB9WgK1l90E/gELZYbIiP8d1czym/k9rVac8Nzwh1j4TLE9ZOeH17JJZr3mALwQxybSw415okFhYtqaQtOSNA6OcBGKxUU+A8oo1qgkE55rWNq3ZnsGZMvmS/pDepm5ddH6aUDaKRpKCjUpeJGkuI+DG90sBpw8Ihd2kV7VxZfMe2fEzlCLqoR4/0Zl53CVG2a9SklFTNm4wIwcR6n1nRMdrlg8QwHvN6x6F1cnK/Yb7oFN7Pc5wKKBgyjwjw6cNdpgvJN547MJW6yyneyohOIf0LOdGdedXFM+7aCwycAKT204h32uVImuzM84YahuCut9q0aGwuhcNYUJE30k3NDEYLB8Kmv9/Q2BsQF9AffUws9zE+MBcGCSqGSIb3DQEJFDEKHggAVABlAHMAdDAjBgkqhkiG9w0BCRUxFgQUoTL8BkW1K9Rojn9dQxxVpi67CfgwLTAhMAkGBSsOAwIaBQAEFGh9oeyTGPMMYTL30MJCYnH7D0iCBAg8bSEfNN5qDQ==";

        static public string EncryptString(string text, string certificatePath, string password)
        {
            byte[] data = Encoding.UTF8.GetBytes(text);
            CmsRecipientCollection collection = new CmsRecipientCollection();
             var secureString = new SecureString();
            foreach (var item in password) secureString.AppendChar(item);
            var certificate = new X509Certificate2(File.ReadAllBytes(certificatePath),secureString);
            collection.Add(new CmsRecipient(certificate,RSAEncryptionPadding.OaepSHA512));
            
            var envelopedCms = new EnvelopedCms(new ContentInfo(data));
            if (envelopedCms.ContentEncryptionAlgorithm.Oid.FriendlyName != "aes256")
                // After .NET Core 3 aes256 is the standard ContentEncryptionAlgorithm, before it was 3des.
                throw new Exception("Only aes256 is allowed.");

            envelopedCms.Encrypt(collection);
            var encrypted = envelopedCms.Encode();

            return Convert.ToBase64String(encrypted);
        }
    }
}

输出

PS C:\DEV\PfxTest> dotnet run
Hello to PfxTest!
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