.net core openssl 加密示例

以下是 .NET Core 中使用 OpenSSL 进行加密的示例代码：

using System;
using System.Security.Cryptography;
using System.Text;
using System.Runtime.InteropServices;

public class OpenSSLExample
{
    public static void Main()
    {
        // 加载 OpenSSL 库
        const string OPENSSL_LIB = "libcrypto.so.1.1";
        IntPtr openssl = LoadLibrary(OPENSSL_LIB);
        if (openssl == IntPtr.Zero)
        {
            Console.WriteLine("无法加载 OpenSSL 库: {0}", OPENSSL_LIB);
            return;
        }

        // 准备密钥和数据
        byte[] key = Encoding.UTF8.GetBytes("my secret key");
        byte[] plaintext = Encoding.UTF8.GetBytes("hello world");

        // 加密数据
        byte[] ciphertext = Encrypt(plaintext, key);

        // 解密数据
        byte[] decryptedtext = Decrypt(ciphertext, key);

        // 输出结果
        Console.WriteLine("原始数据: {0}", Encoding.UTF8.GetString(plaintext));
        Console.WriteLine("加密后的数据: {0}", Convert.ToBase64String(ciphertext));
        Console.WriteLine("解密后的数据: {0}", Encoding.UTF8.GetString(decryptedtext));

        // 卸载 OpenSSL 库
        FreeLibrary(openssl);
    }

    [DllImport("libdl.so")]
    private static extern IntPtr dlopen(string filename, int flags);

    [DllImport("libdl.so")]
    private static extern IntPtr dlerror();

    [DllImport("libdl.so")]
    private static extern IntPtr dlsym(IntPtr handle, string symbol);

    [DllImport("libdl.so")]
    private static extern int dlclose(IntPtr handle);

    [DllImport("libc.so.6")]
    private static extern int puts(string s);

    [DllImport("libc.so.6")]
    private static extern int printf(string format, IntPtr arg);

    private static IntPtr LoadLibrary(string filename)
    {
        int RTLD_NOW = 2;
        IntPtr handle = dlopen(filename, RTLD_NOW);
        if (handle == IntPtr.Zero)
        {
            IntPtr error = dlerror();
            printf("无法加载库: %s\n", error);
        }
        return handle;
    }

    private static void FreeLibrary(IntPtr handle)
    {
        dlclose(handle);
    }

    private static byte[] Encrypt(byte[] plaintext, byte[] key)
    {
        IntPtr evp_cipher = dlsym(LoadLibrary("libcrypto.so.1.1"), "EVP_aes_256_cbc");
        byte[] iv = GenerateRandomBytes(16);
        byte[] ciphertext = new byte[plaintext.Length + 16];
        int ciphertext_len;

        using (var ctx = new EVP_CIPHER_CTX())
        {
            EVP_CipherInit_ex(ctx, evp_cipher, IntPtr.Zero, key, iv, 1);
            EVP_CipherUpdate(ctx, ciphertext, out ciphertext_len, plaintext, plaintext.Length);
            EVP_CipherFinal_ex(ctx, ciphertext, out ciphertext_len);
        }

        return ciphertext;
    }

    private static byte[] Decrypt(byte[] ciphertext, byte[] key)
    {
        IntPtr evp_cipher = dlsym(LoadLibrary("libcrypto.so.1.1"), "EVP_aes_256_cbc");
        byte[] iv = new byte[16];
        Array.Copy(ciphertext, iv, 16);
        byte[] plaintext = new byte[ciphertext.Length - 16];
        int plaintext_len;

        using (var ctx = new EVP_CIPHER_CTX())
        {
            EVP_CipherInit_ex(ctx, evp_cipher, IntPtr.Zero, key, iv, 0);
            EVP_CipherUpdate(ctx, plaintext, out plaintext_len, ciphertext, 16, ciphertext.Length - 16);
            EVP_CipherFinal_ex(ctx, plaintext, out plaintext_len);
        }

        return plaintext;
    }

    private static byte[] GenerateRandomBytes(int length)
    {
        byte[] bytes = new byte[length];
        using (var rng = new RNGCryptoServiceProvider())
        {
            rng.GetBytes(bytes);
        }
        return bytes;
    }

    private class EVP_CIPHER_CTX : SafeHandle
    {
        public EVP_CIPHER_CTX() : base(IntPtr.Zero, true) {}

        public override bool IsInvalid
        {
            get { return handle == IntPtr.Zero; }
        }

        protected override bool ReleaseHandle()
        {
            EVP_CIPHER_CTX_free(handle);
            return true;
        }

        [DllImport("libcrypto.so.1.1")]
        private static extern IntPtr EVP_CIPHER_CTX_new();

        [DllImport("libcrypto.so.1.1")]
        private static extern void EVP_CIPHER_CTX_free(IntPtr ctx);

        [DllImport("libcrypto.so.1.1")]
        private static extern int EVP_CipherInit_ex(EVP_CIPHER_CTX ctx, IntPtr cipher, IntPtr engine, byte[] key, byte[] iv, int enc);

        [DllImport("libcrypto.so.1.1")]
        private static extern int EVP_CipherUpdate(EVP_CIPHER_CTX ctx, byte[] @out, out int outl, byte[] @in, int inl);

        [DllImport("libcrypto.so.1.1")]
        private static extern int EVP_CipherFinal_ex(EVP_CIPHER_CTX ctx, byte[] @out, out int outl);
    }
}

在上面的示例中，我们使用 OpenSSL 库中的 AES-256-CBC 算法对数据进行加密和解密，可以根据需要修改算法和密钥长度。注意，需要在 Linux 环境下编译和运行此示例。