如何将Python实现的AES加密函数转换为运行结果一致的C#代码

结果不匹配的核心原因 #

• 填充规则不一致：Python PyCryptodome库的CFB模式默认无填充，加密后密文长度和明文长度完全一致；你当前C#代码设置了PaddingMode.PKCS7会自动对明文补位，导致密文长度和内容都和Python输出不符
• 反馈段大小不匹配：Python代码显式指定了segment_size = 128，对应C#的RijndaelManaged需要显式设置FeedbackSize = 128，该参数默认值为8，是二者结果不一致的核心原因
• 注意：需要保证传入的key、IV字节长度符合AES规范：AES128对应key长度16字节，IV固定16字节，不要直接对长度不符的字符串用UTF8转字节数组，避免密钥/IV不匹配

修正后完整代码 #

using System.Security.Cryptography;
using System.Text;

public static string AesEncrypt(string plainText, string key, string iv)
{
    byte[] plainBytes = Encoding.UTF8.GetBytes(plainText);
    byte[] keyBytes = Encoding.UTF8.GetBytes(key);
    byte[] ivBytes = Encoding.UTF8.GetBytes(iv);
    int plainLen = plainBytes.Length;
    int blockSize = 16; // BlockSize=128对应16字节

    using (RijndaelManaged rm = new RijndaelManaged())
    {
        rm.Key = keyBytes;
        rm.IV = ivBytes;
        rm.Mode = CipherMode.CFB;
        rm.BlockSize = 128;
        rm.FeedbackSize = 128; // 对应Python的segment_size=128参数
        rm.Padding = PaddingMode.None; // 关闭自动填充

        ICryptoTransform encryptor = rm.CreateEncryptor();
        // 处理非块大小整数倍的明文
        int alignedLen = ((plainLen + blockSize - 1) / blockSize) * blockSize;
        byte[] alignedPlain = new byte[alignedLen];
        Buffer.BlockCopy(plainBytes, 0, alignedPlain, 0, plainLen);
        byte[] encryptedAligned = encryptor.TransformFinalBlock(alignedPlain, 0, alignedLen);
        // 截取和原明文等长的密文
        byte[] resultBytes = new byte[plainLen];
        Buffer.BlockCopy(encryptedAligned, 0, resultBytes, 0, plainLen);

        return ToBCDStringLower(resultBytes);
    }
}

public static string ToBCDStringLower(byte[] buffer)
{
    StringBuilder sb = new StringBuilder();
    foreach (byte b in buffer)
    {
        sb.Append(b.ToString("x2"));
    }
    return sb.ToString();
}

验证说明 #

验证时请确保Python和C#使用的key、iv、明文完全一致，若使用AES192/AES256加密，仅需调整传入的key长度为24字节/32字节即可，其余参数不需要修改。

内容的提问来源于stack exchange，提问作者IShirai_KurokoI