问题描述
我编码一个具有特定要求的加密/解密aes实用程序：
-AES / CBC / PKCS7
-256-Bit以base64字符串形式提供的字符串
-IV以base64字符串形式提供字符串
所以我试图使用相同的密钥和IV来加密/解密这个字符串1234567890123456。加密运行正常，但是当尝试解密加密字符串时，我得到填充无效，不能删除异常。
<$ c $ c> public void Test_AESEncryption_Decrypt（）
{
try
{
var encoding = Encoding.ASCII;
var key = encoding.GetString（Convert.FromBase64String（JVSwvtTHhGHKmH7HIj5clsfQRXGg9ZZ0cOojoAPcGg0 =））;
var iv = encoding.GetString（Convert.FromBase64String（IgEfBiIIHBANIRccFhwJDg ==））;
var strtoencrypt =1234567890123456;
var encrypted = AESEncryption.Encrypt（encoding，strtoencrypt，key，iv，CipherMode.CBC，PaddingMode.PKCS7,128）;
var decryptpted = AESEncryption.Decrypt（encoding，encoding.GetString（encrypted），key，iv，CipherMode.CBC，PaddingMode.PKCS7,128）;
Assert.AreEqual（strtoencrypt，decrypted）;
}
catch（Exception ex）
{
Assert.Fail（ex.Message）;
}
}
//这是我的实用类：
public static class AESEncryption
{
static byte [] Encrypt（Encoding encoding，string strtoencrypt，string key，string iv，CipherMode mode，PaddingMode padding，int blocksize）{
var mstream = new MemoryStream（）;
using（var aes = new AesManaged（））
{
var keybytes = encoding.GetBytes（key）;
aes.BlockSize = blocksize;
aes.KeySize = keybytes.Length * 8;
aes.Key = keybytes;
aes.IV = encoding.GetBytes（iv）;
aes.Mode = mode;
aes.Padding = padding;
using（var cstream = new CryptoStream（mstream，aes.CreateEncryptor（aes.Key，aes.IV），CryptoStreamMode.Write））
{
var bytesToEncrypt = encoding.GetBytes（strtoencrypt）;
cstream.Write（bytesToEncrypt，0，bytesToEncrypt.Length）;
cstream.FlushFinalBlock（）;
}
}
var encrypted = mstream.ToArray（）;
return encrypted;
}
public static string Decrypt（Encoding encoding，string strencrypted，string key，string iv，CipherMode mode，PaddingMode padding，int blocksize）
{
var decryptpted =;
using（var aes = new AesManaged（））
{
var keybytes = encoding.GetBytes（key）;
aes.BlockSize = blocksize;
aes.KeySize = keybytes.Length * 8;
aes.Key = keybytes;
aes.IV = encoding.GetBytes（iv）;
aes.Mode = mode;
aes.Padding = padding;
using（var mstream = new MemoryStream（encoding.GetBytes（strencrypted）））
{
using（var cstream = new CryptoStream（mstream，aes.CreateDecryptor（aes.Key ，aes.IV），CryptoStreamMode.Read））
{
using（var sreader = new StreamReader（cstream））
{
decryptpted = sreader.ReadToEnd
}
}
}
}
return decrypted;
}
}
知道AES仅支持128位的固定块大小，但u仍然可以使用256位密钥。所以如果你128位的块大小，你仍然可以坚持使用aesmanaged类。
如果错误，请纠正我。
I am coding an encryption/decryption aes utility with specific requirements:-AES/CBC/PKCS7-256-Bit Key provided as base64 string-IV provided as base64 string
So I am trying to encryp/decrypt this string "1234567890123456" using the same key and IV. Encryption runs fine but when trying to decrypt the encrypted string I get the "Padding is invalid and cannot be removed" exception. What am I missing?
//This is the calling test method
public void Test_AESEncryption_Decrypt()
{
try
{
var encoding = Encoding.ASCII;
var key = encoding.GetString(Convert.FromBase64String("JVSwvtTHhGHKmH7HIj5clsfQRXGg9ZZ0cOojoAPcGg0="));
var iv = encoding.GetString(Convert.FromBase64String("IgEfBiIIHBANIRccFhwJDg=="));
var strtoencrypt = "1234567890123456";
var encrypted = AESEncryption.Encrypt(encoding,strtoencrypt, key, iv, CipherMode.CBC, PaddingMode.PKCS7,128);
var decrypted = AESEncryption.Decrypt(encoding,encoding.GetString(encrypted), key, iv, CipherMode.CBC, PaddingMode.PKCS7,128);
Assert.AreEqual(strtoencrypt, decrypted);
}
catch (Exception ex)
{
Assert.Fail(ex.Message);
}
}
//This is my Utility Class:
public static class AESEncryption {
public static byte[] Encrypt(Encoding encoding, string strtoencrypt, string key, string iv, CipherMode mode, PaddingMode padding, int blocksize){
var mstream = new MemoryStream();
using (var aes = new AesManaged())
{
var keybytes = encoding.GetBytes(key);
aes.BlockSize = blocksize;
aes.KeySize = keybytes.Length * 8;
aes.Key = keybytes;
aes.IV = encoding.GetBytes(iv);
aes.Mode = mode;
aes.Padding = padding;
using (var cstream = new CryptoStream(mstream, aes.CreateEncryptor(aes.Key, aes.IV), CryptoStreamMode.Write))
{
var bytesToEncrypt = encoding.GetBytes(strtoencrypt);
cstream.Write(bytesToEncrypt, 0, bytesToEncrypt.Length);
cstream.FlushFinalBlock();
}
}
var encrypted = mstream.ToArray();
return encrypted;
}
public static string Decrypt(Encoding encoding,string strencrypted, string key, string iv, CipherMode mode, PaddingMode padding, int blocksize)
{
var decrypted = "";
using (var aes = new AesManaged())
{
var keybytes = encoding.GetBytes(key);
aes.BlockSize = blocksize;
aes.KeySize = keybytes.Length * 8;
aes.Key = keybytes;
aes.IV = encoding.GetBytes(iv);
aes.Mode = mode;
aes.Padding = padding;
using (var mstream = new MemoryStream(encoding.GetBytes(strencrypted)))
{
using (var cstream = new CryptoStream(mstream, aes.CreateDecryptor(aes.Key, aes.IV), CryptoStreamMode.Read))
{
using (var sreader = new StreamReader(cstream))
{
decrypted = sreader.ReadToEnd();
}
}
}
}
return decrypted;
}
}
As far as i know AES supports only a fixed blocksize of 128 bit but u can still use a 256 bit key. So if youre fine with a blocksize of 128 bit you can still stick with the aesmanaged class.
correct me if im wrong.
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