AES 128 -bit Encryption-Decryption in C#

Austin Muts

7y12.4k.NET

I have enrypted text using AES 128 -bit Encryption in my database.I have been given decryption key and want to achieve this using C#.Any code ideas of how to decrypt using C# will be appreciated.

4 Replies

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Austin Muts7y ago
I can not see where i can put key in your code.I want to use decryption key like below but i am getting an error.I am using AES 128-bit key.

private string DecryptOTP(string decryptethis)
{
decryptethis = "4931cb6f11c9f8b24f0b05f9ec9a2cc0";
string decryptionKey = string.Empty;
decryptionKey = "f22704b8bc0dcc606303b5eb97332630";
byte[] cipherBytes = Convert.FromBase64String(decryptedOTP.Trim());
using (Aes encryptor = Aes.Create())
{
Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(decryptionKey.Trim(), new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
encryptor.Key = pdb.GetBytes(32);
encryptor.IV = pdb.GetBytes(16);
using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(cipherBytes, 0, cipherBytes.Length);
cs.Close();
}
decryptethis = Encoding.Unicode.GetString(ms.ToArray());
}
}
return decryptethis;
}

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Austin Muts7y ago
I can not see where i can put key in your code.I want to use decryption key like below but i am getting an error.I am using AES 128-bit key.

private string DecryptOTP(string decryptethis)
{
decryptethis = "4931cb6f11c9f8b24f0b05f9ec9a2cc0";
string decryptionKey = string.Empty;
decryptionKey = "f22704b8bc0dcc606303b5eb97332630";
byte[] cipherBytes = Convert.FromBase64String(decryptedOTP.Trim());
using (Aes encryptor = Aes.Create())
{
Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(decryptionKey.Trim(), new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
encryptor.Key = pdb.GetBytes(32);
encryptor.IV = pdb.GetBytes(16);
using (MemoryStream ms = new MemoryStream())
{
using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(cipherBytes, 0, cipherBytes.Length);
cs.Close();
}
decryptethis = Encoding.Unicode.GetString(ms.ToArray());
}
}
return decryptethis;
}

0
brijesh rathor7y ago
I have attached code with encrypt and decrypt code. please once check.
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;
namespace Common
{
public class EncryptionLibrary
{
public static byte[] AES_Encrypt(byte[] bytesToBeEncrypted, byte[] passwordBytes)
{
byte[] encryptedBytes = null;
// Set your salt here, change it to meet your flavor:
// The salt bytes must be at least 8 bytes.
byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
using (MemoryStream ms = new MemoryStream())
{
using (RijndaelManaged aes = new RijndaelManaged())
{
aes.KeySize = 256;
aes.BlockSize = 128;
var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
aes.Key = key.GetBytes(aes.KeySize / 8);
aes.IV = key.GetBytes(aes.BlockSize / 8);
aes.Mode = CipherMode.CBC;
using (var cs = new CryptoStream(ms, aes.CreateEncryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeEncrypted, 0, bytesToBeEncrypted.Length);
cs.Close();
}
encryptedBytes = ms.ToArray();
}
}
return encryptedBytes;
}
public static byte[] AES_Decrypt(byte[] bytesToBeDecrypted, byte[] passwordBytes)
{
try
{
byte[] decryptedBytes = null;
// Set your salt here, change it to meet your flavor:
// The salt bytes must be at least 8 bytes.
byte[] saltBytes = new byte[] { 1, 2, 3, 4, 5, 6, 7, 8 };
using (MemoryStream ms = new MemoryStream())
{
using (RijndaelManaged AES = new RijndaelManaged())
{
AES.KeySize = 256;
AES.BlockSize = 128;
var key = new Rfc2898DeriveBytes(passwordBytes, saltBytes, 1000);
AES.Key = key.GetBytes(AES.KeySize / 8);
AES.IV = key.GetBytes(AES.BlockSize / 8);
AES.Mode = CipherMode.CBC;
using (var cs = new CryptoStream(ms, AES.CreateDecryptor(), CryptoStreamMode.Write))
{
cs.Write(bytesToBeDecrypted, 0, bytesToBeDecrypted.Length);
cs.Close();
}
decryptedBytes = ms.ToArray();
}
}
return decryptedBytes;
}
catch (Exception)
{
throw;
}
}
public static string EncryptText(string input, string password = "E6t187^D43%F")
{
try
{
// Get the bytes of the string
byte[] bytesToBeEncrypted = Encoding.UTF8.GetBytes(input);
byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
// Hash the password with SHA256
passwordBytes = SHA256.Create().ComputeHash(passwordBytes);
byte[] bytesEncrypted = AES_Encrypt(bytesToBeEncrypted, passwordBytes);
string result = Convert.ToBase64String(bytesEncrypted);
return result;
}
catch (Exception)
{
throw;
}
}
public static string DecryptText(string input, string password = "E6t187^D43%F")
{
try
{
// Get the bytes of the string
byte[] bytesToBeDecrypted = Convert.FromBase64String(input);
byte[] passwordBytes = Encoding.UTF8.GetBytes(password);
passwordBytes = SHA256.Create().ComputeHash(passwordBytes);
byte[] bytesDecrypted = AES_Decrypt(bytesToBeDecrypted, passwordBytes);
string result = Encoding.UTF8.GetString(bytesDecrypted);
return result;
}
catch (Exception)
{
throw;
}
}
}
}
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Mario Scheeren7y ago
https://stackoverflow.com/questions/17511279/c-sharp-aes-decryption
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