AES 128 -bit Encryption-Decryption in C#

Question

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.

Austin Muts · Answer

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; }

Austin Muts · Answer

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; }

brijesh rathor · Answer

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 ; } } } }

Mario Scheeren · Answer

https://stackoverflow.com/questions/17511279/c-sharp-aes-decryption