Encryption

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ANB asked May 9, '22 BrandoZhang-MSFT edited May 12, '22

Encryption

Hi there,
I have a method which gets a encrypted value and will be decrypted to a guid that I have on my database.
It almost works, but the problem is the 4 last guid characteres are missing. Why ?

 public static string Decrypt<T>(string value, string password) where T : SymmetricAlgorithm, new()
         {
             byte[] vectorBytes = Encoding.ASCII.GetBytes(_vector);
             byte[] saltBytes = Encoding.ASCII.GetBytes(_salt);
             byte[] valueBytes = Convert.FromBase64String(value);
    
             byte[] decrypted;
             int decryptedByteCount = 0;
    
             using (T cipher = new T())
             {
                 PasswordDeriveBytes _passwordBytes = new PasswordDeriveBytes(password, saltBytes, _hash, _iterations);
                 byte[] keyBytes = _passwordBytes.GetBytes(_keySize / 8);
    
                 cipher.Mode = CipherMode.CBC;
    
                 try
                 {
                     using (ICryptoTransform decryptor = cipher.CreateDecryptor(keyBytes, vectorBytes))
                     {
                         using (MemoryStream from = new MemoryStream(valueBytes))
                         {
                             using (CryptoStream reader = new CryptoStream(from, decryptor, CryptoStreamMode.Read))
                             {
                                 decrypted = new byte[valueBytes.Length];
                                 decryptedByteCount = reader.Read(decrypted, 0, decrypted.Length);
                             }
                         }
                     }
                 }
                 catch (Exception ex)
                 {
                     return String.Empty;
                 }
    
                 cipher.Clear();
             }
    
             var xxxx = Encoding.UTF8.GetString(decrypted, 0, decryptedByteCount);
             return Encoding.UTF8.GetString(decrypted, 0, decryptedByteCount);
         }

Thx guys !

dotnet-csharp dotnet-aspnet-core-general

· 1

5 |1600 characters needed characters left characters exceeded

Attachments: Up to 10 attachments (including images) can be used with a maximum of 3.0 MiB each and 30.0 MiB total.

Viorel-1 · May 11 at 02:26 AM

Maybe you must repeat reader.Read until it returns zero, using a loop, and append the portions? To simplify it, the samples use StreamReader.ReadToEnd: https://docs.microsoft.com/en-us/dotnet/api/system.security.cryptography.cryptostream.

0 ·

Answer 1 · 2022-05-09T19:57:16.417Z

Bruce-SqlWork answered May 9, '22

when you encrypted the data, you probably missed calling FlushFinalBlock()

5 |1600 characters needed characters left characters exceeded

Attachments: Up to 10 attachments (including images) can be used with a maximum of 3.0 MiB each and 30.0 MiB total.

Answer 2 · 2022-05-10T22:01:47.117Z

ANB answered May 10, '22 ANB commented May 10, '22

No. I do have it.

 public static string Encrypt<T>(string value, string password)
                 where T : SymmetricAlgorithm, new()
         {
             byte[] vectorBytes = Encoding.ASCII.GetBytes(_vector);
             byte[] saltBytes = Encoding.ASCII.GetBytes(_salt);
             byte[] valueBytes = Encoding.UTF8.GetBytes(value);
    
             byte[] encrypted;
             using (T cipher = new T())
             {
                 PasswordDeriveBytes _passwordBytes =
                     new PasswordDeriveBytes(password, saltBytes, _hash, _iterations);
                 byte[] keyBytes = _passwordBytes.GetBytes(_keySize / 8);
    
                 cipher.Mode = CipherMode.CBC;
    
                 using (ICryptoTransform encryptor = cipher.CreateEncryptor(keyBytes, vectorBytes))
                 {
                     using (MemoryStream to = new MemoryStream())
                     {
                         using (CryptoStream writer = new CryptoStream(to, encryptor, CryptoStreamMode.Write))
                         {
                             writer.Write(valueBytes, 0, valueBytes.Length);
                             writer.FlushFinalBlock();
                             encrypted = to.ToArray();
                         }
                     }
                 }
                 cipher.Clear();
             }
             return Convert.ToBase64String(encrypted);
         }

· 1

5 |1600 characters needed characters left characters exceeded

Attachments: Up to 10 attachments (including images) can be used with a maximum of 3.0 MiB each and 30.0 MiB total.

ANB · May 10 at 10:03 PM

I believe it could be something like Padding.

But If I add ----> cipher.Padding = PaddingMode.None;

I have this issue:
The input data is not a complete block."

0 ·

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