Decrypt the SQL Encrypted AES-128 column value in c#

Rakesh reddy

I Have table with the Symmentric (AES-128) Encryption on table.

How can decrypt and use it in c# level. I am able to dycrypt again back Sql level but i want to decrypt in c# class of that.

Geettign Error :

For byte[] cipherBytes = Convert.FromBase64String(cipherText);

"The input is not a valid Base-64 string as it contains a non-base 64 character, more than two padding characters, or an illegal character among the padding characters"

4 Replies

Know the answer? Post it — somebody with the same question will find it here.

Nitin Sontakke8y ago
Accepted answer
Humm....complicated. As stated before you will need to do the decryption at SQL Server level only. I have absolutely no idea, how you plan to decrypt the text which is already encrypted by SQL Server.

You may wish to have a look at the following:
https://stackoverflow.com/questions/3299054/encrypted-columns-with-entity-framework

In particular, see the answer given by Parth Shah.
Rakesh reddy8y ago
Thankk you nitin.

Given stackoverflow blog is very help full for me. and to reduce the DB calls for enity load each time we have applied lazy loading for custom decrypted fileds.
Rakesh reddy8y ago
Thank you Nithin for the clarification

Here my requirement is like :

I Have table with email, Phone for security purpose at DB level we have encrypted those columns.
I am using Enity framework - in Login API i need to send OTP for Phone and Email as well with context table load iam getting encryted text only for fields.

So i have planned to prepare one partial class with extra columns for decrypted data for the edmx generated class and planning decrypt the value with getter method

public partial class Patient
{
public string DycrptedMobile {
get {
return (Encryption.Decrypt(this.Mobile));
}
set{}
}
}
Nitin Sontakke8y ago
Typically, you would do it at SQL Server level itself and not in C#. The critical question is how would decrypt it without key?

Even if you know the key value used in SQL Server, it is pretty likely that SQL Server add more variables to the mix to make it difficult / impossible decrypt outside SQL Server.

Any particular reason why you want to do it this way?