The following is a symmetric encryption/decryption routine using AES in GCM mode. This code operates in the application layer, and is meant to receive user specific and confidential information and encrypt it, after which it is stored in a separate database server. It also is called upon to decrypt encrypted information from the database.

I am looking for a review of the code with respect to its level of security, which in this case refers primarily to the correct implementation of the class called AuthenticatedAesCng found here:

My encryption/decryption routines are based on the code found here:

16 random bytes of salt are extracted from the system's secure random number generator (usually /dev/urandom). The AES key and IV from step 2), in. Cs 1.6 Serial Key Generator Windows 7 Enterprise Mak Key Generator Mount And Blade Warband 1.134 Serial Key Generator Windows 7 Ultimate N Activation Key Generator Pass Need For Speed 2015 Key Generator Txt Assetto Corsa Cd-key Generator Generate Ssh Key In Cygwin. The Aes class has inbuilt capabilities to do this. Aes.GenerateKey replaces the current key with a new random one (of size aes.KeySize). Aes.GenerateIV replaces the current IV with a new random one (of the block size, which is always 16 bytes for AES). Bouncy Castle (cryptography) import java.io.; import java.math.; import java.security.; import org.bouncycastle.crypto.; import org.bouncycastle.crypto.params.; import org.bouncycastle.crypto. Entering the private key - the generator and/or parity check. Input of the initialization vector, calculation of the truncated error vector e.= e - IV.

Any comments or advice is very much appreciated.

Here is the code:

Ниже приведена процедура симметричного шифрования/дешифрования с использованием AES в режиме GCM. Этот код работает на прикладном уровне и предназначен для получения пользовательской и конфиденциальной информации и шифрования, после чего он хранится на отдельном сервере базы данных. Он также призван расшифровать зашифрованную информацию из базы данных.

Ищу обзор кода по уровню безопасности, который в данном случае относится прежде всего к правильному реализации класса под названием AuthenticatedAesCng здесь:

Моего шифрование/дешифрования процедуры основаны на коде найти здесь:

Любые комментарии или советы очень высоко ценится.

Вот код:

There are specific style guides that Microsoft publishes regarding [C# documentation comments](http://msdn.microsoft.com/en-us/library/b2s063f7%28VS.80%29.aspx) and [capitalization conventions](http://msdn.microsoft.com/en-us/library/ms229043.aspx). – Bill Barry16 июл. 122012-07-16 16:29:49

I'm used to writing c++ comments and sometimes forget formatting, sorry – crawfish16 июл. 122012-07-16 20:06:05

It's not **Authentication Data**, but **Authenticated Data**, often referred to as **Additional Authenticated Data**. The idea is that you can have data that doesn't need to be encrypted and needs to be included with the cipher text. You still need it to be authenticated for integrity -- so that you know that this additional unencrypted data hasn't been tampered with. It is also *optional* you don't need to use it. – jbtule08 авг. Turbo fast skidmark. 122012-08-08 19:23:30

Let's illustrate the AES encryption and AES decryption concepts through working source code in Python.

The first example below will illustrate a simple password-based AES encryption (PBKDF2 + AES-CTR) without message authentication (unauthenticated encryption). The next example will add message authentication (using the AES-GCM mode), then will add password to key derivation (AES-256-GCM + Scrypt).

Simple AES-CTR Example

Let's start with simple AES-256-CTR non-authenticated encryption.

Install Python Libraries `pyaes` and `pbkdf2`

First, install the Python library pyaes that implements the AES symmetric key encryption algorithm:

Next, install the Python library pbkdf2 that implements the PBKDF2 password-to-key derivation algorithm:

Now, let's play with a simple AES encrypt / decrypt example.

Password to Key Derivation

First start by key derivation: from password to 256-bit encryption key.

Run the above code example: https://repl.it/@nakov/AES-CTR-in-Python.

The above code derives a 256-bit key using the PBKDF2 key derivation algorithm from the password s3cr3t*c0d3. It uses a random password derivation salt (128-bit). This salt should be stored in the output, together with the ciphertext, because without it the decryption key cannot be derived again and the decryption will be impossible.

The output from the above code may look like this:

The derived key consists of 64 hex digits (32 bytes), which represents a 256-bit integer number. It will be different if you run the above code several times, because a random salt is used every time. If you use the same salt, the same key will be derived.

AES Encryption (CTR Block Mode)

Aes Key And Iv Generator Download

Next, generate a random 256-bit initial vector (IV) for the AES CTR block mode and perform the AES-256-CTR encryption:

Run the above code example: https://repl.it/@nakov/AES-encryption-in-Python.

The output from the above code may look like this:

The ciphertext consists of 38 hex digits (19 bytes, 152 bits). This is the size of the input data, the message Text for encryption.

Note that after AES-CTR encryption the initial vector (IV) should be stored along with the ciphertext, because without it, the decryption will be impossible. The IV should be randomly generated for each AES encryption (not hard-coded) for higher security.

Note also that if you encrypt the same plaintext with the same encryption key several times, the output will be different every time, due to the randomness in the IV. This is intended behavior and it increases the security, e.g. resistance to dictionary attacks.

AES Decryption (CTR Block Mode)

Now let's see how to decrypt a ciphertext using the AES-CTR-256 algorithm. The input consists of ciphertext + encryption key + the IV for the CTR counter. The output is the original plaintext. The code is pretty simple:

Run the above code example: https://repl.it/@nakov/AES-decryption-in-Python.

The output of the above should be like this:

Note that the aes object should be initialized again, because the CTR cipher block mode algorithm keeps an internal state that changes over the time.

Note also that the above code cannot detect wrong key, wrong ciphertext or wrong IV. If you use an incorrect key to decrypt the ciphertext, you will get a wrong unreadable text. This is clearly visible by the code below:

Run the above code example: https://repl.it/@nakov/AES-decryption-wrong-key-in-Python.

The output of the above incorrect decryption attempt might be like this:

Now it is your time to play with the above code example. Try to to encrypt and decrypt different messages, to change the input message, the key size, to hard-code the IV, the key and other parameters, switch to CBC mode, and see how the results change. Enjoy learning by playing.

AES-256-GCM Example

Aes Key And Iv Generator Reviews

Now, let's give a full example how to use the AES-256-GCM symmetric encryption construction. We shall use a different Python library for AES