**Cryptography Tutorials - Herong's Tutorial Examples** - Version 5.33, by Dr. Herong Yang

What Is AES (Advanced Encryption Standard)?

A quick description of the AES (Advanced Encryption Standard) cipher is provided. AES is based on the Rijndael cipher and uses a substitution-permutation network, not a Feistel network. AES is more secure and faster than DES.

**What Is AES (Advanced Encryption Standard)?**
The AES (Advanced Encryption Standard) is a specification for the encryption of electronic data
established by the U.S. National Institute of Standards and Technology (NIST) in 2001,
see the FIPS PUB 197 (Federal Information Processing Standards Publication 197):
"Announcing the ADVANCED ENCRYPTION STANDARD (AES)".

AES has been adopted by the US government and is now used worldwide. It supersedes the Data Encryption Standard (DES), which was published in 1977 by the US government in FIPS PUB 46.

AES is based on the Rijndael cipher developed by two Belgian cryptographers, Joan Daemen and Vincent Rijmen, who submitted a proposal to NIST during the AES selection process. Rijndael cipher is a family of ciphers with different key and block sizes. But AES only selected 3 ciphers with 1 block size of 128 bits and 3 key lengths: 128, 192 and 256 bits:

- AES-128 - AES with a 128-bit key.
- AES-196 - AES with a 196-bit key.
- AES-256 - AES with a 256-bit key.

Unlike its predecessor DES (Data Encryption Standard), AES (or Rijndael) cipher uses a substitution-permutation network, not a Feistel network, see the next tutorial for more details.

Comparing to DES, AES is more secure and faster.

*Last update: 2015.*

Table of Contents

►Introduction to AES (Advanced Encryption Standard)

►What Is AES (Advanced Encryption Standard)?

AES, or Rijndael, Encryption Algorithm

AES MixColumns() Procedure Algorithm

Example Vector of AES Encryption

AES Standard Decryption Algorithm

AES Equivalent Decryption Algorithm

DES Algorithm - Illustrated with Java Programs

DES Algorithm Java Implementation

DES Algorithm - Java Implementation in JDK JCE

DES Encryption Operation Modes

PHP Implementation of DES - mcrypt

Blowfish - 8-Byte Block Cipher

Secret Key Generation and Management

Cipher - Secret Key Encryption and Decryption

RSA Implementation using java.math.BigInteger Class

Introduction of DSA (Digital Signature Algorithm)

Java Default Implementation of DSA

Private key and Public Key Pair Generation

PKCS#8/X.509 Private/Public Encoding Standards

Cipher - Public Key Encryption and Decryption

OpenSSL Introduction and Installation

OpenSSL Generating and Managing RSA Keys

OpenSSL Generating and Signing CSR

OpenSSL Validating Certificate Path

"keytool" and "keystore" from JDK

"OpenSSL" Signing CSR Generated by "keytool"

Migrating Keys from "keystore" to "OpenSSL" Key Files

Certificate X.509 Standard and DER/PEM Formats

Migrating Keys from "OpenSSL" Key Files to "keystore"

Using Certificates in IE (Internet Explorer)