AN3270 Datasheet, PDF (1/23 Pages) STMicroelectronics – Using the STM8L16x AES hardware accelerator

AN3270
Application note
Using the STM8L16x AES hardware accelerator
Introduction
The purpose of cryptography is to protect sensitive data to avoid it being read by
unauthorized persons. There are many algorithms that implement cryptography. These
techniques can be split into:
● Asymmetric cryptography algorithms: These algorithms use a key to encrypt and
another key to decrypt messages. RSA and DSA are examples of this type of
algorithm.
● Symmetric cryptography algorithms: These algorithms use the same key to encrypt
and decrypt messages. Advanced Encryption Standard (AES), Data Encryption
Standard (DES) are examples of this type of algorithm.
The Advanced Encryption Standard (AES) specifies a FIPS-approved cryptography
algorithm that can be used to protect electronic data. AES exists in three versions: 128-bit,
192-bit and 256-bit.
High density STM8L16x microcontrollers have an embedded AES 128-bit hardware
accelerator to off-load the CPU from encryption/decryption tasks. This AES peripheral is a
fully compliant implementation of the AES standard as defined by the Federal information
processing standards publication (FIPS PUB 197, 2001 November 26).
This application note applies to STM8L16x high-density devices with built-in AES peripheral.
The software supplied with this application note provides an implementation of some
commonly used AES chaining modes (ECB, CBC, CFB, OFB and CTR).
For more detailed information you should refer to the AES section of RM0031 STM8L15x
and STM8L16x microcontroller family reference manual.
July 2011
Doc ID 17919 Rev 2
www.st.com
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