Crypto instruction set: Efficient approach for crypto based computation

Introduction

Laymen explanation

Now internet access is very much common. People are accessing web data from mobile (whatsapp, facebook, flipkart, amazon). And most of these data are encrypted. So, additional processing is needed due to crypto operation. Will it slow the access of site? Definitely, How to improve the speed? For the same, built in processor instruction comes in picture.

Technical explanation

Advanced Encryption Standard Instruction Set (or the Intel Advanced Encryption Standard New Instructions; AES-NI) is an extension to the x86 instruction set architecture for microprocessors from Intel.

The architecture consists of six instructions that offer full hardware support for AES. Four instructions support the AES encryption and decryption, and other two instructions support the AES key expansion.

How it works

AES-NI is just a fast way for the processor to execute the calculations of AES. Normally the computer has to calculate every single step of the AES key schedule and the rounds as a single instruction: Substitute it with the S-boxes, shift the rows, mix the columns, XOR the round key. This is called a software implementation. Every instruction has to be done in software from the program.

Using the AES instruction set the program can do a whole round in a single instruction. There are several different instructions to do this: refer New instructions, Wikipedia. The instructions will be executed on hardware level, in the transistors of the processor. Without the whole other things a processor normally does to execute a program the encryption and decryption are much more efficient. This is called a hardware implementation. As far as I know, every block cipher is more efficient in hardware than in software. Some more, some not so much. "More efficient" means faster, less energy-consuming or both.

Security

Beyond improving performance, the AES instructions provide important security benefits. By running in data-independent time and not using tables, they help in eliminating the major timing and cache-based attacks that threaten table-based software implementations of AES. In addition, they make AES simple to implement, with reduced code size, which helps reducing the risk of inadvertent introduction of security flaws, such as difficult-to-detect side channel leaks.

Reference

https://en.wikipedia.org/wiki/AES_instruction_set#New_instructions

https://en.wikipedia.org/wiki/AES_instruction_set

https://software.intel.com/en-us/articles/intel-advanced-encryption-standard-aes-instructions-set