Carry-less Multiplication (CLMUL) is an extension to the x86 instruction set used by microprocessors

Microprocessor

A microprocessor incorporates the functions of a computer's central processing unit on a single integrated circuit, or at most a few integrated circuits. It is a multipurpose, programmable device that accepts digital data as input, processes it according to instructions stored in its memory, and...

 from Intel

Intel Corporation

Intel Corporation is an American multinational semiconductor chip maker corporation headquartered in Santa Clara, California, United States and the world's largest semiconductor chip maker, based on revenue. It is the inventor of the x86 series of microprocessors, the processors found in most...

 and AMD

Advanced Micro Devices

Advanced Micro Devices, Inc. or AMD is an American multinational semiconductor company based in Sunnyvale, California, that develops computer processors and related technologies for commercial and consumer markets...

 which was proposed by Intel in March 2008 and made available in the Intel Westmere processors announced in early 2010. The purpose is to improve the speed of applications doing block cipher encryption in Galois/Counter Mode

Galois/Counter Mode

Galois/Counter Mode is a mode of operation for symmetric key cryptographic block ciphers that has been widely adopted because of its efficiency and performance...

, which depends on finite field

Finite field

In abstract algebra, a finite field or Galois field is a field that contains a finite number of elements. Finite fields are important in number theory, algebraic geometry, Galois theory, cryptography, and coding theory...

 multiplication. Finite field (GF(2^k)) multiplication can be implemented more efficiently with the new CLMUL instructions than with the traditional instruction set

New instructions

Instruction	Description
PCLMULQDQ	Performs a carry-less multiplication of two 64-bit integers

PCLMULLQLQDQ xmmreg,xmmrm [rm: 66 0f 3a 44 /r 00]
PCLMULHQLQDQ xmmreg,xmmrm [rm: 66 0f 3a 44 /r 01]
PCLMULLQHQDQ xmmreg,xmmrm [rm: 66 0f 3a 44 /r 02]
PCLMULHQHQDQ xmmreg,xmmrm [rm: 66 0f 3a 44 /r 03]
PCLMULQDQ xmmreg,xmmrm,imm [rmi: 66 0f 3a 44 /r ib]

CPUs with CLMUL instruction set

• Intel
  Intel Corporation
  Intel Corporation is an American multinational semiconductor chip maker corporation headquartered in Santa Clara, California, United States and the world's largest semiconductor chip maker, based on revenue. It is the inventor of the x86 series of microprocessors, the processors found in most...
  
  
  • Westmere processor, March 2010.
• AMD
  Advanced Micro Devices
  Advanced Micro Devices, Inc. or AMD is an American multinational semiconductor company based in Sunnyvale, California, that develops computer processors and related technologies for commercial and consumer markets...
  
  :
  • Bulldozer
    Bulldozer (processor)
    Bulldozer is the codename Advanced Micro Devices has given to one of the next-generation CPU cores after the K10 microarchitecture for the company's M-SPACE design methodology, with the core specifically aimed at 10-watt to 125-watt TDP computing products. Bulldozer is a completely new design...
    
     processor, 2011.

See also

• Finite field arithmetic
  Finite field arithmetic
  Arithmetic in a finite field is different from standard integer arithmetic. There are a limited number of elements in the finite field; all operations performed in the finite field result in an element within that field....
  
  
• AES instruction set
  AES instruction set
  Advanced Encryption Standard Instruction Set is an extension to the x86 instruction set architecture for microprocessors from Intel and AMD proposed by Intel in March 2008...
  
  
• FMA3 instruction set
• FMA4 instruction set
• AVX instruction set
  Advanced Vector Extensions
  Advanced Vector Extensions is an extension to the x86 instruction set architecture for microprocessors from Intel and AMD proposed by Intel in March 2008 and first supported by Intel with the Westmere processor shipping in Q1 2011 and now by AMD with the Bulldozer processor shipping in Q3 2011.AVX...
  
  
• X86