The Lightweight Encryption Algorithm (also known as LEA) is a 128-bit block cipher developed by South Korea in 2013 to provide confidentiality in high-speed environments such as big data and cloud computing, as well as lightweight environments such as IoT devices and mobile devices.

[1] LEA has three different key lengths: 128, 192, and 256 bits.

LEA encrypts data about 1.5 to 2 times faster than AES, the most widely used block cipher in various software environments.

LEA is one of the cryptographic algorithms approved by the Korean Cryptographic Module Validation Program (KCMVP) and is the national standard of Republic of Korea (KS X 3246).

LEA is included in the ISO/IEC 29192-2:2019 standard (Information security - Lightweight cryptography - Part 2: Block ciphers).

The block cipher LEA consisting of ARX operations (modular Addition:

) for 32-bit words processes data blocks of 128 bits and has three different key lengths: 128, 192, and 256 bits.

is the number of rounds for the LEA algorithm.

The encryption operation is described as follows: The decryption operation is as follows: The key schedule of LEA supports 128, 192, and 256-bit keys and outputs 192-bit round keys

) for the data processing part.

) as inputs and outputs twenty-four 192-bit round keys

The key schedule operation for LEA-128 is as follows: Let

) as inputs and outputs twenty-eight 192-bit round keys

The key schedule operation for LEA-192 is as follows: Let

) as inputs and outputs thirty-two 192-bit round keys

The key schedule operation for LEA-256 is as follows: The eight 32-bit constant values

) used in the key schedule are given in the following table.

As of 2019, no successful attack on full-round LEA is known.

As is typical for iterated block ciphers, reduced-round variants have been attacked.

The security margin to the whole rounds ratio is greater than 37% against various existing cryptanalytic techniques for block ciphers.

LEA has very good performance in a general-purpose software environment.

In particular, it is possible to encrypt at a rate of about 1.5 to 2 times on average, compared to AES, the most widely used block cipher in various software environments.

The tables below compare the performance of LEA and AES using FELICS (Fair Evaluation of Lightweight Cryptographic Systems),[3] a benchmarking framework for evaluation of software implementations of lightweight cryptographic primitives.

Test vectors for LEA for each key length are as follows.

[5] All values are expressed in hexadecimal form.

LEA is free for any use: public or private, commercial or non-commercial.

The source code for distribution of LEA implemented in C, Java, and Python can be downloaded from KISA's website.

[6] In addition, LEA is contained in Crypto++ library, a free C++ class library of cryptographic schemes.

[7] LEA is one of the cryptographic algorithms approved by the Korean Cryptographic Module Validation Program (KCMVP).

[8] LEA is included in the following standards.