ARIA (cipher)

ARIA is a block cipher designed in 2003 by a large group of South Korean researchers, and in 2004 the Korean Agency for Technology and Standards selected it as a standard cryptographic technique. It uses a substitution-permutation network based on AES and shares AES's interface, a 128-bit block with keys of 128, 192 or 256 bits and 12, 14 or 16 rounds depending on key size. ARIA uses two 8 by 8 bit S-boxes and their inverses in alternate rounds, one of which is the Rijndael S-box. Its key schedule runs the key through a three-round 256-bit Feistel cipher, taking the binary expansion of 1/pi as a source of nothing-up-my-sleeve numbers. The cipher is specified in KS X 1213:2004 and described in IETF RFC 5794, with TLS cipher suites in RFC 6209 and use with the Secure Real-Time Transport Protocol in RFC 8269.