This document specifies three block ciphers suitable for applications requiring lightweight cryptographic implementations: — PRESENT: a lightweight block cipher with a block size of 64 bits and a key size of 80 or 128 bits; — CLEFIA: a lightweight block cipher with a block size of 128 bits and a key size of 128, 192 or 256 bits; — LEA: a lightweight block cipher with a block size of 128 bits and a key size of 128, 192 or 256 bits.