This is the IDEA library of the SSLeay project. IDEA is a block cipher invented by Xuejia Lai and James Massey in 1991. A block cipher is an encryption algorithm that encrypts the data in blocks. IDEA has a block size of 64 bits, and a keylength of 128 bits. IDEA is a symmetrical algorithm, which means that the same key is used both for encryption and for decryption.