 ai)) ^ (EK2(n)
ai)) ^ (EK2(n)
 ai)
 ai)|  | denotes multiplication of two polynomials over the binary field GF(2) modulo x128+x7+x2+x+1 | 
| K1 | is the encryption key (256-bit for each supported cipher; i.e, AES, Serpent, and Twofish) | 
| K2 | is the secondary key (256-bit for each supported cipher; i.e, AES, Serpent, and Twofish) | 
| i | is the cipher block index within a data unit; for the first cipher block within a data unit, i = 0 | 
| n | is the data unit index within the scope of K1; for the first data unit, n = 0 | 
| a | is a primitive element of Galois Field (2128) that corresponds to polynomial x (i.e., 2) | 
| Note: The remaining symbols are defined in the section Notation. | |