Polynomial Basis - Inversion

Inversion

Inversion of elements can be accomplished in many ways, including:

• Lookup tables — once again, only for small fields otherwise the table is too large for implementation
• Subfield inversion — by solving systems of equations in subfields
• Repeated square and multiply — for example in GF(2m), A−1 = A2m − 2
• The Extended Euclidean algorithm
• The Itoh-Tsujii inversion algorithm