How many possible encryption keys are there for a Hill cipher using a 2x2 matrix over Z26 Note A matrix is invertible modulo 26

Question

How many possible encryption keys are there for a Hill cipher using a 2x2 matrix over Z26 Note A matrix is invertible modulo 26 if and only if it is invertible both modulo 13 and modulo 2 Please show detailed steps oh how you obtained the result

Kunduz · Accepted Answer

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