Patent ID: 7016929

Claim:
A method for encrypting including calculating a result E of an exponentiation B d , B being a base and d being an exponent, wherein the exponent can be described by a binary number from a plurality of bits, comprising the following steps: initializing a first auxiliary quantity X to a value of 1; initializing a second auxiliary quantity Y to the base B; sequentially processing the bits of the exponent by: first updating the first auxiliary quantity X by X 2 or by a value derived from X 2 and updating the second auxiliary quantity Y by X*Y or by a value derived from X*Y, if a bit of the exponent equals 0, or second updating the first auxiliary quantity X by X*Y or by a value derived from X*Y and updating the second auxiliary quantity Y by Y 2 or by a value derived from Y 2 , if a bit of the exponent equals 1; and after sequentially processing all the bits of the exponent, using the value of the first auxiliary quantity X as the result of the exponentiation in order to secure data transmission.