Patent ID: 8861721

Claim:
A method for securing elliptic curve scalar multiplication of a private key k with a point P against simple power attacks using a cryptographic device, comprising the steps of: establishing buffer memory; precomputing a plurality of points Q[i] on an elliptic curve, wherein i is an integer; partitioning the private key k into m bits, wherein m is an integer, such that k=(k m−1 , . . . , k 0 ); for each of the partitions, for i=0 to m−1, and if k i =1, performing scalar multiplication as: saving Q[1] in the buffer memory; if the buffer memory is full or i=m−1, then, while the buffer memory is not empty, updating Q[0] by adding Q[0] with a point from the buffer memory; and updating the buffer memory by removing the added point from step (e); updating Q[1] by point doubling of Q[1]; setting a scalar product kP equal to Q[0]; and displaying the scalar product kP.