摘要 |
A method of cryptographically processing a digital quantity, e.g. a message, using an asymmetric cryptographic protocol involving a private key including a secret exponent, in a manner resistant to external detection of the secret exponent, includes the step of transforming the exponent to an expanded representation thereof, the expanded representation including a sequence of symbols with each symbol representing a respective modular multiplication operation. An accumulator is loaded with a positive integer power of the digital quantity, and for each symbol in at least a portion of the expanded representation the value in the accumulator is multiplied, modulo the modulus, by a positive integer power of the digital quantity, the integer power being indicated by the symbol, and the result of the multiplication is used to update the accumulator. |