Patent ID: 8311212

Claim:
A data processing method, comprising the following steps: determining a first result data word from a first input data word and a first secret data word by applying a partial modular exponentiation algorithm, wherein the partial modular exponentiation algorithm produces a data word representing a first partial modular exponentiation result; obtaining a first compressed data word from the first result data word using a compression algorithm; applying anew the partial modular exponentiation algorithm, using a second secret data word, to produce a data word representing a second partial modular exponentiation result; determining a second result data word by a calculation including recombination of the first and second partial modular exponentiation results; obtaining a second compressed data word from the second result data word using the compression algorithm; and comparing the first compressed data word and the second compressed data word, wherein, if the first compressed data word is different from the second compressed data word, error is detected in the processing of the first input data word; wherein the aforesaid steps are performed by a data processing device.