1. A method for releasing a lock state of a mobile device, comprising: detecting a signature input for releasing the lock state; identifying an input means corresponding to the input; extracting at least one input feature of the input; calculating similarities of each of the at least one input feature by comparing the extracted input feature with an extracted input feature of previously stored signature information; setting weights of each of the at least one input feature, based on the input means; calculating a total similarity, based on the similarities of each of the at least one input feature and the weights; determining whether a verification is successful, based on the total similarity; and releasing the lock state when the verification has succeeded.