KEY LADDER APPARATUS AND METHOD

摘要

In one embodiment a method, apparatus and system for is described for receiving a first input including a first decryption key and a second input including an encrypted second decryption key at a cryptographic decryption apparatus, the encrypted second decryption key to be decrypted by the cryptographic apparatus according to the first decryption key, storing a value of a key ladder length in a first register by a cryptographic processor, and using the stored value as a loop index by the cryptographic processor for a number of iterations of the cryptographic decryption apparatus executed as a loop, wherein at one stage in the loop execution of the cryptographic decryption apparatus, the second input includes the key ladder length, wherein the loop operation of the cryptographic decryption apparatus operates for a number of iterations equal to an initial value of the loop index. Related methods, apparatuses and systems are also described.

主权项

1. A method comprising:
receiving a first input comprising a first decryption key and a second input comprising an encrypted second decryption key at a cryptographic decryption apparatus, wherein the encrypted second decryption key is to be decrypted by the cryptographic decryption apparatus according to the first decryption key; storing a value of a key ladder length in a first register by a cryptographic processor; and using the stored value as a loop index by the cryptographic processor for a number of iterations of the cryptographic decryption apparatus executed as a loop, wherein at one stage in execution of the loop of the cryptographic decryption apparatus, the second input comprises the key ladder length, wherein the execution of the loop of the cryptographic decryption apparatus operates for the number of iterations equal to an initial value of the loop index.