Integrated circuit for the authentication of a consumable storage device

• US 20090013178A9
• Filed: 03/04/2004
• Published: 01/08/2009
• Est. Priority Date: 07/15/1997
• Status: Abandoned Application

• Current Assignee: Zamtec Limited (Memjet Limited)
• Original Assignee: Zamtec Limited (Memjet Limited)
• Inventors: Silverbrook, Kia
• Application Number:
  US10/791,792
• Publication Number:
  US 20040172532A1
• Time in Patent Office: Days
• US Class Current: 713/161
• CPC Class Codes: G06F 21/31 User authentication
• CPC Class Codes: G06F 21/77 in smart cards
• CPC Class Codes: G06F 2221/2103 Challenge-response
• CPC Class Codes: G06F 2221/2129 Authenticate client device independently of the user
• CPC Class Codes: G06F 2221/2143 Clearing memory, e.g. to prevent the data from being stolen
• CPC Class Codes: H04L 2209/043 of tables, e.g. lookup, substitution or mapping
• CPC Class Codes: H04L 2209/08 Randomization, e.g. dummy operations or using noise
• CPC Class Codes: H04L 9/002 Countermeasures against attacks on cryptographic mechanisms network architectures or network communication protocols for protection against malicious traffic H04L63/1441
• CPC Class Codes: H04L 9/3218 using proof of knowledge, e.g. Fiat-Shamir, GQ, Schnorr, ornon-interactive zero-knowledge proofs
• CPC Class Codes: H04L 9/3242 involving keyed hash functions, e.g. message authentication codes [MACs], CBC-MAC or HMAC
• CPC Class Codes: H04L 9/3271 using challenge-response

Abstract

An integrated circuit for the authentication of a consumable storage device by an apparatus includes a memory space which contains encrypted data defined by a message authentication code (MAC) applied to data relating to a consumable stored by the device and by at least one secret key (K) shared by the apparatus for decryption of the data. The MAC is a construction of a cryptographic function.

Claims

1. An integrated circuit for the authentication of a consumable storage device by an apparatus, the integrated circuit comprising a memory space which contains encrypted data defined by a message authentication code (MAC) applied to data relating to a consumable stored by the device and by at least one secret key (K) shared by the apparatus for decryption of the data, the MAC being a construction of a cryptographic function.

2. An integrated circuit as claimed in claim 1, in which the cryptographic function is a hash function such that the MAC is an algorithm known as HMAC.

3. An integrated circuit as claimed in claim 2 in which the hash function is one of an MD5 function and a SHA-1 function.

4. An integrated circuit as claimed in claim 2, in which the hash function is an SHA-1 function.

5. An integrated circuit as claimed in claim 4, which is configured to define a number of temporary registers and rotating counters and to calculate an output word on an iterative basis by calculating and allocating words to respective registers during processing of the SHA-1 function.

6. An integrated circuit as claimed in claim 1, in which the memory space of the integrated circuit includes two secret keys, K₁ and K₂, the integrated circuit being configured to that the key K₁ is used to decrypt an encrypted random number generated by the apparatus and the key K₂ is used to decrypt encrypted data stored in the memory space.

7. A method of encrypting data relating to a consumable of a consumable storage device for an apparatus and stored by an integrated circuit, the method including the steps of:

applying a message authentication code (MAC) to the data using at least one secret key shared by the apparatus to decrypt the data, the MAC being a construction of a cryptographic function.