Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Transaction Incrementing Message Authentication Key

IP.com Disclosure Number: IPCOM000046186D
Original Publication Date: 1983-Jun-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 3 page(s) / 51K

Publishing Venue

IBM

Related People

Hopkins, WD: AUTHOR

Abstract

Many existing electronic fund transfer or other message systems must identify messages that have been modified, retransmitted or include deletions or insertions. However, because of existing message switching requirements, the message itself must remain in the clear, unencrypted form, and the message format itself does not include fields for time- or transaction-sequence-varying information. It is proposed to provide a message authentication code (MAC) to be appended to the message in order to detect and reject retransmitted or modified messages.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 61% of the total text.

Page 1 of 3

Transaction Incrementing Message Authentication Key

Many existing electronic fund transfer or other message systems must identify messages that have been modified, retransmitted or include deletions or insertions. However, because of existing message switching requirements, the message itself must remain in the clear, unencrypted form, and the message format itself does not include fields for time- or transaction-sequence-varying information.

It is proposed to provide a message authentication code (MAC) to be appended to the message in order to detect and reject retransmitted or modified messages.

The message authentication code is generated using the data encryption algorithm with a key Ki that varies with each message in the following way:

1. Key distribution consists of a starter key K and a 32-bit

randomly chosen sequence T1 .

2. The first transaction sequence is authenticated by

generating a MAC with key K1 = K 0 Ek [T1 T1].

+ - In other

words, T is concatenated with the complement of T, to

obtain a 64-bit value which is encrypted under the starter

key K and then added to the starter key K using a module

two adder.

3. For each succeeding transaction, a new key is generated by

incrementing the sequence T, and generating a new key using

the incremented value.

Ti = f (Ti-1) where f is incremented by "1" funtion

Ki = K 0 Ek [Ti Ti] i = 2, . . .

+ -

4. Resynchronization, if required, is accomplished by using the

previous sequence Ti1 concatenated with the complement of

the second previous sequence as follows:

Ki = K 0 Ek [Ti-1 Ti-2]

+ -

Having generated the key for a transaction, each 64-bit block of the message is...