AS 2805.6.4-2006 pdf download.Electronic funds transfer— Requirements for interfaces
Part 6.4: Key management—Session keys—Terminal to acquirer.
5.1.2 Buck track prL’VL’nhion
The scheme prevents back Lracking of key enciphering key and PIN enciphering key changes and hence prevents hack tracking of transactions prior to the last update of the keys.
5.1.3 Diffrrtns keys for each funciso,,
The scheme provides different keys for each of the following functions:
(a) Key enciphering.
(b) PIN enciphering.
(c) Message authentication code generation.
(d) Message authentication code erifieation.
(e) Send data enciphering.
(1) Receive data enciphering.
5.2 Initialization
This scheme depends on each terminal in the network being initialized with sonie secret information that is only known by the terminal and acquirer. This information is the initial key KI (KlAn for a multi acquirer terminal) and is statistically unique to each terminal-to- acquirer connection.
For terminal to acquirer connections, all keys are [WA 3 keys. KEKs are derived; session keys are dynamically created by the acquirer in such a way as to ensure statistical uniqueness and to prevent the ability to forecast any key. The session keys are transmitted by the acquirer to the terminal enciphered the appropriate KEK (using CRC mode in accordance with AS 2805.6.1).
5.3 Key hierarchy and management
For the terminal to acquirer connections, all keys are I)EA 3 keys and arc dynamically created by the acquirer in such a way as to ensure statistical uniqueness and to prevent the ability to forecast any key. The keys are transmitted by the acquirer to the terminal enciphered under the appropriate KEK (using CRC mode in accordance with AS 2805.6.1).
The following minimum key hierarchy is maintained:
(a) Level 1: Key enciphering keys (KEKI and KEK2i Each KEK is statistically unique to each terminal to acquirer connection and is not accessible as plain text. KFKI is used to encipher the level 2 keys to enable secure transmission of the keys from acquirer to terminal. KEK2 is used to generate a new KEKI and KEK2 pair if the terminal to acquirer COnnection requires rcsynchronization.
5.4 Proofof end points
‘Proof of end points’ is a concept relating to a process that is used to authenticate one end to the other end of a terminal to acquirer connection.
For each terminal 10 acquirer connection, each end of the link proves the other end by its ability to perform the cryptographic functions to update the key enciphering keys. This depends on the secrecy of KEKI. KF.K2, and the PPASN for each terminal to acquirer connect ion.
6 I)FSCRIPTION OF FLNCTIONAI. FLEMINTS
6.1 PIN pad identification numbers (PPID)
The value is normally set by the PIN pad manufacturer and is accessible in the clear.
6.2 Acquirer PIN pad security number (PPASN)
This value is secret and is generated and securely loaded by the acquirer along with KEKI
and KEK2. PPASN is used for changing these keys.
6.3 Key enciphering key pair (KEKI and KEK2)
6.3.1 (,e,iercil
The terminal maintains two key encrypting keys for each acquirer with which it is required to communicate. These are known as KEKI and KEK2.
6.3.2 KEK esiahlish,ne,ii
After initialization, each acquirer shall establish an initial KEK 1 and KEK2 key pair and a
I’PASN.
6.3.3 KEK1 and KEK2 updates
Before each use. the KEKI and KEK2 shall be updated using the appropriate KEK update algorithm described in the following clauses. The inputs to the key enciphering key update algorithms shall be the PPASN and the existing terminal key enciphering keys.
6.3.4 Algorithm KEK) update
KEK I shall be updated as follows:
(a) Concatenate IPASN with itself to form the temporary value D.
(b) Use the OWF with the existing KEKI as the key and the temporary value [) as the data to produce the new 1 28-bit value of KEK 1.
(c) The new value of KEKI replaces the existing value in storage.AS 2805.6.4-2006 pdf download.Electronic funds transfer— Requirements for interfaces
Electronic funds transfer— Requirements for interfaces
