JR/T 0055.4-2009Technical specifications on bankcard interoperability - Part 4: Data secure transmission control (English PDF)

3.1 personal identification number (PIN)

i.e., personal password; the data information that identifies the legitimacy of

cardholder in online transaction

3.2 message authentication code (MAC)

the data used to validate the source and content of information between sender

and receiver

b) encryption/decryption of key generation, storage, destruction and

transaction information shall be performed in hardware cryptographic

equipment;

c) it shall comply with national standards and international standards related

to data security;

d) it shall strengthen the management requirements for operator;

e) the key shall be changed regularly.

4.1.1 Basic requirements of data secure transmission control

The data secure transmission control requirements shall include, but not limited

to, the following four aspects.

a) key management mechanism. technically implement strict and reliable key

distribution process;

b) encryption-decryption and conversion mechanism of personal

identification number (PIN). PIN plain code is not allowed to appear on

communication line and on manually operable storage media;

c) all agencies shall use hardware encryption;

d) peer-to-peer data encryption and decryption network mechanism.

4.1.2 Basic requirements of hardware encryption machine

The main function of the hardware encryption machine is to encrypt and decrypt

PIN, to verify the correctness of the message source and to store the key. All of

these operations shall be completed in a hardware encryption machine to

ensure that the key and PIN plain code only appear in the encryption machine

to prevent the disclosure of key and PIN. The hardware encryption machine

shall pass the national commercial password department safety certification. In

addition, it shall also meet the following requirements.

a) support single-length (B64, used in single-length key algorithm) and

double-length (B128, used in double-length key algorithm) keys;

b) support the provisions of this Part on PIN, the ciphertext of PIN verification,

conversion;

c) support the provisions of this Part on MAC, verify and generate MAC;

d) verify the key;

e) in the event of an unlawful attack, the cryptographic key is automatically

destroyed.

Then PIN data block shall be. 0x06 0x12 0x34 0x56 0xFF 0xFF 0xFF 0xFF

Exclusive OR. 0x00 0x00 0x67 0x89 0x01 0x23 0x45 0x67

Result. 0x06 0x12 0x53 0xDF 0xFE 0xDC 0xBA 0x98

5.4 Encryption and decryption of PIN

Input the PIN data block generated in 5.3 into the hardware encryption machine.

Then use double length key algorithm to calculate it and PIK that is stored in

the hardware encryption machine. Then the PIN ciphertext shall be obtained.

When a message arrives at an inter-bank transaction network, the PIN has

been encrypted by the recipient's PIK. The switching center decrypts the

ciphertext of the PIN with the PIK of the recipient. After the issuer's PIK is

encrypted, it shall be sent to the issuer.

6.1 Conditions for MAC use

MAC is usually used for request message of 01XX, 02XX, 04XX types as well

as successful replay messages of 01XX, 02XX, 04XX (reply code category

means "approved"). The parties involved in the transaction may agree whether

to use the MAC during the online transaction.

6.2 MAC composition rules

6.2.1 Selection of message field

The information involved in forming a MAC data block generally includes the

following message fields.

- data field with uniqueness (such as the system tracking number,

transaction transmission date and time, etc.);

- data field representing message characteristics (message type,

transaction treatment code, service point condition code, etc.);

- transaction related data field (main account, transaction amount, reply

code, acquirer identification code, receiver identification code, etc.).

Message fields involved in MAC calculation in all types of transactions are

agreed upon by the parties involved in the transaction based on the above

principles.

6.2.2 Selection of MAC character

The selected message field used for the composition of MAC data block shall

MAC value agreed by each party. And compare with this MAC value and the

MAC value in the message. If the comparison results are consistent, the

message shall be correct and acceptable, otherwise the message shall be

unreliable and shall be rejected.

6.3.2 Reset key transaction

For the request of resetting key transaction and reply message, the switching

center and the agency shall use the new issued key to calculate MAC. When

resetting PIN key, the MAC calculation shall also use the new issued PIN key.

The MAC field (field 128) in the request message is the combination (8-byte

binary number) that consists of the first half (4-byte binary number) of 8 bytes

of binary data obtained by MAC calculation in single-length key algorithm and

the first half of (4-byte binary number) of 8 bytes of binary data obtained by

check value calculation in single-length key algorithm.

The MAC calculation method of reply message is same with the ordinary

transaction described in 6.3.1. It is unnecessary to calculate the check value

but the key it uses shall still be the new issued key.

The check value is calculated by using a new key for 8-byte binary "0" as a

single-length key.

However, it shall be noted that the MAC value of the reset key message sent

by the switching center is encrypted with the new key value in the message.

Therefore, when the double-length PIK is reset, the MAC of this message shall

be encrypted in double-length key algorithm. This is a special case of MAC

encryption. In the same way, the check value contained in the request message

shall be calculated in double-length key algorithm. The processes of MAC

calculation and check value calculation are identical with the process described

in 6.3.1, i.e., perform the double-length key operation first, then make exclusive

OR to the operation result with the next group of 8-byte MAB. Use the result to

replace the next group of MAB. The rest may be inferred till the last group

completes the double-length key operation.