Gareth EllisGareth EllisSenior Solutions ConsultantSenior Solutions Consultant

Session 5a Key and PIN Management

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Agenda

• EMV Key Management - overview • EMV Key Impacts on Issuance• PIN Management

Key Management Overview

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EMV Security Features

• EMV requires secure key management to enable the following functions– Card authentication

•Offline•Online

– Cardholder verification– Issuer authentication– Non-repudiation of transactions– Secure EMV script delivery– Transport of keys between domains

• For this both Triple DES (symmetric) and PKI (asymmetric) are used

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Symmetric keys: how does DES work?

• Single key to both encrypt and decrypt• Key is generated by a mathematical

process• Encryption combines data and key using

a non-secret formula• Key must be kept secret:

– in the chip & in HSMs/Host of issuer– not at acquirers

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EMV Triple DES keys

• Online Transaction Keys - stored in secure portion of memory in the chip and on the Issuing Host– Online authentication keys – Master Key used

to create a card key– Scripting keys

• Transport keys - used to ensure the secure transport of sensitive data during Issuance– Card Manufacturer– Data Preparation– Bureau/Personalisation Machine

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Public Key Infrastructure

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Asymmetric keys: how does PKI work?

• Related pairs of keys – public and private• Keys are generated by a complex

mathematical process• Encryption combines data and key using

a non-secret formula• Decryption is only possible using the

other key of the same pair– one key must be kept secret, the other

one can be public

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How to use of PKI keys in EMV

• Offline Data Authentication Example:1. Load MasterCard EMV Public key on every terminal2. Send card data to MasterCard and they encrypt

card data using the MasterCard EMV Private key3. During a transaction, card sends encrypted card

data to the terminal4. Terminal uses MasterCard public key to decrypt

encrypted data5. Terminal determines the unencrypted card data6. Card passes same card data to terminal7. Terminal compares card data – only MasterCard

could have put that data on the card

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Certification Process for Static Data Authentication

• Use Data prep device to generate Issuer Key pair• Send the Issuer public key to the card scheme• Scheme returns issuer public key signed with the

scheme private key (Issuer Certificate)• These are input into the data prep device and

validated• The issuer certificate is personalised onto each

card

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Enhanced Security on Card (PKI - SDA)

• Static Data Authentication - SDA• Holds:

– A Certificate for the authentication of the issuer (Issuer Public key signed with Card Scheme Private key)

– A static digital signature for card authentication (data signed by Issuer Private key)

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Dynamic Data Authentication - DDA• Holds:

– A Certificate for the authentication of the issuer

– A Certificate for card authentication• Dynamic generation of the digital

Signature for authentication

Enhanced Security on Card (PKI - DDA)

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Combined Dynamic Data Authentication (CDA) and Application Cryptogram Generation

• CDA uses the same authentication operation as for DDA, but also combines the transaction cryptogram in the signature

TransactionInformation

EMV Key Impacts on Issuance

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Magnetic stripe card issuance (key management aspect)

CardIssuer’s

CMS

CardIssuer’s

CMS

PersodomainPerso

domain

Personalisation Data File normally not encrypted (no sensitive data)

Limited number of (symmetric only) secret keys required:• PIN Verification Value (PVV)• Card Verification Value (CVV)

HSMHSM

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ChipDataConv.

ChipDataConv.

HSMHSM

Smart Card

Personalisation

CardIssuer’s

CMS

CardIssuer’s

CMS

ChippersoChipperso HSMHSM

Smart Card

System

Smart Card

System

Smart card issuance (key management aspect)

Storage of (symmetric) master keys and transport keys EMV key data needs to

be secured using HSMs

Storage of transport keys

Need to generate asymmetric keys and certify them

HSMHSM

PrepDevicePrep

Device

Generate Offline Pin & encrypt it under Transport Key

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How to add EMV (crypto) data to Cards?

• Data preparation phase, you can use – Smart Card Management systems– data prep devices or

• These systems– Generate, store and manage keys for each application– Send Public keys to Certificate Authorities – Stores the certificates returned from CAs in a database– Adds the smart card data for each card to Embossing File

• Personalisation – writing EMV data to the card– Can use Smart Card Management Systems or software

from Printer vendors– Need to decrypt secret data from Data Prep and re-

encrypt it to send it to the card– Need to use issuer keys to ‘open’ each card to write to the

chip

EMV Impacts to PIN Management

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Magnetic stripe PIN management

• PIN required for certain transactions– on-line PIN verification using DES, 3-DES

• Offset mechanism for PIN change• PINs are never stored, but re-computed• Issuer system controls PIN on-line

– blocking and unblocking PIN– changing PIN

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EMV PIN management

• Chip contains offline PIN value for offline verification

• Other applications may use same PIN• Without Offline PIN, CAP is not possible• EMV offers scripting mechanism to

(un)block and change the PIN• Implicit and explicit PIN unblock

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Synchronisation issues

• PIN information rests in (at least) 2 places•In authorisation system for online PIN

verification•In PIN generation domain (when

issuing cards)•New: in the chip

• Counting failed PIN attempts• Blocking and unblocking the PINs• Changing the value of the PINs, recovering

from error situations

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Changing PIN in the field

HostHost

1- Change PIN

2 – Update PIN

3 –Response + Script

5 – Reverse Update

ATMATM

CardCard

4 – Script Confirmation - Fail

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PIN Management conclusions

• (Offline) PIN is becoming best practice• PIN change facilities are needed to

remember PINs on many cards• Implementing offline PIN touches many

systems• Probably the hardest part of implementing

Offline PIN is customer education!