EMV: Integrated Circuit Card Specifications for Payment...

EMV: Integrated Circuit Card Specificationsfor Payment Systems

Jan Krhovjak

Faculty of Informatics, Masaryk University

Jan Krhovjak (FI MU) EMV (Europay, MasterCard, Visa) 20. 3. 2006 1 / 13

EMV Basic Information

Outline

Introduction to EMV

Offline data authenticationI Static data authenticationI Dynamic data authentication

User authenticationI Signature basedI PIN based

Automatic risk managementI Terminal risk managementI Terminal action analysisI Card action analysis

Conclusion



Introduction to EMV

EMV 4.1 specifications consist of four books (786 pages)I Application Independent ICC to Terminal Interface RequirementsI Security and Key ManagementI Application SpecificationI Cardholder, Attendant, and Acquirer Interface Requirements

Basic terminologyI Merchant, payeeI Cardholder, customer, payer, or simply userI Card issuer, cardholder’s bank, or simply bank

F No distinguishing (for this presentation) between issuer or acquirer bank

I Fraud, a deception made for a personal gainF All parties should be protected against the fraudF Unauthorized and illegal use of a credit card to purchase property

I ICC, an acronym for integrated circuit(s) card



Introduction to EMV

EMV 4.1 specifications consist of four books (786 pages)I Application Independent ICC to Terminal Interface RequirementsI Security and Key ManagementI Application SpecificationI Cardholder, Attendant, and Acquirer Interface Requirements

Basic terminologyI Merchant, payeeI Cardholder, customer, payer, or simply userI Card issuer, cardholder’s bank, or simply bank

F No distinguishing (for this presentation) between issuer or acquirer bank

I Fraud, a deception made for a personal gainF All parties should be protected against the fraudF Unauthorized and illegal use of a credit card to purchase property

I ICC, an acronym for integrated circuit(s) card


EMV Offline Data Authentication

Basic Principles of Offline Data Authentication

The goal is offline detection of fake (altered/duplicated) cardsI Based on asymmetric cryptography (namely on RSA)

F RSA public key must be always 3 or 216 − 1

I Existence of a certification authority (CA) is requiredF Integrity of transmitted public keys must be secured

I Each EMV terminal must contain actual CA public key

Supported mechanismsI Static data authentication (SDA)I Dynamic data authentication (DDA)I Combined DDA and application cryptogram generation (CDA)



Basic Principles of Offline Data Authentication

The goal is offline detection of fake (altered/duplicated) cardsI Based on asymmetric cryptography (namely on RSA)

F RSA public key must be always 3 or 216 − 1

I Existence of a certification authority (CA) is requiredF Integrity of transmitted public keys must be secured

I Each EMV terminal must contain actual CA public key

Supported mechanismsI Static data authentication (SDA)I Dynamic data authentication (DDA)I Combined DDA and application cryptogram generation (CDA)



SDA: Static Data Authentication I

Basics of SDAI Performed by terminalI Confirms legitimacy of critical ICC-resident static dataI Detects unauthorized alteration of data after personalization

Settings and process of SDAI Public key of CA is stored in each terminalI Public key of issuer bank is certified by CA and stored on ICCI Static application data are signed by issuer bank and stored on ICC

Security of SDAI Based on secrecy of private RSA keysI Counterfeiting/duplication not solved















SDA: Static Data Authentication II

Diagram of SDA (taken from the original specification)



DDA: Dynamic Data Authentication I

Basics of DDAI Performed by terminal&card (ICC with coprocessor required)I Confirms legitimacy of critical ICC-resident/generated data and data

received from terminalI Detects counterfeited/duplicated cards

Settings and process of DDAI Similar as for SDAI New unique ICC RSA key pair is stored on each card

F ICC private key is securely stored (can not leave the card)F ICC public key is signed & stored together with static application data

I Terminal sends random challenge to be signed by ICC private key

Security of DDAI Based on secrecy of private RSA keysI The chip card must be able to protect ICC private key





















DDA: Dynamic Data Authentication II

Diagram of DDA (taken from the original specification)



CDA: Combined DDA and Application Cryptogram (AC)Generation

Basics of CDAI Performed by terminal&card in parallel with card action analysis

Settings and process of CDAI Similar as for DDAI Random challenge is a part of request for ACI Signed AC contains this random challenge

Security of CDAI Extra security for ACI Advantage if secure communication between terminal and ICC

can not be guaranteed
















EMV User Authentication

Negotiation of authentication method

Supported methodsI Signature-based (handwritten)I PIN-based (offline/online, plaintext/encrypted)I Several combinations

Priority list of card-supported methods stored on ICCI Terminal selects the first terminal-supported method from this list

F Selected method is dependent on the terminal typeF One supported method can be ”no cardholder verification required”

I Successful verificationF At least one metod is successfully performedF The list is exhausted



Negotiation of authentication method

Supported methodsI Signature-based (handwritten)I PIN-based (offline/online, plaintext/encrypted)I Several combinations

Priority list of card-supported methods stored on ICCI Terminal selects the first terminal-supported method from this list

F Selected method is dependent on the terminal typeF One supported method can be ”no cardholder verification required”

I Successful verificationF At least one metod is successfully performedF The list is exhausted



Verification processing

Signature-based or online PIN-based authenticationI Same process as used in the case of magnetic strip cards

F PIN is formatted into PIN-block, encrypted by using 3DES, . . .

I Chip card should provide extra security against skimming

Offline encrypted PIN-based authenticationI New own RSA key pair is associated with PIN enciphermentI This key pair is stored/certified as the key for DDAI Original PIN necessary for verification is securely stored on ICCI PINpad/terminal must be physically/logically well secured



Verification processing

Signature-based or online PIN-based authenticationI Same process as used in the case of magnetic strip cards

F PIN is formatted into PIN-block, encrypted by using 3DES, . . .

I Chip card should provide extra security against skimming

Offline encrypted PIN-based authenticationI New own RSA key pair is associated with PIN enciphermentI This key pair is stored/certified as the key for DDAI Original PIN necessary for verification is securely stored on ICCI PINpad/terminal must be physically/logically well secured


EMV Automatic Risk Management

Automatic Risk Management

Protects against offline undetectable threatsI Decides if transaction should be:

approved offline, declined offline, or transmitted online

Terminal risk managementI Floor limit checkingI Random transaction selectionI Velocity checking

Terminal&card action analysisI T: reject transaction offline ⇒

C: reject offlineI T: transaction should go online ⇒

C: go online ∨ reject offlineI T: transaction might be completed offline ⇒

C: go online ∨ reject offline ∨ approve offline






















Conclusion

Conclusion & References

EMV introduces the Chip&PIN technologyI Chip cards provide more secured storage for sensitive data

F If SDA is not used ...

I PIN-based user authentication is more secure (for whom?)F If the secure method is negotiated ...

Several online references:I EMV 4.1 Specifications

http://www.emvco.com/cgi bin/detailspec.pl?id=5I EMV POS terminal interceptor

http://www.cl.cam.ac.uk/˜mkb23/interceptor/I Chip and SPIN webpage http://www.chipandspin.co.uk/ and article

http://www.cl.cam.ac.uk/˜mkb23/spin/spin.pdf


Conclusion

Conclusion & References

EMV introduces the Chip&PIN technologyI Chip cards provide more secured storage for sensitive data

F If SDA is not used ...

I PIN-based user authentication is more secure (for whom?)F If the secure method is negotiated ...

Several online references:I EMV 4.1 Specifications

http://www.emvco.com/cgi bin/detailspec.pl?id=5I EMV POS terminal interceptor

http://www.cl.cam.ac.uk/˜mkb23/interceptor/I Chip and SPIN webpage http://www.chipandspin.co.uk/ and article

http://www.cl.cam.ac.uk/˜mkb23/spin/spin.pdf


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