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Does any know the difference between triple des dukpt decryption algorithm with PIN variant and Data variant?

I have done Triple DES DUKPT PIN variant, which generate session key from KSN and BDK. And then decrypt message using the session key.

How about Data variant? How is it different from PIn variant?

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BDK and KSN are used to derive a transaction key which is unique for that session. The are unique because KSN is updated after each transaction. Once this key is derived you apply different variants to get PIN, Data or MAC key.

For the PIN and MAC key: these variants are simply XORed with derived key. One more encryption is performed to calculate the data encryption key after applying variant.

These variants are fixed; you can refer to X9.24 Retail Financial Services Symmetric Key Management for more information.

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  • $\begingroup$ Hi Devesh, welcome and of course thanks for the answer. Please reread your question and separate the different sections of the answer using double enter. Could you quickly review the changes I made? $\endgroup$ – Maarten - reinstate Monica Aug 23 '15 at 16:48
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I learned about PIN variant from this online blog....

https://www.parthenonsoftware.com/blog/how-to-decrypt-magnetic-stripe-scanner-data-with-dukpt/

BDK and KSN are used to derive a transaction key which is unique for that session. The are unique because KSN is updated after each transaction. Once this key is derived you apply different variants to get PIN, Data or MAC key.

I’m not sure what you mean by Transaction key, but if you mean the session Key or IPEK (Initial Pin Encryption Key)…

For the PIN and MAC key: these variants are simply XORed with derived key. One more encryption is performed to calculate the data encryption key after applying variant.

These variants are fixed; you can refer to X9.24 Retail Financial Services Symmetric Key Management for more information.

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  • $\begingroup$ I believe what the other answer means is literally DUKPT: Derived Unique Key Per Transaction. $\endgroup$ – Andrew T. Nov 25 at 4:53

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