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Implements a decrypter for ciphertext originating from a device using a Derived Unique Key Per Transaction (DUKPT) scheme
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Latest commit eb3097b @ryanbalsdon ryanbalsdon Merge pull request #11 from Shopify/feature/online-pin-decryption
Added a decrypt_pin method for ISO 9564 PIN blocks

README.md

DUKPT

This library implements a decrypter for ciphertext originating from a device using a Derived Unique Key Per Transaction (DUKPT) scheme.

Installation

Add this line to your application's Gemfile:

gem 'dukpt'

And then execute:

$ bundle

Or install it yourself as:

$ gem install dukpt

Usage

# Instantiate a decrypter with your base derivation key (BDK)
decrypter = DUKPT::Decrypter.new("0123456789ABCDEFFEDCBA9876543210")

# You can specify whether you want to use "ecb" cipher mode if needed. The default is "cbc".
decrypter = DUKPT::Decrypter.new("0123456789ABCDEFFEDCBA9876543210", "ecb")

# Pass the ciphertext and the current Key Serial Number (KSN), as hex encoded strings, to the decryptor to get back the plaintext
ksn = "FFFF9876543210E00008"
ciphertext = "C25C1D1197D31CAA87285D59A892047426D9182EC11353C051ADD6D0F072A6CB3436560B3071FC1FD11D9F7E74886742D9BEE0CFD1EA1064C213BB55278B2F12"

plaintext = decrypter.decrypt(ciphertext, ksn) # => "%B5452300551227189^HOGAN/PAUL      ^08043210000000725000000?\x00\x00\x00\x00"

Contributing

  1. Fork it
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Added some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create new Pull Request
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