Feistel 1.0.6

Feistel 1.0.6

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Maintained by William Vabrinskas.

Feistel 1.0.6

  • By
  • William Vabrinskas

Swift Feistel Cipher

My attempt at implementing a Feistel Cipher completely in Swift

Background

"In cryptography, a Feistel cipher is a symmetric structure used in the construction of block ciphers, named after the German-born physicist and cryptographer Horst Feistel who did pioneering research while working for IBM (USA); it is also commonly known as a Feistel network. A large proportion of block ciphers use the scheme, including the Data Encryption Standard (DES). The Feistel structure has the advantage that encryption and decryption operations are very similar, even identical in some cases, requiring only a reversal of the key schedule. Therefore, the size of the code or circuitry required to implement such a cipher is nearly halved." (Wikipedia)

Installation

  • Add to your podfile pod 'Feistel'

Usage

  1. Create a Feistel object using the shared property.
    • let fest = Feistel.shared
  2. Set the number of passes you would like to take for both decrpyt and encrypt. It defaults to 5.
    • fest.passes = 10
  3. Optionally set the input keys you would like to use in the encryption and decryption.
    • fest.inputKeys = ["key1", "key2", "key3", "key4"]
    • NOTE: when setting input keys the number of passes will be set to the number of input keys
  4. Create the Data object you would like to encrypt.
    • let data = "super duper awesome test".data(using: .utf8)
  5. To encrypt:
    • let encrypted = fest.encrypt(data: data)
  6. To decrypt (using already encrypted data):
    • let decrypt = fest.decrypt(data: encrypted)
  7. The keys used in the cipher are unique per instance session. You can retrieve the keys used in the cipher by calling:
    • fest.keys()

Resources