https://github.com/spider-gazelle/cmac

Crystal implementation of the Cipher-based Message Authentication Code (CMAC)
https://github.com/spider-gazelle/cmac

Last synced: 9 days ago
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Crystal implementation of the Cipher-based Message Authentication Code (CMAC)

• Host: GitHub
• URL: https://github.com/spider-gazelle/cmac
• Owner: spider-gazelle
• License: mit
• Created: 2019-12-14T11:34:58.000Z (almost 5 years ago)
• Default Branch: master
• Last Pushed: 2023-10-16T06:54:10.000Z (about 1 year ago)
• Last Synced: 2024-08-01T17:33:08.088Z (3 months ago)
• Language: Crystal
• Size: 7.81 KB
• Stars: 5
• Watchers: 4
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-crystal - cmac - Crystal implementation of Cipher-based Message Authentication Code (CMAC) (Cryptography)
• awesome-crystal - cmac - Crystal implementation of Cipher-based Message Authentication Code (CMAC) (Cryptography)

README

        
# Crystal Lang CMAC

[![CI](https://github.com/spider-gazelle/cmac/actions/workflows/ci.yml/badge.svg)](https://github.com/spider-gazelle/cmac/actions/workflows/ci.yml)

Crystal implementation of the Cipher-based Message Authentication Code (CMAC) as defined in [RFC4493](http://tools.ietf.org/html/rfc4493), [RFC4494](http://tools.ietf.org/html/rfc4494), and [RFC4615](http://tools.ietf.org/html/rfc4615). Message authentication codes provide integrity protection of data given that two parties share a secret key.

```crystal

key = Random.new.random_bytes(16)

message = "attack at dawn"

cmac = CMAC.new(key)

cmac.sign(message)

 => Bytes[246, 184, 193, 76, 93, 115, 191, 26, 135, 60, 164, 161, 90, 224, 102, 170]

```

Once you've obtained the signature (also called a tag) of a message you can use CMAC to verify it as well.

```crystal

tag = Bytes[246, 184, 193, 76, 93, 115, 191, 26, 135, 60, 164, 161, 90, 224, 102, 170]

cmac.valid_message?(tag, message)

 => true

cmac.valid_message?(tag, "attack at dusk")

 => false

```

CMAC can also be used with a variable length input key as described in RFC4615.

```crystal

key = "setec astronomy"

message = "attack at dawn"

cmac = CMAC.new(key)

cmac.sign(message)

 => Bytes[92, 17, 144, 230, 145, 178, 196, 130, 96, 144, 166, 236, 58, 14, 28, 243]

```