From: "MartinBosslet (Martin Bosslet)" <Martin.Bosslet@...>
Date: 2012-09-05T05:46:41+09:00
Subject: [ruby-core:47428] [ruby-trunk - Feature #6980][Assigned] OpenSSL support for AEAD additional authenticated data and tags


Issue #6980 has been updated by MartinBosslet (Martin Bosslet).

Status changed from Open to Assigned
Assignee set to MartinBosslet (Martin Bosslet)
Target version changed from 1.9.3 to 2.0.0


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Feature #6980: OpenSSL support for AEAD additional authenticated data and tags
https://bugs.ruby-lang.org/issues/6980#change-29179

Author: stouset (Stephen Touset)
Status: Assigned
Priority: Normal
Assignee: MartinBosslet (Martin Bosslet)
Category: ext
Target version: 2.0.0


=begin
I've added support to OpenSSL::Cipher to support AEAD modes of operation. AEAD modes allow for plaintext additional authentication data to be combined with a ciphertext to generate a "tag" (e.g., a MAC). This tag can then be verified during decryption to ensure the secret key, nonce (IV), additional authentication data, ciphertext, and tag have not been changed or manipulated.

Usage can be inferred through documentation and tests.

  
 cipher = OpenSSL::Cipher.new('aes-256-gcm')
 cipher.encrypt
 cipher.key = 'key'
 cipher.iv = 'iv'
 cipher.aad = 'aad'
  
 ct = cipher.update('plain')
 tag = cipher.gcm_tag
 
 cipher.reset
 cipher.decrypt
 cipher.key = 'key'
 cipher.iv = 'iv'
 cipher.gcm_tag = 'tag'
 cipher.aad = 'aad'

 cipher.update(ct) + cipher.verify + cipher.final # => 'plain'

 cipher.reset
 cipher.decrypt
 cipher.key = 'key'
 cipher.iv = 'iv'
 cipher.gcm_tag = 'tag'
 cipher.aad = 'aad'

 cipher.update(ct[0..-2] << ct[-1].succ) + cipher.verify + cipherfinal # => OpenSSL::Cipher::CipherError
=end


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