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Contents
# frozen_string_literal: true
module Noise
module State
# A CipherState can encrypt and decrypt data based on its k and n variables:
#
# - k: A cipher key of 32 bytes (which may be empty). Empty is a special value which indicates k has not yet been
# initialized.
# - n: An 8-byte (64-bit) unsigned integer nonce.
#
class CipherState
MAX_NONCE = 2**64 - 1
attr_reader :k, :n
def initialize(cipher: AesGcm.new)
@cipher = cipher
end
# @param [String] 32 bytes key
def initialize_key(key)
@k = key
@n = 0
end
# @return [Boolean] true if k is non-empty, false otherwise.
def key?
!@k.nil?
end
def nonce=(nonce)
@n = nonce
end
# @return [String] ENCRYPT(k, n++, ad, plaintext) if k is non-empty, otherwise returns plaintext.
def encrypt_with_ad(ad, plaintext)
return plaintext unless key?
raise Noise::Exceptions::MaxNonceError if @n == MAX_NONCE
ciphertext = @cipher.encrypt(@k, @n, ad, plaintext)
@n += 1
ciphertext
end
# @return DECRYPT(k, n++, ad, ciphertext) if k is non-empty, otherwise returns ciphertext.
def decrypt_with_ad(ad, ciphertext)
return ciphertext unless key?
raise Noise::Exceptions::MaxNonceError if @n == MAX_NONCE
plaintext = @cipher.decrypt(@k, @n, ad, ciphertext)
@n += 1
plaintext
end
def rekey
@k = @cipher.rekey(@k)
end
end
end
end
Version data entries
6 entries across 6 versions & 1 rubygems