45 lines
1.3 KiB
Ruby
45 lines
1.3 KiB
Ruby
# frozen_string_literal: true
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module Spec
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module Support
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module Helpers
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class KeyGeneratorHelper
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# The components in a openssh .pub / known_host RSA public key.
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RSA_COMPONENTS = ['ssh-rsa', :e, :n].freeze
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attr_reader :size
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def initialize(size = 2048)
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@size = size
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end
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def generate
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key = OpenSSL::PKey::RSA.generate(size)
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components = RSA_COMPONENTS.map do |component|
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key.respond_to?(component) ? encode_mpi(key.public_send(component)) : component
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end
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# Ruby tries to be helpful and adds new lines every 60 bytes :(
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'ssh-rsa ' + [pack_pubkey_components(components)].pack('m').delete("\n")
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end
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private
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# Encodes an openssh-mpi-encoded integer.
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def encode_mpi(n) # rubocop:disable Naming/UncommunicativeMethodParamName
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chars = []
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n = n.to_i
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chars << (n & 0xff) && n >>= 8 while n != 0
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chars << 0 if chars.empty? || chars.last >= 0x80
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chars.reverse.pack('C*')
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end
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# Packs string components into an openssh-encoded pubkey.
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def pack_pubkey_components(strings)
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(strings.flat_map { |s| [s.length].pack('N') }).zip(strings).join
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end
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end
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end
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end
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end
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