4bdf703ab2
This release upgrades Instiki to Rails 2.3.4, which patches two security holes in Rails. See http://weblog.rubyonrails.org/2009/9/4/ruby-on-rails-2-3-4 There are also some new features, and the usual boatload of bugfixes. See the CHANGELOG for details.
60 lines
1.6 KiB
Ruby
60 lines
1.6 KiB
Ruby
module ActiveSupport
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# MessageVerifier makes it easy to generate and verify messages which are signed
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# to prevent tampering.
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#
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# This is useful for cases like remember-me tokens and auto-unsubscribe links where the
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# session store isn't suitable or available.
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#
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# Remember Me:
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# cookies[:remember_me] = @verifier.generate([@user.id, 2.weeks.from_now])
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#
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# In the authentication filter:
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#
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# id, time = @verifier.verify(cookies[:remember_me])
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# if time < Time.now
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# self.current_user = User.find(id)
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# end
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#
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class MessageVerifier
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class InvalidSignature < StandardError; end
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def initialize(secret, digest = 'SHA1')
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@secret = secret
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@digest = digest
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end
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def verify(signed_message)
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data, digest = signed_message.split("--")
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if secure_compare(digest, generate_digest(data))
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Marshal.load(ActiveSupport::Base64.decode64(data))
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else
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raise InvalidSignature
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end
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end
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def generate(value)
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data = ActiveSupport::Base64.encode64s(Marshal.dump(value))
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"#{data}--#{generate_digest(data)}"
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end
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private
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# constant-time comparison algorithm to prevent timing attacks
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def secure_compare(a, b)
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if a.length == b.length
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result = 0
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for i in 0..(a.length - 1)
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result |= a[i] ^ b[i]
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end
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result == 0
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else
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false
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end
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end
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def generate_digest(data)
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require 'openssl' unless defined?(OpenSSL)
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OpenSSL::HMAC.hexdigest(OpenSSL::Digest::Digest.new(@digest), @secret, data)
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end
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end
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end
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