2017-07-09 12:06:36 +00:00
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# frozen_string_literal: true
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2017-07-10 13:39:13 +00:00
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2016-08-06 15:58:50 +00:00
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require "base64"
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2017-10-21 13:11:29 +00:00
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require "active_support/core_ext/object/blank"
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require "active_support/security_utils"
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require "active_support/messages/metadata"
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require "active_support/messages/rotator"
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2010-01-01 19:59:51 +00:00
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2008-11-23 14:29:11 +00:00
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module ActiveSupport
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2012-09-17 05:22:18 +00:00
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# +MessageVerifier+ makes it easy to generate and verify messages which are
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# signed to prevent tampering.
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2010-08-14 05:13:00 +00:00
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#
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2012-09-17 05:22:18 +00:00
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# This is useful for cases like remember-me tokens and auto-unsubscribe links
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2012-12-05 06:11:54 +00:00
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# where the session store isn't suitable or available.
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2008-11-23 14:29:11 +00:00
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#
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# Remember Me:
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2008-11-23 15:33:56 +00:00
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# cookies[:remember_me] = @verifier.generate([@user.id, 2.weeks.from_now])
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2010-08-14 05:13:00 +00:00
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#
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2008-11-23 14:29:11 +00:00
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# In the authentication filter:
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#
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2008-11-23 15:33:56 +00:00
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# id, time = @verifier.verify(cookies[:remember_me])
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2015-12-10 19:42:41 +00:00
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# if Time.now < time
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2008-11-23 14:29:11 +00:00
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# self.current_user = User.find(id)
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# end
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2010-08-14 05:13:00 +00:00
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#
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2012-09-17 05:22:18 +00:00
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# By default it uses Marshal to serialize the message. If you want to use
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2013-03-24 18:46:46 +00:00
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# another serialization method, you can set the serializer in the options
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# hash upon initialization:
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2011-09-15 17:23:08 +00:00
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#
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2013-03-24 18:46:46 +00:00
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# @verifier = ActiveSupport::MessageVerifier.new('s3Krit', serializer: YAML)
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2016-02-17 21:48:04 +00:00
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#
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# +MessageVerifier+ creates HMAC signatures using SHA1 hash algorithm by default.
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# If you want to use a different hash algorithm, you can change it by providing
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2017-11-22 19:45:51 +00:00
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# +:digest+ key as an option while initializing the verifier:
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2016-02-17 21:48:04 +00:00
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#
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# @verifier = ActiveSupport::MessageVerifier.new('s3Krit', digest: 'SHA256')
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2017-07-22 14:31:53 +00:00
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#
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# === Confining messages to a specific purpose
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#
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# By default any message can be used throughout your app. But they can also be
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# confined to a specific +:purpose+.
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#
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# token = @verifier.generate("this is the chair", purpose: :login)
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#
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# Then that same purpose must be passed when verifying to get the data back out:
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#
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# @verifier.verified(token, purpose: :login) # => "this is the chair"
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# @verifier.verified(token, purpose: :shipping) # => nil
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# @verifier.verified(token) # => nil
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#
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# @verifier.verify(token, purpose: :login) # => "this is the chair"
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# @verifier.verify(token, purpose: :shipping) # => ActiveSupport::MessageVerifier::InvalidSignature
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# @verifier.verify(token) # => ActiveSupport::MessageVerifier::InvalidSignature
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#
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# Likewise, if a message has no purpose it won't be returned when verifying with
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# a specific purpose.
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#
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# token = @verifier.generate("the conversation is lively")
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# @verifier.verified(token, purpose: :scare_tactics) # => nil
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# @verifier.verified(token) # => "the conversation is lively"
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#
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# @verifier.verify(token, purpose: :scare_tactics) # => ActiveSupport::MessageVerifier::InvalidSignature
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# @verifier.verify(token) # => "the conversation is lively"
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#
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# === Making messages expire
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#
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# By default messages last forever and verifying one year from now will still
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# return the original value. But messages can be set to expire at a given
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# time with +:expires_in+ or +:expires_at+.
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#
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# @verifier.generate(parcel, expires_in: 1.month)
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# @verifier.generate(doowad, expires_at: Time.now.end_of_year)
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#
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2019-02-15 15:18:47 +00:00
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# Then the messages can be verified and returned up to the expire time.
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2017-07-22 14:31:53 +00:00
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# Thereafter, the +verified+ method returns +nil+ while +verify+ raises
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# <tt>ActiveSupport::MessageVerifier::InvalidSignature</tt>.
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2017-09-23 21:16:21 +00:00
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#
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# === Rotating keys
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#
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2017-09-24 19:41:16 +00:00
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# MessageVerifier also supports rotating out old configurations by falling
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2017-11-22 19:45:51 +00:00
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# back to a stack of verifiers. Call +rotate+ to build and add a verifier to
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# so either +verified+ or +verify+ will also try verifying with the fallback.
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2017-09-24 19:41:16 +00:00
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#
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# By default any rotated verifiers use the values of the primary
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# verifier unless specified otherwise.
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#
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# You'd give your verifier the new defaults:
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#
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# verifier = ActiveSupport::MessageVerifier.new(@secret, digest: "SHA512", serializer: JSON)
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#
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# Then gradually rotate the old values out by adding them as fallbacks. Any message
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# generated with the old values will then work until the rotation is removed.
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#
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# verifier.rotate old_secret # Fallback to an old secret instead of @secret.
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# verifier.rotate digest: "SHA256" # Fallback to an old digest instead of SHA512.
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# verifier.rotate serializer: Marshal # Fallback to an old serializer instead of JSON.
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#
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# Though the above would most likely be combined into one rotation:
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#
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# verifier.rotate old_secret, digest: "SHA256", serializer: Marshal
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2008-11-23 14:29:11 +00:00
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class MessageVerifier
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2017-09-23 21:16:21 +00:00
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prepend Messages::Rotator::Verifier
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2008-11-23 14:29:11 +00:00
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class InvalidSignature < StandardError; end
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2010-08-14 05:13:00 +00:00
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2011-09-15 18:27:12 +00:00
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def initialize(secret, options = {})
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2016-08-06 15:58:50 +00:00
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raise ArgumentError, "Secret should not be nil." unless secret
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2008-11-23 14:29:11 +00:00
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@secret = secret
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@digest = options[:digest] || "SHA1"
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2011-09-15 18:27:12 +00:00
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@serializer = options[:serializer] || Marshal
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2008-11-23 14:29:11 +00:00
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end
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2010-08-14 05:13:00 +00:00
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2014-12-04 02:00:32 +00:00
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# Checks if a signed message could have been generated by signing an object
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# with the +MessageVerifier+'s secret.
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#
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# verifier = ActiveSupport::MessageVerifier.new 's3Krit'
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# signed_message = verifier.generate 'a private message'
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# verifier.valid_message?(signed_message) # => true
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#
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# tampered_message = signed_message.chop # editing the message invalidates the signature
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# verifier.valid_message?(tampered_message) # => false
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2014-11-21 23:52:22 +00:00
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def valid_message?(signed_message)
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2015-06-04 22:16:02 +00:00
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return if signed_message.nil? || !signed_message.valid_encoding? || signed_message.blank?
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2014-12-02 15:10:18 +00:00
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2018-02-28 04:33:37 +00:00
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data, digest = signed_message.split("--")
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2014-11-21 23:52:22 +00:00
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data.present? && digest.present? && ActiveSupport::SecurityUtils.secure_compare(digest, generate_digest(data))
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end
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2014-12-04 02:00:32 +00:00
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# Decodes the signed message using the +MessageVerifier+'s secret.
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#
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# verifier = ActiveSupport::MessageVerifier.new 's3Krit'
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#
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# signed_message = verifier.generate 'a private message'
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2014-12-04 16:09:47 +00:00
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# verifier.verified(signed_message) # => 'a private message'
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2014-12-04 02:00:32 +00:00
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#
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# Returns +nil+ if the message was not signed with the same secret.
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#
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# other_verifier = ActiveSupport::MessageVerifier.new 'd1ff3r3nt-s3Krit'
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2014-12-04 16:09:47 +00:00
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# other_verifier.verified(signed_message) # => nil
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2014-12-04 02:00:32 +00:00
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#
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# Returns +nil+ if the message is not Base64-encoded.
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#
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# invalid_message = "f--46a0120593880c733a53b6dad75b42ddc1c8996d"
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2014-12-04 16:09:47 +00:00
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# verifier.verified(invalid_message) # => nil
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2014-12-04 02:00:32 +00:00
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#
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# Raises any error raised while decoding the signed message.
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#
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# incompatible_message = "test--dad7b06c94abba8d46a15fafaef56c327665d5ff"
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2014-12-04 16:09:47 +00:00
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# verifier.verified(incompatible_message) # => TypeError: incompatible marshal file format
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2017-09-23 21:16:21 +00:00
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def verified(signed_message, purpose: nil, **)
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2014-11-21 23:52:22 +00:00
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if valid_message?(signed_message)
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2013-05-15 14:11:04 +00:00
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begin
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2018-02-28 04:33:37 +00:00
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data = signed_message.split("--")[0]
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2017-08-09 19:48:25 +00:00
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message = Messages::Metadata.verify(decode(data), purpose)
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@serializer.load(message) if message
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2013-12-07 18:56:09 +00:00
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rescue ArgumentError => argument_error
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2016-08-06 15:58:50 +00:00
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return if argument_error.message.include?("invalid base64")
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2013-12-07 18:56:09 +00:00
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raise
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2013-05-15 14:11:04 +00:00
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end
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2008-11-23 14:29:11 +00:00
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end
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end
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2014-12-02 15:10:18 +00:00
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2014-12-04 02:00:32 +00:00
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# Decodes the signed message using the +MessageVerifier+'s secret.
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#
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# verifier = ActiveSupport::MessageVerifier.new 's3Krit'
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# signed_message = verifier.generate 'a private message'
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#
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2014-12-04 16:09:47 +00:00
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# verifier.verify(signed_message) # => 'a private message'
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2014-12-04 02:00:32 +00:00
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#
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# Raises +InvalidSignature+ if the message was not signed with the same
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# secret or was not Base64-encoded.
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#
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# other_verifier = ActiveSupport::MessageVerifier.new 'd1ff3r3nt-s3Krit'
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2014-12-09 23:23:15 +00:00
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# other_verifier.verify(signed_message) # => ActiveSupport::MessageVerifier::InvalidSignature
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2017-09-23 21:16:21 +00:00
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def verify(*args)
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verified(*args) || raise(InvalidSignature)
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2014-11-21 23:52:22 +00:00
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end
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2010-08-14 05:13:00 +00:00
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2014-12-04 02:00:32 +00:00
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# Generates a signed message for the provided value.
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#
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2019-07-10 15:39:26 +00:00
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# The message is signed with the +MessageVerifier+'s secret.
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# Returns Base64-encoded message joined with the generated signature.
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2014-12-04 02:00:32 +00:00
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#
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# verifier = ActiveSupport::MessageVerifier.new 's3Krit'
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# verifier.generate 'a private message' # => "BAhJIhRwcml2YXRlLW1lc3NhZ2UGOgZFVA==--e2d724331ebdee96a10fb99b089508d1c72bd772"
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2017-07-19 17:21:09 +00:00
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def generate(value, expires_at: nil, expires_in: nil, purpose: nil)
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2017-08-09 19:48:25 +00:00
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data = encode(Messages::Metadata.wrap(@serializer.dump(value), expires_at: expires_at, expires_in: expires_in, purpose: purpose))
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2008-11-23 14:29:11 +00:00
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"#{data}--#{generate_digest(data)}"
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end
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2010-08-14 05:13:00 +00:00
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2008-11-23 14:29:11 +00:00
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private
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2014-11-12 22:48:44 +00:00
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def encode(data)
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::Base64.strict_encode64(data)
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end
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def decode(data)
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::Base64.strict_decode64(data)
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end
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2008-11-23 14:29:11 +00:00
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def generate_digest(data)
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2016-08-06 15:58:50 +00:00
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require "openssl" unless defined?(OpenSSL)
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2009-09-25 05:43:45 +00:00
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OpenSSL::HMAC.hexdigest(OpenSSL::Digest.const_get(@digest).new, @secret, data)
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2008-11-23 14:29:11 +00:00
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end
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end
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2008-11-23 23:29:03 +00:00
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end
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