Class: Flipper::Cloud::MessageVerifier

Inherits:
Object
  • Object
show all
Defined in:
lib/flipper/cloud/message_verifier.rb

Defined Under Namespace

Classes: InvalidSignature

Constant Summary collapse

DEFAULT_VERSION = 
"v1"

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(secret:, version: DEFAULT_VERSION) ⇒ MessageVerifier

Returns a new instance of MessageVerifier.

Raises:

  • (ArgumentError) 


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# File 'lib/flipper/cloud/message_verifier.rb', line 17

def initialize(secret:, version: DEFAULT_VERSION)
  @secret = secret
  @version = version || DEFAULT_VERSION

  raise ArgumentError, "secret should be a string" unless @secret.is_a?(String)
  raise ArgumentError, "version should be a string" unless @version.is_a?(String)
end

Class Method Details

.header(signature, timestamp, version = DEFAULT_VERSION) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/flipper/cloud/message_verifier.rb', line 11

def self.header(signature, timestamp, version = DEFAULT_VERSION)
  raise ArgumentError, "timestamp should be an instance of Time" unless timestamp.is_a?(Time)
  raise ArgumentError, "signature should be a string" unless signature.is_a?(String)
  "t=#{timestamp.to_i},#{version}=#{signature}"
end

Instance Method Details

#generate(payload, timestamp) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/flipper/cloud/message_verifier.rb', line 25

def generate(payload, timestamp)
  raise ArgumentError, "timestamp should be an instance of Time" unless timestamp.is_a?(Time)
  raise ArgumentError, "payload should be a string" unless payload.is_a?(String)

  OpenSSL::HMAC.hexdigest(OpenSSL::Digest.new("sha256"), @secret, "#{timestamp.to_i}.#{payload}")
end

#header(signature, timestamp) ⇒ Object 



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# File 'lib/flipper/cloud/message_verifier.rb', line 32

def header(signature, timestamp)
  self.class.header(signature, timestamp, @version)
end

#verify(payload, header, tolerance: nil) ⇒ Object

Public: Verifies the signature header for a given payload.

Raises a InvalidSignature in the following cases:

  • the header does not match the expected format

  • no signatures found with the expected scheme

  • no signatures matching the expected signature

  • a tolerance is provided and the timestamp is not within the tolerance

Returns true otherwise.



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# File 'lib/flipper/cloud/message_verifier.rb', line 46

def verify(payload, header, tolerance: nil)
  begin
    timestamp, signatures = get_timestamp_and_signatures(header)
  rescue StandardError
    raise InvalidSignature, "Unable to extract timestamp and signatures from header"
  end

  if signatures.empty?
    raise InvalidSignature, "No signatures found with expected version #{@version}"
  end

  expected_sig = generate(payload, timestamp)
  unless signatures.any? { |s| secure_compare(expected_sig, s) }
    raise InvalidSignature, "No signatures found matching the expected signature for payload"
  end

  if tolerance && timestamp < Time.now - tolerance
    raise InvalidSignature, "Timestamp outside the tolerance zone (#{Time.at(timestamp)})"
  end

  true
end