Method: Altcha.verify_server_signature

Defined in:
lib/altcha.rb

.verify_server_signature(payload, hmac_key) ⇒ Array<Boolean, ServerSignatureVerificationData>

Verifies the server’s signature.

Parameters:

  • payload (String, ServerSignaturePayload) —

    The payload to verify, either as a base64 encoded JSON string or a ServerSignaturePayload instance.

  • hmac_key (String) —

    The key used for HMAC verification.

Returns:

  • (Array<Boolean, ServerSignatureVerificationData>) —

    A tuple where the first element is true if the signature is valid, and the second element is the verification data.



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# File 'lib/altcha.rb', line 352

def self.verify_server_signature(payload, hmac_key)
  # Decode and parse base64 JSON string if it's a String
  if payload.is_a?(String)
    decoded_payload = Base64.decode64(payload)
    payload = ServerSignaturePayload.from_json(decoded_payload)

  # Convert payload from hash to ServerSignaturePayload if it's a plain object
  elsif payload.is_a?(Hash)
    payload = ServerSignaturePayload.new(
      algorithm: payload[:algorithm],
      verification_data: payload[:verification_data],
      signature: payload[:signature],
      verified: payload[:verified]
    )
  end

  # Ensure payload is an instance of ServerSignaturePayload
  return [false, nil] unless payload.is_a?(ServerSignaturePayload)

  required_attributes = i[algorithm verification_data signature verified]
  required_attributes.each do |attr|
    value = payload.send(attr)
    return false if value.nil? || value.to_s.strip.empty?
  end

  hash_data = hash(payload.algorithm, payload.verification_data)
  expected_signature = hmac_hex(payload.algorithm, hash_data, hmac_key)
  
  params = URI.decode_www_form(payload.verification_data).to_h
  verification_data = ServerSignatureVerificationData.new.tap do |v|
    v.classification = params['classification'] || nil
    v.country = params['country'] || nil
    v.detected_language = params['detectedLanguage'] || nil
    v.email = params['email'] || nil
    v.expire = params['expire'] ? params['expire'].to_i : nil
    v.fields = params['fields'] ? params['fields'].split(',') : nil
    v.fields_hash = params['fieldsHash'] || nil
    v.ip_address = params['ipAddress'] || nil
    v.reasons = params['reasons'] ? params['reasons'].split(',') : nil
    v.score = params['score'] ? params['score'].to_f : nil
    v.time = params['time'] ? params['time'].to_i : nil
    v.verified = params['verified'] == 'true'
  end

  now = Time.now.to_i
  is_verified = payload.verified &&
                verification_data.verified &&
                (verification_data.expire.nil? || verification_data.expire > now) &&
                payload.signature == expected_signature

  [is_verified, verification_data]
rescue ArgumentError, JSON::ParserError => e
  # Handle specific exceptions for invalid Base64 or JSON
  puts "Error decoding or parsing payload: #{e.message}"
  false
end