fix: fixes postal default-dkim-record

lib/postal/config.rb

@@ -16,6 +16,7 @@ require_relative "error"
 require_relative "version"
 require_relative "config_schema"
 require_relative "legacy_config_source"
+require_relative "signer"
 
 module Postal
 

lib/postal/signer.rb

@@ -0,0 +1,67 @@
+# frozen_string_literal: true
+
+require "base64"
+module Postal
+  class Signer
+
+    # Create a new Signer
+    #
+    # @param [OpenSSL::PKey::RSA] private_key The private key to use for signing
+    # @return [Signer]
+    def initialize(private_key)
+      @private_key = private_key
+    end
+
+    # Return the private key
+    #
+    # @return [OpenSSL::PKey::RSA]
+    attr_reader :private_key
+
+    # Return the public key for the private key
+    #
+    # @return [OpenSSL::PKey::RSA]
+    def public_key
+      @private_key.public_key
+    end
+
+    # Sign the given data
+    #
+    # @param [String] data The data to sign
+    # @return [String] The signature
+    def sign(data)
+      private_key.sign(OpenSSL::Digest.new("SHA256"), data)
+    end
+
+    # Sign the given data and return a Base64-encoded signature
+    #
+    # @param [String] data The data to sign
+    # @return [String] The Base64-encoded signature
+    def sign64(data)
+      Base64.strict_encode64(sign(data))
+    end
+
+    # Return a JWK for the private key
+    #
+    # @return [JWT::JWK] The JWK
+    def jwk
+      @jwk ||= JWT::JWK.new(private_key, { use: "sig", alg: "RS256" })
+    end
+
+    # Sign the given data using SHA1 (for legacy use)
+    #
+    # @param [String] data The data to sign
+    # @return [String] The signature
+    def sha1_sign(data)
+      private_key.sign(OpenSSL::Digest.new("SHA1"), data)
+    end
+
+    # Sign the given data using SHA1 (for legacy use) and return a Base64-encoded string
+    #
+    # @param [String] data The data to sign
+    # @return [String] The signature
+    def sha1_sign64(data)
+      Base64.strict_encode64(sha1_sign(data))
+    end
+
+  end
+end