fix: fixes postal default-dkim-record

lib/postal/config.rb

@@ -16,6 +16,7 @@
 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

spec/lib/postal/signer_spec.rb

@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+require "rails_helper"
+module Postal
+
+  RSpec.describe Signer do
+    STATIC_PRIVATE_KEY = OpenSSL::PKey::RSA.new(2048) # rubocop:disable Lint/ConstantDefinitionInBlock
+
+    subject(:signer) { described_class.new(STATIC_PRIVATE_KEY) }
+
+    describe "#private_key" do
+      it "returns the private key" do
+        expect(signer.private_key).to eq(STATIC_PRIVATE_KEY)
+      end
+    end
+
+    describe "#public_key" do
+      it "returns the public key" do
+        expect(signer.public_key.to_s).to eq(STATIC_PRIVATE_KEY.public_key.to_s)
+      end
+    end
+
+    describe "#sign" do
+      it "returns a valid signature" do
+        data = "hello world!"
+        signature = signer.sign(data)
+        expect(signature).to be_a(String)
+        verification = STATIC_PRIVATE_KEY.public_key.verify(OpenSSL::Digest.new("SHA256"),
+                                                            signature,
+                                                            data)
+        expect(verification).to be true
+      end
+    end
+
+    describe "#sign64" do
+      it "returns a valid Base64-encoded signature" do
+        data = "hello world!"
+        signature = signer.sign64(data)
+        expect(signature).to be_a(String)
+        verification = STATIC_PRIVATE_KEY.public_key.verify(OpenSSL::Digest.new("SHA256"),
+                                                            Base64.strict_decode64(signature),
+                                                            data)
+        expect(verification).to be true
+      end
+    end
+
+    describe "#jwk" do
+      it "returns a valid JWK" do
+        jwk = signer.jwk
+        expect(jwk).to be_a(JWT::JWK::RSA)
+      end
+    end
+
+    describe "#sha1_sign" do
+      it "returns a valid signature" do
+        data = "hello world!"
+        signature = signer.sha1_sign(data)
+        expect(signature).to be_a(String)
+        verification = STATIC_PRIVATE_KEY.public_key.verify(OpenSSL::Digest.new("SHA1"),
+                                                            signature,
+                                                            data)
+        expect(verification).to be true
+      end
+    end
+
+    describe "#sha1_sign64" do
+      it "returns a valid Base64-encoded signature" do
+        data = "hello world!"
+        signature = signer.sha1_sign64(data)
+        expect(signature).to be_a(String)
+        verification = STATIC_PRIVATE_KEY.public_key.verify(OpenSSL::Digest.new("SHA1"),
+                                                            Base64.strict_decode64(signature),
+                                                            data)
+        expect(verification).to be true
+      end
+    end
+  end
+
+end

spec/lib/postal_spec.rb

@@ -5,7 +5,7 @@
 RSpec.describe Postal do
   describe "#signer" do
     it "returns a signer with the installation's signing key" do
-      expect(Postal.signer).to be_a(Signer)
+      expect(Postal.signer).to be_a(Postal::Signer)
       expect(Postal.signer.private_key.to_pem).to eq OpenSSL::PKey::RSA.new(File.read(Postal::Config.postal.signing_key_path)).to_pem
     end
   end