Implement NIP-19 bech32-encoded private and public keys

https://github.com/nostr-protocol/nips/blob/master/19.md

spec/nostr/crypto_spec.rb

@@ -8,8 +8,8 @@ RSpec.describe Nostr::Crypto do
   describe '#sign_event' do
     let(:keypair) do
       Nostr::KeyPair.new(
-        public_key: '8a9d69c56e3c691bec8f9565e4dcbe38ae1d88fffeec3ce66b9f47558a3aa8ca',
-        private_key: '3185a47e3802f956ca5a2b4ea606c1d51c7610f239617e8f0f218d55bdf2b757'
+        public_key: Nostr::PublicKey.new('8a9d69c56e3c691bec8f9565e4dcbe38ae1d88fffeec3ce66b9f47558a3aa8ca'),
+        private_key: Nostr::PrivateKey.new('3185a47e3802f956ca5a2b4ea606c1d51c7610f239617e8f0f218d55bdf2b757')
       )
     end
 
@@ -34,15 +34,15 @@ RSpec.describe Nostr::Crypto do
   describe '#encrypt_text' do
     let(:sender_keypair) do
       Nostr::KeyPair.new(
-        public_key: '8a9d69c56e3c691bec8f9565e4dcbe38ae1d88fffeec3ce66b9f47558a3aa8ca',
-        private_key: '3185a47e3802f956ca5a2b4ea606c1d51c7610f239617e8f0f218d55bdf2b757'
+        public_key: Nostr::PublicKey.new('8a9d69c56e3c691bec8f9565e4dcbe38ae1d88fffeec3ce66b9f47558a3aa8ca'),
+        private_key: Nostr::PrivateKey.new('3185a47e3802f956ca5a2b4ea606c1d51c7610f239617e8f0f218d55bdf2b757')
       )
     end
 
     let(:recipient_keypair) do
       Nostr::KeyPair.new(
-        public_key: '6c31422248998e300a1a457167565da7d15d0da96651296ee2791c29c11b6aa0',
-        private_key: '22cea01c33eccf30fdd54cb6728f814f6de00c778aafd721e017f4582545f9cf'
+        public_key: Nostr::PublicKey.new('6c31422248998e300a1a457167565da7d15d0da96651296ee2791c29c11b6aa0'),
+        private_key: Nostr::PrivateKey.new('22cea01c33eccf30fdd54cb6728f814f6de00c778aafd721e017f4582545f9cf')
       )
     end
 
@@ -57,15 +57,15 @@ RSpec.describe Nostr::Crypto do
   describe '#descrypt_text' do
     let(:sender_keypair) do
       Nostr::KeyPair.new(
-        public_key: '8a9d69c56e3c691bec8f9565e4dcbe38ae1d88fffeec3ce66b9f47558a3aa8ca',
-        private_key: '3185a47e3802f956ca5a2b4ea606c1d51c7610f239617e8f0f218d55bdf2b757'
+        public_key: Nostr::PublicKey.new('8a9d69c56e3c691bec8f9565e4dcbe38ae1d88fffeec3ce66b9f47558a3aa8ca'),
+        private_key: Nostr::PrivateKey.new('3185a47e3802f956ca5a2b4ea606c1d51c7610f239617e8f0f218d55bdf2b757')
       )
     end
 
     let(:recipient_keypair) do
       Nostr::KeyPair.new(
-        public_key: '6c31422248998e300a1a457167565da7d15d0da96651296ee2791c29c11b6aa0',
-        private_key: '22cea01c33eccf30fdd54cb6728f814f6de00c778aafd721e017f4582545f9cf'
+        public_key: Nostr::PublicKey.new('6c31422248998e300a1a457167565da7d15d0da96651296ee2791c29c11b6aa0'),
+        private_key: Nostr::PrivateKey.new('22cea01c33eccf30fdd54cb6728f814f6de00c778aafd721e017f4582545f9cf')
       )
     end
 

spec/nostr/errors/invalid_hrp_error_spec.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Nostr::InvalidHRPError do
+  describe '#initialize' do
+    let(:given_hrp) { 'nwrong' }
+    let(:allowed_hrp) { 'nsec' }
+    let(:error) { described_class.new(given_hrp, allowed_hrp) }
+
+    it 'builds a useful error message' do
+      expect(error.message).to eq("Invalid hrp: nwrong. The allowed hrp value for this kind of entity is 'nsec'.")
+    end
+  end
+end

spec/nostr/errors/invalid_key_format_error_spec.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Nostr::InvalidKeyFormatError do
+  describe '#initialize' do
+    let(:key_kind) { 'private' }
+    let(:error) { described_class.new(key_kind) }
+
+    it 'builds a useful error message' do
+      expect(error.message).to eq('Only lowercase hexadecimal characters are allowed in private keys.')
+    end
+  end
+end

spec/nostr/errors/invalid_key_length_error_spec.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Nostr::InvalidKeyLengthError do
+  describe '#initialize' do
+    let(:key_kind) { 'private' }
+    let(:error) { described_class.new(key_kind) }
+
+    it 'builds a useful error message' do
+      expect(error.message).to eq('Invalid private key length. It should have 64 characters.')
+    end
+  end
+end

spec/nostr/errors/invalid_key_type_error_spec.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Nostr::InvalidKeyTypeError do
+  describe '#initialize' do
+    let(:key_kind) { 'private' }
+    let(:error) { described_class.new(key_kind) }
+
+    it 'builds a useful error message' do
+      expect(error.message).to eq('Invalid private key type')
+    end
+  end
+end

spec/nostr/event_spec.rb

@@ -233,8 +233,8 @@ RSpec.describe Nostr::Event do
     end
     let(:keypair) do
       Nostr::KeyPair.new(
-        public_key: '8a9d69c56e3c691bec8f9565e4dcbe38ae1d88fffeec3ce66b9f47558a3aa8ca',
-        private_key: '3185a47e3802f956ca5a2b4ea606c1d51c7610f239617e8f0f218d55bdf2b757'
+        public_key: Nostr::PublicKey.new('8a9d69c56e3c691bec8f9565e4dcbe38ae1d88fffeec3ce66b9f47558a3aa8ca'),
+        private_key: Nostr::PrivateKey.new('3185a47e3802f956ca5a2b4ea606c1d51c7610f239617e8f0f218d55bdf2b757')
       )
     end
 

spec/nostr/events/encrypted_direct_message_spec.rb

@@ -6,15 +6,15 @@ RSpec.describe Nostr::Events::EncryptedDirectMessage do
   describe '.new' do
     let(:sender_keypair) do
       Nostr::KeyPair.new(
-        public_key: '8a9d69c56e3c691bec8f9565e4dcbe38ae1d88fffeec3ce66b9f47558a3aa8ca',
-        private_key: '3185a47e3802f956ca5a2b4ea606c1d51c7610f239617e8f0f218d55bdf2b757'
+        public_key: Nostr::PublicKey.new('8a9d69c56e3c691bec8f9565e4dcbe38ae1d88fffeec3ce66b9f47558a3aa8ca'),
+        private_key: Nostr::PrivateKey.new('3185a47e3802f956ca5a2b4ea606c1d51c7610f239617e8f0f218d55bdf2b757')
       )
     end
 
     let(:recipient_keypair) do
       Nostr::KeyPair.new(
-        public_key: '6c31422248998e300a1a457167565da7d15d0da96651296ee2791c29c11b6aa0',
-        private_key: '22cea01c33eccf30fdd54cb6728f814f6de00c778aafd721e017f4582545f9cf'
+        public_key: Nostr::PublicKey.new('6c31422248998e300a1a457167565da7d15d0da96651296ee2791c29c11b6aa0'),
+        private_key: Nostr::PrivateKey.new('22cea01c33eccf30fdd54cb6728f814f6de00c778aafd721e017f4582545f9cf')
       )
     end
 

spec/nostr/key_pair_spec.rb

@@ -5,19 +5,43 @@ require 'spec_helper'
 RSpec.describe Nostr::KeyPair do
   let(:keypair) do
     described_class.new(
-      private_key: '893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900',
-      public_key: '2d7661527d573cc8e84f665fa971dd969ba51e2526df00c149ff8e40a58f9558'
+      private_key: Nostr::PrivateKey.new('893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900'),
+      public_key: Nostr::PublicKey.new('2d7661527d573cc8e84f665fa971dd969ba51e2526df00c149ff8e40a58f9558')
     )
   end
 
   describe '.new' do
-    it 'creates an instance of a key pair' do
-      keypair = described_class.new(
-        private_key: '893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900',
-        public_key: '2d7661527d573cc8e84f665fa971dd969ba51e2526df00c149ff8e40a58f9558'
-      )
+    context 'when private_key is not an instance of PrivateKey' do
+      it 'raises an error' do
+        expect do
+          described_class.new(
+            private_key: '893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900',
+            public_key: Nostr::PublicKey.new('2d7661527d573cc8e84f665fa971dd969ba51e2526df00c149ff8e40a58f9558')
+          )
+        end.to raise_error(ArgumentError, 'private_key is not an instance of PrivateKey')
+      end
+    end
 
-      expect(keypair).to be_an_instance_of(described_class)
+    context 'when public_key is not an instance of PublicKey' do
+      it 'raises an error' do
+        expect do
+          described_class.new(
+            private_key: Nostr::PrivateKey.new('893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900'),
+            public_key: '2d7661527d573cc8e84f665fa971dd969ba51e2526df00c149ff8e40a58f9558'
+          )
+        end.to raise_error(ArgumentError, 'public_key is not an instance of PublicKey')
+      end
+    end
+
+    context 'when private_key is an instance of PrivateKey and public_key is an instance of PublicKey' do
+      it 'creates an instance of a key pair' do
+        keypair = described_class.new(
+          private_key: Nostr::PrivateKey.new('893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900'),
+          public_key: Nostr::PublicKey.new('2d7661527d573cc8e84f665fa971dd969ba51e2526df00c149ff8e40a58f9558')
+        )
+
+        expect(keypair).to be_an_instance_of(described_class)
+      end
     end
   end
 

spec/nostr/key_spec.rb

@@ -0,0 +1,73 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Nostr::Key do
+  let(:subclass) do
+    Class.new(Nostr::Key) do
+      def self.hrp
+        'npub'
+      end
+
+      protected
+
+      def validate_hex_value(_hex_value) = nil
+    end
+  end
+
+  let(:valid_hex) { 'a' * 64 }
+
+  describe '.new' do
+    it 'raises an error because this is an abstract class' do
+      expect { described_class.new(valid_hex) }.to raise_error(/Subclasses must implement this method/)
+    end
+  end
+
+  describe '.from_bech32' do
+    context 'when given a valid Bech32 value' do
+      let(:valid_bech32) { 'npub10elfcs4fr0l0r8af98jlmgdh9c8tcxjvz9qkw038js35mp4dma8qzvjptg' }
+
+      it 'creates a new key' do
+        expect { subclass.from_bech32(valid_bech32) }.not_to raise_error
+      end
+    end
+
+    context 'when given an invalid Bech32 value' do
+      let(:invalid_bech32) { 'this is obviously not valid' }
+
+      it 'raises an error' do
+        expect { subclass.from_bech32(invalid_bech32) }.to raise_error(ArgumentError, /Invalid nip19 string\./)
+      end
+    end
+  end
+
+  describe '.hrp' do
+    context 'when called on the abstract class' do
+      it 'raises an error because this is an abstract method' do
+        expect { described_class.hrp }.to raise_error(/Subclasses must implement this method/)
+      end
+    end
+
+    context 'when called on a subclass' do
+      it 'returns the human readable part of a Bech32 string' do
+        expect(subclass.hrp).to eq('npub')
+      end
+    end
+  end
+
+  describe '#to_bech32' do
+    let(:key) { subclass.new(valid_hex) }
+
+    it 'returns a bech32 string representation of the key' do
+      expect(key.to_bech32).to match(/^npub[0-9a-z]+$/)
+    end
+  end
+
+  describe '#validate_hex_value' do
+    let(:invalid_hex) { 'g' * 64 }
+
+    it 'raises an error because this is an abstract method' do
+      expect { described_class.new(invalid_hex) }.to raise_error(/Subclasses must implement this method/)
+    end
+  end
+end

spec/nostr/keygen_spec.rb

@@ -13,6 +13,31 @@ RSpec.describe Nostr::Keygen do
     end
   end
 
+  describe '.get_key_pair_from_private_key' do
+    context 'when given a private key' do
+      let(:private_key) { Nostr::PrivateKey.new('893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900') }
+
+      it 'generates a key pair' do
+        keypair = keygen.get_key_pair_from_private_key(private_key)
+
+        aggregate_failures do
+          expect(keypair.private_key).to be_an_instance_of(Nostr::PrivateKey)
+          expect(keypair.public_key).to be_an_instance_of(Nostr::PublicKey)
+        end
+      end
+    end
+
+    context 'when given another kind of value' do
+      let(:not_a_private_key) { 'something else' }
+
+      it 'raises an error' do
+        expect { keygen.get_key_pair_from_private_key(not_a_private_key) }.to raise_error(
+          ArgumentError, 'private_key is not an instance of PrivateKey'
+        )
+      end
+    end
+  end
+
   describe '#generate_key_pair' do
     it 'generates a private/public key pair' do
       keypair = keygen.generate_key_pair
@@ -33,11 +58,24 @@ RSpec.describe Nostr::Keygen do
   end
 
   describe '#extract_public_key' do
-    it 'extracts a public key from a private key' do
-      private_key = '893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900'
-      public_key = keygen.extract_public_key(private_key)
+    context 'when the given value is not a private key' do
+      let(:not_a_private_key) { 'something else' }
 
-      expect(public_key).to eq('2d7661527d573cc8e84f665fa971dd969ba51e2526df00c149ff8e40a58f9558')
+      it 'raises an error' do
+        expect { keygen.extract_public_key(not_a_private_key) }.to raise_error(
+          ArgumentError, 'private_key is not an instance of PrivateKey'
+        )
+      end
+    end
+
+    context 'when the given value is a private key' do
+      let(:private_key) { Nostr::PrivateKey.new('893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900') }
+
+      it 'extracts a public key from a private key' do
+        public_key = keygen.extract_public_key(private_key)
+
+        expect(public_key).to eq('2d7661527d573cc8e84f665fa971dd969ba51e2526df00c149ff8e40a58f9558')
+      end
     end
   end
 end

spec/nostr/private_key_spec.rb

@@ -0,0 +1,82 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Nostr::PrivateKey do
+  let(:valid_hex) { '67dea2ed018072d675f5415ecfaed7d2597555e202d85b3d65ea4e58d2d92ffa' }
+  let(:private_key) { described_class.new(valid_hex) }
+
+  describe '.new' do
+    context 'when the private key is not a string' do
+      it 'raises an InvalidKeyTypeError' do
+        expect { described_class.new(1234) }.to raise_error(
+          Nostr::InvalidKeyTypeError,
+          'Invalid private key type'
+        )
+      end
+    end
+
+    context "when the private key's length is not 64 characters" do
+      it 'raises an InvalidKeyLengthError' do
+        expect { described_class.new('a' * 65) }.to raise_error(
+          Nostr::InvalidKeyLengthError,
+          'Invalid private key length. It should have 64 characters.'
+        )
+      end
+    end
+
+    context 'when the private key contains non-hexadecimal characters' do
+      it 'raises an InvalidKeyFormatError' do
+        expect { described_class.new('g' * 64) }.to raise_error(
+          Nostr::InvalidKeyFormatError,
+          'Only lowercase hexadecimal characters are allowed in private keys.'
+        )
+      end
+    end
+
+    context 'when the private key contains uppercase characters' do
+      it 'raises an InvalidKeyFormatError' do
+        expect { described_class.new('A' * 64) }.to raise_error(
+          Nostr::InvalidKeyFormatError,
+          'Only lowercase hexadecimal characters are allowed in private keys.'
+        )
+      end
+    end
+
+    context 'when the private key is valid' do
+      it 'does not raise any error' do
+        expect { described_class.new('a' * 64) }.not_to raise_error
+      end
+    end
+  end
+
+  describe '.from_bech32' do
+    context 'when given a valid Bech32 value' do
+      let(:valid_bech32) { 'nsec1vl029mgpspedva04g90vltkh6fvh240zqtv9k0t9af8935ke9laqsnlfe5' }
+
+      it 'instantiates a private key from a Bech32 encoded string' do
+        expect(described_class.from_bech32(valid_bech32)).to eq(valid_hex)
+      end
+    end
+
+    context 'when given an invalid Bech32 value' do
+      let(:invalid_bech32) { 'this is obviously not valid' }
+
+      it 'raises an error' do
+        expect { described_class.from_bech32(invalid_bech32) }.to raise_error(ArgumentError, /Invalid nip19 string\./)
+      end
+    end
+  end
+
+  describe '.hrp' do
+    it 'returns the human readable part of a Bech32 string' do
+      expect(described_class.hrp).to eq('nsec')
+    end
+  end
+
+  describe '#to_bech32' do
+    it 'converts the hex key to bech32' do
+      expect(private_key.to_bech32).to eq('nsec1vl029mgpspedva04g90vltkh6fvh240zqtv9k0t9af8935ke9laqsnlfe5')
+    end
+  end
+end

spec/nostr/public_key_spec.rb

@@ -0,0 +1,82 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Nostr::PublicKey do
+  let(:valid_hex) { '7e7e9c42a91bfef19fa929e5fda1b72e0ebc1a4c1141673e2794234d86addf4e' }
+  let(:public_key) { described_class.new(valid_hex) }
+
+  describe '.new' do
+    context 'when the public key is not a string' do
+      it 'raises an InvalidKeyTypeError' do
+        expect { described_class.new(1234) }.to raise_error(
+          Nostr::InvalidKeyTypeError,
+          'Invalid public key type'
+        )
+      end
+    end
+
+    context "when the public key's length is not 64 characters" do
+      it 'raises an InvalidKeyLengthError' do
+        expect { described_class.new('a' * 65) }.to raise_error(
+          Nostr::InvalidKeyLengthError,
+          'Invalid public key length. It should have 64 characters.'
+        )
+      end
+    end
+
+    context 'when the public key contains non-hexadecimal characters' do
+      it 'raises an InvalidKeyFormatError' do
+        expect { described_class.new('g' * 64) }.to raise_error(
+          Nostr::InvalidKeyFormatError,
+          'Only lowercase hexadecimal characters are allowed in public keys.'
+        )
+      end
+    end
+
+    context 'when the public key contains uppercase characters' do
+      it 'raises an InvalidKeyFormatError' do
+        expect { described_class.new('A' * 64) }.to raise_error(
+          Nostr::InvalidKeyFormatError,
+          'Only lowercase hexadecimal characters are allowed in public keys.'
+        )
+      end
+    end
+
+    context 'when the public key is valid' do
+      it 'does not raise any error' do
+        expect { described_class.new('a' * 64) }.not_to raise_error
+      end
+    end
+  end
+
+  describe '.from_bech32' do
+    context 'when given a valid Bech32 value' do
+      let(:valid_bech32) { 'npub10elfcs4fr0l0r8af98jlmgdh9c8tcxjvz9qkw038js35mp4dma8qzvjptg' }
+
+      it 'instantiates a public key from a Bech32 encoded string' do
+        expect(described_class.from_bech32(valid_bech32)).to eq(valid_hex)
+      end
+    end
+
+    context 'when given an invalid Bech32 value' do
+      let(:invalid_bech32) { 'this is obviously not valid' }
+
+      it 'raises an error' do
+        expect { described_class.from_bech32(invalid_bech32) }.to raise_error(ArgumentError, /Invalid nip19 string\./)
+      end
+    end
+  end
+
+  describe '.hrp' do
+    it 'returns the human readable part of a Bech32 string' do
+      expect(described_class.hrp).to eq('npub')
+    end
+  end
+
+  describe '#to_bech32' do
+    it 'converts the hex key to bech32' do
+      expect(public_key.to_bech32).to eq('npub10elfcs4fr0l0r8af98jlmgdh9c8tcxjvz9qkw038js35mp4dma8qzvjptg')
+    end
+  end
+end

spec/nostr/user_spec.rb

@@ -5,8 +5,8 @@ require 'spec_helper'
 RSpec.describe Nostr::User do
   let(:keypair) do
     Nostr::KeyPair.new(
-      private_key: '893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900',
-      public_key: '2d7661527d573cc8e84f665fa971dd969ba51e2526df00c149ff8e40a58f9558'
+      private_key: Nostr::PrivateKey.new('893c4cc8088924796b41dc788f7e2f746734497010b1a9f005c1faad7074b900'),
+      public_key: Nostr::PublicKey.new('2d7661527d573cc8e84f665fa971dd969ba51e2526df00c149ff8e40a58f9558')
     )
   end