support public key from string or from file (#14)

README.md

@@ -2,17 +2,33 @@
 
 A rubygem for creating and verifying [Minisign](http://jedisct1.github.io/minisign/) signatures.
 
+- [Installation \& Usage](#installation--usage)
+  - [Read a public key](#read-a-public-key)
+  - [Verify a signature](#verify-a-signature)
+  - [Create a signature](#create-a-signature)
+- [Local Development](#local-development)
+- [Documentation](#documentation)
+
 ## Installation & Usage
 
 ```
 gem install minisign
 ```
 
+### Read a public key
+
+```rb
+require 'minisign'
+public_key = Minisign::PublicKey.new('RWSmKaOrT6m3TGwjwBovgOmlhSbyBUw3hyhnSOYruHXbJa36xHr8rq2M')
+# or from a file
+public_key = Minisign::PublicKey.new(File.read("test/minisign.pub"))
+```
+
 ### Verify a signature
 
 ```rb
 require 'minisign'
-public_key = Minisign::PublicKey.new('RWTg6JXWzv6GDtDphRQ/x7eg0LaWBcTxPZ7i49xEeiqXVcR+r79OZRWM')
+public_key = Minisign::PublicKey.new('RWSmKaOrT6m3TGwjwBovgOmlhSbyBUw3hyhnSOYruHXbJa36xHr8rq2M')
 message = File.read("test/example.txt")
 signature = Minisign::Signature.new(File.read("test/example.txt.minisig"))
 public_key.verify(signature, message)
@@ -21,7 +37,7 @@ public_key.verify(signature, message)
 The above is equivalent to:
 
 ```
-minisign -Vm test/example.txt -P RWTg6JXWzv6GDtDphRQ/x7eg0LaWBcTxPZ7i49xEeiqXVcR+r79OZRWM
+minisign -Vm test/example.txt -P RWSmKaOrT6m3TGwjwBovgOmlhSbyBUw3hyhnSOYruHXbJa36xHr8rq2M
 ```
 
 ### Create a signature
@@ -42,7 +58,12 @@ File.write("#{file_path}.minisig", signature.to_s)
 irb -Ilib -rminisign
 ```
 
-## Local Documentation
+## Documentation
+
+The documentation for this gem is published here: 
+https://www.rubydoc.info/gems/minisign/
+
+or if working locally:
 
 ```
 yard server --reload

lib/minisign/public_key.rb

@@ -10,9 +10,15 @@ class PublicKey
     # @example
     #   Minisign::PublicKey.new('RWTg6JXWzv6GDtDphRQ/x7eg0LaWBcTxPZ7i49xEeiqXVcR+r79OZRWM')
     def initialize(str)
-      @decoded = Base64.strict_decode64(str)
+      parts = str.split("\n")
+      @decoded = Base64.strict_decode64(parts.last)
       @public_key = @decoded[10..]
       @verify_key = Ed25519::VerifyKey.new(@public_key)
+      @untrusted_comment = if parts.length == 1
+                             "minisign public key #{key_id}\n#{key_data}\n"
+                           else
+                             parts.first.split('untrusted comment: ').last
+                           end
     end
 
     # @return [String] the key id
@@ -41,9 +47,12 @@ def verify(sig, message)
       "Signature and comment signature verified\nTrusted comment: #{sig.trusted_comment}"
     end
 
+    def key_data
+      Base64.strict_encode64("Ed#{@decoded[2..9]}#{@public_key}")
+    end
+
     def to_s
-      data = Base64.strict_encode64("Ed#{@decoded[2..9]}#{@public_key}")
-      "untrusted comment: minisign public key #{key_id}\n#{data}\n"
+      "untrusted comment: #{@untrusted_comment}\n#{key_data}\n"
     end
 
     private

spec/minisign/public_key_spec.rb

@@ -2,7 +2,7 @@
 
 describe Minisign::PublicKey do
   before do
-    @pk = Minisign::PublicKey.new(File.read('test/minisign.pub').split("\n").pop)
+    @pk = Minisign::PublicKey.new(File.read('test/minisign.pub'))
     @message = File.read('test/example.txt')
   end
   it 'verifies signatures' do
@@ -30,4 +30,8 @@
   it 'can be written to a file' do
     expect(@pk.to_s).to eq(File.read('test/minisign.pub'))
   end
+  it 'regenerates an untrusted comment if not provided' do
+    @pk = Minisign::PublicKey.new('RWSmKaOrT6m3TGwjwBovgOmlhSbyBUw3hyhnSOYruHXbJa36xHr8rq2M')
+    expect(@pk.to_s).to match('minisign public key 4CB7A94FABA329A6')
+  end
 end

test/minisign.pub

@@ -1,2 +1,2 @@
-untrusted comment: minisign public key 4CB7A94FABA329A6
+untrusted comment: minisign public key 4CB7A94FABA329A6 yay
 RWSmKaOrT6m3TGwjwBovgOmlhSbyBUw3hyhnSOYruHXbJa36xHr8rq2M