From 24ffdce5c399d93bf6bd6f87aeef4856bb4925a5 Mon Sep 17 00:00:00 2001
From: Didactic Drunk <1479616+didactic-drunk@users.noreply.github.com>
Date: Wed, 27 Apr 2022 01:04:11 -0700
Subject: [PATCH] Experimental Sign combined mode

---
 spec/sodium/sign/secret_key_spec.cr | 11 +++++++++-
 src/sodium/sign/public_key.cr       | 32 +++++++++++++++++++++++++----
 src/sodium/sign/secret_key.cr       | 20 +++++++++++++++---
 3 files changed, 55 insertions(+), 8 deletions(-)

diff --git a/spec/sodium/sign/secret_key_spec.cr b/spec/sodium/sign/secret_key_spec.cr
index 116ce45..1952bee 100644
--- a/spec/sodium/sign/secret_key_spec.cr
+++ b/spec/sodium/sign/secret_key_spec.cr
@@ -64,7 +64,16 @@ describe Sodium::Sign::SecretKey do
     key1.seed.should eq key3.seed
   end
 
-  it "signs and verifies" do
+  it "signs and verifies combined" do
+    message = "foo"
+    skey = Sodium::Sign::SecretKey.new
+    sig = skey.sign message
+
+    message2 = skey.public_key.verify_string sig
+    message2.should eq message
+  end
+
+  it "signs and verifies detached" do
     message = "foo"
     skey = Sodium::Sign::SecretKey.new
     sig = skey.sign_detached message
diff --git a/src/sodium/sign/public_key.cr b/src/sodium/sign/public_key.cr
index ad66d12..3a838cd 100644
--- a/src/sodium/sign/public_key.cr
+++ b/src/sodium/sign/public_key.cr
@@ -20,13 +20,37 @@ module Sodium
       end
     end
 
-    # Verify signature made by `secret_key.sign_detached(message)`
+    # Verify signature made by `secret_key.sign(message)`
     # Raises on verification failure.
-    def verify_detached(message, sig : Bytes)
-      verify_detached message.to_slice, sig
+    #
+    # WARNING: returns pointer to message within messagesig (zerocopy)
+    # If you reuse messagesig, `#dup` the returned message
+    # `secret_key.verify(messagesig).dup`
+    @[Experimental]
+    def verify(messagesig) : Bytes
+      messagesig = messagesig.to_slice
+      bs = messagesig.bytesize
+      raise Sodium::Error::VerificationFailed.new("message shorter than SIG_SIZE") unless bs >= SIG_SIZE
+
+      message = messagesig[SIG_SIZE, bs - SIG_SIZE]
+      sig = messagesig[0, SIG_SIZE]
+
+      verify_detached message, sig
+      message
     end
 
-    def verify_detached(message : Bytes, sig : Bytes)
+    @[Experimental]
+    def verify_string(messagesig) : String
+      String.new(verify(messagesig))
+    end
+
+    # Verify signature made by `secret_key.sign_detached(message)`
+    # Raises on verification failure.
+    def verify_detached(message, sig) : Nil
+      verify_detached message.to_slice, sig.to_slice
+    end
+
+    def verify_detached(message : Bytes, sig : Bytes) : Nil
       raise ArgumentError.new("Signature must be #{SIG_SIZE} bytes, got #{sig.bytesize}") if sig.bytesize != SIG_SIZE
 
       v = LibSodium.crypto_sign_verify_detached sig, message, message.bytesize, @bytes
diff --git a/src/sodium/sign/secret_key.cr b/src/sodium/sign/secret_key.cr
index 4ca2de1..5d1938b 100644
--- a/src/sodium/sign/secret_key.cr
+++ b/src/sodium/sign/secret_key.cr
@@ -91,14 +91,28 @@ module Sodium
       end.readonly
     end
 
+    # Signs message and returns a combined signature.
+    # Verify using `secret_key.public_key.verify(messagesig).dup`
+    # See warning about object reuse in `#verify` if you don't `#dup`
+    @[Experimental]
+    def sign(message) : Bytes
+      message = message.to_slice
+
+      Bytes.new(SIG_SIZE + message.bytesize).tap do |msgsig|
+        sign_detached message, msgsig[0, SIG_SIZE]
+        message.copy_to msgsig[SIG_SIZE, message.bytesize]
+      end
+    end
+
     # Signs message and returns a detached signature.
     # Verify using `secret_key.public_key.verify_detached(message, sig)`
-    def sign_detached(message)
+    def sign_detached(message) : Bytes
       sign_detached message.to_slice
     end
 
-    def sign_detached(message : Bytes)
-      sig = Bytes.new(SIG_SIZE)
+    def sign_detached(message : Bytes, sig : Bytes? = nil) : Bytes
+      raise ArgumentError.new("expected sig to be #{SIG_SIZE}, got #{sig.try(&.bytesize).inspect}") if sig && sig.bytesize != SIG_SIZE
+      sig ||= Bytes.new(SIG_SIZE)
       @key.readonly do |kslice|
         if LibSodium.crypto_sign_detached(sig, out sig_len, message, message.bytesize, kslice) != 0
           raise Error.new("crypto_sign_detached")