From 57205cb43c3f909ba7bcf96a9b829418bdb4c696 Mon Sep 17 00:00:00 2001
From: Nick Furfaro <nfurfaro33@gmail.com>
Date: Mon, 10 Jan 2022 17:30:46 -0700
Subject: [PATCH] ec-recover (#5)

* Add ecr lib

* Add todo comment

* Add recover_pubkey and refactor ecr

* Fixup

* Update comments

* Add comments to ec-recover asm block

* Modify asm

* Clean up asm

* Fix B512 field assignment

* Fix ordering of lib deps

* Remove ec_recover, to be added in separate PR

* Clean up comments
---
 src/ecr.sw | 19 +++++++++++++++++++
 src/lib.sw |  1 +
 2 files changed, 20 insertions(+)
 create mode 100644 src/ecr.sw

diff --git a/src/ecr.sw b/src/ecr.sw
new file mode 100644
index 00000000000..125f886274c
--- /dev/null
+++ b/src/ecr.sw
@@ -0,0 +1,19 @@
+library ecr;
+
+use ::b512::B512;
+use ::address::Address;
+
+/// Recover the address derived from the private key used to sign a message
+pub fn ec_recover_address(signature: B512, msg_hash: b256) -> Address {
+    let address = asm(pub_key_buffer, sig_ptr: signature.hi, hash: msg_hash, addr_buffer, sixty_four: 64) {
+        move pub_key_buffer sp; // mv sp to pub_key result buffer.
+        cfei i64;
+        ecr pub_key_buffer sig_ptr hash; // recover public_key from sig & hash
+        move addr_buffer sp; // mv sp to addr result buffer.
+        cfei i32;
+        s256 addr_buffer pub_key_buffer sixty_four; // hash 64 bytes to the addr_buffer
+        addr_buffer: b256
+    };
+
+    ~Address::from(address)
+}
diff --git a/src/lib.sw b/src/lib.sw
index e017ac57edd..b60766a2ddb 100644
--- a/src/lib.sw
+++ b/src/lib.sw
@@ -10,5 +10,6 @@ dep context;
 dep address;
 dep block;
 dep result;
+dep ecr;
 
 use core::*;