# HG changeset patch
# User Kim Alvefur <zash@zash.se>
# Date 1491586544 -7200
# Node ID c99db51723091a224aab3c0cdaca477779d8a6c2
# Parent  3c732f1d990c251758e53824f9991a218c6a3a72
util.sasl.scram: Add support for authenticating with pre-hashed password

diff -r 3c732f1d990c -r c99db5172309 util/sasl/scram.lua
--- a/util/sasl/scram.lua	Sat Jun 04 13:37:06 2016 +0200
+++ b/util/sasl/scram.lua	Fri Apr 07 19:35:44 2017 +0200
@@ -66,13 +66,27 @@
 	local channel_binding = "c=" .. base64(cbind_input);
 	local client_final_message_without_proof = channel_binding .. "," .. nonce;
 
-	local SaltedPassword  = Hi(Normalize(stream.password), salt, i);
-	local ClientKey       = HMAC(SaltedPassword, "Client Key");
+	local SaltedPassword;
+	local ClientKey;
+	local ServerKey;
+
+	if stream.client_key and stream.server_key then
+		ClientKey = stream.client_key;
+		ServerKey = stream.server_key;
+	else
+		if stream.salted_password then
+			SaltedPassword = stream.salted_password;
+		elseif stream.password then
+			SaltedPassword = Hi(Normalize(stream.password), salt, i);
+		end
+		ServerKey = HMAC(SaltedPassword, "Server Key");
+		ClientKey = HMAC(SaltedPassword, "Client Key");
+	end
+
 	local StoredKey       = H(ClientKey);
 	local AuthMessage     = client_first_message_bare .. "," ..  server_first_message .. "," ..  client_final_message_without_proof;
 	local ClientSignature = HMAC(StoredKey, AuthMessage);
 	local ClientProof     = XOR(ClientKey, ClientSignature);
-	local ServerKey       = HMAC(SaltedPassword, "Server Key");
 	local ServerSignature = HMAC(ServerKey, AuthMessage);
 
 	local proof = "p=" .. base64(ClientProof);