Algorithm 2 Joining patient records with Sovereign Join: SCP side
Input: Request messages (MSG)
Output: Matching results
1:	bufferCtr ← 0
2:	while TRUE do
3:	wait for new message MSG in blocked state
4:	if get_DB_ID(MSG) = “DB1” then
5:	dataDB1 [bufferCtr] ← decrypt(get_record(MSG))   {buffer the record}
6:	recordDB1 [bufferCtr] ← get_recordID(MSG)
7:	bufferCtr ← bufferCtr + 1 {update buffer counter}
8:	else
9:	if get_DB_ID(MSG) = “DB2” then
10:	dataDB2 ← decrypt(get_record(MSG))
11:	recordDB2 ← get_recordID(MSG)
12:	for i = 0 to BUFFER_SIZE do
13:	if distanceMetric(dataDB1[i], dataDB2) < 1 then
14:	matchedDB1Id ← recordDBl [j]      {send match result}
15:	end if
16:	matchedDB1Id ← “No match”
17:	send_ACK2(matchedDB1Id) {no match found}
18:	end for
19:	bufferCtr ← 0 {reset buffer counter}
20:	end if
21:	end if
22:	end while