Adding a simpler TSA

network5445/contracts/0x0fa811ac6643a29ad9c17acbed34918a4875f63c/abi

+[{"constant":true,"inputs":[{"name":"hash","type":"bytes32"}],"name":"get","outputs":[{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"constant":false,"inputs":[{"name":"hash","type":"bytes32"}],"name":"put","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"}]

network5445/contracts/TimeStampAuthority

+0x0fa811ac6643a29ad9c17acbed34918a4875f63c
\ No newline at end of file

src/contract.TimeStampAuthority.sol

+// 20180718 Robert Martin-Legene <robert@nic.ar>
+// Time stamp authority
+
+pragma solidity ^0.4.24;
+      
+contract TimeStampAuthority {
+	// This mapping is almost an "associative array"
+	mapping (bytes32 => uint) private hashes;
+
+	// Stores the hash of the document in the mapping
+	function put( bytes32 hash ) public {
+                require( hashes[hash] == 0, "That checksum has already been stored." );
+		hashes[hash] = block.number;
+	}
+
+	// Returns the block number in which the hash was first seen
+	function get( bytes32 hash ) public view returns (uint) {
+                require( hashes[hash] != 0, "That checksum has never been stored." );
+		return hashes[hash];
+	}
+}