diff --git a/src/stages/ast_simplified/combinators.ml b/src/stages/ast_simplified/combinators.ml
index 7a5b2cf08..8de9f5b77 100644
--- a/src/stages/ast_simplified/combinators.ml
+++ b/src/stages/ast_simplified/combinators.ml
@@ -39,6 +39,7 @@ let t_address      : type_expression = make_t @@ T_constant (TC_address)
 let t_signature    : type_expression = make_t @@ T_constant (TC_signature)
 let t_key          : type_expression = make_t @@ T_constant (TC_key)
 let t_key_hash     : type_expression = make_t @@ T_constant (TC_key_hash)
+let t_timestamp    : type_expression = make_t @@ T_constant (TC_timestamp)
 let t_option  o    : type_expression = make_t @@ T_operator (TC_option o)
 let t_list  t      : type_expression = make_t @@ T_operator (TC_list t)
 let t_variable n   : type_expression = make_t @@ T_variable (Var.of_name n)
diff --git a/src/stages/ast_simplified/combinators.mli b/src/stages/ast_simplified/combinators.mli
index 9f47482ba..9b18599be 100644
--- a/src/stages/ast_simplified/combinators.mli
+++ b/src/stages/ast_simplified/combinators.mli
@@ -21,6 +21,7 @@ val t_unit      : type_expression
 val t_address   : type_expression
 val t_key       : type_expression
 val t_key_hash  : type_expression
+val t_timestamp : type_expression
 val t_signature : type_expression
 (*
 val t_option    : type_expression -> type_expression
diff --git a/src/test/contracts/hashlock.mligo b/src/test/contracts/hashlock.mligo
new file mode 100644
index 000000000..1f6fa02a1
--- /dev/null
+++ b/src/test/contracts/hashlock.mligo
@@ -0,0 +1,56 @@
+type commit = {
+  date: timestamp;
+  salted_hash: bytes;
+}
+
+type commit_set = (address, commit) big_map
+
+type storage = {
+  hashed: bytes;
+  unused: bool;
+  commits: commit_set;
+}
+
+type reveal = {
+  hashable: bytes;
+  message: unit -> operation list;
+}
+
+type parameter =
+| Commit of bytes
+| Reveal of reveal
+
+(* We use hash-commit so that a baker can't steal *)
+let commit ((p,s): bytes * storage) : operation list * storage =
+  let commit: commit = {date = Current.time + 86400; salted_hash = p;} in
+  let updated_map: commit_set = Big_map.update sender (Some commit) s.commits in
+  let s = {hashed = s.hashed; unused = s.unused; commits = updated_map} in
+  (([]: operation list), s)
+
+let reveal ((p,s): reveal * storage) : operation list * storage =
+  if not s.unused
+  then (failwith "This contract has already been used.": operation list * storage)
+  else
+  let commit: commit =
+    match (Big_map.find_opt sender s.commits) with
+    | Some c -> c
+    | None -> (failwith "You haven't made a commitment to hash against yet.": commit)
+  in
+  if Current.time < commit.date
+  then (failwith "It hasn't been 24 hours since your commit yet.": operation list * storage)
+  else
+  let salted = Crypto.sha256 (Bytes.concat p.hashable (Bytes.pack sender)) in
+  if (salted <> commit.salted_hash)
+  then (failwith "This reveal doesn't match your commitment.": operation list * storage)
+  else
+  if (s.hashed = Crypto.sha256 p.hashable) 
+  then
+    let s: storage = {hashed = s.hashed; unused = false; commits = s.commits} in
+    ((p.message ()), s)
+  else (failwith "Your commitment did not match the storage hash.":
+          operation list * storage)
+
+let main ((p,s): parameter * storage) : operation list * storage =
+  match p with
+  | Commit c -> commit (c, s)
+  | Reveal r -> reveal (r, s)
diff --git a/src/test/hash_lock_tests.ml b/src/test/hash_lock_tests.ml
new file mode 100644
index 000000000..bff1e8219
--- /dev/null
+++ b/src/test/hash_lock_tests.ml
@@ -0,0 +1,274 @@
+open Trace
+open Test_helpers
+open Ast_simplified
+
+let type_file f =
+  let%bind simplified  = Ligo.Compile.Of_source.compile f (Syntax_name "cameligo") in
+  let%bind typed,state = Ligo.Compile.Of_simplified.compile simplified in
+  ok @@ (typed,state)
+
+let get_program =
+  let s = ref None in
+  fun () -> match !s with
+    | Some s -> ok s
+    | None -> (
+        let%bind program = type_file "./contracts/hashlock.mligo" in
+        s := Some program ;
+        ok program
+      )
+
+let compile_main () =
+  let%bind simplified      = Ligo.Compile.Of_source.compile "./contracts/hashlock.mligo" (Syntax_name "cameligo") in
+  let%bind typed_prg,_ = Ligo.Compile.Of_simplified.compile simplified in
+  let%bind mini_c_prg      = Ligo.Compile.Of_typed.compile typed_prg in
+  let%bind michelson_prg   = Ligo.Compile.Of_mini_c.aggregate_and_compile_contract mini_c_prg "main" in
+  let%bind (_contract: Tezos_utils.Michelson.michelson) =
+    (* fails if the given entry point is not a valid contract *)
+    Ligo.Compile.Of_michelson.build_contract michelson_prg in
+  ok ()
+
+let call msg = e_constructor "Call" msg
+let mk_time st =
+  match Memory_proto_alpha.Protocol.Alpha_context.Timestamp.of_notation st with
+  | Some s -> ok s
+  | None -> simple_fail "bad timestamp notation"
+let to_sec t = Tezos_utils.Time.Protocol.to_seconds t
+let storage hashed used commits =
+  e_record_ez [("hashed", hashed);
+               ("unused", e_bool used);
+               ("commits", commits)]
+
+let (first_committer , first_contract) =
+  let open Proto_alpha_utils.Memory_proto_alpha in
+  let id = List.nth dummy_environment.identities 0 in
+  let kt = id.implicit_contract in
+  Protocol.Alpha_context.Contract.to_b58check kt , kt
+
+let empty_op_list =
+  (e_typed_list [] t_operation)
+let empty_message = e_lambda (Var.of_name "arguments")
+  (Some t_unit) (Some (t_list t_operation))
+  empty_op_list
+
+
+let commit () =
+  let%bind program,_ = get_program () in
+  let%bind predecessor_timestamp = mk_time "2000-01-01T00:10:10Z" in
+  let%bind lock_time = mk_time "2000-01-02T00:10:11Z" in
+  let test_hash_raw = sha_256_hash (Bytes.of_string "hello world") in
+  let test_hash = e_bytes_raw test_hash_raw in
+  let%bind packed_sender = pack_payload program (e_address first_committer) in
+  let salted_hash = e_bytes_raw (sha_256_hash
+                                   (Bytes.concat Bytes.empty [test_hash_raw;
+                                                              packed_sender]))
+ 
+  in
+  let pre_commits = e_typed_big_map [] t_address (t_record_ez [("date", t_timestamp);
+                                                              ("salted_hash", t_bytes)])
+  in
+  let init_storage = storage test_hash true pre_commits in
+  let commit =
+    e_record_ez [("date", e_timestamp
+                    (Int64.to_int (to_sec lock_time)));
+                 ("salted_hash", salted_hash)]
+  in
+  let post_commits = e_big_map [((e_address first_committer), commit)]
+  in
+  let post_storage = storage test_hash true post_commits in
+  let options =
+    Proto_alpha_utils.Memory_proto_alpha.make_options
+      ~predecessor_timestamp
+      ~payer:first_contract
+      ()
+  in
+  expect_eq ~options program "commit"
+    (e_pair salted_hash init_storage) (e_pair empty_op_list post_storage)
+
+(* Test that the contract fails if we haven't committed before revealing the answer *)
+let reveal_no_commit () =
+  let%bind program,_ = get_program () in
+  let empty_message = empty_message in
+  let reveal = e_record_ez [("hashable", e_bytes_string "hello world");
+                            ("message", empty_message)]
+  in
+  let test_hash_raw = sha_256_hash (Bytes.of_string "hello world") in
+  let test_hash = e_bytes_raw test_hash_raw in
+  let pre_commits = e_typed_big_map [] t_address (t_record_ez [("date", t_timestamp);
+                                                              ("salted_hash", t_bytes)])
+  in
+  let init_storage = storage test_hash true pre_commits in
+  expect_string_failwith program "reveal"
+    (e_pair reveal init_storage)
+    "You haven't made a commitment to hash against yet."
+
+(* Test that the contract fails if our commit isn't 24 hours old yet *)
+let reveal_young_commit () =
+  let%bind program,_ = get_program () in
+  let empty_message = empty_message in
+  let reveal = e_record_ez [("hashable", e_bytes_string "hello world");
+                            ("message", empty_message)]
+  in
+  let%bind predecessor_timestamp = mk_time "2000-01-01T00:10:10Z" in
+  let%bind lock_time = mk_time "2000-01-02T00:10:11Z" in
+  let test_hash_raw = sha_256_hash (Bytes.of_string "hello world") in
+  let test_hash = e_bytes_raw test_hash_raw in
+  let%bind packed_sender = pack_payload program (e_address first_committer) in
+  let salted_hash = e_bytes_raw (sha_256_hash
+                                   (Bytes.concat Bytes.empty [test_hash_raw;
+                                                              packed_sender])) in
+  let commit =
+    e_record_ez [("date", e_timestamp
+                    (Int64.to_int (to_sec lock_time)));
+                 ("salted_hash", salted_hash)]
+  in
+  let commits = e_big_map [((e_address first_committer), commit)]
+  in
+  let init_storage = storage test_hash true commits in
+  let options =
+    Proto_alpha_utils.Memory_proto_alpha.make_options
+      ~predecessor_timestamp
+      ~payer:first_contract
+      ()
+  in
+  expect_string_failwith ~options program "reveal"
+    (e_pair reveal init_storage)
+    "It hasn't been 24 hours since your commit yet."
+
+(* Test that the contract fails if our reveal doesn't meet our commitment *)
+let reveal_breaks_commit () =
+  let%bind program,_ = get_program () in
+  let empty_message = empty_message in
+  let reveal = e_record_ez [("hashable", e_bytes_string "hello world");
+                            ("message", empty_message)]
+  in
+  let%bind predecessor_timestamp = mk_time "2000-01-01T00:10:10Z" in
+  let test_hash_raw = sha_256_hash (Bytes.of_string "hello world") in
+  let test_hash = e_bytes_raw test_hash_raw in
+  let%bind packed_sender = pack_payload program (e_address first_committer) in
+  let salted_hash = e_bytes_raw (sha_256_hash
+                                   (Bytes.concat Bytes.empty [Bytes.of_string "hello";
+                                                              packed_sender])) in
+  let commit =
+    e_record_ez [("date", e_timestamp
+                    (Int64.to_int (to_sec predecessor_timestamp)));
+                 ("salted_hash", salted_hash)]
+  in
+  let commits = e_big_map [((e_address first_committer), commit)]
+  in
+  let init_storage = storage test_hash true commits in
+  let options =
+    Proto_alpha_utils.Memory_proto_alpha.make_options
+      ~predecessor_timestamp
+      ~payer:first_contract
+      ()
+  in
+  expect_string_failwith ~options program "reveal"
+    (e_pair reveal init_storage)
+    "This reveal doesn't match your commitment."
+
+(* Test that the contract fails if we reveal the wrong bytes for the stored hash *)
+let reveal_wrong_commit () =
+  let%bind program,_ = get_program () in
+  let empty_message = empty_message in
+  let reveal = e_record_ez [("hashable", e_bytes_string "hello");
+                            ("message", empty_message)]
+  in
+  let%bind predecessor_timestamp = mk_time "2000-01-01T00:10:10Z" in
+  let test_hash_raw = sha_256_hash (Bytes.of_string "hello world") in
+  let test_hash = e_bytes_raw test_hash_raw in
+  let%bind packed_sender = pack_payload program (e_address first_committer) in
+  let salted_hash = e_bytes_raw (sha_256_hash
+                                   (Bytes.concat Bytes.empty [Bytes.of_string "hello";
+                                                              packed_sender])) in
+  let commit =
+    e_record_ez [("date", e_timestamp
+                    (Int64.to_int (to_sec predecessor_timestamp)));
+                 ("salted_hash", salted_hash)]
+  in
+  let commits = e_big_map [((e_address first_committer), commit)]
+  in
+  let init_storage = storage test_hash true commits in
+  let options =
+    Proto_alpha_utils.Memory_proto_alpha.make_options
+      ~predecessor_timestamp
+      ~payer:first_contract
+      ()
+  in
+  expect_string_failwith ~options program "reveal"
+    (e_pair reveal init_storage)
+    "Your commitment did not match the storage hash."
+
+(* Test that the contract fails if we try to reuse it after unused flag changed *)
+let reveal_no_reuse () = 
+  let%bind program,_ = get_program () in
+  let empty_message = empty_message in
+  let reveal = e_record_ez [("hashable", e_bytes_string "hello");
+                            ("message", empty_message)]
+  in
+  let%bind predecessor_timestamp = mk_time "2000-01-01T00:10:10Z" in
+  let test_hash_raw = sha_256_hash (Bytes.of_string "hello world") in
+  let test_hash = e_bytes_raw test_hash_raw in
+  let%bind packed_sender = pack_payload program (e_address first_committer) in
+  let salted_hash = e_bytes_raw (sha_256_hash
+                                   (Bytes.concat Bytes.empty [Bytes.of_string "hello";
+                                                              packed_sender])) in
+  let commit =
+    e_record_ez [("date", e_timestamp
+                    (Int64.to_int (to_sec predecessor_timestamp)));
+                 ("salted_hash", salted_hash)]
+  in
+  let commits = e_big_map [((e_address first_committer), commit)]
+  in
+  let init_storage = storage test_hash false commits in
+  let options =
+    Proto_alpha_utils.Memory_proto_alpha.make_options
+      ~predecessor_timestamp
+      ~payer:first_contract
+      ()
+  in
+  expect_string_failwith ~options program "reveal"
+    (e_pair reveal init_storage)
+    "This contract has already been used."
+
+(* Test that the contract executes successfully with valid commit-reveal *)
+let reveal () =
+  let%bind program,_ = get_program () in
+  let empty_message = empty_message in
+  let reveal = e_record_ez [("hashable", e_bytes_string "hello world");
+                            ("message", empty_message)]
+  in
+  let%bind predecessor_timestamp = mk_time "2000-01-01T00:10:10Z" in
+  let test_hash_raw = sha_256_hash (Bytes.of_string "hello world") in
+  let test_hash = e_bytes_raw test_hash_raw in
+  let%bind packed_sender = pack_payload program (e_address first_committer) in
+  let salted_hash = e_bytes_raw (sha_256_hash
+                                   (Bytes.concat Bytes.empty [Bytes.of_string "hello world";
+                                                              packed_sender])) in
+  let commit =
+    e_record_ez [("date", e_timestamp
+                    (Int64.to_int (to_sec predecessor_timestamp)));
+                 ("salted_hash", salted_hash)]
+  in
+  let commits = e_big_map [((e_address first_committer), commit)]
+  in
+  let init_storage = storage test_hash true commits in
+  let post_storage = storage test_hash false commits in
+  let options =
+    Proto_alpha_utils.Memory_proto_alpha.make_options
+      ~predecessor_timestamp
+      ~payer:first_contract
+      ()
+  in
+  expect_eq ~options program "reveal"
+    (e_pair reveal init_storage) (e_pair empty_op_list post_storage)
+
+let main = test_suite "Hashlock" [
+    test "compile" compile_main ;
+    test "commit" commit ;
+    test "reveal (fail if no commitment)" reveal_no_commit ;
+    test "reveal (fail if commit too young)" reveal_young_commit ;
+    test "reveal (fail if breaks commitment)" reveal_breaks_commit ;
+    test "reveal (fail if wrong bytes for hash)" reveal_wrong_commit ;
+    test "reveal (fail if attempt to reuse)" reveal_no_reuse ;
+    test "reveal" reveal ;
+]
diff --git a/src/test/test.ml b/src/test/test.ml
index 2505721e0..617e1cf77 100644
--- a/src/test/test.ml
+++ b/src/test/test.ml
@@ -15,6 +15,7 @@ let () =
     Multisig_v2_tests.main ;
     Replaceable_id_tests.main ;
     Time_lock_tests.main ;
+    Hash_lock_tests.main ;
     Time_lock_repeat_tests.main ;
   ] ;
   ()