Crypto: Only extract checksum when there's one

Specifically, check that there are enough characters to extract the 4-characters
checksum of safe-encoded strings.

The commit also introduces new tests for some parts of the crypto library.

src/lib_crypto/base58.ml

@@ -126,10 +126,12 @@ let safe_encode ?alphabet s =
 let safe_decode ?alphabet s =
   raw_decode ?alphabet s |> Option.apply ~f:begin fun s ->
     let len = String.length s in
-    let msg = String.sub s 0 (len-4) in
-    let msg_hash = String.sub s (len-4) 4 in
-    if msg_hash <> checksum msg then None
-    else Some msg
+    if len < 4 then None else
+      (* only if the string is long enough to extract a checksum do we check it *)
+      let msg = String.sub s 0 (len-4) in
+      let msg_hash = String.sub s (len-4) 4 in
+      if msg_hash <> checksum msg then None
+      else Some msg
   end
 
 type data = ..

src/lib_crypto/test/jbuild

@@ -1,7 +1,10 @@
 (jbuild_version 1)
 
 (executables
- ((names (test_merkle))
+ ((names (test_merkle
+          test_base58
+          test_ed25519
+          test_blake2b))
   (libraries (tezos-stdlib
               tezos-crypto
               alcotest))
@@ -12,15 +15,33 @@
 
 (alias
   ((name buildtest)
-   (deps (test_merkle.exe))))
+   (deps (test_merkle.exe
+          test_base58.exe
+          test_ed25519.exe
+          test_blake2b.exe))))
 
 (alias
  ((name runtest_merkle)
   (action (run ${exe:test_merkle.exe}))))
 
+(alias
+ ((name runtest_base58)
+  (action (run ${exe:test_base58.exe}))))
+
+(alias
+ ((name runtest_ed25519)
+  (action (run ${exe:test_ed25519.exe}))))
+
+(alias
+ ((name runtest_blake2b)
+  (action (run ${exe:test_blake2b.exe}))))
+
 (alias
  ((name runtest)
-  (deps ((alias runtest_merkle)))))
+  (deps ((alias runtest_merkle)
+         (alias runtest_base58)
+         (alias runtest_ed25519)
+         (alias runtest_blake2b)))))
 
 (alias
  ((name runtest_indent)

src/lib_crypto/test/roundtrips.ml

@@ -0,0 +1,46 @@
+(**************************************************************************)
+(*                                                                        *)
+(*    Copyright (c) 2014 - 2018.                                          *)
+(*    Dynamic Ledger Solutions, Inc. <contact@tezos.com>                  *)
+(*                                                                        *)
+(*    All rights reserved. No warranty, explicit or implicit, provided.   *)
+(*                                                                        *)
+(**************************************************************************)
+
+
+let test_rt_opt name pp enc dec input =
+  let encoded = enc input in
+  match dec encoded with
+  | Some output ->
+      if output = input then
+        ()
+      else
+        Format.kasprintf failwith
+          "%s failed for %a: got %a" name pp input pp output
+  | None ->
+      Format.kasprintf failwith
+        "%s failed for %a: unable to decode" name pp input
+  | exception exc ->
+      Format.kasprintf failwith
+        "%s failed for %a: exception whilst decoding: %s"
+        name pp input (Printexc.to_string exc)
+
+let test_decode_opt_safe name pp dec encoded =
+  match dec encoded with
+  | Some _ | None -> ()
+  | exception exc ->
+      Format.kasprintf failwith
+        "%s failed for %a: exception whilst decoding: %s"
+        name pp encoded (Printexc.to_string exc)
+
+let test_decode_opt_fail name pp dec encoded =
+  match dec encoded with
+  | Some _ ->
+      Format.kasprintf failwith
+        "%s failed for %a: successful decoding of invalid input"
+        name pp encoded
+  | None -> ()
+  | exception exc ->
+      Format.kasprintf failwith
+        "%s failed for %a: exception whilst decoding: %s"
+        name pp encoded (Printexc.to_string exc)

src/lib_crypto/test/test_base58.ml

@@ -0,0 +1,77 @@
+(**************************************************************************)
+(*                                                                        *)
+(*    Copyright (c) 2014 - 2018.                                          *)
+(*    Dynamic Ledger Solutions, Inc. <contact@tezos.com>                  *)
+(*                                                                        *)
+(*    All rights reserved. No warranty, explicit or implicit, provided.   *)
+(*                                                                        *)
+(**************************************************************************)
+
+let test_roundtrip_safe input =
+  Roundtrips.test_rt_opt
+    "safe base58"
+    Format.pp_print_string
+    Base58.safe_encode
+    Base58.safe_decode
+    input
+
+let test_roundtrip_raw input =
+  Roundtrips.test_rt_opt
+    "raw base58"
+    Format.pp_print_string
+    Base58.raw_encode
+    Base58.raw_decode
+    input
+
+let inputs = [
+  "abc";
+  (string_of_int max_int);
+  "0";
+  "00";
+  "000";
+  "0000";
+  "0000000000000000";
+  (String.make 64 '0');
+  "1";
+  "11";
+  "111";
+  "1111";
+  (String.make 2048 '0');
+  "2";
+  "22";
+  "5";
+  "Z";
+  (String.make 2048 'Z');
+  "z";
+  "zz";
+  "zzzzzzzz";
+  (String.make 2048 'z');
+  (*loads of ascii characters: codes between 32 and 126 *)
+  (String.init 1000 (fun i -> (Char.chr (32 + (i mod (126 - 32))))));
+  "";
+]
+
+let test_roundtrip_safes () = List.iter test_roundtrip_safe inputs
+
+let test_roundtrip_raws () = List.iter test_roundtrip_raw inputs
+
+
+let test_safety input =
+  Roundtrips.test_decode_opt_safe
+    "safe base58"
+    Format.pp_print_string
+    Base58.safe_decode
+    input
+
+let test_safetys () = List.iter test_safety inputs
+
+let tests = [
+  "safe decoding", `Quick, test_safetys;
+  "safe encoding/decoding", `Quick, test_roundtrip_safes;
+  "raw encoding/decoding", `Quick, test_roundtrip_raws;
+]
+
+let () =
+  Alcotest.run "tezos-crypto" [
+    "base58", tests
+  ]

src/lib_crypto/test/test_blake2b.ml

@@ -0,0 +1,51 @@
+(**************************************************************************)
+(*                                                                        *)
+(*    Copyright (c) 2014 - 2018.                                          *)
+(*    Dynamic Ledger Solutions, Inc. <contact@tezos.com>                  *)
+(*                                                                        *)
+(*    All rights reserved. No warranty, explicit or implicit, provided.   *)
+(*                                                                        *)
+(**************************************************************************)
+
+let test_hashed_roundtrip name enc dec input =
+  (* this wrapper to start with hashing *)
+  Roundtrips.test_rt_opt
+    name
+    (fun fmt (input, _) -> Format.fprintf fmt "%s" input)
+    (fun (_, hashed) -> enc hashed)
+    (fun encoded -> match dec encoded with
+       | None -> None
+       | Some decoded -> Some (input, decoded)
+    )
+    (input, Blake2B.hash_string [input])
+
+let test_roundtrip_hex input =
+  test_hashed_roundtrip "Hex" Blake2B.to_hex Blake2B.of_hex_opt input
+
+let test_roundtrip_string input =
+  test_hashed_roundtrip "String" Blake2B.to_string Blake2B.of_string_opt input
+
+let inputs = [
+  "abc";
+  (string_of_int max_int);
+  "0";
+  "00";
+  (String.make 64 '0');
+  (*loads of ascii characters: codes between 32 and 126 *)
+  (String.init 1000 (fun i -> (Char.chr (32 + (i mod (126 - 32))))));
+  "";
+]
+
+let test_roundtrip_hexs () = List.iter test_roundtrip_hex inputs
+
+let test_roundtrip_strings () = List.iter test_roundtrip_string inputs
+
+let tests = [
+  "hash hex/dehex", `Quick, test_roundtrip_hexs;
+  "hash print/parse", `Quick, test_roundtrip_strings;
+]
+
+let () =
+  Alcotest.run "tezos-crypto" [
+    "blake2b", tests
+  ]

src/lib_crypto/test/test_ed25519.ml

@@ -0,0 +1,58 @@
+(**************************************************************************)
+(*                                                                        *)
+(*    Copyright (c) 2014 - 2018.                                          *)
+(*    Dynamic Ledger Solutions, Inc. <contact@tezos.com>                  *)
+(*                                                                        *)
+(*    All rights reserved. No warranty, explicit or implicit, provided.   *)
+(*                                                                        *)
+(**************************************************************************)
+
+let get_keys () =
+  let seed = Ed25519.Seed.generate () in
+  Ed25519.generate_seeded_key seed
+
+module type B58CHECK = sig
+  type t
+  val pp: Format.formatter -> t -> unit
+  include S.B58_DATA with type t := t
+end
+
+let test_b58check_roundtrip
+  : type t. (module B58CHECK with type t = t) -> t -> unit
+  = fun m input ->
+    let module M = (val m) in
+    Roundtrips.test_rt_opt "b58check" M.pp M.to_b58check M.of_b58check_opt input
+
+let test_b58check_roundtrips () =
+  let (pubkey_hash, pubkey, seckey) = get_keys () in
+  test_b58check_roundtrip (module Ed25519.Public_key_hash) pubkey_hash;
+  test_b58check_roundtrip (module Ed25519.Public_key) pubkey;
+  test_b58check_roundtrip (module Ed25519.Secret_key) seckey
+
+
+let test_b58check_invalid input =
+  Roundtrips.test_decode_opt_fail
+    "b58check"
+    Format.pp_print_string
+    Ed25519.Public_key_hash.of_b58check_opt
+    input
+
+let test_b58check_invalids () =
+  List.iter test_b58check_invalid [
+    "ThisIsGarbageNotACheck";
+    "\x00";
+    (String.make 1000 '\x00');
+    (String.make 2048 'a');
+    (String.init 2048 (fun _ -> Char.chr (Random.int 256)));
+    "";
+  ]
+
+let tests = [
+  "b58check.roundtrip", `Quick, test_b58check_roundtrips;
+  "b58check.invalid", `Slow, test_b58check_invalids;
+]
+
+let () =
+  Alcotest.run "tezos-crypto" [
+    "ed25519", tests
+  ]