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Shell: reduce difficulty for P2P identity...

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... until we properly store the nonce in the configuration file,
together with the expected difficulty.
This commit is contained in:
Grégoire Henry 2016-11-25 18:03:57 +01:00
parent 710e3e755a
commit daf3343dc1
2 changed files with 22 additions and 26 deletions
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45
src/utils/crypto_box.ml
View File

@ -15,10 +15,7 @@ type secret_key = Sodium.Box.secret_key
type public_key = Sodium.Box.public_key
type channel_key = Sodium.Box.channel_key
type nonce = Sodium.Box.nonce
(* target ought to be an unsigned 256 bit integer
but this representation works better with ocplib-endian; make
sure target has length 16! *)
type target = int list
type target = int64 list (* used as unsigned intergers... *)
exception TargetNot256Bit
let random_keypair = Sodium.Box.random_keypair
@ -29,33 +26,33 @@ let box_open sk pk msg nonce =
try Some (Sodium.Box.Bigbytes.box_open sk pk msg nonce) with
| Sodium.Verification_failure -> None
let validate_target target =
if List.length target <> 16 then raise TargetNot256Bit;
if List.for_all (fun t -> t < 0 || t >= 1 lsl 16) target
then raise TargetNot256Bit
let make_target target =
if List.length target > 8 then raise TargetNot256Bit ;
target
(* compare a SHA256 hash to a 256 bit target *)
let compare_target xs target =
let hash =
let hash = Cryptokit.Hash.sha256 () in
List.iter (fun b -> hash#add_string (MBytes.to_string b)) xs;
let r = hash#result in hash#wipe; r in
let bytes = MBytes.of_string hash in
let get_16 = EndianBigstring.BigEndian.get_uint16 bytes in
let offsets = [0;2;4;6;8;10;12;14;16;18;20;22;24;26;28;30] in
List.for_all2 (fun o t -> get_16 o <= t) offsets target
(* Compare a SHA256 hash to a 256bits-target prefix.
The prefix is a list of "unsigned" int64. *)
let compare_target hash target =
let rec check offset = function
| [] -> true
| x :: xs ->
Compare.Uint64.(EndianString.BigEndian.get_int64 hash offset < x)
&& check (offset + 8) xs in
check 0 target
let default_target =
let x = 65535 in [0;256;x;x;x;x;x;x;x;x;x;x;x;x;x;x]
(* FIXME we use an easy target until we allow custom configuration. *)
[ Int64.shift_left 1L 48 ]
let check_proof_of_work pk nonce target =
let what_to_hash =
[ Sodium.Box.Bigbytes.of_public_key pk
; Sodium.Box.Bigbytes.of_nonce nonce ] in
compare_target what_to_hash target
let hash =
let hash = Cryptokit.Hash.sha256 () in
hash#add_string (Bytes.to_string @@ Sodium.Box.Bytes.of_public_key pk) ;
hash#add_string (Bytes.to_string @@ Sodium.Box.Bytes.of_nonce nonce) ;
let r = hash#result in hash#wipe ; r in
compare_target hash target
let generate_proof_of_work pk target =
validate_target target;
let rec loop nonce =
if check_proof_of_work pk nonce target then nonce
else loop (increment_nonce nonce) in

3
src/utils/crypto_box.mli
View File

@ -16,8 +16,7 @@ val increment_nonce : ?step:int -> nonce -> nonce
val nonce_encoding : nonce Data_encoding.t
type target
val compare_target : MBytes.t list -> target -> bool
val validate_target : target -> unit
val make_target : (* unsigned *) Int64.t list -> target
val default_target : target
type secret_key