Hydro

Libhydrogen bindings for Erlang

• Installation
  • Rebar3
  • Mix
• Usage
  • Hydro
    • dice/0
    • generic hashing
    • rand/1
    • rand_uniform/1
  • Hydro API
    • hash_keygen/0
    • random_u32/0
    • random_buf/1
    • random_uniform/1
• Reference

About

hydro provides Erlang bindings to the Hydrogen Crypto Library (libhydrogen).

Working with hydro is simple in both Erlang and Elixr.

• Erlang

1> N = hydro:rand(42).
<<115,97,120,157,28,208,118,165,137,95,122,152,195,49,52,
  188,73,136,216,201,77,183,29,144>>
1> hydro:rand(42).
<<196,216,103,100,59,248,220,7,212,176,11,59,76,54,33,27,
  87,166,157,249,120,120,106,253,233,234,148,136,133,...>>

• Elixir

iex(1)> n = :hydro.rand(42)
<<115,97,120,157,28,208,118,165,137,95,122,152,195,49,52,
  188,73,136,216,201,77,183,29,144,110,108,111,101,180...>>

Installation

Rebar3

{deps, [{hydro, "0.1.0"}]}

Mix

def deps do
  [{:hydro, "~> 0.1.0"}]
end

Usage

Hydro

dice/0

Generates and returns a random value between 0 and 0xffffffff (inclusive).

1> hydro:dice().
3397059606
2> hydro:dice().
2426160804
3> hydro:dice().
2140249458

shuffle/1

Takes and randomly sorts a list.

1> hydro:shuffle(lists:seq(1,100)).
[7,84,18,10,50,65,94,82,97,92,28,9,86,49,37,20,63,46,66,23,
 64,26,39,16,90,33,15,40,57|...]
2> hydro:shuffle(lists:seq(1,100)).
[46,3,5,17,52,38,4,50,55,21,71,80,51,54,88,30,96,18,44,42,
 87,29,68,79,65,14,34,53,99|...]
3> hydro:shuffle(lists:seq(1,100)).
[81,77,38,63,89,43,79,46,31,28,41,8,68,93,92,76,5,24,29,17,
 23,13,26,27,60,71,34,9,40|...]

rand_pick/1

Takes a list, randomly sorts it, and randomly picks an element from the list.

1> hydro:rand_pick(lists:seq(1,100)).
23
2> hydro:rand_pick(lists:seq(1,100)).
27
3> hydro:rand_pick(lists:seq(1,100)).
93
4> hydro:rand_pick(lists:seq(1,100)).
82
5> hydro:rand_pick(lists:seq(1,100)).
98
6> hydro:rand_pick(lists:seq(1,100)).
13

Generic Hashing

Note that a context is an 8 byte binary.

Single part

Without a key

1> hydro:hash(<<"context0">>, <<"msg">>, 64).
{ok,<<231,51,76,246,39,178,123,195,254,34,172,216,53,135,
      95,160,94,6,97,118,224,8,66,187,247,150,58,...>>}

With a key

1> hydro:hash(<<"context1">>, <<"msg">>, 32, hydro:hash_keygen()).
{ok,<<55,230,42,62,224,198,89,79,68,155,73,29,38,82,114,
      199,66,128,43,180,27,92,152,135,252,224,145,...>>}

Multi-part

Without a key

1> {ok, State} = hydro:hash_init(<<"context0">>, 42).
{ok,#Ref<0.4176683979.2420768776.167622>}
2> {ok, true} = hydro:hash_update(State, <<"MyMsg1">>).
{ok,true}
3> {ok, true} = hydro:hash_update(State, <<"MyMsg2">>).
{ok,true}
4> {ok, Hash} = hydro:hash_final(State, 88).
{ok,<<44,201,1,123,196,16,201,224,112,217,21,86,149,189,
      159,139,179,108,69,30,129,180,76,56,95,166,17,...>>}

With key

1> {ok, State} = hydro:hash_init(<<"context0">>, 64, hydro:hash_keygen()).
{ok,#Ref<0.1264487252.3744858120.160049>}
2> {ok, true} = hydro:hash_update(State, <<"MyMsg1">>).
{ok,true}
3> {ok, true} = hydro:hash_update(State, <<"MyMsg2">>).
{ok,true}
4> {ok, Hash} = hydro:hash_final(State, 128).
{ok,<<41,55,10,38,139,118,239,161,123,224,141,247,74,77,
      123,91,119,28,2,34,69,137,146,203,160,122,81,...>>}

rand/1

Generates and returns a random sequence of bytes up to the specified size.

1> N = hydro:rand(42).
<<115,97,120,157,28,208,118,165,137,95,122,152,195,49,52,
  188,73,136,216,201,77,183,29,144>>
1> hydro:rand(42).
<<196,216,103,100,59,248,220,7,212,176,11,59,76,54,33,27,
  87,166,157,249,120,120,106,253,233,234,148,136,133,...>>

rand_uniform/1

Generates and returns a uniform distributed random value between 0 and the supplied upper bound (exlusive).

1> hydro:rand_uniform(100*100).
1243
2> hydro:rand_uniform(100*100).
901
3> hydro:rand_uniform(100*100).
7966

Hydro API

For advanced usage there is the hydro api.

hash_keygen/0

Create a secret key suitable for use with hash*

1> hydro_api:hash_keygen().
<<196,216,103,100,59,248,220,7,212,176,11,59,76,54,33,27,
  87,166,157,249,120,120,106,253,233,234,148,136,133,...>>

random_u32/0

Generates and returns a random value between 0 and 0xffffffff (inclusive).

1> hydro_api:random_u32().
537265334
2> hydro_api:random_u32().
623392245
3> hydro_api:random_u32().
533755626
4>

random_buf/1

1> hydro_api:random_buf(42).
<<196,216,103,100,59,248,220,7,212,176,11,59,76,54,33,27,
  87,166,157,249,120,120,106,253,233,234,148,136,133,...>>
2> hydro_api:random_buf(42).
<<161,240,252,190,45,94,112,230,59,93,7,151,230,50,244,
  105,208,28,6,148,116,101,117,107,226,0,43,9,89,...>>
3> hydro_api:random_buf(42).
<<208,189,65,169,124,15,251,118,0,61,33,12,188,100,91,129,
  95,166,210,85,9,196,247,251,70,74,61,27,19,...>>

Generates and returns a random sequence of bytes up to the specified size.

random_uniform/1

Generates and returns a uniform distributed random value between 0 and the supplied upper bound (exlusive).

5> hydro_api:random_uniform(100*100).
5260
6> hydro_api:random_uniform(100*100).
6564
7> hydro_api:random_uniform(100*100).
9529

Reference

• libhydrogen