Creates an MD5 hash from simple data structures made of numbers, strings, booleans, nil, arrays or hashes.
Add this line to your application's Gemfile:
gem 'crimp'
And then execute:
$ bundle
Or install it yourself as:
$ gem install crimp
require 'crimp'
Crimp.signature({ a: { b: 1 } })
=> "ac13c15d07e5fa3992fc6b15113db900"
At the BBC we use Crimp to build keys for database and cache entries.
If you want to build a similar library with your language of choice you should be able to follow the simple specifications defined in spec/crimp_spec.rb
. Using these simple rules you will produce a string ready to be MD5 signed.
Once you get your string, is very important to be sure that you can produce the same key in any language. MD5 is your friend:
irb(main):001:0> require 'digest'
=> true
irb(main):002:0> Digest::MD5.hexdigest('abc')
=> "900150983cd24fb0d6963f7d28e17f72"
Lua 5.3.5 Copyright (C) 1994-2018 Lua.org, PUC-Rio
> md5 = require 'md5'
> md5.sumhexa('abc')
900150983cd24fb0d6963f7d28e17f72
Erlang/OTP 21 [erts-10.0.4] [source] [64-bit] [smp:4:4] [ds:4:4:10] [async-threads:1] [hipe] [dtrace]
Interactive Elixir (1.7.2) - press Ctrl+C to exit (type h() ENTER for help)
iex(1)> :crypto.hash(:md5 , "abc") |> Base.encode16() |> String.downcase
"900150983cd24fb0d6963f7d28e17f72"
> var crypto = require('crypto');
undefined
> crypto.createHash('md5').update('abc').digest('hex');
'900150983cd24fb0d6963f7d28e17f72'
To make Crimp signatures reproducible in any platform we decided to ignore Ruby symbols and treat them as strings, so:
Crimp.signature(:a) == Crimp.Signature('a')
Also Sets get transformed to Arrays:
Crimp.signature(Set.new(['a', 'b'])) == Crimp.signature(['a', 'b'])
Crimp signatures are generated against sorted collections.
Crimp.signature([1, 2]) == Crimp.signature([2, 1])
Crimp.signature({'b' => 2, 'a' => 1}) == Crimp.signature({'a' => 1, 'b' => 2})
Crimp also sorts nested collections.
Crimp.signature([1, [3, 2], 4]) == Crimp.signature([4, [2, 3], 1])
Crimp.signature({'b' => {'d' => 2,'c' => 1}, 'a' => [3, 1, 2]}) == Crimp.signature({'a' => [1, 2, 3], 'b' => { 'c' => 1, 'd' => 2 }})
Crimp will complain if you try to get a signature from an instance of some custom object:
Crimp.signature(Object.new)
=> TypeError: Expected a (String|Number|Boolean|Nil|Hash|Array), Got Object
It is your responsibility to pass a compatible representation of your object to Crimp.
Under the hood Crimp annotates the passed data structure to a nested array of primitives (strings, numbers, booleans, nils, etc.) and a single byte to indicate the type of the primitive:
Type | Byte |
---|---|
String | S |
Number | N |
Boolean | B |
nil | _ |
Array | A |
Hash | H |
You can verify it using the #annotate
method:
Crimp.annotate({ a: 1 })
=> [[[[[1, "N"], ["a", "S"]], "A"]], "H"]
Notice how Crimp marks the collection as Hash (H
) and then transforms the tuple of key/values to an Array (A
).
Here's an example with nested hashes:
Crimp.annotate({ a: { b: 'c' } })
=> [[[[["a", "S"], [[[[["b", "S"], ["c", "S"]], "A"]], "H"]], "A"]], "H"]
Before signing Crimp transforms the collection of nested array to a string.
Crimp.notation({ a: { b: 'c' } })
=> "aSbScSAHAH"
Please note the Arrays and Hash keys are sorted before signing.
Crimp.notation([3, 1, 2])
=> "1N2N3NA"
key/value tuples get sorted as well.
Crimp.notation({ a: 1 })
=> "1NaSAH"
Version | Changes |
---|---|
v0.x |
Original version of Crimp. |
v0.2.0 |
Crimp compatibility with Ruby >= 2.4, use this for legacy projects. |
v1.0.0 |
Includes breaking changes and returns different signatures from v0.2 |
- Fork it ( http://github.com/BBC-News/crimp/fork )
- Create your feature branch (
git checkout -b my-new-feature
) - Commit your changes (
git commit -am 'Add some feature'
) - Push to the branch (
git push origin my-new-feature
) - Create new Pull Request