Multihash implementation in Elixir
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README.md

ex_multihash

hex.pm version API Docs Travis CI Inline docs

Multihash implementation in Elixir

This is the Multihash implementation in Elixir.

Table of Contents

Install

To use ex_multihash add to your mix.exs file:

defp deps do
  [
    {:ex_multihash, "~> 1.0"}
  ]
end

Usage

Encoding

Encode the provided hashed digest to the provided multihash of hash_code.

Examples

iex> Multihash.encode(:sha1, :crypto.hash(:sha, "Hello"))
{:ok, <<17, 20, 247, 255, 158, 139, 123, 178, 224, 155, 112, 147, 90, 93, 120, 94, 12, 197, 217, 208, 171, 240>>}

iex> Multihash.encode(:sha2_256, :crypto.hash(:sha256, "Hello"))
{:ok, <<18, 32, 24, 95, 141, 179, 34, 113, 254, 37, 245, 97, 166, 252, 147, 139, 46, 38, 67, 6, 236, 48, 78, 218, 81, 128, 7, 209, 118, 72, 38, 56, 25, 105>>}

Invalid hash_code or digest corresponding to the hash function will return an error.

Examples

iex> Multihash.encode(:sha2_unknow, :crypto.hash(:sha, "Hello"))
{:error, "Invalid hash function"}

iex> Multihash.encode(0x20, :crypto.hash(:sha, "Hello"))
{:error, "Invalid hash code"}

It's possible to truncate a digest by passing an optional length parameter. Passing a length longer than the default digest length of the hash function will return an error.

Examples

iex> Multihash.encode(:sha1, :crypto.hash(:sha, "Hello"), 10)
{:ok, <<17, 10, 247, 255, 158, 139, 123, 178, 224, 155, 112, 147>>}
iex> Multihash.encode(:sha1, :crypto.hash(:sha, "Hello"), 30)
{:error, "Invalid digest length"}

Decoding

Decode the provided multihash to:

%Multihash{name: atom, code: integer, length: integer, digest: bitstring}

Examples

iex> Multihash.decode(<<17, 20, 247, 255, 158, 139, 123, 178, 224, 155, 112, 147, 90, 93, 120, 94, 12, 197, 217, 208, 171, 240>>)
{:ok, %Multihash{name: :sha1, code: 17, length: 20, digest: <<247, 255, 158, 139, 123, 178, 224, 155, 112, 147, 90, 93, 120, 94, 12, 197, 217, 208, 171, 240>>}}

Invalid multihash will result in errors

Examples

iex> Multihash.decode(<<17, 20, 247, 255, 158, 139, 123, 178, 224, 155, 112, 147, 90, 93, 120, 94, 12, 197, 217, 208, 171>>)
{:error, "Invalid size"}

iex> Multihash.decode(<<17, 22, 247, 255, 158, 139, 123, 178, 224, 155, 112, 147, 90, 93, 120, 94, 12, 197, 217, 208, 171, 20, 21, 22>>)
{:error, "Invalid digest length"}

iex> Multihash.decode(<<25, 20, 247, 255, 158, 139, 123, 178, 224, 155, 112, 147, 90, 93, 120, 94, 12, 197, 217, 208, 171, 240>>)
{:error, "Invalid hash code"}

iex> Multihash.decode(<<17, 32, 247, 255, 158, 139, 123, 178, 224, 155, 112, 147, 90, 93, 120, 94, 12, 197, 217, 208, 171, 240>>)
{:error, "Invalid length of provided hash function"}

iex> Multihash.decode("Hello")
{:error, "Invalid hash code"}

Maintainers

Captain: @zabirauf.

Contribute

Contributions welcome. Please check out the issues.

Check out our contributing document for more information on how we work, and about contributing in general. Please be aware that all interactions related to multiformats are subject to the IPFS Code of Conduct.

Small note: If editing the Readme, please conform to the standard-readme specification.

License

MIT © 2015 Zohaib Rauf.