Start of HTTP Signatures.

lib/pleroma/web/http_signatures/http_signatures.ex

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+# https://tools.ietf.org/html/draft-cavage-http-signatures-08
+defmodule Pleroma.Web.HTTPSignatures do
+  def split_signature(sig) do
+    default = %{"headers" => ["date"]}
+
+    sig
+    |> String.trim()
+    |> String.split(",")
+    |> Enum.reduce(default, fn(part, acc) ->
+      [key | rest] = String.split(part, "=")
+      value = Enum.join(rest, "=")
+      Map.put(acc, key, String.trim(value, "\""))
+    end)
+  end
+
+  def validate(headers, signature, public_key) do
+    sigstring = build_signing_string(headers, signature["headers"])
+    {:ok, sig} = Base.decode64(signature["signature"])
+    verify = :public_key.verify(sigstring, :sha256, sig, public_key)
+  end
+
+  def build_signing_string(headers, used_headers) do
+    used_headers
+    |> Enum.map(fn (header) -> "#{header}: #{headers[header]}" end)
+    |> Enum.join("\n")
+  end
+end

test/web/http_sigs/http_sig_test.exs

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+# http signatures
+# Test data from https://tools.ietf.org/html/draft-cavage-http-signatures-08#appendix-C
+defmodule Pleroma.Web.HTTPSignaturesTest do
+  use Pleroma.DataCase
+  alias Pleroma.Web.HTTPSignatures
+
+  @private_key (hd(:public_key.pem_decode(File.read!("test/web/http_sigs/priv.key")))
+    |> :public_key.pem_entry_decode())
+
+  @public_key (hd(:public_key.pem_decode(File.read!("test/web/http_sigs/pub.key")))
+    |> :public_key.pem_entry_decode())
+
+  @headers %{
+    "(request-target)" => "post /foo?param=value&pet=dog",
+    "host" => "example.com",
+    "date" => "Thu, 05 Jan 2014 21:31:40 GMT",
+    "content-type" => "application/json",
+    "digest" => "SHA-256=X48E9qOokqqrvdts8nOJRJN3OWDUoyWxBf7kbu9DBPE=",
+    "content-length" => "18"
+  }
+
+  @body "{\"hello\": \"world\"}"
+
+  @default_signature """
+  keyId="Test",algorithm="rsa-sha256",signature="jKyvPcxB4JbmYY4mByyBY7cZfNl4OW9HpFQlG7N4YcJPteKTu4MWCLyk+gIr0wDgqtLWf9NLpMAMimdfsH7FSWGfbMFSrsVTHNTk0rK3usrfFnti1dxsM4jl0kYJCKTGI/UWkqiaxwNiKqGcdlEDrTcUhhsFsOIo8VhddmZTZ8w="
+  """
+
+  test "split up a signature" do
+    expected = %{
+      "keyId" => "Test",
+      "algorithm" => "rsa-sha256",
+      "signature" => "jKyvPcxB4JbmYY4mByyBY7cZfNl4OW9HpFQlG7N4YcJPteKTu4MWCLyk+gIr0wDgqtLWf9NLpMAMimdfsH7FSWGfbMFSrsVTHNTk0rK3usrfFnti1dxsM4jl0kYJCKTGI/UWkqiaxwNiKqGcdlEDrTcUhhsFsOIo8VhddmZTZ8w=",
+      "headers" => ["date"]
+    }
+
+    assert HTTPSignatures.split_signature(@default_signature) == expected
+  end
+
+  test "validates the default case" do
+    signature = HTTPSignatures.split_signature(@default_signature)
+    assert HTTPSignatures.validate(@headers, signature, @public_key)
+  end
+
+  test "it contructs a signing string" do
+    expected = "date: Thu, 05 Jan 2014 21:31:40 GMT\ncontent-length: 18"
+    assert expected == HTTPSignatures.build_signing_string(@headers, ["date", "content-length"])
+  end
+end

test/web/http_sigs/priv.key

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+-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----

test/web/http_sigs/pub.key

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+-----BEGIN PUBLIC KEY-----
+MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDCFENGw33yGihy92pDjZQhl0C3
+6rPJj+CvfSC8+q28hxA161QFNUd13wuCTUcq0Qd2qsBe/2hFyc2DCJJg0h1L78+6
+Z4UMR7EOcpfdUE9Hf3m/hs+FUR45uBJeDK1HSFHD8bHKD6kv8FPGfJTotc+2xjJw
+oYi+1hqp1fIekaxsyQIDAQAB
+-----END PUBLIC KEY-----