add sha256 fingerprint to SSH key view and api to query user by ssh fingerprint

app/finders/keys_finder.rb

+# frozen_string_literal: true
+class KeysFinder
+  InvalidFingerprint = Class.new(StandardError)
+  GitLabAccessDeniedError = Class.new(StandardError)
+
+  FINGERPRINT_ATTRIBUTES = {
+    'sha256' => 'fingerprint_sha256',
+    'md5' => 'fingerprint'
+  }.freeze
+
+  def initialize(current_user, params)
+    @current_user = current_user
+    @params = params
+  end
+
+  def execute
+    raise GitLabAccessDeniedError unless current_user.admin?
+    raise InvalidFingerprint unless valid_fingerprint_param?
+
+    Key.where(fingerprint_query).first # rubocop: disable CodeReuse/ActiveRecord
+  end
+
+  private
+
+  attr_reader :current_user, :params
+
+  def valid_fingerprint_param?
+    if fingerprint_type == "sha256"
+      Base64.decode64(fingerprint).length == 32
+    else
+      fingerprint =~ /^(\h{2}:){15}\h{2}/
+    end
+  end
+
+  def fingerprint_query
+    fingerprint_attribute = FINGERPRINT_ATTRIBUTES[fingerprint_type]
+
+    Key.arel_table[fingerprint_attribute].eq(fingerprint)
+  end
+
+  def fingerprint_type
+    if params[:fingerprint].start_with?(/sha256:|SHA256:/)
+      "sha256"
+    else
+      "md5"
+    end
+  end
+
+  def fingerprint
+    if fingerprint_type == "sha256"
+      params[:fingerprint].gsub(/sha256:|SHA256:/, "")
+    else
+      params[:fingerprint]
+    end
+  end
+end

app/models/concerns/sha256_attribute.rb

+# frozen_string_literal: true
+
+module Sha256Attribute
+  extend ActiveSupport::Concern
+
+  class_methods do
+    def sha256_attribute(name)
+      return if ENV['STATIC_VERIFICATION']
+
+      validate_binary_column_exists!(name) unless Rails.env.production?
+
+      attribute(name, Gitlab::Database::Sha256Attribute.new)
+    end
+
+    # This only gets executed in non-production environments as an additional check to ensure
+    # the column is the correct type.  In production it should behave like any other attribute.
+    # See https://gitlab.com/gitlab-org/gitlab/merge_requests/5502 for more discussion
+    def validate_binary_column_exists!(name)
+      return unless database_exists?
+
+      unless table_exists?
+        warn "WARNING: sha256_attribute #{name.inspect} is invalid since the table doesn't exist - you may need to run database migrations"
+        return
+      end
+
+      column = columns.find { |c| c.name == name.to_s }
+
+      unless column
+        warn "WARNING: sha256_attribute #{name.inspect} is invalid since the column doesn't exist - you may need to run database migrations"
+        return
+      end
+
+      unless column.type == :binary
+        raise ArgumentError.new("sha256_attribute #{name.inspect} is invalid since the column type is not :binary")
+      end
+    rescue => error
+      Gitlab::AppLogger.error "Sha256Attribute initialization: #{error.message}"
+      raise
+    end
+
+    def database_exists?
+      ApplicationRecord.connection
+
+      true
+    rescue
+      false
+    end
+  end
+end

app/models/key.rb

@@ -5,6 +5,9 @@ require 'digest/md5'
 class Key < ApplicationRecord
   include AfterCommitQueue
   include Sortable
+  include Sha256Attribute
+
+  sha256_attribute :fingerprint_sha256
 
   belongs_to :user
 
@@ -34,6 +37,8 @@ class Key < ApplicationRecord
   after_destroy :post_destroy_hook
   after_destroy :refresh_user_cache
 
+  alias_attribute :fingerprint_md5, :fingerprint
+
   def self.regular_keys
     where(type: ['Key', nil])
   end
@@ -114,10 +119,12 @@ class Key < ApplicationRecord
 
   def generate_fingerprint
     self.fingerprint = nil
+    self.fingerprint_sha256 = nil
 
     return unless public_key.valid?
 
-    self.fingerprint = public_key.fingerprint
+    self.fingerprint_md5 = public_key.fingerprint
+    self.fingerprint_sha256 = public_key.fingerprint("SHA256").gsub("SHA256:", "")
   end
 
   def key_meets_restrictions

app/views/profiles/keys/_key_details.html.haml

@@ -17,11 +17,21 @@
 
   .col-md-8
     = form_errors(@key, type: 'key') unless @key.valid?
-    %p
-      %span.light= _('Fingerprint:')
-      %code.key-fingerprint= @key.fingerprint
     %pre.well-pre
       = @key.key
+    .card
+      .card-header
+        = _('Fingerprints')
+      %ul.content-list
+        %li
+          %span.light= 'MD5:'
+          %code.key-fingerprint= @key.fingerprint
+        - if @key.fingerprint_sha256.present?
+          %li
+            %span.light= 'SHA256:'
+            %code.key-fingerprint= @key.fingerprint_sha256
+
+
   .col-md-12
     .float-right
       - if @key.can_delete?

changelogs/unreleased/feat-ssh-sha256.yml

+---
+title: add sha256 fingerprint to keys model, view and extend users API to search user via fingerprint
+merge_request: 19860
+author: Roger Meier
+type: added

db/migrate/20191208071111_add_fingerprint_sha256_to_key.rb

+# frozen_string_literal: true
+
+class AddFingerprintSha256ToKey < ActiveRecord::Migration[5.0]
+  DOWNTIME = false
+
+  def up
+    add_column(:keys, :fingerprint_sha256, :binary)
+  end
+
+  def down
+    remove_column(:keys, :fingerprint_sha256) if column_exists?(:keys, :fingerprint_sha256)
+  end
+end

db/migrate/20191208071112_add_fingerprint_sha256_index_to_key.rb

+# frozen_string_literal: true
+
+class AddFingerprintSha256IndexToKey < ActiveRecord::Migration[5.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    add_concurrent_index(:keys, "fingerprint_sha256")
+  end
+
+  def down
+    remove_concurrent_index(:keys, "fingerprint_sha256")
+  end
+end

db/schema.rb

@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2019_12_06_122926) do
+ActiveRecord::Schema.define(version: 2019_12_08_071112) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "pg_trgm"
@@ -2206,7 +2206,9 @@ ActiveRecord::Schema.define(version: 2019_12_06_122926) do
     t.string "fingerprint"
     t.boolean "public", default: false, null: false
     t.datetime "last_used_at"
+    t.binary "fingerprint_sha256"
     t.index ["fingerprint"], name: "index_keys_on_fingerprint", unique: true
+    t.index ["fingerprint_sha256"], name: "index_keys_on_fingerprint_sha256"
     t.index ["id", "type"], name: "index_on_deploy_keys_id_and_type_and_public", unique: true, where: "(public = true)"
     t.index ["user_id"], name: "index_keys_on_user_id"
   end

doc/api/keys.md

@@ -4,13 +4,19 @@
 
 Get SSH key with user by ID of an SSH key. Note only administrators can lookup SSH key with user by ID of an SSH key.
 
-```
+```text
 GET /keys/:id
 ```
 
-Parameters:
+| Attribute | Type    | Required | Description          |
+|:----------|:--------|:---------|:---------------------|
+| `id`      | integer | yes      | The ID of an SSH key |
+
+Example request:
 
-- `id` (required) - The ID of an SSH key
+```sh
+curl --header "PRIVATE-TOKEN: <your_access_token>" 'https://gitlab.example.com/api/v4/keys/1
+```
 
 ```json
 {
@@ -51,3 +57,74 @@ Parameters:
   }
 }
 ```
+
+## Get user by fingerprint of SSH key
+
+You can search for a user that owns a specific SSH key. Note only administrators can lookup SSH key with the fingerprint of an SSH key.
+
+```text
+GET /keys
+```
+
+| Attribute     | Type   | Required | Description                   |
+|:--------------|:-------|:---------|:------------------------------|
+| `fingerprint` | string | yes      | The fingerprint of an SSH key |
+
+Example request:
+
+```sh
+curl --header "PRIVATE-TOKEN: <your_access_token>" 'https://gitlab.example.com/api/v4/keys?fingerprint=ba:81:59:68:d7:6c:cd:02:02:bf:6a:9b:55:4e:af:d1'
+```
+
+If using sha256 fingerprint API calls, make sure that the fingerprint is URL-encoded.
+
+For example, `/` is represented by `%2F` and `:` is represented by`%3A`:
+
+```sh
+curl --header "PRIVATE-TOKEN: <your_access_token>" 'https://gitlab.example.com/api/v4/keys?fingerprint=SHA256%3AnUhzNyftwADy8AH3wFY31tAKs7HufskYTte2aXo%2FlCg
+```
+
+Example response:
+
+```json
+{
+  "id": 1,
+  "title": "Sample key 1",
+  "key": "ssh-rsa AAAAB3NzaC1yc2EAAAABJQAAAIEAiPWx6WM4lhHNedGfBpPJNPpZ7yKu+dnn1SJejgt1016k6YjzGGphH2TUxwKzxcKDKKezwkpfnxPkSMkuEspGRt/aZZ9wa++Oi7Qkr8prgHc4soW6NUlfDzpvZK2H5E7eQaSeP3SAwGmQKUFHCddNaP0L+hM7zhFNzjFvpaMgJw0=",
+  "created_at": "2019-11-14T15:11:13.222Z",
+  "user": {
+    "id": 1,
+    "name": "Administrator",
+    "username": "root",
+    "state": "active",
+    "avatar_url": "https://www.gravatar.com/avatar/e64c7d89f26bd1972efa854d13d7dd61?s=80&d=identicon",
+    "web_url": "http://0.0.0.0:3000/root",
+    "created_at": "2019-11-14T15:09:34.831Z",
+    "bio": null,
+    "location": null,
+    "public_email": "",
+    "skype": "",
+    "linkedin": "",
+    "twitter": "",
+    "website_url": "",
+    "organization": null,
+    "last_sign_in_at": "2019-11-16T22:41:26.663Z",
+    "confirmed_at": "2019-11-14T15:09:34.575Z",
+    "last_activity_on": "2019-11-20",
+    "email": "admin@example.com",
+    "theme_id": 1,
+    "color_scheme_id": 1,
+    "projects_limit": 100000,
+    "current_sign_in_at": "2019-11-19T14:42:18.078Z",
+    "identities": [
+    ],
+    "can_create_group": true,
+    "can_create_project": true,
+    "two_factor_enabled": false,
+    "external": false,
+    "private_profile": false,
+    "shared_runners_minutes_limit": null,
+    "extra_shared_runners_minutes_limit": null
+  }
+}
+```

lib/api/keys.rb

@@ -16,6 +16,23 @@ module API
 
         present key, with: Entities::SSHKeyWithUser, current_user: current_user
       end
+
+      desc 'Get SSH Key information' do
+        success Entities::UserWithAdmin
+      end
+      params do
+        requires :fingerprint, type: String, desc: 'Search for a SSH fingerprint'
+      end
+      get do
+        authenticated_with_full_private_access!
+
+        key = KeysFinder.new(current_user, params).execute
+
+        not_found!('Key') unless key
+        present key, with: Entities::SSHKeyWithUser, current_user: current_user
+      rescue KeysFinder::InvalidFingerprint
+        render_api_error!('Failed to return the key', 400)
+      end
     end
   end
 end

lib/gitlab/database/sha256_attribute.rb

+# frozen_string_literal: true
+
+module Gitlab
+  module Database
+    # Class for casting binary data to hexadecimal SHA256 hashes (and vice-versa).
+    #
+    # Using Sha256Attribute allows you to store SHA256 values as binary while still
+    # using them as if they were stored as string values. This gives you the
+    # ease of use of string values, but without the storage overhead.
+    class Sha256Attribute < ActiveRecord::ConnectionAdapters::PostgreSQL::OID::Bytea
+      # Casts binary data to a SHA256 and remove trailing = and newline from encode64
+      def deserialize(value)
+        value = super(value)
+        if value.present?
+          Base64.encode64(value).delete("=").chomp("\n")
+        else
+          nil
+        end
+      end
+
+      # Casts a SHA256 in a proper binary format. which is 32 bytes long
+      def serialize(value)
+        arg = if value.present?
+                Base64.decode64(value)
+              else
+                nil
+              end
+
+        super(arg)
+      end
+    end
+  end
+end

lib/gitlab/insecure_key_fingerprint.rb

@@ -10,6 +10,7 @@ module Gitlab
   #
   class InsecureKeyFingerprint
     attr_accessor :key
+    alias_attribute :fingerprint_md5, :fingerprint
 
     #
     # Gets the base64 encoded string representing a rsa or dsa key
@@ -21,5 +22,9 @@ module Gitlab
     def fingerprint
       OpenSSL::Digest::MD5.hexdigest(Base64.decode64(@key)).scan(/../).join(':')
     end
+
+    def fingerprint_sha256
+      Digest::SHA256.base64digest(Base64.decode64(@key)).scan(/../).join('').delete("=")
+    end
   end
 end

locale/gitlab.pot

@@ -7703,9 +7703,6 @@ msgstr ""
 msgid "Fingerprint"
 msgstr ""
 
-msgid "Fingerprint:"
-msgstr ""
-
 msgid "Fingerprints"
 msgstr ""
 

spec/finders/keys_finder_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe KeysFinder do
+  subject(:keys_finder) { described_class.new(user, params) }
+
+  let(:user) { create(:user) }
+  let(:fingerprint_type) { 'md5' }
+  let(:fingerprint) { 'ba:81:59:68:d7:6c:cd:02:02:bf:6a:9b:55:4e:af:d1' }
+
+  let(:params) do
+    {
+      type: fingerprint_type,
+      fingerprint: fingerprint
+    }
+  end
+
+  let!(:key) do
+    create(:key, user: user,
+      key: 'ssh-rsa AAAAB3NzaC1yc2EAAAABJQAAAIEAiPWx6WM4lhHNedGfBpPJNPpZ7yKu+dnn1SJejgt1016k6YjzGGphH2TUxwKzxcKDKKezwkpfnxPkSMkuEspGRt/aZZ9wa++Oi7Qkr8prgHc4soW6NUlfDzpvZK2H5E7eQaSeP3SAwGmQKUFHCddNaP0L+hM7zhFNzjFvpaMgJw0=',
+      fingerprint: 'ba:81:59:68:d7:6c:cd:02:02:bf:6a:9b:55:4e:af:d1',
+      fingerprint_sha256: 'nUhzNyftwADy8AH3wFY31tAKs7HufskYTte2aXo/lCg'
+    )
+  end
+
+  context 'with a regular user' do
+    it 'raises GitLabAccessDeniedError' do
+      expect do
+        keys_finder.execute
+      end.to raise_error(KeysFinder::GitLabAccessDeniedError)
+    end
+  end
+
+  context 'with an admin user' do
+    let(:user) {create(:admin)}
+
+    context 'with invalid MD5 fingerprint' do
+      let(:fingerprint) { '11:11:11:11' }
+
+      it 'raises InvalidFingerprint' do
+        expect { keys_finder.execute }
+          .to raise_error(KeysFinder::InvalidFingerprint)
+      end
+    end
+
+    context 'with invalid SHA fingerprint' do
+      let(:fingerprint_type) { 'sha256' }
+      let(:fingerprint) { 'nUhzNyftwAAKs7HufskYTte2g' }
+
+      it 'raises InvalidFingerprint' do
+        expect { keys_finder.execute }
+          .to raise_error(KeysFinder::InvalidFingerprint)
+      end
+    end
+
+    context 'with valid MD5 params' do
+      it 'returns key if the fingerprint is found' do
+        result = keys_finder.execute
+
+        expect(result).to eq(key)
+        expect(key.user).to eq(user)
+      end
+    end
+
+    context 'with valid SHA256 params' do
+      let(:fingerprint) { 'ba:81:59:68:d7:6c:cd:02:02:bf:6a:9b:55:4e:af:d1' }
+
+      it 'returns key if the fingerprint is found' do
+        result = keys_finder.execute
+
+        expect(result).to eq(key)
+        expect(key.user).to eq(user)
+      end
+    end
+  end
+end

spec/lib/gitlab/insecure_key_fingerprint_spec.rb

@@ -11,10 +11,17 @@ describe Gitlab::InsecureKeyFingerprint do
   end
 
   let(:fingerprint) { "3f:a2:ee:de:b5:de:53:c3:aa:2f:9c:45:24:4c:47:7b" }
+  let(:fingerprint_sha256) { "MQHWhS9nhzUezUdD42ytxubZoBKrZLbyBZzxCkmnxXc" }
 
   describe "#fingerprint" do
     it "generates the key's fingerprint" do
-      expect(described_class.new(key.split[1]).fingerprint).to eq(fingerprint)
+      expect(described_class.new(key.split[1]).fingerprint_md5).to eq(fingerprint)
+    end
+  end
+
+  describe "#fingerprint" do
+    it "generates the key's fingerprint" do
+      expect(described_class.new(key.split[1]).fingerprint_sha256).to eq(fingerprint_sha256)
     end
   end
 end

spec/lib/gitlab/ssh_public_key_spec.rb

@@ -183,6 +183,34 @@ describe Gitlab::SSHPublicKey, lib: true do
     end
   end
 
+  describe '#fingerprint in SHA256 format' do
+    subject { public_key.fingerprint("SHA256").gsub("SHA256:", "") if public_key.fingerprint("SHA256") }
+
+    where(:factory, :fingerprint_sha256) do
+      [
+        [:rsa_key_2048, 'GdtgO0eHbwLB+mK47zblkoXujkqKRZjgMQrHH6Kks3E'],
+        [:rsa_key_4096, 'ByDU7hQ1JB95l6p53rHrffc4eXvEtqGUtQhS+Dhyy7g'],
+        [:rsa_key_5120, 'PCCupLbFHScm4AbEufbGDvhBU27IM0MVAor715qKQK8'],
+        [:rsa_key_8192, 'CtHFQAS+9Hb8z4vrv4gVQPsHjNN0WIZhWODaB1mQLs4'],
+        [:dsa_key_2048, '+a3DQ7cU5GM+gaYOfmc0VWNnykHQSuth3VRcCpWuYNI'],
+        [:ecdsa_key_256, 'C+I5k3D+IGeM6k5iBR1ZsphqTKV+7uvL/XZ5hcrTr7g'],
+        [:ed25519_key_256, 'DCKAjzxWrdOTjaGKBBjtCW8qY5++GaiAJflrHPmp6W0']
+      ]
+    end
+
+    with_them do
+      let(:key) { attributes_for(factory)[:key] }
+
+      it { is_expected.to eq(fingerprint_sha256) }
+    end
+
+    context 'with an invalid SSH key' do
+      let(:key) { 'this is not a key' }
+
+      it { is_expected.to be_nil }
+    end
+  end
+
   describe '#key_text' do
     let(:key) { 'this is not a key' }
 

spec/models/concerns/sha256_attribute_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+describe Sha256Attribute do
+  let(:model) { Class.new { include Sha256Attribute } }
+
+  before do
+    columns = [
+      double(:column, name: 'name', type: :text),
+      double(:column, name: 'sha256', type: :binary)
+    ]
+
+    allow(model).to receive(:columns).and_return(columns)
+  end
+
+  describe '#sha_attribute' do
+    context 'when in non-production' do
+      before do
+        stub_rails_env('development')
+      end
+
+      context 'when the table exists' do
+        before do
+          allow(model).to receive(:table_exists?).and_return(true)
+        end
+
+        it 'defines a SHA attribute for a binary column' do
+          expect(model).to receive(:attribute)
+            .with(:sha256, an_instance_of(Gitlab::Database::Sha256Attribute))
+
+          model.sha256_attribute(:sha256)
+        end
+
+        it 'raises ArgumentError when the column type is not :binary' do
+          expect { model.sha256_attribute(:name) }.to raise_error(ArgumentError)
+        end
+      end
+
+      context 'when the table does not exist' do
+        it 'allows the attribute to be added and issues a warning' do
+          allow(model).to receive(:table_exists?).and_return(false)
+
+          expect(model).not_to receive(:columns)
+          expect(model).to receive(:attribute)
+          expect(model).to receive(:warn)
+
+          model.sha256_attribute(:name)
+        end
+      end
+
+      context 'when the column does not exist' do
+        it 'allows the attribute to be added and issues a warning' do
+          allow(model).to receive(:table_exists?).and_return(true)
+
+          expect(model).to receive(:columns)
+          expect(model).to receive(:attribute)
+          expect(model).to receive(:warn)
+
+          model.sha256_attribute(:no_name)
+        end
+      end
+
+      context 'when other execeptions are raised' do
+        it 'logs and re-rasises the error' do
+          allow(model).to receive(:table_exists?).and_raise(ActiveRecord::NoDatabaseError.new('does not exist'))
+
+          expect(model).not_to receive(:columns)
+          expect(model).not_to receive(:attribute)
+          expect(Gitlab::AppLogger).to receive(:error)
+
+          expect { model.sha256_attribute(:name) }.to raise_error(ActiveRecord::NoDatabaseError)
+        end
+      end
+    end
+
+    context 'when in production' do
+      before do
+        stub_rails_env('production')
+      end
+
+      it 'defines a SHA attribute' do
+        expect(model).not_to receive(:table_exists?)
+        expect(model).not_to receive(:columns)
+        expect(model).to receive(:attribute).with(:sha256, an_instance_of(Gitlab::Database::Sha256Attribute))
+
+        model.sha256_attribute(:sha256)
+      end
+    end
+  end
+end

spec/models/key_spec.rb

@@ -92,6 +92,7 @@ describe Key, :mailer do
     with_them do
       let!(:key) { create(factory) }
       let!(:original_fingerprint) { key.fingerprint }
+      let!(:original_fingerprint_sha256) { key.fingerprint_sha256 }
 
       it 'accepts a key with blank space characters after stripping them' do
         modified_key = key.key.insert(100, chars.first).insert(40, chars.last)
@@ -104,6 +105,8 @@ describe Key, :mailer do
 
         expect(content).not_to match(/\s/)
         expect(original_fingerprint).to eq(key.fingerprint)
+        expect(original_fingerprint).to eq(key.fingerprint_md5)
+        expect(original_fingerprint_sha256).to eq(key.fingerprint_sha256)
       end
     end
   end

spec/requests/api/keys_spec.rb

@@ -25,7 +25,6 @@ describe API::Keys do
 
       it 'returns single ssh key with user information' do
         user.keys << key
-        user.save
         get api("/keys/#{key.id}", admin)
         expect(response).to have_gitlab_http_status(200)
         expect(json_response['title']).to eq(key.title)
@@ -40,4 +39,73 @@ describe API::Keys do
       end
     end
   end
+
+  describe 'GET /keys?fingerprint=' do
+    it 'returns authentication error' do
+      get api("/keys?fingerprint=#{key.fingerprint}")
+
+      expect(response).to have_gitlab_http_status(401)
+    end
+
+    it 'returns authentication error when authenticated as user' do
+      get api("/keys?fingerprint=#{key.fingerprint}", user)
+
+      expect(response).to have_gitlab_http_status(403)
+    end
+
+    context 'when authenticated as admin' do
+      it 'returns 404 for non-existing SSH md5 fingerprint' do
+        get api("/keys?fingerprint=11:11:11:11:11:11:11:11:11:11:11:11:11:11:11:11", admin)
+
+        expect(response).to have_gitlab_http_status(404)
+        expect(json_response['message']).to eq('404 Key Not Found')
+      end
+
+      it 'returns 404 for non-existing SSH sha256 fingerprint' do
+        get api("/keys?fingerprint=#{URI.encode_www_form_component("SHA256:nUhzNyftwADy8AH3wFY31tAKs7HufskYTte2aXo1lCg")}", admin)
+
+        expect(response).to have_gitlab_http_status(404)
+        expect(json_response['message']).to eq('404 Key Not Found')
+      end
+
+      it 'returns user if SSH md5 fingerprint found' do
+        user.keys << key
+
+        get api("/keys?fingerprint=#{key.fingerprint}", admin)
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(json_response['title']).to eq(key.title)
+        expect(json_response['user']['id']).to eq(user.id)
+        expect(json_response['user']['username']).to eq(user.username)
+      end
+
+      it 'returns user if SSH sha256 fingerprint found' do
+        user.keys << key
+
+        get api("/keys?fingerprint=#{URI.encode_www_form_component("SHA256:" + key.fingerprint_sha256)}", admin)
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(json_response['title']).to eq(key.title)
+        expect(json_response['user']['id']).to eq(user.id)
+        expect(json_response['user']['username']).to eq(user.username)
+      end
+
+      it 'returns user if SSH sha256 fingerprint found' do
+        user.keys << key
+
+        get api("/keys?fingerprint=#{URI.encode_www_form_component("sha256:" + key.fingerprint_sha256)}", admin)
+
+        expect(response).to have_gitlab_http_status(200)
+        expect(json_response['title']).to eq(key.title)
+        expect(json_response['user']['id']).to eq(user.id)
+        expect(json_response['user']['username']).to eq(user.username)
+      end
+
+      it "does not include the user's `is_admin` flag" do
+        get api("/keys?fingerprint=#{key.fingerprint}", admin)
+
+        expect(json_response['user']['is_admin']).to be_nil
+      end
+    end
+  end
 end