HasherMatcherActionerApi

Wrapper around the HasherMatcherActioner service from Meta.

This gem can be used to hash content, or search for matches for a piece of content in one or more exchange banks.

Installation

Install the gem and add to the application's Gemfile by executing:

bundle add hasher_matcher_actioner_api --github 'fetlife/hasher_matcher_actioner_api'

Or add to your Gemfile:

gem "hasher_matcher_actioner_api", github: "fetlife/hasher_matcher_actioner_api"

Usage

The HasherMatcherActionerApi gem provides functionality to hash URLs and files for content matching. Here are some examples of how to use it:

Basic Setup

require 'hasher_matcher_actioner_api'

# Configure the API client
client = HasherMatcherActionerApi::Client.new(
  base_url: 'https://api.example.com'
)

Hashing URLs

# Hash a URL with default settings
result = client.hash_url(url: 'https://example.com/image.jpg')

# Hash a URL with specific content type
result = client.hash_url(
  url: 'https://example.com/image.jpg',
  content_type: 'photo'
)

# Hash a URL with specific signal types
result = client.hash_url(
  url: 'https://example.com/image.jpg',
  signal_types: ['pdq', 'md5']
)

Hashing Files

# Hash a file from disk
File.open('path/to/image.jpg', 'rb') do |file|
  result = client.hash_file(
    file: file,
    content_type: 'photo'
  )
end

# Hash a file from memory
require 'stringio'
file = StringIO.new(file_content)
result = client.hash_file(
  file: file,
  content_type: 'photo'
)

Working with Results

The hash results are returned as a HashResult object with attributes for each signal type:

result = client.hash_url(url: 'https://example.com/image.jpg')

# Access individual hash values
puts result.pdq    # PDQ hash value
puts result.md5    # MD5 hash value
puts result.sha256 # SHA256 hash value

Looking Up Content

You can search for matches in banks using different methods:

Lookup by URL

# Search for matches by URL
matches = client.lookup_url('https://example.com/image.jpg')

# Search with specific content type
matches = client.lookup_url(
  'https://example.com/image.jpg',
  content_type: 'photo'
)

# Search with specific signal types
matches = client.lookup_url(
  'https://example.com/image.jpg',
  signal_types: ['pdq', 'md5']
)

# Search in specific banks only
matches = client.lookup_url(
  'https://example.com/image.jpg',
  bank_names: ['bank1', 'bank2']
)

Lookup by File

# Search for matches by file
File.open('path/to/image.jpg', 'rb') do |file|
  matches = client.lookup_file(file, content_type: 'photo')
end

# Search in specific banks only
File.open('path/to/image.jpg', 'rb') do |file|
  matches = client.lookup_file(
    file, 
    content_type: 'photo',
    bank_names: ['bank1', 'bank2']
  )
end

Lookup by Signal

# Search for matches by hash signal
matches = client.lookup_signal(
  signal: 'abc123def456...',  # Hash value
  signal_type: 'pdq'
)

# Search for matches in specific banks only
matches = client.lookup_signal(
  signal: 'abc123def456...',  # Hash value
  signal_type: 'pdq',
  bank_names: ['bank1', 'bank2']
)

# Access match details
matches.each do |match|
  puts "Found in bank: #{match.bank_name}"
  puts "Content ID: #{match.bank_content_id}"
  puts "Distance: #{match.distance}"
end

Adding Content to Banks

You can add content to banks for threat intelligence storage using two separate methods:

Adding Content from URLs

# Add content from a URL
result = client.add_url_to_bank(
  bank_name: 'my_threat_bank',
  url: 'https://example.com/suspicious-image.jpg',
  content_type: 'photo'
)

# Add content from URL with metadata
metadata = {
  content_id: 'unique-content-123',
  content_uri: 'https://example.com/original-source.jpg',
  json: { source: 'user_report', priority: 'high' }
}

result = client.add_url_to_bank(
  bank_name: 'my_threat_bank',
  url: 'https://example.com/suspicious-image.jpg',
  content_type: 'photo',
  metadata: metadata
)

# Works without content_type (auto-detected)
result = client.add_url_to_bank(
  bank_name: 'my_threat_bank',
  url: 'https://example.com/suspicious-image.jpg'
)

Adding Content from Files

# Add content from a file
File.open('path/to/suspicious-image.jpg', 'rb') do |file|
  result = client.add_file_to_bank(
    bank_name: 'my_threat_bank',
    file: file,
    content_type: 'photo'
  )
end

# Add content from file with metadata
metadata = {
  content_id: 'unique-content-456',
  content_uri: 'https://example.com/original-source.jpg',
  json: { source: 'file_upload', priority: 'high' }
}

File.open('path/to/suspicious-image.jpg', 'rb') do |file|
  result = client.add_file_to_bank(
    bank_name: 'my_threat_bank',
    file: file,
    content_type: 'photo',
    metadata: metadata
  )
end

# Access the result
puts result.id          # Content ID in the bank
puts result.signals     # Generated hash signals

Error Handling

The gem raises ValidationError for invalid inputs:

begin
  result = client.hash_url(
    url: 'https://example.com/image.jpg',
    content_type: 'invalid_type'
  )
rescue HasherMatcherActionerApi::ValidationError => e
  puts "Error: #{e.message}"
end

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install.

Code Style

This project uses standard for Ruby code formatting and linting.

Commit Messages

Use gitmoji in commit messages to indicate the type of change.

Releasing a New Version

To release a new version:

1. Update the version number in version.rb
2. Run bundle exec rake release

This will:

• Create a git tag for the version
• Push git commits and the created tag
• Trigger Github release workflow

Using the local gem in another project

To use this gem locally during development in another project:

1. Configure the local gem path:

bundle config set local.hasher_matcher_actioner_api ../hasher_matcher_actioner_api
bundle config disable_local_branch_check true

2. Add the gem to your project's Gemfile:

gem "hasher_matcher_actioner_api", git: "https://github.com/fetlife/hasher_matcher_actioner_api", branch: 'main'

3. Run bundle install:

bundle install

Now you can use the gem in your project and any changes you make to the local gem will be immediately available without needing to rebuild or reinstall.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/fetlife/hasher_matcher_actioner_api. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the HasherMatcherActionerApi project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.