GPGME

This README is better viewed through the YARD formatted documentation: rdoc.info/github/ueno/gpgme/master/frames for latest github version, or rdoc.info/gems/gpgme for latest gem release.

Requirements

  • Ruby 1.8 or later

  • GPGME 1.1.2 or later

  • gpg-agent (optional, but recommended)

Installation

$ gem install gpgme

API

GPGME provides three levels of API. The highest level API is as simple as it gets, the mid level API provides more functionality but might be less user-friendly, and the lowest level API is close to the C interface of GPGME.

The highest level API

For example, to create a cleartext signature of the plaintext from stdin and write the result to stdout can be written as follows.

crypto = GPGME::Crypto.new
crypto.clearsign $stdin, :output => $stdout

The mid level API

The same example can be rewritten in the mid level API as follows.

plain = GPGME::Data.new($stdin)
sig   = GPGME::Data.new($stdout)
GPGME::Ctx.new do |ctx|
  ctx.sign(plain, sig, GPGME::SIG_MODE_CLEAR)
end

The lowest level API

The same example can be rewritten in the lowest level API as follows.

ret = []
GPGME::gpgme_new(ret)
ctx = ret.shift
GPGME::gpgme_data_new_from_fd(ret, 0)
plain = ret.shift
GPGME::gpgme_data_new_from_fd(ret, 1)
sig = ret.shift
GPGME::gpgme_op_sign(ctx, plain, sig, GPGME::SIG_MODE_CLEAR)

As you see, it's much harder to write a program in this API than the highest level API. However, if you are already familiar with the C interface of GPGME and want to control detailed behavior of GPGME, it might be useful.

Usage

All the high level methods attack the mid level GPGME::Ctx API. It is recommended to read through the #GPGME::Ctx.new methods for common options.

Also, most of the input/output is done via GPGME::Data objects that create a common interface for reading/writing to normal strings, or other common objects like files. Read the GPGME::Data documentation to understand how it works. Every time the lib needs a GPGME::Data object, it will be automatically converted to it.

Crypto

The GPGME::Crypto class has the high level convenience methods to encrypt, decrypt, sign and verify signatures. Here are some examples, but it is recommended to read through the GPGME::Crypto class to see all the options.

crypto = GPGME::Crypto.new
crypto.encrypt "Hello world!", :recipients => "someone@example.com"
  • Symmetric encryption:

crypto = GPGME::Crypto.new :password => "gpgme"
crypto.encrypt "Hello world!", :symmetric => true
crypto.decrypt File.open("text.gpg")
crypto.sign "I hereby proclaim Github the beneficiary of all my money when I die"
sign = crypto.sign "Some text"
data = crypto.verify(sign) { |signature| signature.valid? }

Key

The GPGME::Key object represents a key, and has the high level related methods to work with them and find them, export, import, deletetion and creation.

  • Key listing

GPGME::Key.find(:secret, "someone@example.com")
# => Returns an array with all the secret keys available in the keychain.
#    that match "someone@example.com"
  • Key exporting

GPGME::Key.export("someone@example.com")
# => Returns a {GPGME::Data} object with the exported key.

key = GPGME::Key.find(:secret, "someone@example.com").first
key.export
# => Returns a {GPGME::Data} object with the exported key.
  • Key importing

GPGME::Key.import(File.open("my.key"))
  • TODO: Key generation

Engine

Provides three convenience methods to obtain information about the gpg engine one is currently using. For example:

  • Getting current information

GPGME::Engine.info.first
     # => #<GPGME::EngineInfo:0x00000100d4fbd8
            @file_name="/usr/local/bin/gpg",
            @protocol=0,
            @req_version="1.3.0",
            @version="1.4.11">
  • Changing home directory to work with different settings:

GPGME::Engine.home_dir = '/tmp'

Contributing

To run the local test suite you need bundler and gpg:

bundle
rake compile   # simple rake task to compile the extension
rake           # runs the test suite

License

The library itself is licensed under LGPLv2.1+. See the file COPYING.LESSER and each file for copyright and warranty information.