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# This code is based on the library from http://schleuder2.nadir.org/
require 'gpgme'
module Backend
# Wrapper for ruby-gpgme. Method naming is not strictly logical, this might
# change but aliases will be set up then.
class Crypt
# Instantiates and stores password
def initialize(password)
@password = password
@ctx = GPGME::Ctx.new
# feed the passphrase into the Context
@ctx.set_passphrase_cb(method(:passfunc))
end
# TODO: use a logging facility
def debug(message)
puts message
end
# TODO: use a logging facility
def error(message)
puts message
end
# Verify a gpg-signature. Use +signed_string+ if the signature is
# detached. Returns a GPGME::SignatureResult
def verify(sig, signed_string='')
in_signed = ''
if signed_string.empty?
# verify +sig+ as cleartext (aka pgp/inline) signature
debug 'No extra signed_string, verifying cleartext signature'
output = GPGME.verify(sig) do |sig|
in_signed = sig
end
else
# verify detached signature
debug 'Verifying detached signature'
# Don't know why we need a GPGME::Data object this time but without gpgme throws exceptions
plain = GPGME::Data.new
GPGME.verify(sig, signed_string, plain) do |sig|
in_signed = sig
end
output = signed_string
end
debug 'verify_result: ' + in_signed.inspect
[output, in_signed]
end
# Decrypt a string.
def decrypt(str)
output = ""
in_encrypted = nil
in_signed = nil
# TODO: return ciphertext if missing key. Sensible e.g. if it is part
# of a nested MIME-message and encrypted to someone else on purpose.
# Breaking if even the whole message is not decryptable is a job for
# the processor.
# return input instead of empty String if not encrypted
unless str =~ /^-----BEGIN PGP MESSAGE-----/
# match pgp-mime- and inline-pgp-signatures
if str =~ /^-----BEGIN PGP SIG/
debug 'found signed, not encrypted message, verifying'
output, in_signed = verify(str)
else
debug 'found not signed, not encrypted message, returning input'
output = str
end
else
debug 'found pgp content, decrypting and verifying with gpgme'
in_encrypted = true
output = GPGME.decrypt(str, :passphrase_callback => method(:passfunc)) do |sig|
in_signed = sig
end
if output.empty?
Exception.new("Output from GPGME.decrypt was empty!")
end
# TODO: return mailadresses or keys instead of signature-objects?
end
[output, in_encrypted, in_signed]
end
# Encrypt a string to a single receiver and sign it. +receiver+ must be a
# Keyringer::Member
def encrypt_str(str, receiver)
# encypt and sign and return encrypted data as string
key = receiver.key || receiver.email
GPGME.encrypt([key], str, {:passphrase_callback => method(:passfunc), :armor => true, :sign => true, :always_trust => true})
end
# Lists all public keys matching +pattern+. Returns an array of
# GPGME::GpgKey's
def list_keys(pattern='')
GPGME.list_keys(pattern)
end
# Returns the GPGME::GpgKey matching +pattern+. Log an error if more than
# one matches, because duplicated user-ids is a sensitive issue.
def get_key(pattern)
pattern = "<#{pattern}>" if pattern =~ /.*@.*/
k = list_keys(pattern)
if k.length > 1
error "There's more than one key matching the pattern you gave me!\nPattern: #{pattern}\nkeys: #{k.inspect}"
false
else
k.first
end
end
# Signs +string+ with the private key of the list (aka detached signature)
def sign(string)
GPGME::detach_sign(string, {:armor => true, :passphrase_callback => method(:passfunc)})
end
# Clearsigns +string+ with the private key of the list
def clearsign(string)
GPGME::clearsign(string, {:armor => true, :passphrase_callback => method(:passfunc)})
end
# Exports the public key matching +keyid+ as ascii key block.
def export(keyid)
GPGME.export(keyid, :armor=>:true)
end
# Delete the public key matching +pattern+ from the public key ring of the
# list
def delete_key(key)
key = get_key(key) if key.kind_of?(String)
begin
@ctx.delete_key(key)
return true
rescue => e
return e
end
end
# Import +keydata+ into public key ring of the list
def add_key(keydata)
GPGME.import(keydata)
end
def add_key_from_file(keyfile)
add_key(File.read(keyfile))
end
private
def passfunc(hook, uid_hint, passphrase_info, prev_was_bad, fd)
io = IO.for_fd(fd, 'w')
io.puts @password
io.flush
end
end
end
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