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/// Decrypts asymmetrically-encrypted OpenPGP messages using the
/// openpgp crate, Sequoia's low-level API.
use std::collections::HashMap;
use std::env;
use std::io;
extern crate failure;
extern crate openpgp;
use openpgp::parse::stream::{
Decryptor, DecryptionHelper, Secret, VerificationHelper, VerificationResult,
};
pub fn main() {
let args: Vec<String> = env::args().collect();
if args.len() < 2 {
panic!("A simple decryption filter.\n\n\
Usage: {} <keyfile> [<keyfile>...] <input >output\n", args[0]);
}
// Read the transferable secret keys from the given files.
let tpks =
args[1..].iter().map(|f| {
openpgp::TPK::from_reader(
// Use an openpgp::Reader so that we accept both armored
// and plain PGP data.
openpgp::Reader::from_file(f)
.expect("Failed to open file"))
.expect("Failed to read key")
}).collect();
// First, use an openpgp::Reader so that we accept both armored
// and plain PGP data.
let reader = openpgp::Reader::from_reader(io::stdin())
.expect("Failed to open file");
// Now, create a decryptor with a helper using the given TPKs.
let mut decryptor =
Decryptor::from_reader(reader, Helper::new(tpks)).unwrap();
// Finally, stream the decrypted data to stdout.
io::copy(&mut decryptor, &mut io::stdout())
.expect("Decryption failed");
}
/// This helper provides secrets for the decryption, fetches public
/// keys for the signature verification and implements the
/// verification policy.
struct Helper {
keys: HashMap<openpgp::KeyID, Secret>,
i: usize,
}
impl Helper {
/// Creates a Helper for the given TPKs with appropriate secrets.
fn new(tpks: Vec<openpgp::TPK>) -> Self {
// Map (sub)KeyIDs to secrets.
let mut keys = HashMap::new();
for tpk in tpks {
for (sig, key) in tpk.keys() {
if sig.map(|s| (s.key_flags().can_encrypt_at_rest()
|| s.key_flags().can_encrypt_for_transport()))
.unwrap_or(false)
{
// Only handle unencrypted secret keys.
if let Some(openpgp::SecretKey::Unencrypted { ref mpis }) =
key.secret()
{
keys.insert(key.fingerprint().to_keyid(),
Secret::Asymmetric {
identity: tpk.fingerprint(),
key: key.clone(),
secret: mpis.clone(),
});
}
}
}
}
Helper {
keys: keys,
i: 0,
}
}
}
impl DecryptionHelper for Helper {
fn get_secret(&mut self,
pkesks: &[&openpgp::packet::PKESK],
_: &[&openpgp::packet::SKESK])
-> failure::Fallible<Option<Secret>> {
let r = pkesks
.iter()
.nth(self.i)
.and_then(|pkesk| {
self.keys.get(pkesk.recipient())
.map(|s| (*s).clone())
});
self.i += 1;
Ok(r)
}
}
impl VerificationHelper for Helper {
fn get_public_keys(&mut self, _ids: &[openpgp::KeyID])
-> failure::Fallible<Vec<openpgp::TPK>> {
Ok(Vec::new()) // Feed the TPKs to the verifier here.
}
fn check(&mut self, _sigs: Vec<Vec<VerificationResult>>)
-> failure::Fallible<()> {
Ok(()) // Implement your verification policy here.
}
}
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