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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 sequoia_openpgp as openpgp;
use crate::openpgp::cert::prelude::*;
use crate::openpgp::crypto::{KeyPair, SessionKey};
use crate::openpgp::types::SymmetricAlgorithm;
use crate::openpgp::parse::{
Parse,
stream::{
DecryptionHelper,
Decryptor,
VerificationHelper,
GoodChecksum,
MessageStructure,
MessageLayer,
},
};
use crate::openpgp::policy::Policy;
use crate::openpgp::policy::StandardPolicy as P;
pub fn main() {
let p = &P::new();
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 certs =
args[1..].iter().map(|f| {
openpgp::Cert::from_file(f)
.expect("Failed to read key")
}).collect();
// Now, create a decryptor with a helper using the given Certs.
let mut decryptor =
Decryptor::from_reader(p, io::stdin(), Helper::new(p, certs), None).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, KeyPair>,
}
impl Helper {
/// Creates a Helper for the given Certs with appropriate secrets.
fn new(p: &dyn Policy, certs: Vec<openpgp::Cert>) -> Self {
// Map (sub)KeyIDs to secrets.
let mut keys = HashMap::new();
for cert in certs {
for ka in cert.keys().unencrypted_secret().with_policy(p, None)
.for_storage_encryption().for_transport_encryption()
{
keys.insert(ka.key().keyid(),
ka.key().clone().into_keypair().unwrap());
}
}
Helper {
keys: keys,
}
}
}
impl DecryptionHelper for Helper {
fn decrypt<D>(&mut self,
pkesks: &[openpgp::packet::PKESK],
_skesks: &[openpgp::packet::SKESK],
sym_algo: Option<SymmetricAlgorithm>,
mut decrypt: D)
-> openpgp::Result<Option<openpgp::Fingerprint>>
where D: FnMut(SymmetricAlgorithm, &SessionKey) -> openpgp::Result<()>
{
// Try each PKESK until we succeed.
for pkesk in pkesks {
if let Some(pair) = self.keys.get_mut(pkesk.recipient()) {
if let Ok(_) = pkesk.decrypt(pair, sym_algo)
.and_then(|(algo, session_key)| decrypt(algo, &session_key))
{
break;
}
}
}
// XXX: In production code, return the Fingerprint of the
// recipient's Cert here
Ok(None)
}
}
impl VerificationHelper for Helper {
fn get_public_keys(&mut self, _ids: &[openpgp::KeyHandle])
-> failure::Fallible<Vec<openpgp::Cert>> {
Ok(Vec::new()) // Feed the Certs to the verifier here.
}
fn check(&mut self, structure: MessageStructure)
-> failure::Fallible<()> {
for layer in structure.iter() {
match layer {
MessageLayer::Compression { algo } =>
eprintln!("Compressed using {}", algo),
MessageLayer::Encryption { sym_algo, aead_algo } =>
if let Some(aead_algo) = aead_algo {
eprintln!("Encrypted and protected using {}/{}",
sym_algo, aead_algo);
} else {
eprintln!("Encrypted using {}", sym_algo);
},
MessageLayer::SignatureGroup { ref results } =>
for result in results {
match result {
Ok(GoodChecksum { ka, .. }) => {
eprintln!("Good signature from {}", ka.cert());
},
Err(e) =>
eprintln!("Error: {:?}", e),
}
}
}
}
Ok(()) // Implement your verification policy here.
}
}
|
