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|
/// Decrypts data using the openpgp crate and secrets in gpg-agent.
use std::collections::HashMap;
use std::io;
use sequoia_openpgp as openpgp;
use sequoia_ipc as ipc;
use openpgp::cert::prelude::*;
use openpgp::crypto::SessionKey;
use openpgp::types::SymmetricAlgorithm;
use openpgp::packet::key;
use openpgp::parse::{
Parse,
stream::{
DecryptionHelper,
DecryptorBuilder,
VerificationHelper,
GoodChecksum,
VerificationError,
MessageStructure,
MessageLayer,
},
};
use openpgp::policy::Policy;
use openpgp::policy::StandardPolicy as P;
use ipc::gnupg::{Context, KeyPair};
fn main() -> openpgp::Result<()> {
let p = &P::new();
let matches = clap::App::new("gpg-agent-decrypt")
.version(env!("CARGO_PKG_VERSION"))
.about("Connects to gpg-agent and decrypts a message.")
.arg(clap::Arg::with_name("homedir").value_name("PATH")
.long("homedir")
.help("Use this GnuPG home directory, default: $GNUPGHOME"))
.arg(clap::Arg::with_name("cert").value_name("Cert")
.required(true)
.multiple(true)
.help("Public part of the secret keys managed by gpg-agent"))
.get_matches();
let ctx = if let Some(homedir) = matches.value_of("homedir") {
Context::with_homedir(homedir)?
} else {
Context::new()?
};
// Read the Certs from the given files.
let certs =
matches.values_of("cert").expect("required").map(
openpgp::Cert::from_file
).collect::<Result<_, _>>()?;
// Now, create a decryptor with a helper using the given Certs.
let mut decryptor = DecryptorBuilder::from_reader(io::stdin())?
.with_policy(p, None, Helper::new(&ctx, p, certs))?;
// Finally, stream the decrypted data to stdout.
io::copy(&mut decryptor, &mut io::stdout())?;
Ok(())
}
/// This helper provides secrets for the decryption, fetches public
/// keys for the signature verification and implements the
/// verification policy.
struct Helper<'a> {
ctx: &'a Context,
keys: HashMap<openpgp::KeyID,
openpgp::packet::Key<key::PublicParts, key::UnspecifiedRole>>,
}
impl<'a> Helper<'a> {
/// Creates a Helper for the given Certs with appropriate secrets.
fn new(ctx: &'a Context, policy: &'a 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().with_policy(policy, None)
.for_storage_encryption().for_transport_encryption()
{
let key = ka.key();
keys.insert(key.keyid(), key.clone().into());
}
}
Helper { ctx, keys, }
}
}
impl<'a> DecryptionHelper for Helper<'a> {
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) -> bool
{
// Try each PKESK until we succeed.
for pkesk in pkesks {
if let Some(key) = self.keys.get(pkesk.recipient()) {
let mut pair = KeyPair::new(self.ctx, key)?;
if pkesk.decrypt(&mut pair, sym_algo)
.map(|(algo, session_key)| decrypt(algo, &session_key))
.unwrap_or(false)
{
break;
}
}
}
// XXX: In production code, return the Fingerprint of the
// recipient's Cert here
Ok(None)
}
}
impl<'a> VerificationHelper for Helper<'a> {
fn get_certs(&mut self, _ids: &[openpgp::KeyHandle])
-> openpgp::Result<Vec<openpgp::Cert>> {
Ok(Vec::new()) // Feed the Certs to the verifier here.
}
fn check(&mut self, structure: MessageStructure)
-> openpgp::Result<()> {
use self::VerificationError::*;
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(MalformedSignature { error, .. }) => {
eprintln!("Signature is malformed: {}", error);
},
Err(MissingKey { sig, .. }) => {
let issuers = sig.get_issuers();
eprintln!("Missing key {:X}, which is needed to \
verify signature.",
issuers.first().unwrap());
},
Err(UnboundKey { cert, error, .. }) => {
eprintln!("Signing key on {:X} is not bound: {}",
cert.fingerprint(), error);
},
Err(BadKey { ka, error, .. }) => {
eprintln!("Signing key on {:X} is bad: {}",
ka.cert().fingerprint(),
error);
},
Err(BadSignature { error, .. }) => {
eprintln!("Verifying signature: {}.", error);
},
}
}
}
}
Ok(()) // Implement your verification policy here.
}
}
|
