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/// Generates a key, then signs and verifies a message.
use std::io::{self, Write};
extern crate failure;
extern crate sequoia_openpgp as openpgp;
use openpgp::serialize::stream::*;
use openpgp::parse::stream::*;
const MESSAGE: &'static str = "дружба";
fn main() {
// Generate a key.
let key = generate().unwrap();
// Sign the message.
let mut signed_message = Vec::new();
sign(&mut signed_message, MESSAGE, &key).unwrap();
// Verify the message.
let mut plaintext = Vec::new();
verify(&mut plaintext, &signed_message, &key).unwrap();
assert_eq!(MESSAGE.as_bytes(), &plaintext[..]);
}
/// Generates an signing-capable key.
fn generate() -> openpgp::Result<openpgp::TPK> {
let (tpk, _revocation) = openpgp::tpk::TPKBuilder::new()
.add_userid("someone@example.org")
.add_signing_subkey()
.generate()?;
// Save the revocation certificate somewhere.
Ok(tpk)
}
/// Signs the given message.
fn sign(sink: &mut Write, plaintext: &str, tsk: &openpgp::TPK)
-> openpgp::Result<()> {
// Get the keypair to do the signing from the TPK.
let mut keypair = tsk.keys_valid().signing_capable().nth(0).unwrap().2
.clone().into_keypair()?;
// Start streaming an OpenPGP message.
let message = Message::new(sink);
// We want to sign a literal data packet.
let signer = Signer::new(message, vec![&mut keypair], None)?;
// Emit a literal data packet.
let mut literal_writer = LiteralWriter::new(
signer, openpgp::constants::DataFormat::Binary, None, None)?;
// Sign the data.
literal_writer.write_all(plaintext.as_bytes())?;
// Finalize the OpenPGP message to make sure that all data is
// written.
literal_writer.finalize()?;
Ok(())
}
/// Verifies the given message.
fn verify(sink: &mut Write, signed_message: &[u8], sender: &openpgp::TPK)
-> openpgp::Result<()> {
// Make a helper that that feeds the sender's public key to the
// verifier.
let helper = Helper {
tpk: sender,
};
// Now, create a verifier with a helper using the given TPKs.
let mut verifier = Verifier::from_bytes(signed_message, helper, None)?;
// Verify the data.
io::copy(&mut verifier, sink)?;
Ok(())
}
struct Helper<'a> {
tpk: &'a openpgp::TPK,
}
impl<'a> VerificationHelper for Helper<'a> {
fn get_public_keys(&mut self, _ids: &[openpgp::KeyID])
-> openpgp::Result<Vec<openpgp::TPK>> {
// Return public keys for signature verification here.
Ok(vec![self.tpk.clone()])
}
fn check(&mut self, structure: &MessageStructure)
-> openpgp::Result<()> {
// In this function, we implement our signature verification
// policy.
let mut good = false;
for (i, layer) in structure.iter().enumerate() {
match (i, layer) {
// First, we are interested in signatures over the
// data, i.e. level 0 signatures.
(0, MessageLayer::SignatureGroup { ref results }) => {
// Finally, given a VerificationResult, which only says
// whether the signature checks out mathematically, we apply
// our policy.
match results.get(0) {
Some(VerificationResult::GoodChecksum(..)) =>
good = true,
Some(VerificationResult::MissingKey(_)) =>
return Err(failure::err_msg(
"Missing key to verify signature")),
Some(VerificationResult::BadChecksum(_)) =>
return Err(failure::err_msg("Bad signature")),
None =>
return Err(failure::err_msg("No signature")),
}
},
_ => return Err(failure::err_msg(
"Unexpected message structure")),
}
}
if good {
Ok(()) // Good signature.
} else {
Err(failure::err_msg("Signature verification failed"))
}
}
}
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