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/// Generates a key, then signs and verifies a message.
use std::io::{self, Write};
use sequoia_openpgp as openpgp;
use crate::openpgp::cert::prelude::*;
use crate::openpgp::serialize::stream::*;
use crate::openpgp::parse::{Parse, stream::*};
use crate::openpgp::policy::Policy;
use crate::openpgp::policy::StandardPolicy as P;
const MESSAGE: &str = "дружба";
fn main() -> openpgp::Result<()> {
let p = &P::new();
// Generate a key.
let key = generate()?;
// Sign the message.
let mut signed_message = Vec::new();
sign(p, &mut signed_message, MESSAGE, &key)?;
// Verify the message.
let mut plaintext = Vec::new();
verify(p, &mut plaintext, &signed_message, &key)?;
assert_eq!(MESSAGE.as_bytes(), &plaintext[..]);
Ok(())
}
/// Generates an signing-capable key.
fn generate() -> openpgp::Result<openpgp::Cert> {
let (cert, _revocation) = CertBuilder::new()
.add_userid("someone@example.org")
.add_signing_subkey()
.generate()?;
// Save the revocation certificate somewhere.
Ok(cert)
}
/// Signs the given message.
fn sign(p: &dyn Policy, sink: &mut (dyn Write + Send + Sync),
plaintext: &str, tsk: &openpgp::Cert)
-> openpgp::Result<()> {
// Get the keypair to do the signing from the Cert.
let keypair = tsk
.keys().unencrypted_secret()
.with_policy(p, None).supported().alive().revoked(false).for_signing()
.next().unwrap().key().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, keypair)?.build()?;
// Emit a literal data packet.
let mut literal_writer = LiteralWriter::new(signer).build()?;
// 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(p: &dyn Policy, sink: &mut dyn Write,
signed_message: &[u8], sender: &openpgp::Cert)
-> openpgp::Result<()> {
// Make a helper that that feeds the sender's public key to the
// verifier.
let helper = Helper {
cert: sender,
};
// Now, create a verifier with a helper using the given Certs.
let mut verifier = VerifierBuilder::from_bytes(signed_message)?
.with_policy(p, None, helper)?;
// Verify the data.
io::copy(&mut verifier, sink)?;
Ok(())
}
struct Helper<'a> {
cert: &'a openpgp::Cert,
}
impl<'a> VerificationHelper for Helper<'a> {
fn get_certs(&mut self, _ids: &[openpgp::KeyHandle])
-> openpgp::Result<Vec<openpgp::Cert>> {
// Return public keys for signature verification here.
Ok(vec![self.cert.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.into_iter().enumerate() {
match (i, layer) {
// First, we are interested in signatures over the
// data, i.e. level 0 signatures.
(0, MessageLayer::SignatureGroup { results }) => {
// Finally, given a VerificationResult, which only says
// whether the signature checks out mathematically, we apply
// our policy.
match results.into_iter().next() {
Some(Ok(_)) =>
good = true,
Some(Err(e)) =>
return Err(openpgp::Error::from(e).into()),
None =>
return Err(anyhow::anyhow!("No signature")),
}
},
_ => return Err(anyhow::anyhow!(
"Unexpected message structure")),
}
}
if good {
Ok(()) // Good signature.
} else {
Err(anyhow::anyhow!("Signature verification failed"))
}
}
}
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