signature.rs

//  Copyright 2021, The Tari Project
//
//  Redistribution and use in source and binary forms, with or without modification, are permitted provided that the
//  following conditions are met:
//
//  1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following
//  disclaimer.
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//  2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the
//  following disclaimer in the documentation and/or other materials provided with the distribution.
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//  3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote
//  products derived from this software without specific prior written permission.
//
//  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
//  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
//  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
//  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
//  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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//  USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

use tari_utilities::hex::from_hex;

use crate::auto_update::dns::UpdateSpec;

pub struct SignedMessageVerifier {
    maintainers: Vec<pgp::SignedPublicKey>,
}

impl SignedMessageVerifier {
    pub fn new(maintainers: Vec<pgp::SignedPublicKey>) -> Self {
        Self { maintainers }
    }

    pub fn verify_signed_update(
        &self,
        signature: &pgp::StandaloneSignature,
        hashes: &str,
        update: &UpdateSpec,
    ) -> Option<(Vec<u8>, String)> {
        self.verify_signature(signature, hashes)?;

        hashes
            .lines()
            .filter_map(|line| {
                let mut parts = line.splitn(2, ' ');
                let hash = parts.next().map(|s| s.trim()).map(from_hex)?.ok()?;
                let filename = parts.next()?;
                Some((hash, filename.trim().to_string()))
            })
            .find(|(hash, _)| update.hash == *hash)
    }

    fn verify_signature(&self, signature: &pgp::StandaloneSignature, message: &str) -> Option<&pgp::SignedPublicKey> {
        self.maintainers
            .iter()
            .find(|pk| signature.verify(pk, message.as_bytes()).is_ok())
    }
}

#[cfg(test)]
mod test {
    use pgp::Deserializable;

    use super::*;
    use crate::auto_update::maintainers;

    const PUBLIC_KEY: &str = r#"-----BEGIN PGP PUBLIC KEY BLOCK-----
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=7S7i
-----END PGP PUBLIC KEY BLOCK-----"#;

    const VALID_SIGNATURE: &str = r#"-----BEGIN PGP SIGNATURE-----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=vcW8
-----END PGP SIGNATURE-----"#;

    const MESSAGE: &str = "Philip R. Zimmermann";

    #[test]
    fn it_verifies_signed_message() {
        let (sig, _) = pgp::StandaloneSignature::from_string(VALID_SIGNATURE.trim()).unwrap();
        let (key, _) = pgp::SignedPublicKey::from_string(PUBLIC_KEY).unwrap();
        let verifier = SignedMessageVerifier::new(vec![key]);
        let signer = verifier.verify_signature(&sig, MESSAGE).unwrap();

        let (maintainer, _) = pgp::SignedPublicKey::from_string(PUBLIC_KEY).unwrap();
        assert_eq!(*signer, maintainer);
    }

    #[test]
    fn it_does_not_validate_with_tampered_message() {
        let (sig, _) = pgp::StandaloneSignature::from_string(VALID_SIGNATURE.trim()).unwrap();
        let verifier = SignedMessageVerifier::new(maintainers().collect());
        assert!(verifier.verify_signature(&sig, "Zilip R. Phimmermann").is_none());
    }
}