mauth-core 0.6.0

Generate and verify Medidata MAuth protocol signatures
Documentation
use crate::{error::Error, signable::Signable};
use base64::{engine::general_purpose, Engine as _};
use rsa::pkcs1v15::Signature;
use rsa::pkcs8::DecodePublicKey;
use rsa::RsaPublicKey;
use sha2::Sha512;

/// Used to verify incoming requests. Struct can be initialized once and used to verify many requests.
#[derive(Debug, Clone)]
pub struct Verifier {
    app_uuid: String,
    public_key: RsaPublicKey,
    verifying_key: rsa::pkcs1v15::VerifyingKey<Sha512>,
}

impl Verifier {
    /// Initialize a new verifier with the source app UUID and the public key. The format of the public key
    /// should be a raw RSA public key in the public key PEM format, as generated by `openssl rsa -pubout -out`.
    /// An error will be returned if the input data is unable to be parsed as a public key. The `app_uuid`
    /// is expected to be a valid UUID, however this is not checked. If you pass something other than
    /// a valid UUID, no error will be returned, but none of the signatures will be able to be validated.
    ///
    /// ```
    /// # use mauth_core::verifier::Verifier;
    /// # let public_key = std::fs::read_to_string("tests/mauth-protocol-test-suite/signing-params/rsa-key-pub").unwrap();
    /// let verifier = Verifier::new("101c139a-236c-11ef-b5e3-125eb8485a60", public_key);
    /// assert!(verifier.is_ok());
    /// ```
    pub fn new(app_uuid: impl Into<String>, public_key_data: String) -> Result<Self, Error> {
        let public_key = RsaPublicKey::from_public_key_pem(&public_key_data)?;
        let verifying_key = rsa::pkcs1v15::VerifyingKey::<Sha512>::new(public_key.to_owned());

        Ok(Self {
            app_uuid: app_uuid.into(),
            public_key,
            verifying_key,
        })
    }

    /// This function will verify that a provided signature is valid given the uuid and public key the
    /// struct was constructed with, the request properties passed into the function, and the signature
    /// passed in. It will return Ok(()) if the signature validates successfully, and Err if it does
    /// not. It is the responsibility of the consuming crate and application to use these cases to
    /// determine whether to process a request further, or return error information.
    ///
    /// ```
    /// # use mauth_core::verifier::Verifier;
    /// # use mauth_core::error::Error;
    /// # let public_key = std::fs::read_to_string("tests/mauth-protocol-test-suite/signing-params/rsa-key-pub").unwrap();
    /// # let verifier = Verifier::new("101c139a-236c-11ef-b5e3-125eb8485a60", public_key).unwrap();
    /// let result = verifier.verify_signature(2, "GET", "/item", "page=2", b"", "2024-01-28T19:11:35.000", "");
    /// // Passing in an empty signature, so it will result in a verification error
    /// assert!(matches!(result, Err(Error::SignatureVerifyError(_))));
    /// ```
    #[allow(clippy::too_many_arguments)]
    pub fn verify_signature(
        &self,
        version: u8,
        verb: impl Into<String>,
        path: impl Into<String>,
        query: impl Into<String>,
        body: &[u8],
        timestamp: impl Into<String>,
        signature: impl Into<String>,
    ) -> Result<(), Error> {
        let signable = Signable::new(verb, path, query, body, timestamp, &self.app_uuid);

        match version {
            1 => self.verify_signature_v1(&signable, signature.into()),
            2 => self.verify_signature_v2(&signable, signature.into()),
            v => Err(Error::UnsupportedVersion(v)),
        }
    }

    fn verify_signature_v1(&self, signable: &Signable, signature: String) -> Result<(), Error> {
        self.public_key.verify(
            rsa::Pkcs1v15Sign::new_unprefixed(),
            &signable.signing_string_v1()?,
            &general_purpose::STANDARD.decode(signature)?,
        )?;

        Ok(())
    }

    fn verify_signature_v2(&self, signable: &Signable, signature: String) -> Result<(), Error> {
        use rsa::signature::Verifier;

        let signature =
            Signature::try_from(general_purpose::STANDARD.decode(signature)?.as_slice())?;
        self.verifying_key
            .verify(&signable.signing_string_v2()?, &signature)?;

        Ok(())
    }
}