Changes to support ACME, including JWS

Author: andrew

src/decoding.rs

@@ -6,6 +6,7 @@ use crate::crypto::verify;
 use crate::errors::{new_error, ErrorKind, Result};
 use crate::header::Header;
 use crate::jwk::{AlgorithmParameters, Jwk};
+use crate::jws::Jws;
 #[cfg(feature = "use_pem")]
 use crate::pem::decoder::PemEncodedKey;
 use crate::serialization::{b64_decode, DecodedJwtPartClaims};
@@ -286,3 +287,58 @@ pub fn decode_header(token: &str) -> Result<Header> {
     let (_, header) = expect_two!(message.rsplitn(2, '.'));
     Header::from_encoded(header)
 }
+
+/// Verify signature of a JWS, and return the header object
+///
+/// If the token or its signature is invalid, it will return an error.
+fn verify_jws_signature<T>(
+    jws: &Jws<T>,
+    key: &DecodingKey,
+    validation: &Validation,
+) -> Result<Header> {
+    if validation.validate_signature && validation.algorithms.is_empty() {
+        return Err(new_error(ErrorKind::MissingAlgorithm));
+    }
+
+    if validation.validate_signature {
+        for alg in &validation.algorithms {
+            if key.family != alg.family() {
+                return Err(new_error(ErrorKind::InvalidAlgorithm));
+            }
+        }
+    }
+
+    let header = Header::from_encoded(&jws.protected)?;
+
+    if validation.validate_signature && !validation.algorithms.contains(&header.alg) {
+        return Err(new_error(ErrorKind::InvalidAlgorithm));
+    }
+
+    let message = [jws.protected.as_str(), jws.payload.as_str()].join(".");
+
+    if validation.validate_signature
+        && !verify(&jws.signature, message.as_bytes(), key, header.alg)?
+    {
+        return Err(new_error(ErrorKind::InvalidSignature));
+    }
+
+    Ok(header)
+}
+
+/// Validate a received JWS and decode into the header and claims.
+pub fn decode_jws<T: DeserializeOwned>(
+    jws: &Jws<T>,
+    key: &DecodingKey,
+    validation: &Validation,
+) -> Result<TokenData<T>> {
+    match verify_jws_signature(jws, key, validation) {
+        Err(e) => Err(e),
+        Ok(header) => {
+            let decoded_claims = DecodedJwtPartClaims::from_jwt_part_claims(&jws.payload)?;
+            let claims = decoded_claims.deserialize()?;
+            validate(decoded_claims.deserialize()?, validation)?;
+
+            Ok(TokenData { header, claims })
+        }
+    }
+}

src/encoding.rs

@@ -5,6 +5,7 @@ use crate::algorithms::AlgorithmFamily;
 use crate::crypto;
 use crate::errors::{new_error, ErrorKind, Result};
 use crate::header::Header;
+use crate::jws::Jws;
 #[cfg(feature = "use_pem")]
 use crate::pem::decoder::PemEncodedKey;
 use crate::serialization::b64_encode_part;
@@ -129,3 +130,30 @@ pub fn encode<T: Serialize>(header: &Header, claims: &T, key: &EncodingKey) -> R
 
     Ok([message, signature].join("."))
 }
+
+/// Encode the header and claims given and sign the payload using the algorithm from the header and the key.
+/// If the algorithm given is RSA or EC, the key needs to be in the PEM format. This produces a JWS instead of
+/// a JWT -- usage is similar to `encode`, see that for more details.
+pub fn encode_jws<T: Serialize>(
+    header: &Header,
+    claims: Option<&T>,
+    key: &EncodingKey,
+) -> Result<Jws<T>> {
+    if key.family != header.alg.family() {
+        return Err(new_error(ErrorKind::InvalidAlgorithm));
+    }
+    let encoded_header = b64_encode_part(header)?;
+    let encoded_claims = match claims {
+        Some(claims) => b64_encode_part(claims)?,
+        None => "".to_string(),
+    };
+    let message = [encoded_header.as_str(), encoded_claims.as_str()].join(".");
+    let signature = crypto::sign(message.as_bytes(), key, header.alg)?;
+
+    Ok(Jws {
+        protected: encoded_header,
+        payload: encoded_claims,
+        signature: signature,
+        _pd: Default::default(),
+    })
+}

src/header.rs

@@ -64,6 +64,16 @@ pub struct Header {
     #[serde(skip_serializing_if = "Option::is_none")]
     #[serde(rename = "x5t#S256")]
     pub x5t_s256: Option<String>,
+    /// ACME: The URL to which this JWS object is directed
+    ///
+    /// Defined in [RFC8555#6.4](https://datatracker.ietf.org/doc/html/rfc8555#section-6.4).
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub url: Option<String>,
+    /// ACME: Random data for preventing replay attacks.
+    ///
+    /// Defined in [RFC8555#6.5.2](https://datatracker.ietf.org/doc/html/rfc8555#section-6.5.2).
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub nonce: Option<String>,
 }
 
 impl Header {
@@ -80,6 +90,8 @@ impl Header {
             x5c: None,
             x5t: None,
             x5t_s256: None,
+            url: None,
+            nonce: None,
         }
     }
 

src/jws.rs

@@ -0,0 +1,24 @@
+//! JSON Web Signatures data type.
+use std::marker::PhantomData;
+
+use serde::{Deserialize, Serialize};
+
+/// This is a serde-compatible JSON Web Signature structure.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct Jws<C> {
+    /// The base64 encoded header data.
+    ///
+    /// Defined in [RFC7515#3.2](https://tools.ietf.org/html/rfc7515#section-3.2).
+    pub protected: String,
+    /// The base64 encoded claims data.
+    ///
+    /// Defined in [RFC7515#3.2](https://tools.ietf.org/html/rfc7515#section-3.2).
+    pub payload: String,
+    /// The signature on the other fields.
+    ///
+    /// Defined in [RFC7515#3.2](https://tools.ietf.org/html/rfc7515#section-3.2).
+    pub signature: String,
+    /// Unused, for associating type metadata.
+    #[serde(skip)]
+    pub _pd: PhantomData<C>,
+}

src/lib.rs

@@ -12,13 +12,14 @@ mod encoding;
 pub mod errors;
 mod header;
 pub mod jwk;
+pub mod jws;
 #[cfg(feature = "use_pem")]
 mod pem;
 mod serialization;
 mod validation;
 
 pub use algorithms::Algorithm;
-pub use decoding::{decode, decode_header, DecodingKey, TokenData};
-pub use encoding::{encode, EncodingKey};
+pub use decoding::{decode, decode_header, decode_jws, DecodingKey, TokenData};
+pub use encoding::{encode, encode_jws, EncodingKey};
 pub use header::Header;
 pub use validation::{get_current_timestamp, Validation};