From fa22e01714e6a892551d2753c7b96713244dcb86 Mon Sep 17 00:00:00 2001
From: Nick Hynes <nhynes@oasislabs.com>
Date: Mon, 13 Jul 2020 22:11:10 +0000
Subject: [PATCH] Add jsonwebtoken conversions

---
 Cargo.toml |  1 +
 README.md  |  1 +
 src/lib.rs | 62 ++++++++++++++++++++++++++++++++++++++++--------------
 3 files changed, 48 insertions(+), 16 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index 5ae407a..707d79b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,6 +12,7 @@ edition = "2018"
 base64 = "0.12"
 bitflags = "1.2"
 derive_more = "0.99"
+jsonwebtoken = { version = "7.2", optional = true }
 num-bigint = { version = "0.2", optional = true }
 paste = "0.1"
 serde = { version = "1.0", features = ["derive"] }
diff --git a/README.md b/README.md
index 1106d1b..84cf456 100644
--- a/README.md
+++ b/README.md
@@ -40,3 +40,4 @@ fn main() {
 
 * `convert` - enables `Key::{to_der, to_pem}`.
               This pulls in the [yasna](https://crates.io/crates/yasna) crate.
+* `jsonwebtoken` - enables conversions to types in the [jsonwebtoken](https://crates.io/crates/jsonwebtoken) crate.
diff --git a/src/lib.rs b/src/lib.rs
index 7ab5695..04763d8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -36,9 +36,41 @@ pub struct JsonWebKey {
 }
 
 impl JsonWebKey {
+    pub fn new(key: Key) -> Self {
+        Self {
+            key: box key,
+            key_use: None,
+            key_ops: KeyOps::empty(),
+            key_id: None,
+            algorithm: None,
+        }
+    }
+
+    pub fn set_algorithm(&mut self, alg: JsonWebAlgorithm) -> Result<(), Error> {
+        Self::validate_algorithm(alg, &*self.key)?;
+        self.algorithm = Some(alg);
+        Ok(())
+    }
+
     pub fn from_slice(bytes: impl AsRef<[u8]>) -> Result<Self, Error> {
         Ok(serde_json::from_slice(bytes.as_ref())?)
     }
+
+    fn validate_algorithm(alg: JsonWebAlgorithm, key: &Key) -> Result<(), Error> {
+        use JsonWebAlgorithm::*;
+        use Key::*;
+        match (alg, key) {
+            (
+                ES256,
+                EC {
+                    curve: Curve::P256 { .. },
+                },
+            )
+            | (RS256, RSA { .. })
+            | (HS256, Symmetric { .. }) => Ok(()),
+            _ => Err(Error::MismatchedAlgorithm),
+        }
+    }
 }
 
 impl std::str::FromStr for JsonWebKey {
@@ -46,24 +78,11 @@ impl std::str::FromStr for JsonWebKey {
     fn from_str(json: &str) -> Result<Self, Self::Err> {
         let jwk = Self::from_slice(json.as_bytes())?;
 
-        // Validate alg.
-        use JsonWebAlgorithm::*;
-        use Key::*;
-        let alg = match &jwk.algorithm {
+        let alg = match jwk.algorithm {
             Some(alg) => alg,
             None => return Ok(jwk),
         };
-        match (alg, &*jwk.key) {
-            (
-                ES256,
-                EC {
-                    curve: Curve::P256 { .. },
-                },
-            )
-            | (RS256, RSA { .. })
-            | (HS256, Symmetric { .. }) => Ok(jwk),
-            _ => Err(Error::MismatchedAlgorithm),
-        }
+        Self::validate_algorithm(alg, &*jwk.key).map(|_| jwk)
     }
 }
 
@@ -346,13 +365,24 @@ pub enum KeyUse {
     Encryption,
 }
 
-#[derive(Debug, PartialEq, Eq, Serialize, Deserialize, Zeroize)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize, Zeroize)]
 pub enum JsonWebAlgorithm {
     HS256,
     RS256,
     ES256,
 }
 
+#[cfg(any(test, feature = "jsonwebtoken"))]
+impl Into<jsonwebtoken::Algorithm> for JsonWebAlgorithm {
+    fn into(self) -> jsonwebtoken::Algorithm {
+        match self {
+            Self::HS256 => jsonwebtoken::Algorithm::HS256,
+            Self::ES256 => jsonwebtoken::Algorithm::ES256,
+            Self::RS256 => jsonwebtoken::Algorithm::RS256,
+        }
+    }
+}
+
 #[derive(Debug, thiserror::Error)]
 pub enum Error {
     #[error(transparent)]