Update API surface to support Kanidm KeyObjects

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "compact_jwt"
-version = "0.3.5"
+version = "0.4.0-dev"
 edition = "2021"
 authors = ["William Brown <[email protected]>"]
 description = "Minimal implementation of JWT for OIDC and other applications"

src/compact.rs

@@ -152,11 +152,6 @@ impl fmt::Debug for JwsCompact {
 }
 
 impl JwsCompact {
-    /// Get the KID used to sign this Jws if present
-    pub fn get_jwk_kid(&self) -> Option<&str> {
-        self.header.kid.as_deref()
-    }
-
     /// Get the embedded Url for the Jwk that signed this Jws.
     ///
     /// You MUST ensure this url uses HTTPS and you MUST ensure that your
@@ -261,6 +256,14 @@ impl JwsVerifiable for JwsCompact {
         }
     }
 
+    fn alg(&self) -> JwaAlg {
+        self.header.alg
+    }
+
+    fn kid(&self) -> Option<&str> {
+        self.header.kid.as_deref()
+    }
+
     fn post_process(&self, value: Jws) -> Result<Self::Verified, JwtError> {
         Ok(value)
     }
@@ -384,9 +387,18 @@ pub struct JweCompact {
     pub(crate) authentication_tag: Vec<u8>,
 }
 
+impl fmt::Debug for JweCompact {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("JweCompact")
+            .field("header", &self.header)
+            .field("encrypted_payload_length", &self.ciphertext.len())
+            .finish()
+    }
+}
+
 impl JweCompact {
     /// Get the KID used to encipher this Jwe if present
-    pub fn get_jwk_kid(&self) -> Option<&str> {
+    pub fn kid(&self) -> Option<&str> {
         self.header.kid.as_deref()
     }
 
@@ -402,6 +414,11 @@ impl JweCompact {
     pub fn get_jwk_pubkey(&self) -> Option<&Jwk> {
         self.header.jwk.as_ref()
     }
+
+    /// Return the CEK Algorithm and the inner encryption type.
+    pub fn get_alg_enc(&self) -> (JweAlg, JweEnc) {
+        (self.header.alg, self.header.enc)
+    }
 }
 
 impl FromStr for JweCompact {

src/crypto/a128gcm.rs

@@ -13,6 +13,8 @@ pub(crate) const KEY_LEN: usize = 16;
 const IV_LEN: usize = 12;
 const AUTH_TAG_LEN: usize = 16;
 
+/// A JWE inner encipher and decipher for AES 128 GCM. This is the recommended inner
+/// encryption algorithm to use.
 #[derive(Clone)]
 pub struct JweA128GCMEncipher {
     aes_key: [u8; KEY_LEN],
@@ -93,11 +95,12 @@ impl JweEncipherInner for JweA128GCMEncipher {
 }
 
 impl JweA128GCMEncipher {
+    /// The required length for this cipher key
     pub fn key_len() -> usize {
-        16
+        KEY_LEN
     }
 
-    pub fn decipher_inner(&self, jwec: &JweCompact) -> Result<Vec<u8>, JwtError> {
+    pub(crate) fn decipher_inner(&self, jwec: &JweCompact) -> Result<Vec<u8>, JwtError> {
         aes_gcm_decipher(
             Cipher::aes_128_gcm(),
             &jwec.ciphertext,

src/crypto/a128kw.rs

@@ -4,8 +4,11 @@ use crate::traits::*;
 use crate::JwtError;
 
 use openssl::aes::{unwrap_key, wrap_key, AesKey};
+use openssl::hash;
 use openssl::rand::rand_bytes;
 
+use std::fmt;
+
 // Do I need some inner type to handle the enc bit?
 
 pub(crate) const KEY_LEN: usize = 16;
@@ -16,13 +19,32 @@ const KW_EXTRA: usize = 8;
 /// shared keys, or are creating encrypted service tokens.
 #[derive(Clone)]
 pub struct JweA128KWEncipher {
+    /// Mark that the key is ephemeral and shall not be exported.
+    is_ephemeral: bool,
+    /// If the KID should be embedded during signing
+    sign_option_embed_kid: bool,
+    /// The KID of this encryption key. This is a truncated sha256 digest.
+    kid: String,
+    /// The wrapping key.
     wrap_key: [u8; KEY_LEN],
 }
 
+impl fmt::Debug for JweA128KWEncipher {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("JweA128KWEncipher")
+            .field("kid", &self.kid)
+            .finish()
+    }
+}
+
 impl JweEncipherOuter for JweA128KWEncipher {
     /// See [JweEncipherOuter]
     fn set_header_alg(&self, hdr: &mut JweProtectedHeader) -> Result<(), JwtError> {
         hdr.alg = JweAlg::A128KW;
+        if self.sign_option_embed_kid {
+            hdr.kid = Some(self.kid.clone());
+        }
+
         Ok(())
     }
 
@@ -55,16 +77,46 @@ impl JweEncipherOuter for JweA128KWEncipher {
 }
 
 impl JweA128KWEncipher {
-    /// Generate an ephemeral outer key.
-    pub fn generate_ephemeral() -> Result<Self, JwtError> {
+    /// Create a new direct A128KW Encipher. The key will be randomly generated.
+    pub fn new() -> Result<Self, JwtError> {
         let mut wrap_key = [0; KEY_LEN];
 
         rand_bytes(&mut wrap_key).map_err(|ossl_err| {
             debug!(?ossl_err);
             JwtError::OpenSSLError
         })?;
 
-        Ok(JweA128KWEncipher { wrap_key })
+        Self::try_from(wrap_key)
+    }
+
+    /// Get the Key ID of this encipher
+    pub fn kid(&self) -> &str {
+        self.kid.as_str()
+    }
+
+    /// If this key is not ephemeral, expose the bytes of the AES wrap key. This
+    /// allows the key to be persisted.
+    pub fn key_bytes(&self) -> Result<[u8; KEY_LEN], JwtError> {
+        if self.is_ephemeral {
+            Err(JwtError::UnableToReleaseKey)
+        } else {
+            Ok(self.wrap_key)
+        }
+    }
+
+    /// Enable or disable setting the KID into the header of any encrypted JWE's
+    pub fn set_sign_option_embed_kid(mut self, value: bool) -> Self {
+        self.sign_option_embed_kid = value;
+        self
+    }
+
+    /// Generate an ephemeral outer key.
+    pub fn generate_ephemeral() -> Result<Self, JwtError> {
+        Self::new().map(|mut key| {
+            key.is_ephemeral = true;
+            key.sign_option_embed_kid = false;
+            key
+        })
     }
 
     /// Given a JWE, encipher its content to a compact form.
@@ -105,18 +157,45 @@ impl JweA128KWEncipher {
             payload,
         })
     }
+
+    pub(crate) fn load_ephemeral(wrap_key: [u8; KEY_LEN]) -> Self {
+        JweA128KWEncipher {
+            is_ephemeral: true,
+            sign_option_embed_kid: false,
+            kid: String::default(),
+            wrap_key,
+        }
+    }
 }
 
-impl From<[u8; KEY_LEN]> for JweA128KWEncipher {
-    fn from(wrap_key: [u8; KEY_LEN]) -> JweA128KWEncipher {
-        JweA128KWEncipher { wrap_key }
+impl TryFrom<[u8; KEY_LEN]> for JweA128KWEncipher {
+    type Error = JwtError;
+
+    fn try_from(wrap_key: [u8; KEY_LEN]) -> Result<Self, Self::Error> {
+        let digest = hash::MessageDigest::sha256();
+
+        let kid = hash::hash(digest, &wrap_key)
+            .map(|hashout| {
+                let mut s = hex::encode(hashout);
+                // 192 bits
+                s.truncate(48);
+                s
+            })
+            .map_err(|_| JwtError::OpenSSLError)?;
+
+        Ok(JweA128KWEncipher {
+            is_ephemeral: false,
+            sign_option_embed_kid: true,
+            kid,
+            wrap_key,
+        })
     }
 }
 
-impl TryFrom<Vec<u8>> for JweA128KWEncipher {
+impl TryFrom<&[u8]> for JweA128KWEncipher {
     type Error = JwtError;
 
-    fn try_from(value: Vec<u8>) -> Result<Self, Self::Error> {
+    fn try_from(value: &[u8]) -> Result<Self, Self::Error> {
         if value.len() != KEY_LEN {
             // Wrong key size.
             return Err(JwtError::InvalidKey);
@@ -126,7 +205,7 @@ impl TryFrom<Vec<u8>> for JweA128KWEncipher {
 
         wrap_key.copy_from_slice(&value);
 
-        Ok(JweA128KWEncipher { wrap_key })
+        Self::try_from(wrap_key)
     }
 }
 
@@ -181,7 +260,7 @@ mod tests {
         assert!(jwec.get_jwk_pubkey().is_none());
 
         let a128kw_encipher =
-            JweA128KWEncipher::try_from(a128kw_key).expect("Unable to create encipher");
+            JweA128KWEncipher::try_from(a128kw_key.as_slice()).expect("Unable to create encipher");
 
         let released = a128kw_encipher
             .decipher(&jwec)

src/crypto/a256gcm.rs

@@ -14,6 +14,7 @@ pub(crate) const KEY_LEN: usize = 32;
 const IV_LEN: usize = 12;
 const AUTH_TAG_LEN: usize = 16;
 
+/// A JWE inner encipher and decipher for AES 256 GCM.
 #[derive(Clone)]
 pub struct JweA256GCMEncipher {
     aes_key: [u8; KEY_LEN],
@@ -111,11 +112,12 @@ impl JweEncipherInner for JweA256GCMEncipher {
 }
 
 impl JweA256GCMEncipher {
+    /// The required length for this cipher key
     pub fn key_len() -> usize {
         KEY_LEN
     }
 
-    pub fn decipher_inner(&self, jwec: &JweCompact) -> Result<Vec<u8>, JwtError> {
+    pub(crate) fn decipher_inner(&self, jwec: &JweCompact) -> Result<Vec<u8>, JwtError> {
         super::a128gcm::aes_gcm_decipher(
             Cipher::aes_256_gcm(),
             &jwec.ciphertext,

src/crypto/ecdhes_a128kw.rs

@@ -91,7 +91,7 @@ impl JweEncipherOuter for JweEcdhEsA128KWEncipher {
 
         derive_key(&self.priv_key, &self.peer_public_key).and_then(|wrapping_key|
                 // use A128KW with the derived wrap key as usual.
-                JweA128KWEncipher::from(wrapping_key)
+                JweA128KWEncipher::load_ephemeral(wrapping_key)
                     .wrap_key(key_to_wrap))
     }
 }
@@ -228,10 +228,10 @@ impl JweEcdhEsA128KWDecipher {
             }
         };
 
-        derive_key(&self.priv_key, &ephemeral_public_key).and_then(|wrapping_key|
-                // use A128KW with the derived wrap key as usual.
-                JweA128KWEncipher::from(wrapping_key)
-                    .decipher(jwec))
+        derive_key(&self.priv_key, &ephemeral_public_key).and_then(|wrapping_key| {
+            // use A128KW with the derived wrap key as usual.
+            JweA128KWEncipher::load_ephemeral(wrapping_key).decipher(jwec)
+        })
     }
 }