Merge pull request #215 from dajiaji/expose-ciphersuite-native

Expose CipherSuiteNative class.

mod.ts

@@ -17,6 +17,7 @@ export * from "./src/errors.ts";
 
 export { Aead, AeadId, Kdf, KdfId, Kem, KemId } from "./src/identifiers.ts";
 export { CipherSuite } from "./src/cipherSuite.ts";
+export { CipherSuiteNative } from "./src/cipherSuiteNative.ts";
 export { DhkemP256HkdfSha256 } from "./src/kems/dhkemP256.ts";
 export { DhkemP384HkdfSha384 } from "./src/kems/dhkemP384.ts";
 export { DhkemP521HkdfSha512 } from "./src/kems/dhkemP521.ts";

src/cipherSuiteNative.ts

@@ -38,10 +38,24 @@ import * as consts from "./consts.ts";
 import * as errors from "./errors.ts";
 
 /**
- * The class of Hybrid Public Key Encryption (HPKE) cipher suite.
+ * The class of Hybrid Public Key Encryption (HPKE) ciphersuite.
  * The calling of the constructor of this class is the starting
  * point for HPKE operations for both senders and recipients.
  *
+ * This class supports only the ciphersuites which are
+ * supported by the native Web Cryptography API. Therefore,
+ * the following cryptographic algorithms are not supported for now:
+ *   - DHKEM(X25519, HKDF-SHA256)
+ *   - DHKEM(X448, HKDF-SHA512)
+ *   - ChaCha20/Poly1305
+ *
+ * In addtion, the HKDF functions contained in this `CipherSuiteNative`
+ * class can only derive keys of the same length as the `hashSize`.
+ *
+ * Therefore, if you want to use the unsupported cryptographic algorithms
+ * above or derive keys longer than the `hashSize`,
+ * please use {@link CipherSuite}
+ *
  * This class provides following functions:
  *
  * - Generates a key pair for the cipher suite.