add constants and javadoc

tweetnacl-multiplatform/src/commonMain/kotlin/net/avianlabs/solana/tweetnacl/TweetNaCl.kt

@@ -5,7 +5,7 @@ import net.avianlabs.solana.tweetnacl.ed25519.Ed25519Keypair
 public interface TweetNaCl {
 
   /**
-   * Implements Ed25519
+   * Implements the Ed25519 signature scheme
    *
    * @see <a href="https://ed25519.cr.yp.to/">Ed25519 spec</a>
    */
@@ -14,24 +14,30 @@ public interface TweetNaCl {
     /**
      * Signs the message using the secret key and returns a signed message
      *
-     * @param message:
-     * @param secretKey:
+     * @param message: The message to sign
+     * @param secretKey: The secret key to sign the message with
+     * @return The signature of the message
      */
     public fun sign(message: ByteArray, secretKey: ByteArray): ByteArray
 
     /**
      * Returns a new signing key pair generated deterministically from a seed
      *
      * @param seed: 32 byte seed. Must contain enough entropy to be secure.
+     * @return A new key pair generated from the seed
      */
     public fun generateKey(seed: ByteArray): Ed25519Keypair
 
     /**
      * Returns whether the given publicKey falls in the Ed25519 elliptic curve
+     *
+     * @param publicKey: The public key to check
+     * @return Whether the public key is on the curve
      */
     public fun isOnCurve(publicKey: ByteArray): Boolean
 
     public companion object : Signature {
+      public const val SEED_BYTES: Int = 32
       public const val SECRET_KEY_BYTES: Int = 64
       public const val PUBLIC_KEY_BYTES: Int = 32
       public const val SIGNATURE_BYTES: Int = 64
@@ -48,21 +54,34 @@ public interface TweetNaCl {
   }
 
   /**
-   * Implements xsalsa20-poly1305
+   * Implements NaCl SecretBox (xsalsa20-poly1305)
+   *
+   * @see <a href="https://nacl.cr.yp.to/secretbox.html">SecretBox spec</a>
    */
   public interface SecretBox {
 
     /**
      * Encrypts and authenticates message using the key and the nonce. The nonce must be unique for each distinct message for this key.
+     *
+     * @param message: The message to encrypt
+     * @param nonce: The nonce to use for encryption
+     * @return The encrypted message
      */
     public fun box(message: ByteArray, nonce: ByteArray): ByteArray
 
     /**
      * Authenticates and decrypts the given secret box using the key and the nonce.
+     *
+     * @param box: The encrypted message
+     * @param nonce: The nonce used for encryption
+     * @return The decrypted message
      */
     public fun open(box: ByteArray, nonce: ByteArray): ByteArray
 
     public companion object {
+      public const val NONCE_BYTES: Int = 24
+      public const val KEY_BYTES: Int = 32
+
       public operator fun invoke(secretKey: ByteArray): SecretBox =
         secretBoxInternal(secretKey)
     }