fix: unbox nonce and key length

unbox.js

@@ -6,6 +6,7 @@ const through = require('through2')
 const {
  crypto_secretbox_KEYBYTES,
  crypto_secretbox_MACBYTES,
+ crypto_secretbox_NONCEBYTES,
 
  crypto_secretbox_open_easy,
 } = require('./sodium')
@@ -46,14 +47,15 @@ function unbox(buffer, opts) {
  if (false === isBuffer(key)) {
  throw new TypeError('crypto.unbox: Expecting secret key.')
  }
-
+
+ key = key.slice(0, crypto_secretbox_KEYBYTES)
  const nonces = [ copy(nonce), increment(copy(nonce)) ]
  const header = Buffer.allocUnsafe(2 + crypto_secretbox_MACBYTES)
 
  crypto_secretbox_open_easy(
  header,
  buffer.slice(0, 2 + (2 * crypto_secretbox_MACBYTES)),
- nonces[0],
+ nonces[0].slice(0, crypto_secretbox_NONCEBYTES),
  key
  )
 
@@ -75,7 +77,7 @@ function unbox(buffer, opts) {
  crypto_secretbox_open_easy(
  unboxed,
  combined,
- nonces[1],
+ nonces[1].slice(0, crypto_secretbox_NONCEBYTES),
  key
  )