docs: public SecretKey decryptKey(String encryptedKey, PrivateKey privateKey) {
  
          // Basic null check
          if (encryptedKey == null) {
              return null;
          }
  
          // Convert the encryptedKey key String back to a byte array:
          byte[] bytes = ByteArray.fromBase64(encryptedKey);
  
          // Decrypt the bytes:
          byte[] decrypted;
          try {
              Cipher cipher = getCipher(privateKey);
              decrypted = cipher.doFinal(bytes);
          } catch (IllegalBlockSizeException e) {
              throw new IllegalArgumentException("Error encrypting SecretKey: " + IllegalBlockSizeException.class.getSimpleName(), e);
          } catch (BadPaddingException e) {
              throw new IllegalArgumentException("Error decrypting SecretKey", e);
          }
  
          // Reconstruct the key:
          return new SecretKeySpec(decrypted, Crypto.CIPHER_ALGORITHM);
      }