code: public EnvironmentConfig setCipherKey(final String cipherKey) {
          if (cipherKey == null) {
              return (EnvironmentConfig) removeSetting(CIPHER_KEY);
          }
          return setSetting(CIPHER_KEY, KryptKt.toBinaryKey(cipherKey));
      }
docs: Sets the key which will be used to encrypt the database. The key is expected to be a hex string representing
  a byte array which is passed to {@linkplain StreamCipher#init(byte[], long)}. Is applicable only if
  {@linkplain #getCipherId()} returns not {@code null}. The setting cannot be changed for existing databases.
  Default value is {@code null}.
  <p>Mutable at runtime: no
  
  @param cipherKey hex string representing cipher key
  @return this {@code EnvironmentConfig} instance
  @see #setCipherId(String)
  @see #setCipherBasicIV(long)
  @see StreamCipher
  @see StreamCipher#init(byte[], long)
  @see StreamCipherProvider