/// <summary>
        /// Gets an instance of <see cref="IEncryptor"/> for the provided key identifier.
        /// </summary>
        /// <param name="keyIdentifier">
        /// An implementation-specific object used to identify the key for this
        /// encryption operation.
        /// </param>
        /// <returns>An object that can be used for encryption operations.</returns>
        public IEncryptor GetEncryptor(object keyIdentifier)
        {
            ICredential credential;

            if (!_credentialRepository.TryGet(keyIdentifier, out credential))
            {
                throw new KeyNotFoundException($"Unable to locate credential using keyIdentifier: {keyIdentifier}");
            }

            return(new SymmetricEncryptor(credential, _encoding));
        }