transformers *lru.Cache

	// baseTransformerFunc creates a new transformer for encrypting the data with the DEK.
	baseTransformerFunc func(cipher.Block) (value.Transformer, error)

	cacheSize    int
	cacheEnabled bool
}

// NewEnvelopeTransformer returns a transformer which implements a KEK-DEK based envelope encryption scheme.
// It uses envelopeService to encrypt and decrypt DEKs. Respective DEKs (in encrypted form) are prepended to