The Length Preserving Randomized Encryption for Text Areas scheme uses regular randomized encryption (AES-256 CBC encryption with random IV) for text areas. This encrypts the content in the text field, while preserving the length and searchability.
To encrypt the content, this scheme uses a header and a footer. The header includes a sentinel, an algorithm enumerator, and a key version. The footer includes a sentinel, a capitalization bit fiend, and a punctuation bit field.
For example, if you had a text field with the following sentence: The guy’s name was Fred.
If you searched for "fred" (lowercase), you would still find it, because this scheme also encrypts the lowercase version of the name in the capitalization bit field in the footer.
Use Case: Use this scheme for a text area when you want to preserve the length of the field, encrypt the content, and preserve searchability.