Format-preserving encryption

Format-Preserving Encryption (FPE) is a type of encryption that allows the encryption of data while preserving its original format. This means that the output ciphertext has the same structure and characteristics as the plaintext data, which can be particularly useful for integrating encryption into existing systems that expect certain data formats. For example, if you're encrypting a Social Security Number (SSN), using FPE would allow you to obtain a ciphertext that still looks like a valid SSN (i.e.