Format Preserving Encryption (FPE)

In cryptography, format-preserving-encryption (FPE), refers to encrypting in such a way that the output (the ciphertext) is is the same format as the input (the plain text) - Wikipedia

Which means…

• To encrypt a 16-digit credit card number so that the ciphertext is another 16-digit number
• To encrypt an English word so that the ciphertext is another English word
• To encrypt an hex encoded text so that the ciphertext is another hex encoded text

The goal of a Format Preserving Encryption scheme is to securely encrypt while preserving the original formatting of the plaintext data

References

• https://en.wikipedia.org/wiki/Format-preserving_encryption
• https://github.com/idealista/format-preserving-encryption-java
• https://blog.cryptographyengineering.com/2011/11/10/format-preserving-encryption-or-how-to/
• https://www.encryptionconsulting.com/format-preserving-encryption-on-google-cloud/
• https://www.coursera.org/lecture/crypto/format-preserving-encryption-aFRSZ