Sometimes we want to use a field value in a url or form and not show its actual value to the user. For example: 

https://myzohoform.myzohoorganization.com/?&subscriber=joeblow@me.com&provider=suzie@experts.com

What if I dont want to expose "suzie@experts.com"? I dont want people contacting her or sending her spam. So I have to encrypt it.  Zoho lets me do that with Base64 encoding/decoding and MD5 one-way encryption, but I have to mess with that in functions. Why not offer those as options in a Formula field so that I dont have to create Zoho functions. That way I would have 2 fields in the module: (1) for the normal value (2) another for the encrypted value. That way the URL I expose to the public would be 

https://myzohoform.myzohoorganization.com/?&subscriber=joeblow@me.com&provider=a4ebc2dffc5e2f456f

Noone would know suzie's email, and I could keep its encrypted value a4ebc2dffc5e2f456f as a separate field in the module as a lookup value as a way to lookup her REAL email, all without having to calculate the encryption outside of zoho. Today I have the 2 fields - (1) an email field (2) a string field for the encrypted value. When I need an encrypted value I have to go to an outside website to calculate it so that I can paste its value in the encrypted field. If there was an encrypt/decrypt function available in Formula fields I would not have to go to an outside website to calculate and save the value.