Platofrm Encryption Documentation doesn't include "Birthdate" as one of the standard fields that can be encrypted and I don't see the option to encrypt the field in the org. Is there any way to encrypt it? One solution I can think of is to create a custom field and encrypt that.
Thank you for your interest in shield encryption.
Unfortunately, supporting standard date fields is very challenging because they're stored as dates in our database, giving no option for replacing them by their corresponding ciphertext that require a varchar column.
Custom date fields, on the other hand, can be encrypted, thanks to the way they are stored in the database.