i got my answer. if keys are not deleted from key ring there is no issue in decrypting the old data.
PII PHI data encyption using data protection api

Somnath Shukla
411
Reputation points
I am using data protection api in asp.net core 3.1 . I have PII and PHI data in database. can I use data protection api to encrypt the data. what if my data is not accessed for more than 6 month how key rotation will effect that