https://learn.microsoft.com/en-us/dotnet/api/system.security.cryptography.dataprotector.prependhashedpurposetoplaintext?view=netframework-4.8.1
DataProtector.PrependHashedPurposeToPlaintext Property (System.Security.Cryptography) | Microsoft...
Specifies whether the hash is prepended to the text array before encryption.
property systemsecuritycryptographymicrosoft