DataProtector.GetHashedPurpose Method
Definition
Important
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Creates a hash of the property values specified by the constructor.
protected:
virtual cli::array <System::Byte> ^ GetHashedPurpose();protected virtual byte[] GetHashedPurpose ();abstract member GetHashedPurpose : unit -> byte[]
override this.GetHashedPurpose : unit -> byte[]Protected Overridable Function GetHashedPurpose () As Byte()Returns
An array of bytes that contain the hash of the ApplicationName, PrimaryPurpose, and SpecificPurposes properties.
Examples
The following example shows how to use the GetHashedPurpose method to hash the purpose properties for use as extra entropy. It is part of a larger code example for the DataProtector class.
// To allow a service to hand out instances of a DataProtector we demand unrestricted DataProtectionPermission
// in the constructor, but Assert the permission when ProviderProtect is called. This is similar to FileStream
// where access is checked at time of creation, not time of use.
[SecuritySafeCritical]
[DataProtectionPermission(SecurityAction.Assert, ProtectData = true)]
protected override byte[] ProviderProtect(byte[] userData)
{
// Delegate to ProtectedData
return ProtectedData.Protect(userData, GetHashedPurpose(), Scope);
}
' To allow a service to hand out instances of a DataProtector we demand unrestricted DataProtectionPermission
' in the constructor, but Assert the permission when ProviderProtect is called. This is similar to FileStream
' where access is checked at time of creation, not time of use.
<SecuritySafeCritical(), DataProtectionPermission(SecurityAction.Assert, ProtectData:=True)> _
Protected Overrides Function ProviderProtect(ByVal userData() As Byte) As Byte()
' Delegate to ProtectedData
Return ProtectedData.Protect(userData, GetHashedPurpose(), Scope)
End Function 'ProviderProtect
Remarks
GetHashedPurpose computes the hash of the application name and the full purpose. The full purpose is a concatenation of all the PrimaryPurpose and SpecificPurposes properties. Each of the three parts is prefaced with its length so the hash can be reversed.
