[cryptography] Anti-GSS falsehoods (was Re: IETF Working Group Charter on Common Interface to Cryptographic Modules (CICM))

Marsh Ray marsh at extendedsubset.com
Fri Jun 24 12:00:31 EDT 2011


On 06/24/2011 02:04 AM, Nico Williams wrote:
>
> Every bank that uses Active Directory uses Kerberos, and the GSS-like
> SSPI.  And the Kerberos GSS mechanism (through SSPI, on Windows).  The
> native Windows TLS implementation is accessed via SSPI.

I've used/abused the Windows SSPI a few times for various things. It's 
pretty darn abstract. Which is not a criticism, only that it's less of 
an API than a intra-host transport protocol for shipping loosely related 
structures between apps and the security providers which are as diverse 
as Kerb and TLS.

> http://msdn.microsoft.com/en-us/library/aa375506%28v=vs.85%29.aspx
For example, the Microsoft doco on InitializeSecurityContext()
has a description and then again separate pages for every security 
support provider (SSP) that ships with Windows.

Most of the SSPI functions have descriptions like "Used by a server to
create a security context based on an opaque message received from a 
client" and "Applies a supplemental security message to an existing 
security context".
> http://msdn.microsoft.com/en-us/library/aa374731%28v=VS.85%29.aspx

Again, there's nothing wrong with this. But I suggest a guideline for 
our discussion of the design of crypto APIs: The API must not be so 
abstract that it doesn't actually encrypt any data.

- Marsh



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