Subject: PSARC FastTrack [04/11/2007]: Support KCF Providers with Limited Digest Capability

I am self-sponsoring the following case and marking it as
"closed approved automatic". It only modifies consolidation private
interfaces and does so in a compatible way.


Template Version: @(#)sac_nextcase 1.2 04/14/09 SMI
Copyright 2007 Sun Microsystems, Inc.
1. Introduction
    1.1. Project/Component Working Name:
	 Support KCF Providers with Limited Digest Capability
    1.2. Name of Document Author/Supplier:
	 Author:  Krishna Yenduri
    1.3  Date of This Document:
	11 April, 2007
4. Technical Description

1. Overview

This document describes changes to the Solaris Kernel Cryptographic
SPI to support hardware providers with limitation.

The Interface taxonomy is Consolidation Private.
The Release taxonomy is Patch/Micro.

2. Problem

Some crypto accelerator products like Sun Crypto Accelerator 6000
have a limit on the maximum input data that they can digest and hence
can not do multi-part digest (and HMAC which uses a digest) operations.
They can do single-part digest operation provided the input
data size is below the maximum supported value.

Currently, these providers when registered with Solaris Crypto Framework
can not export the digest mechanisms at all. This limitation prevents
PKCS #11 applications and some kernel clients from accelerating the
digest operations using the hardware.

So, there is a need to solve this limitation and enable consumers
to use the hardware as much as possible.


3. Solution

We relax the existing constraint that a provider must support multi-part
digest routines to be able to set CRYPTO_FG_DIGEST flag for a digest
mechanism. A provider is now allowed to export only a single-part digest
routine and still set the CRYPTO_FG_DIGEST flag.

A provider with the limitation needs to do the following:

1. Set the CRYPTO_LIMITED_HASH_SUPPORT flag, in pi_flags field of the
crypto_provider_info_t structure, to indicate this limitation.

2. For each digest mechanism, specify the maximum buffer length it can
digest in the cm_max_input_length field in crypto_mech_info_t structure
and set the CRYPTO_FG_DIGEST flag in cm_func_group_mask field.

3. Return the error code, CRYPTO_BUFFER_TOO_BIG, if it gets an input
buffer greater than the maximum supported length.

The framework will use only the digest_init and digest SPI routines
from such a provider. It will not use the routines - digest_update,
digest_key, and digest_final from the provider.

3.1. Compatibility issues

The size of crypto_mech_info_t structure remains unchanged as the
field cm_max_input_length is an alias for the existing field,
cm_max_key_length. We can safely do this because cm_max_key_length
field is unused for a digest mechanism.

There is no change in use of cm_max_key_length field for
a HMAC mechanism. The framework will get the limit on maximum input data 
from the underlying digest used by the HMAC mechanism.


4. Bug/RFE Number(s): 6473274


5. Exported Interfaces:

+--------------------------------+---------------------------+--------------+
|   Interface                    |  Classification           | Comments     |
+--------------------------------+---------------------------+--------------+
|                                |                           |              |
|   spi.h                        | Consolidation             | include file |
|                                | Private                   |              |
|                                |                           |              |
+--------------------------------+---------------------------+--------------+


6. Resources and Schedule
    6.4. Steering Committee requested information
   	6.4.1. Consolidation C-team Name:
		ON
    6.5. ARC review type: FastTrack