[cifs-protocol] [EXTERNAL] is MS-DRSR 4.1.10.5.21 CompressOrDecompressWin2k3 the same as MS-WUSP 2.1.1.1 CompressOrDecompressWin2k3 ? - TrackingID#2512240040003184

[Douglas Bagnall]

hi Kristian,

Thank you. I have no further questions.

Douglas

On 14/01/2026 13:56, Kristian Smith wrote:
> Hi Douglas,
> 
> They are parallel implementations of the same functionality. Essentially separate source, but same design. Hope that helps.
> 
> Regards,
> Kristian Smith
> Escalation Engineer | Microsoft(r) Corporation
> Email: kristian.smith at microsoft.com
> 
> -----Original Message-----
> From: Douglas Bagnall <douglas.bagnall at catalyst.net.nz>
> Sent: Tuesday, January 13, 2026 4:52 PM
> To: Kristian Smith <Kristian.Smith at microsoft.com>
> Cc: Microsoft Support <supportmail at microsoft.com>; cifs-protocol at lists.samba.org
> Subject: Re: [EXTERNAL] is MS-DRSR 4.1.10.5.21 CompressOrDecompressWin2k3 the same as MS-WUSP 2.1.1.1 CompressOrDecompressWin2k3 ? - TrackingID#2512240040003184
> 
> hi Kristian,
> 
> I am still interested to know whether they are exactly the same or not.
> 
> thanks
> Douglas
> 
> 
> On 14/01/2026 13:38, Kristian Smith wrote:
>> Hi Douglas,
>>
>> I reached out to the engineering team and we determined that the discrepancies are in MS-DRSR. MS-DRSR should reflect " a match length of up to 65,535 bytes + 3 bytes" as well as " This scheme is good for lengths of up to 279". I've submitted a bug against the document and you should see this updated in a future document release.
>>
>> Thank you for helping us keep the docs up to date. Please let me know if you have any further questions.
>>
>> Regards,
>> Kristian Smith
>> Escalation Engineer | Microsoft(r) Corporation
>> Email: kristian.smith at microsoft.com
>>
>> -----Original Message-----
>> From: Tom Jebo <tomjebo at microsoft.com>
>> Sent: Wednesday, December 24, 2025 8:57 AM
>> To: Douglas Bagnall <douglas.bagnall at catalyst.net.nz>; cifs-protocol at lists.samba.org
>> Cc: Interoperability Documentation Help <dochelp at microsoft.com>; Microsoft Support <supportmail at microsoft.com>
>> Subject: RE: [EXTERNAL] is MS-DRSR 4.1.10.5.21 CompressOrDecompressWin2k3 the same as MS-WUSP 2.1.1.1 CompressOrDecompressWin2k3 ? - TrackingID#2512240040003184
>>
>> [dochelp to cc]
>> [support mail to cc]
>>
>> Hi Douglas,
>>
>> Thanks for your request regarding MS-DRSR 4.1.10.5.21 and MS-WUSP 2.1.1.1. One of the Open Specifications team members will respond to assist you. In the meantime, we've created case 2512240040003184 to track this request. Please leave the case number in the subject when communicating with our team about this request.
>>
>> Best regards,
>> Tom Jebo
>> Microsoft Open Specifications Support
>>
>> -----Original Message-----
>> From: Douglas Bagnall <douglas.bagnall at catalyst.net.nz>
>> Sent: Tuesday, December 23, 2025 3:40 PM
>> To: Interoperability Documentation Help <dochelp at microsoft.com>; cifs-protocol at lists.samba.org
>> Subject: [EXTERNAL] is MS-DRSR 4.1.10.5.21 CompressOrDecompressWin2k3 the same as MS-WUSP 2.1.1.1 CompressOrDecompressWin2k3 ?
>>
>> hi Dochelp.
>>
>> The MS-DRSR and MS-WUSP definitions of CompressOrDecompressWin2k3 look very similar.
>> Are they really the same procedure?
>>
>> If they are in fact the same, my next question is which document is most correct.
>> I haven't looked closely, but I see these differences:
>>
>> MS-WUSP: This scheme is good for lengths of up to 279
>> MS-DRSR: This scheme is good for lengths of up to 278
>>
>> MS-WUSP: a match length of up to 65,535 bytes + 3 bytes
>> MS-DRSR: a match length of up to 32,768 bytes + 3 bytes
>>
>> Perhaps one has been updated and not the other?
>>
>>
>> In November 2022[1] I asked if MS-XCA 2.3 and 2.4 "Plain LZ77" was the same as the MS-DRSR procedure. The answer was "MS-DRSR uses a different API than what MS-XCA uses", which I took to mean that even if it was initially intended that they were the same, they could easily be accidentally different. I guess my first question could be answered in the same way -- are these using the same shared library function?
>>
>> [1] https://lists.samba.org/archive/cifs-protocol/2022-November/003902.html
>>
>> cheers,
>> Douglas
>>
>