phc-discussions - Re: [PHC] Q: int return from PHS()

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Date: Tue, 19 Feb 2013 08:04:37 +0100
From: Jean-Philippe Aumasson <jeanphilippe.aumasson@...il.com>
To: discussions@...sword-hashing.net
Subject: Re: [PHC] Q: int return from PHS()

Like Samuel said, the call does not set any rule for return values,
however it is expected that implementers return 0 upon success, and
something else upon error.


On Tue, Feb 19, 2013 at 8:00 AM, Dennis E. Hamilton
<dennis.hamilton@....org> wrote:
> What I don't know is which case it is?
>
> I have one response that says the returned int is a result code, with 0 for
> success.
>
> I have another response that says the returned int is the size of hash that
> was actually produced.
>
> What's intended?  Or is it implementation-defined?
>
>  - Dennis
>
> -----Original Message-----
> From: Jean-Philippe Aumasson [mailto:jeanphilippe.aumasson@...il.com]
> Sent: Monday, February 18, 2013 22:43
> To: discussions@...sword-hashing.net
> Subject: Re: [PHC] Q: int return from PHS()
>
> On Mon, Feb 18, 2013 at 10:26 PM, Dennis E. Hamilton
> <dennis.hamilton@....org> wrote:
>> !? (glad I asked)
>>
>> If PHS( ) returns the length of the data delivered in the output buffer,
> type disharmony is avoided by (1) making the result a size_t or (2) making
> outlen an int.  In case (1), 0 is probably the failure result.  In case (2)
> negative results can signify errors (and 0 is a strange success case?).  I'm
> not clear whether (2) is now considered an archaic device.  I'm agnostic
> about that.  I just want definiteness.
>>
>> If PHS( ) returns a straightforward result code (with 0 signifying
> success), I would expect that outlen is a request for a specific size of
> result and the function should fail if it can't deliver.
>>
>
> As the call states, at least the value 16 (i.e., 16 bytes) should be
> supported. The function may then return an error (a non-zero value) if
> the outlen received is not supported.
>
>
>> In the case of failure/error in either case, the content of the output
> buffer should be considered unpredictable and should also not leak anything.
> (If it were up to me, I'd always clear the output buffer at the beginning
> and endeavor to leave it that way except just before a success return.)
>>
>
> We don't care about such leaks in a reference implementation (as
> opposed to a production implementation).
>
>> -----Original Message-----
>> From: Steve Thomas [mailto:steve@...tu.com]
>> Sent: Monday, February 18, 2013 12:40
>> To: discussions@...sword-hashing.net
>> Subject: Re: [PHC] Q: int return from PHS()
>>
>>> On February 18, 2013 at 1:00 PM Samuel Neves <sneves@....uc.pt> wrote:
>>>
>>>
>>> On 18-02-2013 18:46, Dennis E. Hamilton wrote:
>>> > Reference implementations for submissions are requested to provide an
> API
>>> > having signature int PHS( ...)
>>> >
>>> > What are the prescribed return values and their significance?
>>> >
>>> > - Dennis
>>> >
>>> > PS: Sorry if this has been asked. I haven't found the list archive yet.
>>> >
>>> It has not been asked.
>>>
>>> In typical C fashion, return value should be 0 for success, and
>>> otherwise for any error that may occur during computation. Error codes,
>>> if any, should be up to implementors, since sources of error may wildly
>>> vary between schemes/implementations.
>>
>> I was under the impression that the return value was the amount of data
> copied to the output buffer.
>>
>