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Subject: Re: [boost] New Boost.XInt Library, request preliminary review
From: Chad Nelson (chad.thecomfychair_at_[hidden])
Date: 2010-03-29 21:04:51

Hash: SHA1

On 03/29/2010 08:42 PM, Scott McMurray wrote:

> Those two functions, invmod and random_prime, can use xint() as their
> error code, if the relevant exception is blocked, since 0 is obviously
> neither a multiplicative inverse or a prime.

Close, but not quite: the inverse of zero is zero.

> That even lets you use them like error codes: [...] Though personally
> I think I'd still prefer an exception. If I'm doing RSA and there's
> no inverse, something has gone drastically wrong.

Agreed, if you're doing RSA. And in that case, you can ignore the
Not-a-Number return value, secure in the knowledge that, if your prime
number isn't actually prime, you'll get a signaling NaN back, and the
library will pitch a fit (and an exception) when you try to use it. ;-)
- --
Chad Nelson
Oak Circle Software, Inc.
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