oss-sec mailing list archives

Re: broken RSA keys


From: Solar Designer <solar () openwall com>
Date: Wed, 4 May 2016 21:01:21 +0300

On Wed, May 04, 2016 at 08:28:03PM +0300, Solar Designer wrote:
BTW, had I not realized the above, I would now come up with an even more
complex conspiracy theory about 149784613473514443594783892995, which is
0x1E3FAEDA6A4F093A7C0F5A603, so:

limb[0] = 0xC0F5A603
limb[1] = 0xA4F093A7
limb[2] = 0xE3FAEDA6
limb[3] = 1

which satisfies:

limb[1] = limb[0] + limb[2] + 2

No idea why it's "+ 2" here

Actually, it's "- 2", not "+ 2".  Sorry.  Not that it matters, but I was
uncomfortable leaving the error uncorrected in case someone wants to try
and figure out why exactly this artifact manifests itself like it does.

There's probably an explanation of why the algorithm is likely to hit
numbers of this form, but this is beside the point for software bugs,
which is what I want us to discuss further in this thread.

Alexander


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