[openssl-users] [AES-GCM] TLS packet nounce_explicit overflow

Michael Wojcik Michael.Wojcik at microfocus.com
Fri Mar 10 14:55:54 UTC 2017

> From: openssl-users [mailto:openssl-users-bounces at openssl.org] On Behalf
> Of Jakob Bohm
> Sent: Thursday, March 09, 2017 21:43
> To: openssl-users at openssl.org
> Subject: Re: [openssl-users] [AES-GCM] TLS packet nounce_explicit overflow
> I seem to recall (I haven't looked at GCM details in years) that
> the 128 bit value is incremented for each 128 bit block of plaintext,
> plus once more for the mac-like tag.

I'll have to check the spec myself; I haven't read it in years either.

>  From this I assumed the 32 bit field was the per-128-bit counter and the
> 64 bit field you asked about was the per-record counter.

A minor correction - it wasn't my question. I had followed up after Rich's initial reply. But no matter; it's a discussion now.

Michael Wojcik 
Distinguished Engineer, Micro Focus 

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