[ih] Internet Protocol Implementation Guide

[John Day]

Wouldn’t that be susceptible to a substitution attack?

> On Aug 21, 2025, at 09:21, Vint Cerf via Internet-history <internet-history at elists.isoc.org> wrote:
> 
> David, it was always believed that segments might have to be decrypted out
> of order if they were encrypted - that was an important design criterion
> for packet cryptography but maybe you are thinking of something else? We
> assumed the reassembly would take place within a buffer window so they
> could be placed in the right part of the buffer before assembly was
> completed and the result delivered to the next layer up.
> 
> v
> 
> 
> On Thu, Aug 21, 2025 at 9:09 AM David Finnigan via Internet-history <
> internet-history at elists.isoc.org> wrote:
> 
>> On 20 Aug 2025 4:17 pm, Barbara Denny via Internet-history wrote:
>>> Quite some time ago I sent email out with links to the handbooks
>>> produced by the NIC at SRI. I don't remember if that email also
>>> included the Internet Protocol Implementation Guide.  Sending this
>>> message in case this document wasn't included.
>>> https://apps.dtic.mil/sti/tr/pdf/ADA153624.pdf
>>> The end of the document has an interesting snapshot of the status of
>>> TCP/IP implantations as of June 8, 1982.
>>> barbara
>> 
>> While looking at the sources for some early TCP implementations, I
>> noticed that some of them will process most TCP controls out of order
>> (except FIN), so long as the segment sequence fits within the receive
>> window. Segment text is always kept in sequence to be delivered to the
>> user in correct order, of course.
>> 
>> Who was the one to notice that this was possible, when RFC 793 states
>> that segments "are generally queued and processed in sequence number
>> order" ?
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