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Re: [rare-dev] ecdh vs dh


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  • From: Cristina Klippel Dominicini <>
  • To: "" <>
  • Subject: Re: [rare-dev] ecdh vs dh
  • Date: Mon, 29 Aug 2022 16:04:47 +0000
  • Accept-language: pt-BR, en-US


Following the initial track, this link is very nice:
https://andrea.corbellini.name/2015/05/17/elliptic-curve-cryptography-a-gentle-introduction/

The conclusion of the first part of this material (attached print screen) is
more didactic.

Best regards,
Cristina

________________________________________
De: <> em
nome de Cristina Klippel Dominicini <>
Enviado: segunda-feira, 29 de agosto de 2022 12:14
Para:
Assunto: Re: [rare-dev] ecdh vs dh

Hi Csaba!

I am happy to hear this :-)

I sent the e-mail to my friends, but in the meanwhile I am investigating and
found this track:

Section 15.5, page 419
https://shoup.net/ntb/ntb-v2.pdf

"There are two other factoring algorithms not discussed here, but that should
anyway at least be mentioned. The first is the elliptic curve method,
introduced by Lenstra [60]. Unlike all of the other known subexponential-time
algorithms, the running time of this algorithm is sensitive to the sizes of
the factors of n; in particular, if p is the smallest prime dividing n, the
algorithm will find p (heuristically) in expected time
exp[(√2 + o(1))(log p log log p)1/2] · len(n)O(1).
This algorithm is quite practical, and is the method of choice when it is
known (or suspected) that n has some small factors. It also has the advantage
that it uses only polynomial space (unlike all of the other known
subexponential-time factoring algorithms)."

Best regards,
Cristina

________________________________________
De: mc36 <>
Enviado: segunda-feira, 29 de agosto de 2022 11:12
Para: ; Cristina Klippel Dominicini
Assunto: Re: [rare-dev] ecdh vs dh

ps: thanks for the math pdf you sent me a year ago or so...
we learnt math in hungarian so it really helped me a lot!

On 8/29/22 16:06, mc36 wrote:
> thanks for confirming the reception of the mail...
> and thanks for taking care of the question...
> please take your time, it have a good change that
> i\m not right so dont put too much effort into it,
> just if it really catches an interest somewhere....
> thanks,
> cs
>
>
>
> On 8/29/22 16:01, Cristina Klippel Dominicini wrote:
>> Hi Csaba!
>>
>> Sorry for the delay. For some reason, I am not receiving all the threads
>> from the rare list, and my mail server also blocked some messages. I will
>> check the archives.
>>
>> Interesting question! I am honored by your mention as a skilled
>> mathematician, but I am more a computer engineering trying to understand
>> and apply the math concepts to computing
>> problems :-D But I have some very skilled mathematician friends that help
>> me when I have some doubts. I will check with them if they have any
>> insights about your question and get
>> back to you soon :-)
>>
>> Best regards,
>> Cristina
>>
>> ________________________________________
>> De: <> em
>> nome de mc36 <>
>> Enviado: sexta-feira, 26 de agosto de 2022 06:45
>> Para: Cristina Klippel Dominicini
>> Cc:
>> Assunto: [rare-dev] ecdh vs dh
>>
>> hi,
>>
>> can i ask you to help me solve a long lived question of me please:
>> (i ask you because you're the only well skilled mathematician i know)
>> (if it's outside of your interest, please forward it someone)
>>
>> which is harder to find out both a and b:
>>
>> ( (g^a)^b) % p == ( (g^b)^a) % p
>> where g is 2 or 5, p is a 8192 bit prime, both well known, a and b are
>> both secrets
>> here we are talking about positive integers
>>
>> or
>>
>> a*b == b*a
>> here the computation is performed over 448bit elliptic curves
>>
>>
>> my reasoning is that reversing the multiplication should be easier than
>> solving the discrete logarithm problem
>>
>> i see that it is an apples to oranges kind of question so a weak
>> conjecture is much more than enough
>>
>> thanks,
>> cs
>>
>>
>> ________________________________
>>
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>>


________________________________

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sem conformidade com as normas internas do Ifes são proibidas e passíveis de
sanção disciplinar, cível e criminal.

________________________________

Esta mensagem (incluindo anexos) contém informação confidencial destinada a
um usuário específico e seu conteúdo é protegido por lei. Se você não é o
destinatário correto deve apagar esta mensagem.

O emitente desta mensagem é responsável por seu conteúdo e endereçamento.
Cabe ao destinatário cuidar quanto ao tratamento adequado. A divulgação,
reprodução e/ou distribuição sem a devida autorização ou qualquer outra ação
sem conformidade com as normas internas do Ifes são proibidas e passíveis de
sanção disciplinar, cível e criminal.

Attachment: logarithm.png
Description: logarithm.png




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