RE: MD5 is too fast

[nanog--- via NANOG <nanog () lists nanog org>]

[seems to have accidentally moved off list]

Passwords for TCP-MD5 and TCP-AO do not have to be remembered, and they are configured by experts who know they should 
be random.


On 12 September 2025 13:31:03 CEST, Vasilenko Eduard <vasilenko.eduard () huawei com> wrote:
>  *   You will see that the number of random letters is very very important.
> For sure, very important, every letter is 75x.
> But nobody would be capable of remembering even 8 random letters. People would continue to choose not very strong 
> passwords.
> It is possible to fight with people or help them with technology that would not need such strong passwords.
> The IT world has chosen the latter. Many smart people have participated in this – I do not believe that they have 
> forgotten to account for something.
>
> And do not forget that for the process of brute force, the password “7Jon%Brain&Letter” (17 letters) is weaker than 
> “n4H*h!s$” (8 letters).
> I mean: there is a way to downgrade too, even for long passwords.
>
> Only full automation when passwords are not appointed manually permits raising the bar of password complexity.
> Eduard
> From: nanog () immibis com <nanog () immibis com>
> Sent: Friday, September 12, 2025 13:33
> To: Vasilenko Eduard <vasilenko.eduard () huawei com>
> Subject: RE: MD5 is too fast
>
> You did 10 random letters with 8 5090s and you calculated 19 days.
>
> Have you calculated 12 random letters? 16 random letters? 24 random letters? 40 random letters?
>
> You will see that the number of random letters is very very important.
>
> On 12 September 2025 09:53:36 CEST, Vasilenko Eduard <vasilenko.eduard () huawei com<mailto:vasilenko.eduard () huawei 
> com>> wrote:
>
> I hope I have answered in the thread.
> If not, ping me.
> Ed/
> -----Original Message-----
> From: nanog--- via NANOG <nanog () lists nanog org<mailto:nanog () lists nanog org>>
> Sent: Thursday, September 11, 2025 18:17
> To: North American Network Operators Group <nanog () lists nanog org<mailto:nanog () lists nanog org>>
> Cc: nanog () immibis com<mailto:nanog () immibis com>
> Subject: RE: MD5 is too fast
>
> Have you calculated how long it should take to test all 80-bit passwords? 200-bit passwords? 2000-bit passwords?
>
> Suppose that a good server can try about a billion passwords per second. How long do you think it takes to try all the 
> passwords?
>
>
> On 11 September 2025 12:18:00 CEST, Vasilenko Eduard via NANOG <nanog () lists nanog org<mailto:nanog () lists nanog 
> org>> wrote:
>
> The simple integer division on the processor takes something like 40 cycles (fast). Hence, the factorization challenge 
> should have thousands of bits. Then it is going to take millions of years for one processor to try all possibilities.
>
> If the password is just 12 letters (80 bits?), then the time to test the password should be longer. Or else the good 
> processor would try all combinations for a limited time.
> Of course, a longer password would help a lot, but even 200 bits is not 2000. The check should be proportionally 
> slower.
> It is especially a problem when we are dealing with predictable passwords based on human language words.
>
> Maybe SHA-2/3 have not been developed with "slowness" as a goal. It may be that only randomness was the target. Hence, 
> so many assembler instructions for one round.
> But only the slowness permits its use for HMAC or the password fingerprint that you have discussed before.
> I could not believe that slowness is just a byproduct of randomness. It is so evident why it is needed by itself (for 
> some applications).
> Ed/
> -----Original Message-----
> From: Thomas Bellman via NANOG <nanog () lists nanog org<mailto:nanog () lists nanog org>>
> Sent: Thursday, September 11, 2025 12:03
> To: North American Network Operators Group <nanog () lists nanog org<mailto:nanog () lists nanog org>>
> Cc: Thomas Bellman <bellman () nsc liu se<mailto:bellman () nsc liu se>>
> Subject: Re: MD5 is slow
>
> On 2025-09-11 09:23, Vasilenko Eduard via NANOG wrote:
>
> SHA-2 and SHA-3 are used not only for networking, they are general.
> Hence, they were developed to be slow enough to prevent brute force
> for some other applications.
>
> Since you are asserting that the hash functions must be "slow" in order to resist brute force attacks, could you 
> perhaps give us an estimate of *how* slow they must be?  And how you arrive at that (e.g. how much resources does the 
> attacker deploy, and how long walltime do you give the attacker)?
>
>
>    /Bellman
>
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