yogsototh on On cryptography and dogmas

Comment on On cryptography and dogmas parent

The main problem with this question is I get a lot a answer that simply aren't answer to this question, but only the basic good usage of cryptography.

Until here, nobody said 'yes', then I assume my method is secure.

I would have loved to know if this specific question is asked for any kind of hash function, or if nobody never ask such question. For me it seems as a natural question which seem a bit more difficult than finding a collision but easier than cracking completely the hash function.

dchest 14y

To answer your question, AFAIK there are no known first preimage attacks on SHA-1 yet.

And no, your method is not secure.

yogsototh 14y

Thanks for your answer. Could you explain me how my method is not secure assuming:

    1. The pass is long
    2. The preimage is known

If nobody can find `sha1(knownpart|hiddenpart)`, how is my method insecure?

Is the problem linked to sha1 or if I use any other hash this method also fail?

I presume the _only_ method you advocate for is to have a lot of different passwords for each website is to store randomly generated password inside a keychain system. Could you enlighten me? How do you deal with your own password?

Thanks.

edit: it seems we reached the max depth. Thank you Dmitry!

dchest 14y

Table on estimated cost of hardware to crack a password in 1 year from scrypt paper: http://i.imgur.com/sAOwS.png

I personally use a scheme similar to yours, but with PBKDF2. Also, I'm no crypto expert.

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