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May
19
answered Are digital signatures using preprocessed paper pads possible?
May
19
comment Are digital signatures using preprocessed paper pads possible?
@SOJPM I doubt it is possible, but given that such an approach could allow itself to be a lot less secure than present methods given the lack of processing power at the time, I theorized that there just might be some way of doing this. After all we have some paper based solutions for symmetric encryption.
May
18
comment Are digital signatures using preprocessed paper pads possible?
@SOJPM You could e.g. use the letters in the source text walk through the text pad in some way, in a manner decided by the private key. Or use some paper based hashing function first.
May
18
asked Are digital signatures using preprocessed paper pads possible?
May
16
awarded  Commentator
May
16
accepted Is concatenated data hashed with scrypt vulunarable to a length extension attack?
May
16
comment Is concatenated data hashed with scrypt vulunarable to a length extension attack?
Okay, I didn't quite understand that. But I at least understand that length extension attacks do not work how I imagined them and need to read up more on it. Anyway you convinced me that scrypt should work for my purposes.
May
16
comment Is concatenated data hashed with scrypt vulunarable to a length extension attack?
I trust scrypt works with correct usage. I am just trying to make sure I understand how it is supposed to be used correctly. So if I understand you correctly if an attacker doesn't know "foobar" but knows its scrypt hash, then he has not advantage in finding "foobar1", "foobar2" etc. That is just as hard as finding the hash for "spamandeggs" e.g. But with MD5 hashing they could guess the hash of "foobar1" if they knew the hash of "foobar". Right?
May
16
comment Is concatenated data hashed with scrypt vulunarable to a length extension attack?
I assume the hmac in question is doing: hmac(masterpassword, salt). But my case is that masterpassword consists of multiple parts. I want to achieve something like hmac(part1, hmac(part2, hmac(part3, salt))). I don't see how scrypt could be doing this since it doesn't know the parts making up my master password.
May
16
asked Is concatenated data hashed with scrypt vulunarable to a length extension attack?
May
9
awarded  Teacher
May
9
awarded  Editor
May
2
comment A single password manager vs password generator/hash
okay that is a good point. I've seen generators though which I believe stores data locally for the salt. Variations of the scheme: plevyak.com/dpg.html. Where a lot of extra data which the user could reproduce more easily than something completely random. A deterministic password generator could also be used with multiple master passwords. E.g. you use different passwords as seed for different categories of websites. I am challenging you in this point, because I want to create a secure deterministic generator, but I want to be aware of weaknesses. Thanks for your great input
May
1
comment A single password manager vs password generator/hash
wouldn't it be harder than this? Should we not assume the use of a salt for PBKDF2-HMAC-SHA256. The attacker will only know the salt used for bcrypt. So if the master password is "foobar" for both encrypted database and deterministically generated password. Then my dictionary attack for the database just needs to find "foobar". While the attack on my generated password needs to find "foobar"+salt. Which means for every entry in the dictionary they will have to try every possible salt. Wouldn't that be way more expensive?
Apr
23
comment A single password manager vs password generator/hash
Would not stealing a generated password be considerably harder than stealing a password database? A generated password would usually be stored on a server as hash right? While password database would be stored as is. So you could immediately use a dictionary attack on the database. While you need an extra step to get hold of the hashed derived password. Or am I missing something here?
Apr
5
comment How do I create a short signature? (e.g. less than 100 bytes)
What software packages support this approach. E.g. can the GPG suit do this? Also are there iOS libraries to use these algorithms?
Apr
2
awarded  Scholar
Apr
2
awarded  Supporter
Apr
2
accepted How do I create a short signature? (e.g. less than 100 bytes)
Apr
2
awarded  Student