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Old 2017-02-02, 21:06   #34
xilman
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Quote:
Originally Posted by chalsall View Post
Yup.
Shadow passwords were introduced into Unix before the 8-character limit was removed.

The infamous crypt16() routine introduced by DEC to allow 16-character passwords was actually less secure than the standard 8-char crypt() hash function, as I discovered, documented and published back in the day.
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Old 2017-02-02, 21:35   #35
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Quote:
Originally Posted by xilman View Post
The infamous crypt16() routine introduced by DEC to allow 16-character passwords was actually less secure than the standard 8-char crypt() hash function, as I discovered, documented and published back in the day.
Yeah. I remember that. It had to do with some "leakage" between the first 8 bytes and the second 8 bytes. particularly if only a few of the second 8 bytes were used.

Please correct me if I am wrong on that.

I remember lying in bed trying to impress my girlfriend by showing her a picture, but google insisted I re-login. I typed many characters. "That's your password? "No, that's my passphrase.
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Old 2017-02-02, 21:56   #36
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Quote:
Originally Posted by chalsall View Post
Yeah. I remember that. It had to do with some "leakage" between the first 8 bytes and the second 8 bytes. particularly if only a few of the second 8 bytes were used.

Please correct me if I am wrong on that.
You are largely correct. The full story is as follows.

A crypt() hash uses a 8-round modified DES to hash a password. crypt(16) uses 5 rounds of modified DES on the the first eight characters of the password, stores the result and then uses a further 3 rounds with the result of the first pass as the initial value and hashes in the second eight characters, appending that result to the first half to yield the final hash..

There are two problems with this which I identified. First, one can crack <= 8 character passwords with only 5/8 the effort -- just look at the first half of the hash and ignore the other half. Second, 9-16 character passwords with common suffices in their second half, "ing", "es", "s", "123" etc, can have their prefixes computed at 5/8 effort and then the suffices attacked at 3/8 effort, thereby extending the range of the dictionary at very little extra cost.

Last fiddled with by xilman on 2017-02-02 at 21:58
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Old 2017-02-02, 23:03   #37
chalsall
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Quote:
Originally Posted by xilman View Post
You are largely correct.
Thank you for that. It is rare that it's said I'm correct.
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Old 2017-02-03, 15:17   #38
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Even without the reason of user login and authenticaion, https is still an extremely good idea:

https://developers.google.com/web/fu...nsit/why-https

https://https.cio.gov/everything/
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Old 2017-02-03, 15:27   #39
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Quote:
Originally Posted by Dubslow View Post
... https is still an extremely good idea:
Perhaps, yes. But there is an occasional difficulty if every website becomes 100% HTTPS: Those annoying hotel redirect pages. F I hate those things.
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Old 2017-02-03, 18:11   #40
chalsall
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Quote:
Originally Posted by xilman View Post
Shadow passwords were introduced into Unix before the 8-character limit was removed.
Thank you for that as well.

For those who don't remember, under early Unix the "/etc/password" file used to contain the hashed passwords, which could be accessed by "Group" (read: any user who could log in). And then an offline attack could be done by anyone who had access to the machine in question, or anyone who had compromised them.

The implementation of the "/etc/shadow" file meant that the password hashes were in a "root accessible only" file.

Happy to be corrected, but this was about the time when "someone in the middle" attacks started happening.
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Old 2017-02-03, 21:56   #41
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If I remember correctly, it was around that time that attackers discovered the control sequence causing terminals to dump their entire screen to input...
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Old 2017-02-10, 18:53   #42
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I am glad to see the move to https. Great job!

I just have one thing to point out. When I access the website over https, my browser says that the website uses an obsolete cipher (AES_128_CBC with HMAC-SHA1). Don't know if this is a problem or not, but I guess it would be nice to take a look.
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Old 2017-02-10, 20:24   #43
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Is your browser using TLS 1.2?
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Old 2017-02-10, 20:29   #44
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Yes. I'm using Chrome on Windows, and this is what it says:

"The connection to this site uses a strong protocol (TLS 1.2), a strong key exchange (ECDHE_RSA with P-256), and an obsolete cipher (AES_128_CBC with HMAC-SHA1)."
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