[j-nsp] Format of SHA1 Passwords

Post by Chip Marshall
I'm trying to write a utility for generating JUNOS-compatible
password hashes outside of JUNOS, and I've hit a bit of a
stumbling block with JUNOS SHA-1 passwords. They don't seem to
follow the normal crypt() pattern of $format$salt$hash and I
can't seem to find the format documented anywhere.
I get things like "$sha1$19418$aoTClyGU$cix8MhZsXwG6OrwUgeHAoOA8f.AX"
where it appears to have the format, some number, what I think is
the salt, and then the hash.
Anyone know how these things are calculated?

we do this calculation.... I believe your intended format is:
$1$salt$hash

or that seems to be what our code does.

Chip Marshall

2013-12-03 16:46:43 UTC

Post by Chip Marshall
I get things like "$sha1$19418$aoTClyGU$cix8MhZsXwG6OrwUgeHAoOA8f.AX"
where it appears to have the format, some number, what I think is
the salt, and then the hash.
Anyone know how these things are calculated?

$1$salt$hash
or that seems to be what our code does.

That's for MD5 passwords. I have a requirement to use SHA-1.

--
Chip Marshall <chip at 2bithacker.net>
http://2bithacker.net/

Chris Morrow

2013-12-03 17:05:47 UTC

$1$salt$hash
or that seems to be what our code does.

That's for MD5 passwords. I have a requirement to use SHA-1.

oh, ha! :( hrm... so, I set a passwd of 'flipfl0p!' for a user after
setting the passwd format to sha1 ... and I see:

"$sha1$19295$mROzSQ4a$SFnJ1fAbP4cHqw/16.xDV4s1LpMA"

Post by Chip Marshall
import hashlib
p = 'flipfl0p!'
s = 'mROzSQ4a'
hashlib.sha1(p+s).hexdigest()

bummer.

Paul Goyette

2013-12-03 17:20:15 UTC

Looks like the output is identical to what would be generated by
the *BSD pwhash(1) utility.

# pwhash -S 24680 stuff
$sha1$23933$/WgTkHoe$25rdwdZ95cfgY/Tl6li2/LRIbuVT
#

pwhash(1) in turn calls the crypt(3) library function after it
generates a salt.

Digging through the sources, we find the following comment block
in src/lib/libcrypt/crypt-sha1.c

* The format of the encrypted password is:
* $<tag>$<iterations>$<salt>$<digest>
*
* where:
* <tag> is "sha1"
* <iterations> is an unsigned int identifying how many rounds
* have been applied to <digest>. The number
* should vary slightly for each password to make
* it harder to generate a dictionary of
* pre-computed hashes. See crypt_sha1_iterations.
* <salt> up to 64 bytes of random data, 8 bytes is
* currently considered more than enough.
* <digest> the hashed password.

-----Original Message-----
From: juniper-nsp [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf Of Chris Morrow
Sent: Tuesday, December 03, 2013 9:06 AM
To: chip at 2bithacker.net; juniper-nsp at puck.nether.net
Subject: Re: [j-nsp] Format of SHA1 Passwords

$1$salt$hash
or that seems to be what our code does.

That's for MD5 passwords. I have a requirement to use SHA-1.

oh, ha! :( hrm... so, I set a passwd of 'flipfl0p!' for a user after
setting the passwd format to sha1 ... and I see:

"$sha1$19295$mROzSQ4a$SFnJ1fAbP4cHqw/16.xDV4s1LpMA"

Post by Chip Marshall
import hashlib
p = 'flipfl0p!'
s = 'mROzSQ4a'
hashlib.sha1(p+s).hexdigest()

bummer.
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Chip Marshall

2013-12-03 17:32:24 UTC

Post by Paul Goyette
Looks like the output is identical to what would be generated by
the *BSD pwhash(1) utility.
# pwhash -S 24680 stuff
$sha1$23933$/WgTkHoe$25rdwdZ95cfgY/Tl6li2/LRIbuVT
#
pwhash(1) in turn calls the crypt(3) library function after it
generates a salt.
Digging through the sources, we find the following comment block
in src/lib/libcrypt/crypt-sha1.c

Ah ha! Perfect! It appears this is specifically a NetBSD thing,
or at least my OpenBSD and FreeBSD boxes don't have crypt-sha1.c
or the pwhash utility.

--
Chip Marshall <chip at 2bithacker.net>
http://2bithacker.net/

Mark Felder

2013-12-03 17:16:05 UTC

$1$salt$hash
or that seems to be what our code does.

That's for MD5 passwords. I have a requirement to use SHA-1.

JunOS is based on FreeBSD, and FreeBSD doesn't support SHA-1 password
hashes. Your choices are:

DES: (no identifier)
MD5: $1$
Blowfish: $2$
NTHASH: $3$
SHA256: $5$
SHA512: $6$ (likely not supported as it's recent to FreeBSD)

And how to generate a hash (just change the identifier; it will create
the right hash):

python -c "import crypt, getpass, pwd; print crypt.crypt('password',
'\$1\$SALTsalt\$')"

Just make sure you use a different salt for each password.

Giuliano Cardozo Medalha

2013-12-03 17:21:52 UTC

set system password format sha-1

Sent from my iPhone

Post by Mark Felder

$1$salt$hash
or that seems to be what our code does.

That's for MD5 passwords. I have a requirement to use SHA-1.

JunOS is based on FreeBSD, and FreeBSD doesn't support SHA-1 password
DES: (no identifier)
MD5: $1$
Blowfish: $2$
NTHASH: $3$
SHA256: $5$
SHA512: $6$ (likely not supported as it's recent to FreeBSD)
And how to generate a hash (just change the identifier; it will create
python -c "import crypt, getpass, pwd; print crypt.crypt('password',
'\$1\$SALTsalt\$')"
Just make sure you use a different salt for each password.
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Mark Felder

2013-12-03 17:47:03 UTC