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The previous SF questions I've seen have lead to answers that produce MD5 hashed password.

Does anyone have a suggestion on to produce an SHA-512 hashed password? I'd prefer a one liner instead of a script but, if a script is the only solution, that's fine as well.

Update

Based on davey's answer, I've created a one-liner that's a bit longer than davey's but some others may find useful:

python -c "import crypt,random,string; print crypt.crypt(raw_input('clear-text password: '), '\$6\$' + ''.join([random.choice(string.ascii_letters + string.digits) for _ in range(16)]))"

There's also this more elegant one but requires the passlib module which isn't installed by default:

python -c "from passlib.hash import sha512_crypt; print sha512_crypt.encrypt(raw_input('clear-text password: '))"
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2  
SHA and MD5 are not encryption. They're hashing algorithms. The crucial difference being that the hashed data is not recoverable. What do you need to do? – SmallClanger Nov 11 '11 at 11:28
    
Thank you. Modified the question. man 5 shadow refers to it as "encrypted password" so I went along with that term. – Belmin Fernandez Nov 11 '11 at 12:22
2  
Apologies if that was a bit snarky. Are you trying to manually generate shadow-compatible password hashes? If so, take a look at your /etc/shadow contents. You'll see $x$salt$hash. x denotes the algorithm used by crypt, with 6 being typical on modern linuxes, which is sha512 (see man 3 crypt). Either of the below answers will produce the same hash, so long as you give it the same salt. – SmallClanger Nov 11 '11 at 13:20
2  
Oh no, not snarky at all. You clarified something I was confused about so I am very thankful sir! – Belmin Fernandez Nov 11 '11 at 15:26
1  
Thank you! The passlib-based one is the only one I've been able to make work on OS X. – Stig Brautaset Sep 1 '15 at 15:49

14 Answers 14

up vote 47 down vote accepted

Here's a one liner:

python -c 'import crypt; print crypt.crypt("test", "$6$random_salt")'

Python 3.3+ includes mksalt in crypt, which makes it much easier (and more secure) to use:

python3 -c 'import crypt; print(crypt.crypt("test", crypt.mksalt(crypt.METHOD_SHA512)))'

If you don't provide an argument to crypt.mksalt (it could accept crypt.METHOD_CRYPT, ...MD5, SHA256, and SHA512), it will use the strongest available.

The ID of the hash (number after the first $) is related to the method used:

  • 1 -> MD5
  • 2a -> Blowfish (not in mainline glibc; added in some Linux distributions)
  • 5 -> SHA-256 (since glibc 2.7)
  • 6 -> SHA-512 (since glibc 2.7)

I'd recommend you look up what salts are and such and as per smallclamgers comment the difference between encryption and hashing.

Update 1: The string produced is suitable for shadow and kickstart scripts. Update 2: Warning. If you are using a Mac, see the comment about using this in python on a mac where it doesn't seem to work as expected.

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1  
Importing the getpass and pwd modules is not necessary. – akaihola Feb 16 '12 at 13:17
2  
Replace random_salt with an actual random salt. – Belmin Fernandez Jul 31 '14 at 13:44
1  
I can't get this to work in Yosemite. This is what it spits out: $6asQOJRqB1i2 - that doesn't seem nearly long enough to be correct! – Stig Brautaset Jul 12 '15 at 11:12
2  
Let the crypt module make the salt for you: python -c 'import crypt; print crypt.crypt("test", crypt.mksalt(crypt.METHOD_SHA512))' – rrauenza Sep 14 '15 at 17:32
1  
@kasperd I should have looked at the docs; it's in 3.3+ – Nick T Oct 20 '15 at 20:48

Best Answer: grub-crypt

Usage: grub-crypt [OPTION]...
Encrypt a password.

-h, --helpPrint this message and exit
-v, --version           Print the version information and exit
--md5                   Use MD5 to encrypt the password
--sha-256               Use SHA-256 to encrypt the password
**--sha-512             Use SHA-512 to encrypt the password (default)**
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1  
Simple solution..worked for me on CentOS 6. – Banjer May 1 '13 at 12:15
3  
On systems that have the grub-crypt command, this really is the most foolproof & convenient way to do it. No sense playing around with salts manually when you could screw it up. The problem is that more and more modern systems have GRUB2 and will thus not include this command. – rsaw Jul 3 '15 at 18:22

On Debian you can use mkpasswd to create passwords with different hashing algorithms suitable for /etc/shadow. It is included in the package whois (according to apt-file)

mkpasswd -m sha-512
mkpasswd -m md5

to get a list of available hashing algoritms type:

mkpasswd -m help 

HTH

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3  
What package provides it? There's a mkpasswd program (part of expect) under Fedora too, but it's useless for this purpose. – Cristian Ciupitu Mar 2 '13 at 2:31
    
As he said, the version of mkpasswd he's talking about is for Debian/Ubuntu. The mkpasswd on Fedora (at least up to 14) is missing the -m switch. – slm May 19 '13 at 3:47
2  
Curiously, it's the whois package, legacy from Debian. See dpkg -S /usr/bin/mkpasswd I couldn't believe it myself :D – Robert Cutajar - Robajz Jun 18 '14 at 21:23

Here's a short C code to generate the SHA-512 password on various Unix type OSes.

File: passwd-sha512.c

#define _XOPEN_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

int main(int argc, char *argv[]) {
  if ( argc < 3 || (int) strlen(argv[2]) > 16 ) {
    printf("usage: %s password salt\n", argv[0]);
    printf("--salt must not larger than 16 characters\n");
    return;
  }

  char salt[21];
  sprintf(salt, "$6$%s$", argv[2]);

  printf("%s\n", crypt((char*) argv[1], (char*) salt));
  return;
}

to compile:

/usr/bin/gcc -lcrypt -o passwd-sha512 passwd-sha512.c

usage:

passwd-sha512 <password> <salt (16 chars max)>
share|improve this answer
    
This question is 3 years old... – Grumpy Feb 13 '14 at 10:47

Why not perform the following check and modification to Centos/RHEL machines to ensure that all password hashing for /etc/shadow is done with sha512. Then you can just set your passworkd normally with the passwd command

#Set stronger password hasing
/usr/sbin/authconfig --test | grep sha512 > /dev/null
if [ $? -ne 0 ]; then
echo "Configuring sha512 password hashing"
sudo /usr/sbin/authconfig --enableshadow --passalgo=sha512 --updateall
fi
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Here is a one-liner that uses shell commands to create a SHA-512 hashed password with a random salt:

[root@host] mkpasswd -m sha-512 MyPAsSwOrD $(openssl rand -base64 16 | tr -d '+=' | head -c 16)

Notes

  1. You may need to install the "whois" package (Debian, SuSE, etc.), which provides "mkpasswd".
  2. See crypt(3) for details on the format of lines in "/etc/shadow".
share|improve this answer
    
Unfortunately the whois package from Fedora 18 doesn't provide any mkpasswd. – Cristian Ciupitu Mar 2 '13 at 2:38
1  
In Arch Linux: /usr/bin/mkpasswd is owned by expect 5.45-3 – Nowaker Nov 9 '13 at 21:18
    
Same on Fedora 20 and it does something else. – Cristian Ciupitu Apr 17 '14 at 19:23
2  
Unfortunately the suggested command has two problems: 1) The supplied password is now stored in your shell's history, and is visible to anyone with the 'history' command or similar. 2) You don't need to supply the random salt on the command line - and I think you should let mkpasswd do it for you instead of using funky openssl tricks. (Note that this is true at least on Ubuntu Quantal. You can test it by running 'mkpasswd -m sha-512 foo' multiple times. You will see the salt changes. The salt is the value between the 2nd and 3rd $ characters.) – oskarpearson Jun 3 '14 at 8:40

Its not a one liner, but it might help someone:

import crypt, getpass, pwd, string, sys, random
randomsalt = ""
password = getpass.getpass()
choices = string.ascii_uppercase + string.digits + string.ascii_lowercase
for _ in range(0,8):
    randomsalt += random.choice(choices)
print crypt.crypt(password, '$6$%s$' % randomsalt)
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For those of the Ruby mindset here is a one-liner:

'password'.crypt('$6$' + rand(36 ** 8).to_s(36))
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Perl one-liner solution to generate SHA-512 hashed password:

perl -e 'print crypt("desiredPassword","\$6\$customSalt\$") . "\n"'

Worked on RHEL 6

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HASH algos are for producing MESSAGE digests, they are never suitable for passwords, which should use some kind of HKDF ( http://tools.ietf.org/rfc/rfc5869.txt ) - see PBKDF2 or BCrypt

share|improve this answer
    
Good point, but man crypt tells me PBKDF2 is not supported. – Huygens Sep 15 '15 at 11:15
#!/usr/bin/env python

import getpass

from passlib.hash import sha512_crypt

if __name__ == "__main__":
    passwd = getpass.getpass('Password to hash: ')
    hash = sha512_crypt.encrypt(passwd)

    print hash

You can clone it from my github repo if you want: https://github.com/antoncohen/mksha

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$ htpasswd -c /tmp/my_hash user1
New password: 
Re-type new password: 
Adding password for user user1
$ cat /tmp/my_hash
user1:$apr1$oj1ypcQz$4.6lFVtKz2nr8acsQ8hD30

Obviously, you just grab the 2nd field, and can delete the file once you're added it to shadow or for use with sudo (still most likely shadow).

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This script worked for me on Ubuntu 12.04 LTS: https://gist.github.com/JensRantil/ac691a4854a4f6cb4bd9

#!/bin/bash
read -p "Enter username: " username
read -s -p "Enter password: " mypassword
echo
echo -n $username:$mypassword | chpasswd -S -c SHA512

It has the following features which some of the other alternatives lack:

  • It generates its salt securely. Nobody should rely on doing this manually. Ever.
  • it doesn't store anything in shell history.
  • for clarity, it prints which user's password it generated which can be nice when generating many users' passwords.
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1  
Note this will only work if you have chpasswd on your system. – Matt Sanders Dec 17 '15 at 19:01

I'm not sure how SHA-512 is related to /etc/shadow. These passwords are crypted.

But if you want a password hashed with SHA-512 you can do this by echo -n the_password | sha512sum. You can't use the output for /etc/shadow.

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1  
echo -n the_password so you're not hashing the newline. </pedant> – SmallClanger Nov 11 '11 at 13:14
    
Passwords in shadow aren't crypt()ed any more since years. Modern systems use at least md5. – Alexander Janssen Oct 3 '12 at 20:40
6  
Actually passwords in shadow are still crypt()ed but the function has been updated to support several different algorithms. Regardless, the method described in this answer does not produce suitable hash for /etc/shadow. The algorithm is more complex than a single SHA-512 hash round. – snap Jan 5 '13 at 0:12

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