245

How do I check the SHA1 hash of a file?

  • 6
    adding this note to whom it may concern: SHA-1 is now compromised, proven by a Google-CWI joint research. TL;DR Don't use it anywhere carrying any value. – kmonsoor Feb 23 '17 at 15:53
  • 2
    TL;DR what else to use ??? – Benjamin Eckstein Feb 8 '18 at 15:30
281

sha1sum

Print or check SHA1 (160-bit) checksums. With no FILE, or when FILE is -, read standard input.

sha1sum {file}

If you want to send the file together with its sha1sum output redirect the output to a file:

sha1sum {file} > {file}.sha1

Send both files and the other party can do a...

sha1sum -c {file}.sha1

It should show OK if the sha1 is correct.

  • 3
    Great! But how do you run sha1sum -c when {file}.sha1 contains only the hash and no filename (as often to be downloaded from various corners of the Internet)? I came up with for f in *.sha1; do echo "$(cat $f) ${f/.sha1/}"; done | sha1sum -c (note double space), but this must be much simpler. – Piotr Findeisen Oct 17 '13 at 1:45
  • 3
    or shasum -- the default SHA is (if I am correct) SHA1. Also you set it with -a, --algorithm option: shasum -a 1 – xealits Sep 23 '15 at 15:05
  • 3
    @PiotrFindeisen - The output of sha1sum is <hash> <full file path> so there is enough information for sha1sum -c to know which file it's to verify – CrazyPenguin Jan 5 '16 at 18:41
  • 1
    Pardon my ignorance, but why is it that hard to check a file sum? Could we not simply do sha1sum <file_path> <the_expected_hash> ? – Romain Vincent May 17 '18 at 17:37
67

Without creating local file:

$ sha1sum filename

8dd10000eb1b768800000e1d2fe1c3100005d2dc *filename

For checking, go to the directory that contains filename and run this command:

echo "8dd10000eb1b768800000e1d2fe1c3100005d2dc *filename" | sha1sum -c -
  • 4
    Thanks, though I don't think you should have the * in there. Here's a concrete example: echo 'b78bb50bdac5ec8c108f34104f788e214ac23635 raspbian.zip' | sha1sum -c - That will check a file name raspbian.zip in the current directory. – Luke Apr 8 '16 at 6:57
  • 1
    This should be the accepted answer. Creating a file is an unnecessary intermediate. – Joel B Jul 30 '16 at 2:07
  • Just in case anyone gets here and is on a mac, there are two spaces between the filename and the output of shasum as of OSX 10.13.3. When I used just one, I got a incorrect formatting error for shasum -c – ae0709 Mar 13 '18 at 7:15
21

Its very simple.

Navigate to the terminal and key in:

sha1sum  filename

to confirm a sha1 hash use:

sha1sum -c filename
  • 1
    what does confirming the sha1 hash do? – Alexander Mills May 1 '19 at 17:28
10

For those who are on mac and don't have coreutils/sha1sum installed.

openssl sha1 <file>

Example:

$ openssl sha1 `mktemp`
SHA1(/tmp/tmp.jkyfOWma3t)= da39a3ee5e6b4b0d3255bfef95601890afd80709
  • this is askubunutu, so being on a Mac would be off-topic ;) but this should work on ubuntu too, so +1 – Jeff Puckett Sep 22 '18 at 18:50
4

What are you people talking about? Yes, I get the concept behind sha1sum, but the info above is confusing to say the best. First, Ubuntu does not seem to have sha1sum files - just strings on a web page such as this for Mate 16.04 Beta 1:

bfba577970d573e0ba5095fbb72787de97f88b4b *ubuntu-mate-16.04-beta1-desktop-amd64.iso
efcbbc70b10173cea203df30396d0848ba8fa0d8 *ubuntu-mate-16.04-beta1-desktop-i386.iso
8563fec4d66bce851b0800f5ac746f38e4041a6a *ubuntu-mate-16.04-beta1-desktop-powerpc.iso

To check the integrity of a downloaded .iso, one opens the terminal program, does "cd Downloads", then sha1sum . After a bit, the terminal will produce a hash such as

efcbbc70b10173cea203df30396d0848ba8fa0d8  ubuntu-mate-16.04-beta1-desktop-i386.iso

Next, we have to go to the web page and compare the strings to verify that the verification works. Not nearly as easy as it could be.

Dave,

1

Python

Python has excellent hashlib library, that allows calculating multiple hashsums, including sha1. Here's a simple script that can do the job:

#!/usr/bin/env python3
import sys
import hashlib
import os
from collections import OrderedDict as od

def get_hashsums(file_path):
    hash_sums = od()
    hash_sums['md5sum'] = hashlib.md5()
    hash_sums['sha1sum'] = hashlib.sha1()
    hash_sums['sha224sum'] = hashlib.sha224()
    hash_sums['sha256sum'] = hashlib.sha256()
    hash_sums['sha384sum'] = hashlib.sha384()
    hash_sums['sha512sum'] = hashlib.sha512()

    with open(file_path, 'rb') as fd:
        data_chunk = fd.read(1024)
        while data_chunk:
              for hashsum in hash_sums.keys():
                  hash_sums[hashsum].update(data_chunk)
              data_chunk = fd.read(1024)

    results = od()
    for key,value in hash_sums.items():
         results[key] = value.hexdigest()         
    return results



def main():
    for path in sys.argv[1:]:
        print(">>> ",path)
        for key,value in get_hashsums(path).items():
            print(key,value)

if __name__ == '__main__': main()

Test run:

With a single file:

$ ./hash_sums.py /etc/passwd                                                                                                                         
>>>  /etc/passwd
md5sum ce5f247e016ba2bb92049fc86158376a
sha1sum b8abadf4618b09bd3eebb6064fc2df5b90e5ae03
sha224sum 044579d46e0d969a860602216ea4764465e5618ed714109cf782ff50
sha256sum 53f2ff8997625c958f77aef034f9c96d9fcfc8bcb4bb8a96fd8ac89a5ed5adf6
sha384sum b84b6cafa178147614e6b7903e1b7a342e09d95e3101e55c6a3b5b093a22190f2d367c69b1ee12b1ec59726337a40e9c
sha512sum edacca8237d3be5095f392c9d347dce3a5249c79d09f9b99a055b796edd74541b4529c499ff0e4f25e817b702c206073bfe5b0fccae6773680c79ea1e0efa9e2

With glob:

$ ./hash_sums.py *                                                                                                                                   
>>>  3-4-placement.py
md5sum a81dd2a6eb122176204cacd92d76d08c
sha1sum 4972f8cf08701cdfc6308def05d3ec2eedfcdd9a
sha224sum 32c4dad60f59584ba39ce73c1a1c96d4da36ee6fe3fd291145692b2b
sha256sum 7460ebf8736b0d6e7be8a1025743d0498871c7013cf5ad4463366fd95fe7576a
sha384sum 77de28b4b185d9a5d7d49aef0aad432d37145b914557dc6ecf3e6cdcbd6cd4a1999d717c027489ac99751f066050199b
sha512sum 7bf6a8059601c72e1278e321f225fef82f12a7bad73e1e8c5c43c1fcbdc2243934bf7d1ad07534bdbf10e2dd9ea9265e1debcbdf6603bec24ede665d2f651cf5
>>>  SHA256SUMS
md5sum 3c37318d45676c1db2598aa817b37679
sha1sum 8338b8ae5f749551d131dc28aebb80a2b125d651
sha224sum e89ad392f10a77b0940792a03470f3a23df2f2df9c8b6a91a1c496e0
sha256sum dd4a53f7da270f3b6ab691841ca911a231e20af53d7fabc5a39059b9dbdb036d
sha384sum aadfb55856730eb5b7e4192111bfb8fc4c022396a5809cb37fdd8e8b6ac8dbb3b7e462266cde2b34f90d7015fb42fe2b
sha512sum baba0ed86ad781daffb5905512459e353b7ca7da7b04cf67a26cfb320906041da2d4bc73673926aab7c98869f25bc2fd6ea0116c21c40c07188e6dcbbba3dbcf
>>>  answer.md
md5sum b6111facdba5978e6cf3a200706ba6fd
sha1sum 5c2eb00c4c0c4799d4457d3a84eea283a3a0d249
sha224sum 7172f877ab579e1ee845c723e0d42ff3acb96859cc43a56aebc39f59
sha256sum dc6ac7365f680e98b9f1279d2e22ed21b9b82c988b99b0facd5e8a98ff50ddd6
sha384sum 5082b3b62d677c5b1b8938f871da16c595be16a540bd76bc9c25ea6572dc9020f236237ec310cfa78fdaa1d0c0a51b0f
sha512sum 81f21316ab6c5a4038cdcde528766e620988a0ccf53bf2e9932399f4534c070468949a5a43ea68629c07e622404574e46bb20cf60c51da4e2a7a44a1df71d920

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