When I call openssl sha1 from the command line

 echo "00" | xxd -r -p | openssl dgst -sha1

the output I am receive is

(stdin)= 5ba93c9db0cff93f52b521d7420e43f6eda2784f

But the NIST Vector output is:

 MD = da39a3ee5e6b4b0d3255bfef95601890afd80709

Can anyone please explain this?

  • 1
    $\begingroup$ for reference, 5ba93c9db0cff93f52b521d7420e43f6eda2784f is the correct result for a 1 byte input of 0x00 $\endgroup$ Apr 28, 2017 at 9:46
  • $\begingroup$ Almost cross-posted: Getting Message Digest from SHA1 message $\endgroup$
    – Artjom B.
    Apr 28, 2017 at 17:59
  • $\begingroup$ Note you need to use -n with echo to prevent adding a trailing new line. You can test this by writing in the terminal $ echo 'foo' and $ echo -n 'foo'. $\endgroup$
    – Daniel
    Feb 13, 2019 at 15:03

1 Answer 1


You read the testvector incorrectly.

I assume you are referring to the following part of the file SHA1ShortMsg.rsp of the FIPS 180-4 vectors:

[L = 20]

Len = 0 
Msg = 00 
MD = da39a3ee5e6b4b0d3255bfef95601890afd80709

This test vector has length 0, so the specified hash is for an empty message and not for a single zero byte. This openssl command shows the correct result.

$ echo -n ""|openssl dgst -sha1
(stdin)= da39a3ee5e6b4b0d3255bfef95601890afd80709

  • $\begingroup$ when the input is not of len 0 Len = 2 Msg = 40 MD = ec6b39952e1a3ec3ab3507185cf756181c84bbe2 The result is echo -n "\x40" | openssl dgst -sha1 (stdin)= 798f17bb2ad6914266daf60dc6e8e2571d779a39 echo -n "40" | xxd -r -p | openssl dgst -sha1 (stdin)= 9a78211436f6d425ec38f5c4e02270801f3524f8 echo -n "40" | openssl dgst -sha1 (stdin)= af3e133428b9e25c55bc59fe534248e6a0c0f17b None are matching with the result $\endgroup$ Apr 28, 2017 at 9:59
  • $\begingroup$ @user3405360 I can't find that example here, but for example the second one works: printf "\x36" | openssl dgst -sha1 gives (stdin)= c1dfd96eea8cc2b62785275bca38ac261256e278 $\endgroup$
    – matsjoyce
    Apr 28, 2017 at 11:00
  • $\begingroup$ I am checking for BIT oriented implementations but your example is for BYTE oriented implementation $\endgroup$ Apr 28, 2017 at 11:32
  • $\begingroup$ openssl dgst can only process full bytes. $\endgroup$
    – mat
    Apr 30, 2017 at 16:29

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