CODEWITHSUNDEEP
linuxbashopenssl
Adam Sznajder
Adam Sznajder

Reputation: 9206

Openssl sha1 length

Why after executing the command openssl sha1 < /dev/null | wc --bytes the output is 50? The output size of SHA-1 should have 160 bits what gives us 20 bytes.

Upvotes: 3

Views: 1667

Answers (2)

Alex Reynolds
Alex Reynolds

Reputation: 96937

If you want the raw, unformatted bytes, pipe the hexadecimal-formatted output from OpenSSL to xxd -r -p, to convert that representation to raw bytes.

For example, to make a Base64-encoded SHA-1 digest of the string foo:

$ echo "foo" | openssl sha1 | xxd -r -p | base64
8dLS+STphqyG/fezbJS83zK+7BU=

Or to simply validate the message length:

$ echo "foo" | openssl sha1 | xxd -r -p | wc --bytes
20

Upvotes: 2

MattH
MattH

Reputation: 38247

Why is the output of openssl sha1 < /dev/null | wc --bytes 50?

$ openssl sha1 < /dev/null
(stdin)= da39a3ee5e6b4b0d3255bfef95601890afd80709

Because the 20 byte digest is prefixed by (stdin)= and is expressed in hex.

Upvotes: 6

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