ssh

Usage

Get SSH key fingerprint

$ ssh-keygen -lf id_martinsimon.pub
256 SHA256:btO1ftKaZ1AxBLvfuFLS2J4a6Aw6aNStsnB6FB23e7g [email protected] (ED25519)

In newer versions of OpenSSH, Base64 encoded SHA-256 is shown instead of hexadecimal MD5. To show the legacy style hash, use:

$ ssh-keygen -l -E md5 -f id_martinsimon.pub
256 MD5:f0:cc:6d:7c:3c:84:15:c1:d0:52:57:c2:c4:1e:c5:09 [email protected] (ED25519)

However, if you’re dealing with the fingerprints that Amazon shows in the EC2 Key Pairs console, unfortunately that may be a different beast. If it’s a 32-digit hex string, it’s the standard MD5 SSH public key fingerprint above. But if it’s 40 hex digits, it’s actually a fingerprint computed by taking the SHA1 of the private key in PKCS#8 format:

$ openssl pkcs8 -in aws_root -nocrypt -topk8 -outform DER | openssl sha1 -c
(stdin)= 82:90:cb:b6:c4:ce:ee:e4:d5:f6:13:76:48:07:49:4d:a9:8d:cc:f2

Source: superuser