CODEWITHSUNDEEP
gossh
CESCO
CESCO

Reputation: 7758

SSH Fingerprint with Golang

How can I get my own ssh fingerprint with Go?

Finger, err := ssh.**
log.Println(Finger)
// 12:f8:7e:78:61:b4:bf:e2:de:24:15:96:4e:d4:72:53

Upvotes: 1

Views: 3259

Answers (3)

Vít Kotačka
Vít Kotačka

Reputation: 1612

In case that you need a fingerprint of an rsa.PublicKey you can use the ssh.FingerprintLegacyMD5() function (or the ssh.FingerprintSHA256() one).

The only issue is that you have to convert the rsa.PublicKey to an ssh.PublicKey which can be done via the ssh.NewPublicKey() function.

func getFingerprint(key *rsa.PublicKey) string {
    pubKey, _ := ssh.NewPublicKey(key)
    return ssh.FingerprintLegacyMD5(pubKey)
}

Upvotes: 1

Kenny Grant
Kenny Grant

Reputation: 9623

Another way to do this is to parse the key using the ssh package and then use FingerprintLegacyMD5 in order to generate the fingerprint. See this answer:

https://stackoverflow.com/a/46430102/1601137

Upvotes: 3

JimB
JimB

Reputation: 109318

A key signature is is just a cryptographic hash of the unencoded key data in ssh wire format.

Here is a basic example of parsing an ssh key from the OpenSSH format public key, and getting an MD5 fingerprint:

key, err := ioutil.ReadFile("/path/to/id_rsa.pub")
if err != nil {
    log.Fatal(err)
}

parts := strings.Fields(string(key))
if len(parts) < 2 {
    log.Fatal("bad key")
}

k, err := base64.StdEncoding.DecodeString(parts[1])
if err != nil {
    log.Fatal(err)
}

fp := md5.Sum([]byte(k))
fmt.Print("MD5:")
for i, b := range fp {
    fmt.Printf("%02x", b)
    if i < len(fp)-1 {
        fmt.Print(":")
    }
}
fmt.Println()

Upvotes: 6

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