diff --git a/ssh/keys.go b/ssh/keys.go index f2fc9b6c99..21f7d0d2eb 100644 --- a/ssh/keys.go +++ b/ssh/keys.go @@ -10,10 +10,13 @@ import ( "crypto/dsa" "crypto/ecdsa" "crypto/elliptic" + "crypto/md5" "crypto/rsa" + "crypto/sha256" "crypto/x509" "encoding/asn1" "encoding/base64" + "encoding/hex" "encoding/pem" "errors" "fmt" @@ -878,3 +881,25 @@ func parseOpenSSHPrivateKey(key []byte) (*ed25519.PrivateKey, error) { copy(pk, pk1.Priv) return &pk, nil } + +// FingerprintLegacyMD5 returns the user presentation of the key's +// fingerprint as described by RFC 4716 section 4. +func FingerprintLegacyMD5(pubKey PublicKey) string { + md5sum := md5.Sum(pubKey.Marshal()) + hexarray := make([]string, len(md5sum)) + for i, c := range md5sum { + hexarray[i] = hex.EncodeToString([]byte{c}) + } + return strings.Join(hexarray, ":") +} + +// FingerprintSHA256 returns the user presentation of the key's +// fingerprint as unpadded base64 encoded sha256 hash. +// This format was introduced from OpenSSH 6.8. +// https://www.openssh.com/txt/release-6.8 +// https://tools.ietf.org/html/rfc4648#section-3.2 (unpadded base64 encoding) +func FingerprintSHA256(pubKey PublicKey) string { + sha256sum := sha256.Sum256(pubKey.Marshal()) + hash := base64.RawStdEncoding.EncodeToString(sha256sum[:]) + return "SHA256:" + hash +} diff --git a/ssh/keys_test.go b/ssh/keys_test.go index 0739c66275..a65e87e535 100644 --- a/ssh/keys_test.go +++ b/ssh/keys_test.go @@ -454,3 +454,21 @@ func TestKnownHostsParsing(t *testing.T) { } } } + +func TestFingerprintLegacyMD5(t *testing.T) { + pub, _ := getTestKey() + fingerprint := FingerprintLegacyMD5(pub) + want := "fb:61:6d:1a:e3:f0:95:45:3c:a0:79:be:4a:93:63:66" // ssh-keygen -lf -E md5 rsa + if fingerprint != want { + t.Errorf("got fingerprint %q want %q", fingerprint, want) + } +} + +func TestFingerprintSHA256(t *testing.T) { + pub, _ := getTestKey() + fingerprint := FingerprintSHA256(pub) + want := "SHA256:Anr3LjZK8YVpjrxu79myrW9Hrb/wpcMNpVvTq/RcBm8" // ssh-keygen -lf rsa + if fingerprint != want { + t.Errorf("got fingerprint %q want %q", fingerprint, want) + } +}