ssh: add hmac-sha2-512.

Author: fbettag

ssh/common.go

@@ -67,7 +67,7 @@ var supportedHostKeyAlgos = []string{
 // This is based on RFC 4253, section 6.4, but with hmac-md5 variants removed
 // because they have reached the end of their useful life.
 var supportedMACs = []string{
-	"[email protected]", "hmac-sha2-256", "hmac-sha1", "hmac-sha1-96",
+	"[email protected]", "hmac-sha2-512", "hmac-sha2-256", "hmac-sha1", "hmac-sha1-96",
 }
 
 var supportedCompressions = []string{compressionNone}

ssh/mac.go

@@ -10,6 +10,7 @@ import (
 	"crypto/hmac"
 	"crypto/sha1"
 	"crypto/sha256"
+	"crypto/sha512"
 	"hash"
 )
 
@@ -49,6 +50,9 @@ var macModes = map[string]*macMode{
 	"[email protected]": {32, true, func(key []byte) hash.Hash {
 		return hmac.New(sha256.New, key)
 	}},
+	"hmac-sha2-512": {64, false, func(key []byte) hash.Hash {
+		return hmac.New(sha512.New, key)
+	}},
 	"hmac-sha2-256": {32, false, func(key []byte) hash.Hash {
 		return hmac.New(sha256.New, key)
 	}},