diff --git a/ssh/client_auth_test.go b/ssh/client_auth_test.go
index 55833e5..1409276 100644
--- a/ssh/client_auth_test.go
+++ b/ssh/client_auth_test.go
@@ -464,7 +464,7 @@ func TestClientAuthNone(t *testing.T) {
 	go NewClientConn(c2, "", clientConfig)
 	serverConn, err := newServer(c1, serverConfig)
 	if err != nil {
-		t.Fatal("newServer: %v", err)
+		t.Fatalf("newServer: %v", err)
 	}
 	if serverConn.User() != user {
 		t.Fatalf("server: got %q, want %q", serverConn.User(), user)
diff --git a/ssh/keys.go b/ssh/keys.go
index 0324e12..ffcdb18 100644
--- a/ssh/keys.go
+++ b/ssh/keys.go
@@ -731,6 +731,14 @@ func ParsePrivateKey(pemBytes []byte) (Signer, error) {
 	return NewSignerFromKey(key)
 }
 
+// encryptedBlock tells whether a private key is
+// encrypted by examining its Proc-Type header
+// for a mention of ENCRYPTED
+// according to RFC 1421 Section 4.6.1.1.
+func encryptedBlock(block *pem.Block) bool {
+	return strings.Contains(block.Headers["Proc-Type"], "ENCRYPTED")
+}
+
 // ParseRawPrivateKey returns a private key from a PEM encoded private key. It
 // supports RSA (PKCS#1), DSA (OpenSSL), and ECDSA private keys.
 func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
@@ -739,6 +747,10 @@ func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
 		return nil, errors.New("ssh: no key found")
 	}
 
+	if encryptedBlock(block) {
+		return nil, errors.New("ssh: cannot decode encrypted private keys")
+	}
+
 	switch block.Type {
 	case "RSA PRIVATE KEY":
 		return x509.ParsePKCS1PrivateKey(block.Bytes)
diff --git a/ssh/keys_test.go b/ssh/keys_test.go
index 4c4c5be..0739c66 100644
--- a/ssh/keys_test.go
+++ b/ssh/keys_test.go
@@ -132,6 +132,22 @@ func TestParseECPrivateKey(t *testing.T) {
 	}
 }
 
+// See Issue https://github.com/golang/go/issues/6650.
+func TestParseEncryptedPrivateKeysFails(t *testing.T) {
+	const wantSubstring = "encrypted"
+	for i, tt := range testdata.PEMEncryptedKeys {
+		_, err := ParsePrivateKey(tt.PEMBytes)
+		if err == nil {
+			t.Errorf("#%d key %s: ParsePrivateKey successfully parsed, expected an error", i, tt.Name)
+			continue
+		}
+
+		if !strings.Contains(err.Error(), wantSubstring) {
+			t.Errorf("#%d key %s: got error %q, want substring %q", i, tt.Name, err, wantSubstring)
+		}
+	}
+}
+
 func TestParseDSA(t *testing.T) {
 	// We actually exercise the ParsePrivateKey codepath here, as opposed to
 	// using the ParseRawPrivateKey+NewSignerFromKey path that testdata_test.go
@@ -309,14 +325,14 @@ func TestInvalidEntry(t *testing.T) {
 }
 
 var knownHostsParseTests = []struct {
-	input     string
-	err       string
+	input string
+	err   string
 
-	marker   string
-	comment  string
-	hosts    []string
-	rest     string
-} {
+	marker  string
+	comment string
+	hosts   []string
+	rest    string
+}{
 	{
 		"",
 		"EOF",
@@ -375,13 +391,13 @@ var knownHostsParseTests = []struct {
 		"localhost,[host2:123]\tssh-rsa {RSAPUB}\tcomment comment",
 		"",
 
-		"", "comment comment", []string{"localhost","[host2:123]"}, "",
+		"", "comment comment", []string{"localhost", "[host2:123]"}, "",
 	},
 	{
 		"@marker \tlocalhost,[host2:123]\tssh-rsa {RSAPUB}",
 		"",
 
-		"marker", "", []string{"localhost","[host2:123]"}, "",
+		"marker", "", []string{"localhost", "[host2:123]"}, "",
 	},
 	{
 		"@marker \tlocalhost,[host2:123]\tssh-rsa aabbccdd",
diff --git a/ssh/testdata/keys.go b/ssh/testdata/keys.go
index 9b76905..736dad9 100644
--- a/ssh/testdata/keys.go
+++ b/ssh/testdata/keys.go
@@ -55,3 +55,66 @@ PLL8IEwvYu2wq+lpXfGQnNMbzYf9gspG0w==
 -----END EC PRIVATE KEY-----
 `),
 }
+
+var PEMEncryptedKeys = []struct {
+	Name          string
+	EncryptionKey string
+	PEMBytes      []byte
+}{
+	0: {
+		Name:          "rsa-encrypted",
+		EncryptionKey: "r54-G0pher_t3st$",
+		PEMBytes: []byte(`-----BEGIN RSA PRIVATE KEY-----
+Proc-Type: 4,ENCRYPTED
+DEK-Info: AES-128-CBC,3E1714DE130BC5E81327F36564B05462
+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-----END RSA PRIVATE KEY-----
+`),
+	},
+
+	1: {
+		Name:          "dsa-encrypted",
+		EncryptionKey: "qG0pher-dsa_t3st$",
+		PEMBytes: []byte(`-----BEGIN DSA PRIVATE KEY-----
+Proc-Type: 4,ENCRYPTED
+DEK-Info: AES-128-CBC,7CE7A6E4A647DC01AF860210B15ADE3E
+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+-----END DSA PRIVATE KEY-----
+`),
+	},
+}