cmd/age: initial support for SSH identities and recipients

Signed-off-by: Matt Layher <mdlayher@gmail.com>

cmd/age/age.go

@@ -13,6 +13,7 @@ import (
 	"io"
 	"log"
 	"os"
+	"path/filepath"
 	"time"
 
 	"github.com/FiloSottile/age/internal/age"
@@ -89,7 +90,17 @@ func decrypt() {
 	var identities []age.Identity
 	// TODO: use the default location if no arguments are provided.
 	for _, name := range flag.Args() {
-		ids, err := parseIdentitiesFile(name)
+		var (
+			ids []age.Identity
+			err error
+		)
+
+		// TODO: smarter detection logic than looking for .ssh/* in the path.
+		if filepath.Base(filepath.Dir(name)) == ".ssh" {
+			ids, err = parseSSHIdentity(name)
+		} else {
+			ids, err = parseIdentitiesFile(name)
+		}
 		if err != nil {
 			log.Fatalf("Error: %v", err)
 		}

cmd/age/parse.go

@@ -9,6 +9,8 @@ package main
 import (
 	"bufio"
 	"fmt"
+	"io"
+	"io/ioutil"
 	"os"
 	"strings"
 
@@ -16,10 +18,14 @@ import (
 )
 
 func parseRecipient(arg string) (age.Recipient, error) {
-	if strings.HasPrefix(arg, "pubkey:") {
+	switch {
+	case strings.HasPrefix(arg, "pubkey:"):
 		return age.ParseX25519Recipient(arg)
+	case strings.HasPrefix(arg, "ssh-"):
+		return age.ParseSSHRecipient(arg)
 	}
-	return nil, fmt.Errorf("unknown recipient type: %s", arg)
+
+	return nil, fmt.Errorf("unknown recipient type: %q", arg)
 }
 
 func parseIdentitiesFile(name string) ([]age.Identity, error) {
@@ -50,3 +56,26 @@ func parseIdentitiesFile(name string) ([]age.Identity, error) {
 	}
 	return ids, nil
 }
+
+func parseSSHIdentity(name string) ([]age.Identity, error) {
+	f, err := os.Open(name)
+	if err != nil {
+		return nil, fmt.Errorf("failed to open file: %v", err)
+	}
+	defer f.Close()
+
+	// Don't allow unbounded reads.
+	// TODO: support for multiple keys in the same stream, such as user.keys
+	// on GitHub.
+	pemBytes, err := ioutil.ReadAll(io.LimitReader(f, 1<<20))
+	if err != nil {
+		return nil, fmt.Errorf("failed to read %q: %v", name, err)
+	}
+
+	id, err := age.ParseSSHIdentity(pemBytes)
+	if err != nil {
+		return nil, fmt.Errorf("malformed SSH identity in %q: %v", name, err)
+	}
+
+	return []age.Identity{id}, nil
+}