cmd/age-keygen: print the public key to standard error

HomebrewFormula/age.rb

@@ -0,0 +1,21 @@
+# Copyright 2019 Google LLC
+#
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file or at
+# https://developers.google.com/open-source/licenses/bsd
+
+class Age < Formula
+  desc "Simple, modern, secure file encryption"
+  homepage "https://filippo.io/age"
+  url "https://github.com/FiloSottile/age/archive/v1.0.0-beta1.zip"
+  sha256 "6c7b1de0f312bc6e17e6b26ec27598672d1064e0287f202da5ab7efa9a1bb9d8"
+
+  depends_on "go" => :build
+
+  def install
+    ENV["GOPATH"] = HOMEBREW_CACHE/"go_cache"
+    system "mkdir", bin
+    system "go", "build", "-o", bin, "filippo.io/age/cmd/..."
+    prefix.install_metafiles
+  end
+end

README.md

@@ -1,7 +1,57 @@
-age is meant to be a simple, secure and modern encryption tool with small explicit keys, no config options, and UNIX-style composability. The spec is at [age-encryption.org/v1](https://age-encryption.org/v1).
+# age
 
-This implementation is in progress, and things will keep moving around, so it's not yet a good time to contribute, and it's definitely not a good time to rely on it.
+age is a simple, modern and secure file encryption tool.
 
-To discuss the spec or other age related topics, please email the mailing list at age-dev@googlegroups.com. Subscribe at [groups.google.com/d/forum/age-dev](https://groups.google.com/d/forum/age-dev) or by emailing age-dev+subscribe@googlegroups.com.
+I features small explicit keys, no config options, and UNIX-style composability.
 
-Development is sometimes livestreamed at [twitch.tv/filosottile](https://www.twitch.tv/filosottile).
+```
+$ age-keygen -o key.txt
+Public key: age1ql3z7hjy54pw3hyww5ayyfg7zqgvc7w3j2elw8zmrj2kg5sfn9aqmcac8p
+$ tar cvz ~/data | age -r age1ql3z7hjy54pw3hyww5ayyfg7zqgvc7w3j2elw8zmrj2kg5sfn9aqmcac8p > data.tar.gz.age
+$ age -d -i key.txt -o data.tar.gz data.tar.gz.age
+```
+
+The format specification is at [age-encryption.org/v1](https://age-encryption.org/v1). To discuss the spec or other age related topics, please email the mailing list at age-dev@googlegroups.com. Subscribe at [groups.google.com/d/forum/age-dev](https://groups.google.com/d/forum/age-dev) or by emailing age-dev+subscribe@googlegroups.com.
+
+## Usage
+
+```
+Usage:
+    age -r RECIPIENT [-a] [-o OUTPUT] [INPUT]
+    age --decrypt [-i KEY] [-o OUTPUT] [INPUT]
+
+Options:
+    -o OUTPUT                   Write the result to the file at path OUTPUT.
+    -a, --armor                 Encrypt to a PEM encoded format.
+    -p, --passphrase            Encrypt with a passphrase.
+    -r, --recipient RECIPIENT   Encrypt to the specified RECIPIENT. Can be repeated.
+    -d, --decrypt               Decrypt the input to the output.
+    -i, --identity KEY          Use the private key file at path KEY. Can be repeated.
+
+INPUT defaults to standard input, and OUTPUT defaults to standard output.
+
+RECIPIENT can be an age public key, as generated by age-keygen, ("age1...")
+or an SSH public key ("ssh-ed25519 AAAA...", "ssh-rsa AAAA...").
+
+KEY is a path to a file with age secret keys, one per line
+(ignoring "#" prefixed comments and empty lines), or to an SSH key file.
+Multiple keys can be provided, and any unused ones will be ignored.
+```
+
+## Installation
+
+On macOS, use Homebrew.
+
+```
+brew tap filippo.io/age https://filippo.io/age
+brew install age
+```
+
+On Linux and Windows, use [the pre-built binaries](https://github.com/FiloSottile/age/releases) or build from source with Go 1.13+.
+
+```
+git clone https://filippo.io/age && cd age
+go build filippo.io/cmd/age/...
+```
+
+Help from new packagers is very welcome.

cmd/age-keygen/keygen.go

@@ -9,12 +9,12 @@ package main
 import (
 	"flag"
 	"fmt"
-	"io"
 	"log"
 	"os"
 	"time"
 
 	"filippo.io/age/internal/age"
+	"golang.org/x/crypto/ssh/terminal"
 )
 
 func main() {
@@ -46,12 +46,16 @@ func main() {
 	generate(out)
 }
 
-func generate(out io.Writer) {
+func generate(out *os.File) {
 	k, err := age.GenerateX25519Identity()
 	if err != nil {
 		log.Fatalf("Internal error: %v", err)
 	}
 
+	if !terminal.IsTerminal(int(out.Fd())) {
+		fmt.Fprintf(os.Stderr, "Public key: %s\n", k.Recipient())
+	}
+
 	fmt.Fprintf(out, "# created: %s\n", time.Now().Format(time.RFC3339))
 	fmt.Fprintf(out, "# public key: %s\n", k.Recipient())
 	fmt.Fprintf(out, "%s\n", k)

cmd/age/age.go

@@ -27,8 +27,36 @@ func (f *multiFlag) Set(value string) error {
 	return nil
 }
 
+const usage = `Usage:
+    age -r RECIPIENT [-a] [-o OUTPUT] [INPUT]
+    age --decrypt [-i KEY] [-o OUTPUT] [INPUT]
+
+Options:
+    -o OUTPUT                   Write the result to the file at path OUTPUT.
+    -a, --armor                 Encrypt to a PEM encoded format.
+    -p, --passphrase            Encrypt with a passphrase.
+    -r, --recipient RECIPIENT   Encrypt to the specified RECIPIENT. Can be repeated.
+    -d, --decrypt               Decrypt the input to the output.
+    -i, --identity KEY          Use the private key file at path KEY. Can be repeated.
+
+INPUT defaults to standard input, and OUTPUT defaults to standard output.
+
+RECIPIENT can be an age public key, as generated by age-keygen, ("age1...")
+or an SSH public key ("ssh-ed25519 AAAA...", "ssh-rsa AAAA...").
+
+KEY is a path to a file with age secret keys, one per line
+(ignoring "#" prefixed comments and empty lines), or to an SSH key file.
+Multiple keys can be provided, and any unused ones will be ignored.
+
+Example:
+    $ age-keygen -o key.txt
+    Public key: age1ql3z7hjy54pw3hyww5ayyfg7zqgvc7w3j2elw8zmrj2kg5sfn9aqmcac8p
+    $ tar cvz ~/data | age -r age1ql3z7hjy54pw3hyww5ayyfg7zqgvc7w3j2elw8zmrj2kg5sfn9aqmcac8p > data.tar.gz.age
+    $ age -d -i key.txt -o data.tar.gz data.tar.gz.age`
+
 func main() {
 	_log.SetFlags(0)
+	flag.Usage = func() { fmt.Fprintf(os.Stderr, "%s\n", usage) }
 
 	var (
 		outFlag                          string