internal/age,internal/armor: add examples

internal/age/age.go

@@ -4,7 +4,16 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
-// Package age implements file encryption according to age-encryption.org/v1.
+// Package age implements file encryption according to the age-encryption.org/v1
+// specification.
+//
+// For most use cases, use the Encrypt and Decrypt functions with
+// X25519Recipient and X25519Identity. If passphrase encryption is required, use
+// ScryptRecipient and ScryptIdentity. For compatibility with existing SSH keys
+// use the filippo.io/age/internal/agessh package.
+//
+// Age encrypted files are binary and not malleable, for encoding them as text,
+// use the filippo.io/age/internal/armor package.
 package age
 
 import (

internal/age/age_test.go

@@ -9,14 +9,89 @@ package age_test
 import (
 	"bytes"
 	"crypto/rand"
+	"encoding/hex"
+	"fmt"
 	"io"
 	"io/ioutil"
+	"log"
 	"testing"
 
 	"filippo.io/age/internal/age"
 	"golang.org/x/crypto/curve25519"
 )
 
+func ExampleEncrypt() {
+	publicKey := "age1cy0su9fwf3gf9mw868g5yut09p6nytfmmnktexz2ya5uqg9vl9sss4euqm"
+	recipient, err := age.ParseX25519Recipient(publicKey)
+	if err != nil {
+		log.Fatalf("Failed to parse public key %q: %v", publicKey, err)
+	}
+
+	out := &bytes.Buffer{}
+
+	w, err := age.Encrypt(out, recipient)
+	if err != nil {
+		log.Fatalf("Failed to create encrypted file: %v", err)
+	}
+	if _, err := io.WriteString(w, "Black lives matter."); err != nil {
+		log.Fatalf("Failed to write to encrypted file: %v", err)
+	}
+	if err := w.Close(); err != nil {
+		log.Fatalf("Failed to close encrypted file: %v", err)
+	}
+
+	fmt.Printf("Encrypted file size: %d\n", out.Len())
+	// Output:
+	// Encrypted file size: 219
+}
+
+var fileContents, _ = hex.DecodeString("6167652d656e6372797074696f6e2e6f72" +
+	"672f76310a2d3e20583235353139203868726c4d2b5a4247334464346646322b61353" +
+	"8337a64544957446b382f5234316b43595a7376775457340a794f345059646c4d5744" +
+	"4a2b437867554e527159355a30542f6d2b6733464368356a4978474c62435658630a2" +
+	"d2d2d20492f696d65765a7a79383132304a537a6d4a6e6d6e2f4b4d6b337035413131" +
+	"5638334e6b34316d394e50450a70c5e53624a1520753f92c5ad10ecab273ba4d61178" +
+	"07713e83820417a1df2ca08182272c8f85c857734a1311a3b75e98d0eaf")
+
+var privateKey = "AGE-SECRET-KEY-184JMZMVQH3E6U0PSL869004Y3U2NYV7R30EU99CSEDNPH02YUVFSZW44VU"
+
+func ExampleDecrypt() {
+	// DO NOT hardcode the private key. Store it in a secret storage solution,
+	// on disk if the local machine is trusted, or have the user provide it.
+	identity, err := age.ParseX25519Identity(privateKey)
+	if err != nil {
+		log.Fatalf("Failed to parse private key %q: %v", privateKey, err)
+	}
+
+	out := &bytes.Buffer{}
+	f := bytes.NewReader(fileContents)
+
+	r, err := age.Decrypt(f, identity)
+	if err != nil {
+		log.Fatalf("Failed to open encrypted file: %v", err)
+	}
+	if _, err := io.Copy(out, r); err != nil {
+		log.Fatalf("Failed to read encrypted file: %v", err)
+	}
+
+	fmt.Printf("File contents: %q\n", out.Bytes())
+	// Output:
+	// File contents: "Black lives matter."
+}
+
+func ExampleGenerateX25519Identity() {
+	identity, err := age.GenerateX25519Identity()
+	if err != nil {
+		log.Fatalf("Failed to generate key pair: %v", err)
+	}
+
+	fmt.Printf("Public key: %s...\n", identity.Recipient().String()[:4])
+	fmt.Printf("Private key: %s...\n", identity.String()[:16])
+	// Output:
+	// Public key: age1...
+	// Private key: AGE-SECRET-KEY-1...
+}
+
 const helloWorld = "Hello, Twitch!"
 
 func TestEncryptDecryptX25519(t *testing.T) {

internal/armor/armor_test.go

@@ -9,12 +9,83 @@ package armor_test
 import (
 	"bytes"
 	"encoding/pem"
+	"fmt"
+	"io"
 	"io/ioutil"
+	"log"
+	"strings"
 	"testing"
 
+	"filippo.io/age/internal/age"
 	"filippo.io/age/internal/armor"
 )
 
+func ExampleNewWriter() {
+	publicKey := "age1cy0su9fwf3gf9mw868g5yut09p6nytfmmnktexz2ya5uqg9vl9sss4euqm"
+	recipient, err := age.ParseX25519Recipient(publicKey)
+	if err != nil {
+		log.Fatalf("Failed to parse public key %q: %v", publicKey, err)
+	}
+
+	buf := &bytes.Buffer{}
+	armorWriter := armor.NewWriter(buf)
+
+	w, err := age.Encrypt(armorWriter, recipient)
+	if err != nil {
+		log.Fatalf("Failed to create encrypted file: %v", err)
+	}
+	if _, err := io.WriteString(w, "Black lives matter."); err != nil {
+		log.Fatalf("Failed to write to encrypted file: %v", err)
+	}
+	if err := w.Close(); err != nil {
+		log.Fatalf("Failed to close encrypted file: %v", err)
+	}
+
+	if err := armorWriter.Close(); err != nil {
+		log.Fatalf("Failed to close armor: %v", err)
+	}
+
+	fmt.Printf("%s[...]", buf.Bytes()[:35])
+	// Output:
+	// -----BEGIN AGE ENCRYPTED FILE-----
+	// [...]
+}
+
+var privateKey = "AGE-SECRET-KEY-184JMZMVQH3E6U0PSL869004Y3U2NYV7R30EU99CSEDNPH02YUVFSZW44VU"
+
+func ExampleNewReader() {
+	fileContents := `-----BEGIN AGE ENCRYPTED FILE-----
+YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSB4YWdhZHZ0WG1PZldDT1hD
+K3RPRzFkUlJnWlFBQlUwemtjeXFRMFp6V1VFCnRzZFV3a3Vkd1dSUWw2eEtrRkVv
+SHcvZnp6Q3lqLy9HMkM4ZjUyUGdDZjQKLS0tIDlpVUpuVUQ5YUJyUENFZ0lNSTB2
+ekUvS3E5WjVUN0F5ZWR1ejhpeU5rZUUKsvPGYt7vf0o1kyJ1eVFMz1e4JnYYk1y1
+kB/RRusYjn+KVJ+KTioxj0THtzZPXcjFKuQ1
+-----END AGE ENCRYPTED FILE-----`
+
+	// DO NOT hardcode the private key. Store it in a secret storage solution,
+	// on disk if the local machine is trusted, or have the user provide it.
+	identity, err := age.ParseX25519Identity(privateKey)
+	if err != nil {
+		log.Fatalf("Failed to parse private key %q: %v", privateKey, err)
+	}
+
+	out := &bytes.Buffer{}
+	f := strings.NewReader(fileContents)
+	armorReader := armor.NewReader(f)
+
+	r, err := age.Decrypt(armorReader, identity)
+	if err != nil {
+		log.Fatalf("Failed to open encrypted file: %v", err)
+	}
+	if _, err := io.Copy(out, r); err != nil {
+		log.Fatalf("Failed to read encrypted file: %v", err)
+	}
+
+	fmt.Printf("File contents: %q\n", out.Bytes())
+	// Output:
+	// File contents: "Black lives matter."
+}
+
 func TestArmor(t *testing.T) {
 	buf := &bytes.Buffer{}
 	w := armor.NewWriter(buf)