From e40281a273a7907f8cf47ec18026bca4c6263ed2 Mon Sep 17 00:00:00 2001
From: emersion <contact@emersion.fr>
Date: Mon, 6 Jun 2016 22:55:15 +0200
Subject: [PATCH] First commit

---
 encrypted.go | 102 +++++++++++++++++++++++++++++++++++++++++++++++++++
 message.go   |  32 ++++++++++++++++
 2 files changed, 134 insertions(+)
 create mode 100644 encrypted.go
 create mode 100644 message.go

diff --git a/encrypted.go b/encrypted.go
new file mode 100644
index 0000000..de44b11
--- /dev/null
+++ b/encrypted.go
@@ -0,0 +1,102 @@
+// Implements MIME security with OpenPGP, as defined in RFC 3156.
+package pgpmime
+
+import (
+	"io"
+	"mime/multipart"
+	"net/textproto"
+
+	"golang.org/x/crypto/openpgp"
+)
+
+// A PGP/MIME encrypter.
+type Encrypter struct {
+	multipart *multipart.Writer
+	armored io.WriteCloser
+	encrypted io.WriteCloser
+
+	to []*openpgp.Entity
+	signed *openpgp.Entity
+
+	opened bool
+}
+
+// Write control information and create encrypted part.
+func (ew *Encrypter) open() (err error) {
+	// Create control information
+	h := make(textproto.MIMEHeader)
+	h.Add("Content-Type", "application/pgp-encrypted")
+	hw, err := ew.multipart.CreatePart(h)
+	if err != nil {
+		return
+	}
+	if _, err = io.WriteString(hw, "Version: 1\r\n"); err != nil {
+		return
+	}
+
+	// Create body part
+	h = make(textproto.MIMEHeader)
+	h.Add("Content-Type", "application/octet-stream")
+	h.Add("Content-Disposition", "inline")
+	bw, err := ew.multipart.CreatePart(h)
+	if err != nil {
+		return
+	}
+
+	// Create encrypted part
+	if ew.armored, err = EncodeArmoredMessage(bw); err != nil {
+		return
+	}
+	if ew.encrypted, err = openpgp.Encrypt(ew.armored, ew.to, ew.signed, nil, nil); err != nil {
+		return
+	}
+
+	return
+}
+
+// Write encrypted data.
+func (ew *Encrypter) Write(b []byte) (n int, err error) {
+	// Make sure parts required at the begining of the message have been written
+	if !ew.opened {
+		if err = ew.open(); err != nil {
+			return
+		}
+		ew.opened = true
+	}
+
+	return ew.encrypted.Write(b)
+}
+
+// Finish the PGP/MIME message.
+func (ew *Encrypter) Close() (err error) {
+	if !ew.opened {
+		if err = ew.open(); err != nil {
+			return
+		}
+		ew.opened = true
+	}
+
+	if err = ew.encrypted.Close(); err != nil {
+		return
+	}
+	if err = ew.armored.Close(); err != nil {
+		return
+	}
+	err = ew.multipart.Close()
+	return
+}
+
+// Get the Content-Type of this PGP/MIME message.
+func (ew *Encrypter) ContentType() string {
+	return "multipart/encrypted; boundary=" + ew.multipart.Boundary() + "; protocol=\"application/pgp-encrypted\""
+}
+
+// Create a new PGP/MIME encrypter.
+func NewEncrypter(w io.Writer, to []*openpgp.Entity, signed *openpgp.Entity) *Encrypter {
+	return &Encrypter{
+		multipart: multipart.NewWriter(w),
+
+		to: to,
+		signed: signed,
+	}
+}
diff --git a/message.go b/message.go
new file mode 100644
index 0000000..81dd480
--- /dev/null
+++ b/message.go
@@ -0,0 +1,32 @@
+package pgpmime
+
+import (
+	"errors"
+	"io"
+
+	"golang.org/x/crypto/openpgp/armor"
+)
+
+// Armored type for PGP encrypted messages.
+const MessageType = "PGP MESSAGE"
+
+// Encode a PGP message armor.
+func EncodeArmoredMessage(w io.Writer) (io.WriteCloser, error) {
+	return armor.Encode(w, MessageType, nil)
+}
+
+// Decode an armored PGP message.
+func DecodeArmoredMessage(in io.Reader) (out io.Reader, err error) {
+	block, err := armor.Decode(in)
+	if err != nil {
+		return
+	}
+
+	if block.Type != MessageType {
+		err = errors.New("Not an armored PGP message")
+		return
+	}
+
+	out = block.Body
+	return
+}