feat: add gpg integration

This commit adds gpg system integration. This is done through two new
packages: gpgbin, which handles the system calls and parsing; and gpg
which is mostly a copy of emersion/go-pgpmail with modifications to
interface with package gpgbin. gpg includes tests for many cases, and
by it's nature also tests package gpgbin. I separated these in case an
external dependency is ever used for the gpg sys-calls/parsing (IE we
mirror how go-pgpmail+openpgp currently are dependencies)

Two new config options are introduced:
* pgp-provider. If it is not explicitly set to "gpg", aerc will default to
it's internal pgp provider
* pgp-key-id: (Optionally) specify a key by short or long keyId

Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
Acked-by: Koni Marti <koni.marti@gmail.com>
Acked-by: Robin Jarry <robin@jarry.cc>

1 files changed, 27 insertions, 0 deletions

diff --git a/lib/crypto/gpg/gpgbin/sign.go b/lib/crypto/gpg/gpgbin/sign.go
new file mode 100644
index 00000000..35ab7e7f
--- /dev/null
+++ b/lib/crypto/gpg/gpgbin/sign.go
@@ -0,0 +1,27 @@
+package gpgbin
+
+import (
+	"bytes"
+	"io"
+
+	"git.sr.ht/~rjarry/aerc/models"
+)
+
+// Sign creates a detached signature based on the contents of r
+func Sign(r io.Reader, from string) ([]byte, string, error) {
+	args := []string{
+		"--armor",
+		"--detach-sign",
+		"--default-key", from,
+	}
+
+	g := newGpg(r, args)
+	g.cmd.Run()
+
+	outRdr := bytes.NewReader(g.stdout.Bytes())
+	var md models.MessageDetails
+	parse(outRdr, &md)
+	var buf bytes.Buffer
+	io.Copy(&buf, md.Body)
+	return buf.Bytes(), md.Micalg, nil
+}