Add three proof of concept scripts

Signed-off-by: Aoi Koizumi <novaburst@kalli.st>

experimental/age_encrypt

@@ -0,0 +1,24 @@
+#!/bin/sh
+
+[ -f "$1" ] || exit 1
+
+IFS='
+'
+
+FLAGS=$(maddr -a -h from:to:cc:bcc "$1" | sort -u | sed 's/^/--recipients-file/')
+FROM=$(maddr -a -h from: "$1" | sed 1q)
+TO=$(maddr -a -h to: "$1" | sed 1q)
+
+TMPD=$(mktemp -d magecrypt.XXXXXX)
+trap "rm -rf '$TMPD'" INT TERM EXIT
+
+awk '/^$/,0' | mmime | age --encrypt "$FLAGS" "$TO.age" -o "$TMPD/msg.age" || exit $?
+
+printf 'Version: 1\n' > "$TMPD/version"
+
+{
+	sed 's/^$/q' "$1"
+	printf '#application/age-encrypted %s/version' "$TMPD" 
+	printf '#application/octet-stream %s/msg.age\n' "$TMPD"
+} |
+	mmime -t 'multipart/encrypted; protocol="application/age-encrypted"'

experimental/mautocrypt

@@ -0,0 +1,33 @@
+#!/bin/sh
+# mencrypt PLAINMSG - generate a PGP/MIME signed and encrypted message
+
+[ -f "$1" ] || exit 1
+
+IFS='
+'
+FLAGS=$(maddr -a -h from:to:cc:bcc: "$1" |sort -u |sed 's/^/--recipient=/')
+
+FROM=$(maddr -a -h from "$1" | sed 1q)
+[ "$FROM" ] && key="--default-key=$FROM"
+
+if command -v gpg2 >/dev/null; then
+	GPG=gpg2
+else
+	GPG=gpg
+fi
+
+TMPD=$(mktemp -d -t mencrypt.XXXXXX)
+trap "rm -rf '$TMPD'" INT TERM EXIT
+
+export GPG_TTY=$(tty)
+awk '/^$/,0' "$1" | mmime | $GPG "$key" --armor --encrypt --sign $FLAGS -o "$TMPD/msg.asc" || exit $?
+unset GPG_TTY
+
+printf 'Version: 1\n' >"$TMPD/version"
+
+{
+	sed '/^$/q' "$1"
+	printf '#application/pgp-encrypted %s/version\n' "$TMPD"
+	printf '#application/octet-stream %s/msg.asc\n' "$TMPD"
+} | 
+	mmime -t 'multipart/encrypted; protocol="application/pgp-encrypted"'

experimental/saltpack_encrypt

@@ -0,0 +1,24 @@
+#!/bin/sh
+
+[ -f "$1" ] || exit 1
+
+IFS='
+'
+
+FLAGS=$(maddr -a -h from:to:cc:bcc "$1" | sort -u | sed 's/^/--recipients/')
+FROM=$(maddr -a -h from: "$1" | sed 1q)
+TO=$(maddr -a -h to: "$1" | sed 1q)
+
+TMPD=$(mktemp -d msaltcrypt.XXXXXX)
+trap "rm -rf '$TMPD'" INT TERM EXIT
+
+awk '/^$/,0' | mmime | salty --encrypt "$FLAGS" "$TO.slt" -o "$TMPD/msg.slt" || exit $?
+
+printf 'Version: 1\n' > "$TMPD/version"
+
+{
+	sed 's/^$/q' "$1"
+	printf '#application/salty-encrypted %s/version' "$TMPD" 
+	printf '#application/octet-stream %s/msg.slt\n' "$TMPD"
+} |
+	mmime -t 'multipart/encrypted; protocol="application/saltpack-encrypted"'