openpgp: Add support for parsing Autocrypt headers.

  - Also implement 'sq autocrypt decode' to convert an autocrypt
    header to an OpenPGP key.

3 files changed, 69 insertions, 1 deletions

diff --git a/tool/src/cli.rs b/tool/src/cli.rs
index eb1f4004..098aa6e8 100644
--- a/tool/src/cli.rs
+++ b/tool/src/cli.rs
@@ -83,6 +83,18 @@ pub fn build() -> App<'static, 'static> {
                          .long("output")
                          .short("o")
                          .help("Sets the output file to use")))
+        .subcommand(SubCommand::with_name("autocrypt")
+                    .about("Autocrypt support")
+                    .subcommand(SubCommand::with_name("decode")
+                                .about("Converts Autocrypt-encoded keys to OpenPGP TPKs")
+                                .arg(Arg::with_name("input").value_name("FILE")
+                                     .long("input")
+                                     .short("i")
+                                     .help("Sets the input file to use"))
+                                .arg(Arg::with_name("output").value_name("FILE")
+                                     .long("output")
+                                     .short("o")
+                                     .help("Sets the output file to use"))))
         .subcommand(SubCommand::with_name("dump")
                     .about("Lists OpenPGP packets")
                     .arg(Arg::with_name("input").value_name("FILE")
diff --git a/tool/src/sq-usage.rs b/tool/src/sq-usage.rs
index f6e4220d..37a0c7cd 100644
--- a/tool/src/sq-usage.rs
+++ b/tool/src/sq-usage.rs
@@ -18,6 +18,7 @@
 //!     -s, --store <STORE>              Sets the store to use (default: 'default')
 //!
 //! SUBCOMMANDS:
+//!     autocrypt    Autocrypt support
 //!     dearmor      Removes ASCII Armor from a file
 //!     decrypt      Decrypts an OpenPGP message
 //!     dump         Lists OpenPGP packets
@@ -30,6 +31,40 @@
 //!     store        Interacts with key stores
 //! ```
 //!
+//! ## Subcommand autocrypt
+//!
+//! ```text
+//! Autocrypt support
+//!
+//! USAGE:
+//!     sq autocrypt [SUBCOMMAND]
+//!
+//! FLAGS:
+//!     -h, --help       Prints help information
+//!     -V, --version    Prints version information
+//!
+//! SUBCOMMANDS:
+//!     decode    Converts Autocrypt-encoded keys to OpenPGP TPKs
+//!     help      Prints this message or the help of the given subcommand(s)
+//! ```
+//!
+//! ### Subcommand autocrypt decode
+//!
+//! ```text
+//! Converts Autocrypt-encoded keys to OpenPGP TPKs
+//!
+//! USAGE:
+//!     sq autocrypt decode [OPTIONS]
+//!
+//! FLAGS:
+//!     -h, --help       Prints help information
+//!     -V, --version    Prints version information
+//!
+//! OPTIONS:
+//!     -i, --input <FILE>     Sets the input file to use
+//!     -o, --output <FILE>    Sets the output file to use
+//! ```
+//!
 //! ## Subcommand dearmor
 //!
 //! ```text
diff --git a/tool/src/sq.rs b/tool/src/sq.rs
index 738b291d..5ecf8a7d 100644
--- a/tool/src/sq.rs
+++ b/tool/src/sq.rs
@@ -20,7 +20,7 @@ extern crate sequoia_core;
 extern crate sequoia_net;
 extern crate sequoia_store;
 
-use openpgp::{armor, Fingerprint, TPK};
+use openpgp::{armor, autocrypt, Fingerprint, TPK};
 use sequoia_core::{Context, NetworkPolicy};
 use sequoia_net::KeyServer;
 use sequoia_store::{Store, LogIter};
@@ -101,6 +101,27 @@ fn real_main() -> Result<(), failure::Error> {
             let mut filter = armor::Reader::new(&mut input, armor::Kind::Any);
             io::copy(&mut filter, &mut output)?;
         },
+        ("autocrypt", Some(m)) => {
+            match m.subcommand() {
+                ("decode",  Some(m)) => {
+                    let mut input = open_or_stdin(m.value_of("input"))?;
+                    let mut output = create_or_stdout(m.value_of("output"))?;
+                    let ac = autocrypt::AutocryptHeaders::from_reader(input)?;
+                    for h in &ac.headers {
+                        if let Some(ref tpk) = h.key {
+                            let mut filter = armor::Writer::new(
+                                &mut output, armor::Kind::PublicKey);
+                            tpk.serialize(&mut filter)?;
+                        }
+                    }
+                }
+                _ => {
+                    eprintln!("No autocrypt subcommand given.");
+                    exit(1);
+                }
+            }
+        },
+
         ("dump",  Some(m)) => {
             let input = open_or_stdin(m.value_of("input"))?;
             let mut output = create_or_stdout(m.value_of("output"))?;