openpgp: Implement creation and serialization of Autocrypt headers.

3 files changed, 72 insertions, 4 deletions

diff --git a/tool/src/sq-usage.rs b/tool/src/sq-usage.rs
index 6e931570..f3159937 100644
--- a/tool/src/sq-usage.rs
+++ b/tool/src/sq-usage.rs
@@ -340,8 +340,9 @@
 //!     -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)
+//!     decode           Converts Autocrypt-encoded keys to OpenPGP TPKs
+//!     encode-sender    Encodes the senders' OpenPGP TPKs into an Autocrypt header
+//!     help             Prints this message or the help of the given subcommand(s)
 //! ```
 //!
 //! ### Subcommand autocrypt decode
@@ -363,6 +364,28 @@
 //!     <FILE>    Sets the input file to use
 //! ```
 //!
+//! ### Subcommand autocrypt encode-sender
+//!
+//! ```text
+//! Encodes the senders' OpenPGP TPKs into an Autocrypt header
+//!
+//! USAGE:
+//!     sq autocrypt encode-sender [OPTIONS] [FILE]
+//!
+//! FLAGS:
+//!     -h, --help       Prints help information
+//!     -V, --version    Prints version information
+//!
+//! OPTIONS:
+//!         --address <address>                  Select userid to use.  [default: primary userid]
+//!     -o, --output <FILE>                      Sets the output file to use
+//!         --prefer-encrypt <prefer-encrypt>    Sets the prefer-encrypt attribute [default: nopreference]  [possible
+//!                                              values: nopreference, mutual]
+//!
+//! ARGS:
+//!     <FILE>    Sets the input file to use
+//! ```
+//!
 //! ## Subcommand dearmor
 //!
 //! ```text
diff --git a/tool/src/sq.rs b/tool/src/sq.rs
index c82698e3..1902e8bd 100644
--- a/tool/src/sq.rs
+++ b/tool/src/sq.rs
@@ -221,7 +221,31 @@ fn real_main() -> Result<(), failure::Error> {
                             tpk.serialize(&mut filter)?;
                         }
                     }
-                }
+                },
+                ("encode-sender",  Some(m)) => {
+                    let mut input = open_or_stdin(m.value_of("input"))?;
+                    let mut output = create_or_stdout(m.value_of("output"),
+                                                      force)?;
+                    let tpk = TPK::from_reader(input)?;
+                    let addr = m.value_of("address").map(|a| a.to_string())
+                        .or_else(|| {
+                            if let Some(Ok(Some(a))) =
+                                tpk.userids().nth(0).map(|u| u.userid().address())
+                            {
+                                Some(a)
+                            } else {
+                                None
+                            }
+                        });
+                    let ac = autocrypt::AutocryptHeader::new_sender(
+                        &tpk,
+                        &addr.ok_or(failure::err_msg(
+                            "No well-formed primary userid found, use \
+                             --address to specify one"))?,
+                        m.value_of("prefer-encrypt").expect("has default"))?;
+                    write!(&mut output, "Autocrypt: ")?;
+                    ac.serialize(&mut output)?;
+                },
                 _ => unreachable!(),
             }
         },
diff --git a/tool/src/sq_cli.rs b/tool/src/sq_cli.rs
index bfa64601..a75d1349 100644
--- a/tool/src/sq_cli.rs
+++ b/tool/src/sq_cli.rs
@@ -211,7 +211,28 @@ pub fn build() -> App<'static, 'static> {
                                 .arg(Arg::with_name("output").value_name("FILE")
                                      .long("output")
                                      .short("o")
-                                     .help("Sets the output file to use"))))
+                                     .help("Sets the output file to use")))
+                    .subcommand(SubCommand::with_name("encode-sender")
+                                .about("Encodes the senders' OpenPGP TPKs into \
+                                        an Autocrypt header")
+                                .arg(Arg::with_name("input").value_name("FILE")
+                                     .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"))
+                                .arg(Arg::with_name("address")
+                                     .long("address")
+                                     .takes_value(true)
+                                     .help("Select userid to use.  \
+                                            [default: primary userid]"))
+                                .arg(Arg::with_name("prefer-encrypt")
+                                     .long("prefer-encrypt")
+                                     .possible_values(&["nopreference",
+                                                        "mutual"])
+                                     .default_value("nopreference")
+                                     .help("Sets the prefer-encrypt \
+                                            attribute"))))
         .subcommand(SubCommand::with_name("inspect")
                     .about("Inspects a sequence of OpenPGP packets")
                     .arg(Arg::with_name("input").value_name("FILE")