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core / src /imex /key_transfer.rs
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 //! # Key transfer via Autocrypt Setup Message.
use std::io::BufReader;
use anyhow::{Result, bail, ensure};
use crate::blob::BlobObject;
use crate::chat::{self, ChatId};
use crate::config::Config;
use crate::constants::{ASM_BODY, ASM_SUBJECT};
use crate::contact::ContactId;
use crate::context::Context;
use crate::imex::set_self_key;
use crate::key::{DcKey, load_self_secret_key};
use crate::message::{Message, MsgId, Viewtype};
use crate::mimeparser::SystemMessage;
use crate::param::Param;
use crate::pgp;
use crate::tools::open_file_std;
/// Initiates key transfer via Autocrypt Setup Message.
///
/// Returns setup code.
pub async fn initiate_key_transfer(context: &Context) -> Result<String> {
let setup_code = create_setup_code(context);
/* this may require a keypair to be created. this may take a second ... */
let setup_file_content = render_setup_file(context, &setup_code).await?;
/* encrypting may also take a while ... */
let setup_file_blob = BlobObject::create_and_deduplicate_from_bytes(
context,
setup_file_content.as_bytes(),
"autocrypt-setup-message.html",
)?;
let chat_id = ChatId::create_for_contact(context, ContactId::SELF).await?;
let mut msg = Message::new(Viewtype::File);
msg.param.set(Param::File, setup_file_blob.as_name());
msg.param
.set(Param::Filename, "autocrypt-setup-message.html");
msg.subject = ASM_SUBJECT.to_owned();
msg.param
.set(Param::MimeType, "application/autocrypt-setup");
msg.param.set_cmd(SystemMessage::AutocryptSetupMessage);
msg.force_plaintext();
msg.param.set_int(Param::SkipAutocrypt, 1);
// Enable BCC-self, because transferring a key
// means we have a multi-device setup.
context.set_config_bool(Config::BccSelf, true).await?;
chat::send_msg(context, chat_id, &mut msg).await?;
Ok(setup_code)
}
/// Continue key transfer via Autocrypt Setup Message.
///
/// `msg_id` is the ID of the received Autocrypt Setup Message.
/// `setup_code` is the code entered by the user.
pub async fn continue_key_transfer(
context: &Context,
msg_id: MsgId,
setup_code: &str,
) -> Result<()> {
ensure!(!msg_id.is_special(), "wrong id");
let msg = Message::load_from_db(context, msg_id).await?;
ensure!(
msg.is_setupmessage(),
"Message is no Autocrypt Setup Message."
);
if let Some(filename) = msg.get_file(context) {
let file = open_file_std(context, filename)?;
let sc = normalize_setup_code(setup_code);
let armored_key = decrypt_setup_file(&sc, BufReader::new(file)).await?;
set_self_key(context, &armored_key).await?;
context.set_config_bool(Config::BccSelf, true).await?;
Ok(())
} else {
bail!("Message is no Autocrypt Setup Message.");
}
}
/// Renders HTML body of a setup file message.
///
/// The `passphrase` must be at least 2 characters long.
pub async fn render_setup_file(context: &Context, passphrase: &str) -> Result<String> {
let passphrase_begin = if let Some(passphrase_begin) = passphrase.get(..2) {
passphrase_begin
} else {
bail!("Passphrase must be at least 2 chars long.");
};
let private_key = load_self_secret_key(context).await?;
let ac_headers = Some(("Autocrypt-Prefer-Encrypt", "mutual"));
let private_key_asc = private_key.to_asc(ac_headers);
let encr = pgp::symm_encrypt_autocrypt_setup(passphrase, private_key_asc.into_bytes())
.await?
.replace('\n', "\r\n");
let replacement = format!(
concat!(
"-----BEGIN PGP MESSAGE-----\r\n",
"Passphrase-Format: numeric9x4\r\n",
"Passphrase-Begin: {}"
),
passphrase_begin
);
let pgp_msg = encr.replace("-----BEGIN PGP MESSAGE-----", &replacement);
let msg_subj = ASM_SUBJECT;
let msg_body = ASM_BODY.to_string();
let msg_body_html = msg_body.replace('\r', "").replace('\n', "<br>");
Ok(format!(
concat!(
"<!DOCTYPE html>\r\n",
"<html>\r\n",
" <head>\r\n",
" <title>{}</title>\r\n",
" </head>\r\n",
" <body>\r\n",
" <h1>{}</h1>\r\n",
" <p>{}</p>\r\n",
" <pre>\r\n{}\r\n</pre>\r\n",
" </body>\r\n",
"</html>\r\n"
),
msg_subj, msg_subj, msg_body_html, pgp_msg
))
}
/// Creates a new setup code for Autocrypt Setup Message.
fn create_setup_code(_context: &Context) -> String {
let mut random_val: u16;
let mut ret = String::new();
for i in 0..9 {
loop {
random_val = rand::random();
if random_val as usize <= 60000 {
break;
}
}
random_val = (random_val as usize % 10000) as u16;
ret += &format!(
"{}{:04}",
if 0 != i { "-" } else { "" },
random_val as usize
);
}
ret
}
async fn decrypt_setup_file<T: std::fmt::Debug + std::io::BufRead + Send + 'static>(
passphrase: &str,
file: T,
) -> Result<String> {
let plain_bytes = pgp::symm_decrypt(passphrase, file).await?;
let plain_text = std::string::String::from_utf8(plain_bytes)?;
Ok(plain_text)
}
fn normalize_setup_code(s: &str) -> String {
let mut out = String::new();
for c in s.chars() {
if c.is_ascii_digit() {
out.push(c);
if let 4 | 9 | 14 | 19 | 24 | 29 | 34 | 39 = out.len() {
out += "-"
}
}
}
out
}
#[cfg(test)]
mod tests {
use super::*;
use crate::pgp::{HEADER_AUTOCRYPT, HEADER_SETUPCODE, split_armored_data};
use crate::receive_imf::receive_imf;
use crate::test_utils::{TestContext, TestContextManager};
use ::pgp::armor::BlockType;
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn test_render_setup_file() {
let t = TestContext::new_alice().await;
let msg = render_setup_file(&t, "hello").await.unwrap();
println!("{}", &msg);
// Check some substrings, indicating things got substituted.
assert!(msg.contains("<title>Autocrypt Setup Message</title"));
assert!(msg.contains("<h1>Autocrypt Setup Message</h1>"));
assert!(msg.contains("<p>This is the Autocrypt Setup Message used to"));
assert!(msg.contains("-----BEGIN PGP MESSAGE-----\r\n"));
assert!(msg.contains("Passphrase-Format: numeric9x4\r\n"));
assert!(msg.contains("Passphrase-Begin: he\r\n"));
assert!(msg.contains("-----END PGP MESSAGE-----\r\n"));
for line in msg.rsplit_terminator('\n') {
assert!(line.ends_with('\r'));
}
}
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn test_render_setup_file_newline_replace() {
let t = TestContext::new_alice().await;
let msg = render_setup_file(&t, "pw").await.unwrap();
println!("{}", &msg);
assert!(msg.contains("<p>This is the Autocrypt Setup Message used to transfer your end-to-end setup between clients.<br>"));
}
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn test_create_setup_code() {
let t = TestContext::new().await;
let setupcode = create_setup_code(&t);
assert_eq!(setupcode.len(), 44);
assert_eq!(setupcode.chars().nth(4).unwrap(), '-');
assert_eq!(setupcode.chars().nth(9).unwrap(), '-');
assert_eq!(setupcode.chars().nth(14).unwrap(), '-');
assert_eq!(setupcode.chars().nth(19).unwrap(), '-');
assert_eq!(setupcode.chars().nth(24).unwrap(), '-');
assert_eq!(setupcode.chars().nth(29).unwrap(), '-');
assert_eq!(setupcode.chars().nth(34).unwrap(), '-');
assert_eq!(setupcode.chars().nth(39).unwrap(), '-');
}
#[test]
fn test_normalize_setup_code() {
let norm = normalize_setup_code("123422343234423452346234723482349234");
assert_eq!(norm, "1234-2234-3234-4234-5234-6234-7234-8234-9234");
let norm =
normalize_setup_code("\t1 2 3422343234- foo bar-- 423-45 2 34 6234723482349234 ");
assert_eq!(norm, "1234-2234-3234-4234-5234-6234-7234-8234-9234");
}
/* S_EM_SETUPFILE is a AES-256 symm. encrypted setup message created by Enigmail
with an "encrypted session key", see RFC 4880. The code is in S_EM_SETUPCODE */
const S_EM_SETUPCODE: &str = "1742-0185-6197-1303-7016-8412-3581-4441-0597";
const S_EM_SETUPFILE: &str = include_str!("../../test-data/message/stress.txt");
// Autocrypt Setup Message payload "encrypted" with plaintext algorithm.
const S_PLAINTEXT_SETUPFILE: &str =
include_str!("../../test-data/message/plaintext-autocrypt-setup.txt");
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn test_split_and_decrypt() {
let buf_1 = S_EM_SETUPFILE.as_bytes().to_vec();
let (typ, headers, base64) = split_armored_data(&buf_1).unwrap();
assert_eq!(typ, BlockType::Message);
assert!(S_EM_SETUPCODE.starts_with(headers.get(HEADER_SETUPCODE).unwrap()));
assert!(!headers.contains_key(HEADER_AUTOCRYPT));
assert!(!base64.is_empty());
let setup_file = S_EM_SETUPFILE;
let decrypted = decrypt_setup_file(S_EM_SETUPCODE, setup_file.as_bytes())
.await
.unwrap();
let (typ, headers, _base64) = split_armored_data(decrypted.as_bytes()).unwrap();
assert_eq!(typ, BlockType::PrivateKey);
assert_eq!(headers.get(HEADER_AUTOCRYPT), Some(&"mutual".to_string()));
assert!(!headers.contains_key(HEADER_SETUPCODE));
}
/// Tests that Autocrypt Setup Message encrypted with "plaintext" algorithm cannot be
/// decrypted.
///
/// According to <https://datatracker.ietf.org/doc/html/rfc4880#section-13.4>
/// "Implementations MUST NOT use plaintext in Symmetrically Encrypted Data packets".
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn test_decrypt_plaintext_autocrypt_setup_message() {
let setup_file = S_PLAINTEXT_SETUPFILE;
let incorrect_setupcode = "0000-0000-0000-0000-0000-0000-0000-0000-0000";
assert!(
decrypt_setup_file(incorrect_setupcode, setup_file.as_bytes(),)
.await
.is_err()
);
}
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn test_key_transfer() -> Result<()> {
let mut tcm = TestContextManager::new();
let alice = &tcm.alice().await;
tcm.section("Alice sends Autocrypt setup message");
alice.set_config(Config::BccSelf, Some("0")).await?;
let setup_code = initiate_key_transfer(alice).await?;
// Test that sending Autocrypt Setup Message enables `bcc_self`.
assert_eq!(alice.get_config_bool(Config::BccSelf).await?, true);
// Get Autocrypt Setup Message.
let sent = alice.pop_sent_msg().await;
tcm.section("Alice sets up a second device");
let alice2 = &tcm.unconfigured().await;
alice2.set_name("alice2");
alice2.configure_addr("alice@example.org").await;
alice2.recv_msg(&sent).await;
let msg = alice2.get_last_msg().await;
assert!(msg.is_setupmessage());
assert_eq!(crate::key::load_self_secret_keyring(alice2).await?.len(), 0);
// Transfer the key.
tcm.section("Alice imports a key from Autocrypt Setup Message");
alice2.set_config(Config::BccSelf, Some("0")).await?;
continue_key_transfer(alice2, msg.id, &setup_code).await?;
assert_eq!(alice2.get_config_bool(Config::BccSelf).await?, true);
assert_eq!(crate::key::load_self_secret_keyring(alice2).await?.len(), 1);
// Alice sends a message to self from the new device.
let sent = alice2.send_text(msg.chat_id, "Test").await;
let rcvd_msg = alice.recv_msg(&sent).await;
assert_eq!(rcvd_msg.get_text(), "Test");
Ok(())
}
/// Tests that Autocrypt Setup Messages is only clickable if it is self-sent.
/// This prevents Bob from tricking Alice into changing the key
/// by sending her an Autocrypt Setup Message as long as Alice's server
/// does not allow to forge the `From:` header.
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn test_key_transfer_non_self_sent() -> Result<()> {
let mut tcm = TestContextManager::new();
let alice = tcm.alice().await;
let bob = tcm.bob().await;
let _setup_code = initiate_key_transfer(&alice).await?;
// Get Autocrypt Setup Message.
let sent = alice.pop_sent_msg().await;
let rcvd = bob.recv_msg(&sent).await;
assert!(!rcvd.is_setupmessage());
Ok(())
}
/// Tests reception of Autocrypt Setup Message from K-9 6.802.
///
/// Unlike Autocrypt Setup Message sent by Delta Chat,
/// this message does not contain `Autocrypt-Prefer-Encrypt` header.
#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn test_key_transfer_k_9() -> Result<()> {
let t = &TestContext::new().await;
t.configure_addr("autocrypt@nine.testrun.org").await;
let raw = include_bytes!("../../test-data/message/k-9-autocrypt-setup-message.eml");
let received = receive_imf(t, raw, false).await?.unwrap();
let setup_code = "0655-9868-8252-5455-4232-5158-1237-5333-2638";
continue_key_transfer(t, *received.msg_ids.last().unwrap(), setup_code).await?;
Ok(())
}
}