Jack Grigg
505 lines
17 KiB
Rust
505 lines
17 KiB
Rust
//! Structs for handling YubiKeys.
|
|
|
|
use age_core::{
|
|
format::{FileKey, FILE_KEY_BYTES},
|
|
primitives::{aead_decrypt, hkdf},
|
|
secrecy::ExposeSecret,
|
|
};
|
|
use age_plugin::{identity, Callbacks};
|
|
use bech32::{ToBase32, Variant};
|
|
use dialoguer::Password;
|
|
use log::warn;
|
|
use std::fmt;
|
|
use std::io;
|
|
use std::iter;
|
|
use std::thread::sleep;
|
|
use std::time::{Duration, Instant, SystemTime};
|
|
use yubikey::{
|
|
certificate::{Certificate, PublicKeyInfo},
|
|
piv::{decrypt_data, AlgorithmId, RetiredSlotId, SlotId},
|
|
reader::{Context, Reader},
|
|
MgmKey, PinPolicy, Serial, TouchPolicy, YubiKey,
|
|
};
|
|
|
|
use crate::{
|
|
error::Error,
|
|
format::{RecipientLine, STANZA_KEY_LABEL},
|
|
p256::{Recipient, TAG_BYTES},
|
|
util::{otp_serial_prefix, Metadata},
|
|
IDENTITY_PREFIX,
|
|
};
|
|
|
|
const ONE_SECOND: Duration = Duration::from_secs(1);
|
|
const FIFTEEN_SECONDS: Duration = Duration::from_secs(15);
|
|
|
|
pub(crate) fn is_connected(reader: Reader) -> bool {
|
|
filter_connected(&reader)
|
|
}
|
|
|
|
pub(crate) fn filter_connected(reader: &Reader) -> bool {
|
|
match reader.open() {
|
|
Ok(_) => true,
|
|
Err(e) => {
|
|
use std::error::Error;
|
|
if let Some(pcsc::Error::RemovedCard) =
|
|
e.source().and_then(|inner| inner.downcast_ref())
|
|
{
|
|
warn!("Ignoring {}: not connected", reader.name());
|
|
false
|
|
} else {
|
|
true
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
pub(crate) fn wait_for_readers() -> Result<Context, Error> {
|
|
// Start a 15-second timer waiting for a YubiKey to be inserted (if necessary).
|
|
let start = SystemTime::now();
|
|
loop {
|
|
let mut readers = Context::open()?;
|
|
if readers.iter()?.any(is_connected) {
|
|
break Ok(readers);
|
|
}
|
|
|
|
match SystemTime::now().duration_since(start) {
|
|
Ok(end) if end >= FIFTEEN_SECONDS => return Err(Error::TimedOut),
|
|
_ => sleep(ONE_SECOND),
|
|
}
|
|
}
|
|
}
|
|
|
|
pub(crate) fn open(serial: Option<Serial>) -> Result<YubiKey, Error> {
|
|
if !Context::open()?.iter()?.any(is_connected) {
|
|
if let Some(serial) = serial {
|
|
eprintln!("⏳ Please insert the YubiKey with serial {}.", serial);
|
|
} else {
|
|
eprintln!("⏳ Please insert the YubiKey.");
|
|
}
|
|
}
|
|
let mut readers = wait_for_readers()?;
|
|
let mut readers_iter = readers.iter()?.filter(filter_connected);
|
|
|
|
// --serial selects the YubiKey to use. If not provided, and more than one YubiKey is
|
|
// connected, an error is returned.
|
|
let yubikey = match (readers_iter.next(), readers_iter.next(), serial) {
|
|
(None, _, _) => unreachable!(),
|
|
(Some(reader), None, None) => reader.open()?,
|
|
(Some(reader), None, Some(serial)) => {
|
|
let yubikey = reader.open()?;
|
|
if yubikey.serial() != serial {
|
|
return Err(Error::NoMatchingSerial(serial));
|
|
}
|
|
yubikey
|
|
}
|
|
(Some(a), Some(b), Some(serial)) => {
|
|
let reader = iter::empty()
|
|
.chain(Some(a))
|
|
.chain(Some(b))
|
|
.chain(readers_iter)
|
|
.find(|reader| match reader.open() {
|
|
Ok(yk) => yk.serial() == serial,
|
|
_ => false,
|
|
})
|
|
.ok_or(Error::NoMatchingSerial(serial))?;
|
|
reader.open()?
|
|
}
|
|
(Some(_), Some(_), None) => return Err(Error::MultipleYubiKeys),
|
|
};
|
|
|
|
Ok(yubikey)
|
|
}
|
|
|
|
pub(crate) fn manage(yubikey: &mut YubiKey) -> Result<(), Error> {
|
|
eprintln!();
|
|
let pin = Password::new()
|
|
.with_prompt(&format!(
|
|
"Enter PIN for YubiKey with serial {} (default is 123456)",
|
|
yubikey.serial(),
|
|
))
|
|
.interact()?;
|
|
yubikey.verify_pin(pin.as_bytes())?;
|
|
|
|
// If the user is using the default PIN, help them to change it.
|
|
if pin == "123456" {
|
|
eprintln!();
|
|
eprintln!("✨ Your YubiKey is using the default PIN. Let's change it!");
|
|
eprintln!("✨ We'll also set the PUK equal to the PIN.");
|
|
eprintln!();
|
|
eprintln!("🔐 The PIN is up to 8 numbers, letters, or symbols. Not just numbers!");
|
|
eprintln!(
|
|
"❌ Your keys will be lost if the PIN and PUK are locked after 3 incorrect tries."
|
|
);
|
|
eprintln!();
|
|
let current_puk = Password::new()
|
|
.with_prompt("Enter current PUK (default is 12345678)")
|
|
.interact()?;
|
|
let new_pin = Password::new()
|
|
.with_prompt("Choose a new PIN/PUK")
|
|
.with_confirmation("Repeat the PIN/PUK", "PINs don't match")
|
|
.interact()?;
|
|
if new_pin.len() > 8 {
|
|
return Err(Error::InvalidPinLength);
|
|
}
|
|
yubikey.change_puk(current_puk.as_bytes(), new_pin.as_bytes())?;
|
|
yubikey.change_pin(pin.as_bytes(), new_pin.as_bytes())?;
|
|
}
|
|
|
|
if let Ok(mgm_key) = MgmKey::get_protected(yubikey) {
|
|
yubikey.authenticate(mgm_key)?;
|
|
} else {
|
|
// Try to authenticate with the default management key.
|
|
yubikey
|
|
.authenticate(MgmKey::default())
|
|
.map_err(|_| Error::CustomManagementKey)?;
|
|
|
|
// Migrate to a PIN-protected management key.
|
|
let mgm_key = MgmKey::generate();
|
|
eprintln!();
|
|
eprintln!("✨ Your YubiKey is using the default management key.");
|
|
eprintln!("✨ We'll migrate it to a PIN-protected management key.");
|
|
eprint!("... ");
|
|
mgm_key.set_protected(yubikey).map_err(|e| {
|
|
eprintln!("An error occurred while setting the new management key.");
|
|
eprintln!("⚠️ SAVE THIS MANAGEMENT KEY - YOU MAY NEED IT TO MANAGE YOUR YubiKey! ⚠️");
|
|
eprintln!(" {}", hex::encode(mgm_key.as_ref()));
|
|
e
|
|
})?;
|
|
eprintln!("Success!");
|
|
}
|
|
|
|
Ok(())
|
|
}
|
|
|
|
/// A reference to an age key stored in a YubiKey.
|
|
#[derive(Debug)]
|
|
pub struct Stub {
|
|
pub(crate) serial: Serial,
|
|
pub(crate) slot: RetiredSlotId,
|
|
pub(crate) tag: [u8; TAG_BYTES],
|
|
identity_index: usize,
|
|
}
|
|
|
|
impl fmt::Display for Stub {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
f.write_str(
|
|
bech32::encode(
|
|
IDENTITY_PREFIX,
|
|
self.to_bytes().to_base32(),
|
|
Variant::Bech32,
|
|
)
|
|
.expect("HRP is valid")
|
|
.to_uppercase()
|
|
.as_str(),
|
|
)
|
|
}
|
|
}
|
|
|
|
impl PartialEq for Stub {
|
|
fn eq(&self, other: &Self) -> bool {
|
|
self.to_bytes().eq(&other.to_bytes())
|
|
}
|
|
}
|
|
|
|
impl Stub {
|
|
/// Returns a key stub and recipient for this `(Serial, SlotId, PublicKey)` tuple.
|
|
///
|
|
/// Does not check that the `PublicKey` matches the given `(Serial, SlotId)` tuple;
|
|
/// this is checked at decryption time.
|
|
pub(crate) fn new(serial: Serial, slot: RetiredSlotId, recipient: &Recipient) -> Self {
|
|
Stub {
|
|
serial,
|
|
slot,
|
|
tag: recipient.tag(),
|
|
identity_index: 0,
|
|
}
|
|
}
|
|
|
|
pub(crate) fn from_bytes(bytes: &[u8], identity_index: usize) -> Option<Self> {
|
|
let serial = Serial::from(u32::from_le_bytes(bytes[0..4].try_into().unwrap()));
|
|
let slot: RetiredSlotId = bytes[4].try_into().ok()?;
|
|
Some(Stub {
|
|
serial,
|
|
slot,
|
|
tag: bytes[5..9].try_into().unwrap(),
|
|
identity_index,
|
|
})
|
|
}
|
|
|
|
fn to_bytes(&self) -> Vec<u8> {
|
|
let mut bytes = Vec::with_capacity(9);
|
|
bytes.extend_from_slice(&self.serial.0.to_le_bytes());
|
|
bytes.push(self.slot.into());
|
|
bytes.extend_from_slice(&self.tag);
|
|
bytes
|
|
}
|
|
|
|
pub(crate) fn matches(&self, line: &RecipientLine) -> bool {
|
|
self.tag == line.tag
|
|
}
|
|
|
|
pub(crate) fn connect<E>(
|
|
&self,
|
|
callbacks: &mut dyn Callbacks<E>,
|
|
) -> io::Result<Result<Connection, identity::Error>> {
|
|
let mut yubikey = match YubiKey::open_by_serial(self.serial) {
|
|
Ok(yk) => yk,
|
|
Err(yubikey::Error::NotFound) => {
|
|
if callbacks
|
|
.message(&format!(
|
|
"Please insert YubiKey with serial {}",
|
|
self.serial
|
|
))?
|
|
.is_err()
|
|
{
|
|
return Ok(Err(identity::Error::Identity {
|
|
index: self.identity_index,
|
|
message: format!("Could not find YubiKey with serial {}", self.serial),
|
|
}));
|
|
}
|
|
|
|
// Start a 15-second timer waiting for the YubiKey to be inserted
|
|
let start = SystemTime::now();
|
|
loop {
|
|
match YubiKey::open_by_serial(self.serial) {
|
|
Ok(yubikey) => break yubikey,
|
|
Err(yubikey::Error::NotFound) => (),
|
|
Err(_) => {
|
|
return Ok(Err(identity::Error::Identity {
|
|
index: self.identity_index,
|
|
message: format!(
|
|
"Could not open YubiKey with serial {}",
|
|
self.serial
|
|
),
|
|
}));
|
|
}
|
|
}
|
|
|
|
match SystemTime::now().duration_since(start) {
|
|
Ok(end) if end >= FIFTEEN_SECONDS => {
|
|
return Ok(Err(identity::Error::Identity {
|
|
index: self.identity_index,
|
|
message: format!(
|
|
"Timed out while waiting for YubiKey with serial {} to be inserted",
|
|
self.serial
|
|
),
|
|
}))
|
|
}
|
|
_ => sleep(ONE_SECOND),
|
|
}
|
|
}
|
|
}
|
|
Err(_) => {
|
|
return Ok(Err(identity::Error::Identity {
|
|
index: self.identity_index,
|
|
message: format!("Could not open YubiKey with serial {}", self.serial),
|
|
}))
|
|
}
|
|
};
|
|
|
|
// Read the pubkey from the YubiKey slot and check it still matches.
|
|
let (cert, pk) = match Certificate::read(&mut yubikey, SlotId::Retired(self.slot))
|
|
.ok()
|
|
.and_then(|cert| match cert.subject_pki() {
|
|
PublicKeyInfo::EcP256(pubkey) => Recipient::from_encoded(pubkey)
|
|
.filter(|pk| pk.tag() == self.tag)
|
|
.map(|pk| (cert, pk)),
|
|
_ => None,
|
|
}) {
|
|
Some(pk) => pk,
|
|
None => {
|
|
return Ok(Err(identity::Error::Identity {
|
|
index: self.identity_index,
|
|
message: "A YubiKey stub did not match the YubiKey".to_owned(),
|
|
}))
|
|
}
|
|
};
|
|
|
|
Ok(Ok(Connection {
|
|
yubikey,
|
|
cert,
|
|
pk,
|
|
slot: self.slot,
|
|
tag: self.tag,
|
|
identity_index: self.identity_index,
|
|
cached_metadata: None,
|
|
last_touch: None,
|
|
}))
|
|
}
|
|
}
|
|
|
|
pub(crate) struct Connection {
|
|
yubikey: YubiKey,
|
|
cert: Certificate,
|
|
pk: Recipient,
|
|
slot: RetiredSlotId,
|
|
tag: [u8; 4],
|
|
identity_index: usize,
|
|
cached_metadata: Option<Metadata>,
|
|
last_touch: Option<Instant>,
|
|
}
|
|
|
|
impl Connection {
|
|
pub(crate) fn recipient(&self) -> &Recipient {
|
|
&self.pk
|
|
}
|
|
|
|
pub(crate) fn request_pin_if_necessary<E>(
|
|
&mut self,
|
|
callbacks: &mut dyn Callbacks<E>,
|
|
) -> io::Result<Result<(), identity::Error>> {
|
|
// Check if we can skip requesting a PIN.
|
|
if self.cached_metadata.is_none() {
|
|
let (_, cert) = x509_parser::parse_x509_certificate(self.cert.as_ref()).unwrap();
|
|
self.cached_metadata =
|
|
match Metadata::extract(&mut self.yubikey, self.slot, &cert, true) {
|
|
None => {
|
|
return Ok(Err(identity::Error::Identity {
|
|
index: self.identity_index,
|
|
message:
|
|
"Certificate for YubiKey identity contains an invalid PIN policy"
|
|
.to_string(),
|
|
}))
|
|
}
|
|
metadata => metadata,
|
|
};
|
|
}
|
|
if let Some(PinPolicy::Never) = self.cached_metadata.as_ref().and_then(|m| m.pin_policy) {
|
|
return Ok(Ok(()));
|
|
}
|
|
|
|
// The policy requires a PIN, so request it.
|
|
// Note that we can't distinguish between PinPolicy::Once and PinPolicy::Always
|
|
// because this plugin is ephemeral, so we always request the PIN.
|
|
let mut message = format!(
|
|
"Enter PIN for YubiKey with serial {}",
|
|
self.yubikey.serial()
|
|
);
|
|
let pin = loop {
|
|
message = match callbacks.request_secret(&message)? {
|
|
Ok(pin) => match pin.expose_secret().len() {
|
|
// A PIN must be between 6 and 8 characters.
|
|
6..=8 => break pin,
|
|
// If the string is 44 bytes and starts with the YubiKey's serial
|
|
// encoded as 12-byte modhex, the user probably touched the YubiKey
|
|
// early and "typed" an OTP.
|
|
44 if pin
|
|
.expose_secret()
|
|
.starts_with(&otp_serial_prefix(self.yubikey.serial())) =>
|
|
{
|
|
format!(
|
|
"Did you touch the YubiKey by accident? Enter PIN for YubiKey with serial {}",
|
|
self.yubikey.serial()
|
|
)
|
|
}
|
|
// Otherwise, the PIN is either too short or too long.
|
|
0..=5 => format!(
|
|
"PIN was too short. Enter PIN for YubiKey with serial {}",
|
|
self.yubikey.serial()
|
|
),
|
|
_ => format!(
|
|
"PIN was too long. Enter PIN for YubiKey with serial {}",
|
|
self.yubikey.serial()
|
|
),
|
|
},
|
|
Err(_) => {
|
|
return Ok(Err(identity::Error::Identity {
|
|
index: self.identity_index,
|
|
message: format!(
|
|
"A PIN is required for YubiKey with serial {}",
|
|
self.yubikey.serial()
|
|
),
|
|
}))
|
|
}
|
|
};
|
|
};
|
|
if let Err(e) = self.yubikey.verify_pin(pin.expose_secret().as_bytes()) {
|
|
return Ok(Err(identity::Error::Identity {
|
|
index: self.identity_index,
|
|
message: format!("{:?}", Error::YubiKey(e)),
|
|
}));
|
|
}
|
|
Ok(Ok(()))
|
|
}
|
|
|
|
pub(crate) fn unwrap_file_key<E>(
|
|
&mut self,
|
|
line: &RecipientLine,
|
|
callbacks: &mut dyn Callbacks<E>,
|
|
) -> io::Result<Result<FileKey, ()>> {
|
|
assert_eq!(self.tag, line.tag);
|
|
|
|
// If the touch policy requires it, request a touch.
|
|
let requested_touch = match (
|
|
self.cached_metadata.as_ref().and_then(|m| m.touch_policy),
|
|
self.last_touch,
|
|
) {
|
|
(Some(TouchPolicy::Always), _) | (Some(TouchPolicy::Cached), None) => {
|
|
callbacks.message("👆 Please touch the YubiKey")?.unwrap();
|
|
true
|
|
}
|
|
(Some(TouchPolicy::Cached), Some(last)) if last.elapsed() >= FIFTEEN_SECONDS => {
|
|
callbacks.message("👆 Please touch the YubiKey")?.unwrap();
|
|
true
|
|
}
|
|
_ => false,
|
|
};
|
|
|
|
// The YubiKey API for performing scalar multiplication takes the point in its
|
|
// uncompressed SEC-1 encoding.
|
|
let shared_secret = match decrypt_data(
|
|
&mut self.yubikey,
|
|
line.epk_bytes.decompress().as_bytes(),
|
|
AlgorithmId::EccP256,
|
|
SlotId::Retired(self.slot),
|
|
) {
|
|
Ok(res) => res,
|
|
Err(_) => return Ok(Err(())),
|
|
};
|
|
|
|
// If we requested a touch and reached here, the user touched the YubiKey.
|
|
if requested_touch {
|
|
if let Some(TouchPolicy::Cached) =
|
|
self.cached_metadata.as_ref().and_then(|m| m.touch_policy)
|
|
{
|
|
self.last_touch = Some(Instant::now());
|
|
}
|
|
}
|
|
|
|
let mut salt = vec![];
|
|
salt.extend_from_slice(line.epk_bytes.as_bytes());
|
|
salt.extend_from_slice(self.pk.to_encoded().as_bytes());
|
|
|
|
let enc_key = hkdf(&salt, STANZA_KEY_LABEL, shared_secret.as_ref());
|
|
|
|
// A failure to decrypt is fatal, because we assume that we won't
|
|
// encounter 32-bit collisions on the key tag embedded in the header.
|
|
match aead_decrypt(&enc_key, FILE_KEY_BYTES, &line.encrypted_file_key) {
|
|
Ok(pt) => Ok(Ok(TryInto::<[u8; FILE_KEY_BYTES]>::try_into(&pt[..])
|
|
.unwrap()
|
|
.into())),
|
|
Err(_) => Ok(Err(())),
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod tests {
|
|
use yubikey::{piv::RetiredSlotId, Serial};
|
|
|
|
use super::Stub;
|
|
|
|
#[test]
|
|
fn stub_round_trip() {
|
|
let stub = Stub {
|
|
serial: Serial::from(42),
|
|
slot: RetiredSlotId::R1,
|
|
tag: [7; 4],
|
|
identity_index: 0,
|
|
};
|
|
|
|
let encoded = stub.to_bytes();
|
|
assert_eq!(Stub::from_bytes(&encoded, 0), Some(stub));
|
|
}
|
|
}
|