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577 lines
18 KiB
Rust
577 lines
18 KiB
Rust
//! OpenPGP helper module using [rPGP facilities](https://github.com/rpgp/rpgp)
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use std::collections::{BTreeMap, HashSet};
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use std::convert::TryInto;
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use std::io;
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use std::io::Cursor;
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use pgp::armor::BlockType;
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use pgp::composed::{
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Deserializable, KeyType as PgpKeyType, Message, SecretKeyParamsBuilder, SignedPublicKey,
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SignedPublicSubKey, SignedSecretKey, SubkeyParamsBuilder,
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};
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use pgp::crypto::{HashAlgorithm, SymmetricKeyAlgorithm};
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use pgp::types::{
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CompressionAlgorithm, KeyTrait, Mpi, PublicKeyTrait, SecretKeyTrait, StringToKey,
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};
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use rand::{thread_rng, CryptoRng, Rng};
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use crate::constants::KeyGenType;
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use crate::dc_tools::EmailAddress;
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use crate::error::Result;
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use crate::key::*;
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use crate::keyring::*;
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pub const HEADER_AUTOCRYPT: &str = "autocrypt-prefer-encrypt";
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pub const HEADER_SETUPCODE: &str = "passphrase-begin";
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/// A wrapper for rPGP public key types
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#[derive(Debug)]
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enum SignedPublicKeyOrSubkey<'a> {
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Key(&'a SignedPublicKey),
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Subkey(&'a SignedPublicSubKey),
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}
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impl<'a> KeyTrait for SignedPublicKeyOrSubkey<'a> {
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fn fingerprint(&self) -> Vec<u8> {
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match self {
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Self::Key(k) => k.fingerprint(),
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Self::Subkey(k) => k.fingerprint(),
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}
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}
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fn key_id(&self) -> pgp::types::KeyId {
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match self {
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Self::Key(k) => k.key_id(),
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Self::Subkey(k) => k.key_id(),
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}
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}
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fn algorithm(&self) -> pgp::crypto::PublicKeyAlgorithm {
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match self {
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Self::Key(k) => k.algorithm(),
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Self::Subkey(k) => k.algorithm(),
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}
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}
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}
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impl<'a> PublicKeyTrait for SignedPublicKeyOrSubkey<'a> {
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fn verify_signature(
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&self,
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hash: HashAlgorithm,
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data: &[u8],
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sig: &[Mpi],
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) -> pgp::errors::Result<()> {
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match self {
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Self::Key(k) => k.verify_signature(hash, data, sig),
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Self::Subkey(k) => k.verify_signature(hash, data, sig),
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}
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}
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fn encrypt<R: Rng + CryptoRng>(
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&self,
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rng: &mut R,
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plain: &[u8],
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) -> pgp::errors::Result<Vec<Mpi>> {
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match self {
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Self::Key(k) => k.encrypt(rng, plain),
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Self::Subkey(k) => k.encrypt(rng, plain),
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}
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}
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fn to_writer_old(&self, writer: &mut impl io::Write) -> pgp::errors::Result<()> {
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match self {
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Self::Key(k) => k.to_writer_old(writer),
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Self::Subkey(k) => k.to_writer_old(writer),
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}
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}
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}
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/// Split data from PGP Armored Data as defined in https://tools.ietf.org/html/rfc4880#section-6.2.
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///
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/// Returns (type, headers, base64 encoded body).
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pub fn split_armored_data(buf: &[u8]) -> Result<(BlockType, BTreeMap<String, String>, Vec<u8>)> {
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use std::io::Read;
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let cursor = Cursor::new(buf);
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let mut dearmor = pgp::armor::Dearmor::new(cursor);
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let mut bytes = Vec::with_capacity(buf.len());
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dearmor.read_to_end(&mut bytes)?;
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ensure!(dearmor.typ.is_some(), "Failed to parse type");
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let typ = dearmor.typ.unwrap();
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// normalize headers
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let headers = dearmor
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.headers
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.into_iter()
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.map(|(key, value)| (key.trim().to_lowercase(), value.trim().to_string()))
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.collect();
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Ok((typ, headers, bytes))
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}
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/// Error with generating a PGP keypair.
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///
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/// Most of these are likely coding errors rather than user errors
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/// since all variability is hardcoded.
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#[derive(Fail, Debug)]
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#[fail(display = "PgpKeygenError: {}", message)]
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pub(crate) struct PgpKeygenError {
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message: String,
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#[cause]
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cause: failure::Error,
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backtrace: failure::Backtrace,
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}
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impl PgpKeygenError {
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fn new(message: impl Into<String>, cause: impl Into<failure::Error>) -> Self {
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Self {
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message: message.into(),
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cause: cause.into(),
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backtrace: failure::Backtrace::new(),
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}
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}
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}
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/// A PGP keypair.
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///
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/// This has it's own struct to be able to keep the public and secret
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/// keys together as they are one unit.
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#[derive(Debug, Clone, Eq, PartialEq)]
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pub struct KeyPair {
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pub addr: EmailAddress,
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pub public: SignedPublicKey,
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pub secret: SignedSecretKey,
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}
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/// Create a new key pair.
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pub(crate) fn create_keypair(
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addr: EmailAddress,
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keygen_type: KeyGenType,
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) -> std::result::Result<KeyPair, PgpKeygenError> {
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let (secret_key_type, public_key_type) = match keygen_type {
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KeyGenType::Rsa2048 => (PgpKeyType::Rsa(2048), PgpKeyType::Rsa(2048)),
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KeyGenType::Ed25519 | KeyGenType::Default => (PgpKeyType::EdDSA, PgpKeyType::ECDH),
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};
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let user_id = format!("<{}>", addr);
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let key_params = SecretKeyParamsBuilder::default()
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.key_type(secret_key_type)
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.can_create_certificates(true)
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.can_sign(true)
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.primary_user_id(user_id)
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.passphrase(None)
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.preferred_symmetric_algorithms(smallvec![
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SymmetricKeyAlgorithm::AES256,
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SymmetricKeyAlgorithm::AES192,
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SymmetricKeyAlgorithm::AES128,
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])
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.preferred_hash_algorithms(smallvec![
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HashAlgorithm::SHA2_256,
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HashAlgorithm::SHA2_384,
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HashAlgorithm::SHA2_512,
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HashAlgorithm::SHA2_224,
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HashAlgorithm::SHA1,
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])
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.preferred_compression_algorithms(smallvec![
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CompressionAlgorithm::ZLIB,
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CompressionAlgorithm::ZIP,
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])
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.subkey(
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SubkeyParamsBuilder::default()
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.key_type(public_key_type)
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.can_encrypt(true)
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.passphrase(None)
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.build()
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.unwrap(),
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)
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.build()
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.map_err(|err| PgpKeygenError::new("invalid key params", failure::err_msg(err)))?;
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let key = key_params
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.generate()
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.map_err(|err| PgpKeygenError::new("invalid params", err))?;
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let private_key = key.sign(|| "".into()).expect("failed to sign secret key");
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let public_key = private_key.public_key();
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let public_key = public_key
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.sign(&private_key, || "".into())
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.map_err(|err| PgpKeygenError::new("failed to sign public key", err))?;
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private_key
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.verify()
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.map_err(|err| PgpKeygenError::new("invalid private key generated", err))?;
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public_key
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.verify()
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.map_err(|err| PgpKeygenError::new("invalid public key generated", err))?;
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Ok(KeyPair {
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addr,
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public: public_key,
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secret: private_key,
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})
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}
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/// Select public key or subkey to use for encryption.
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///
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/// First, tries to use subkeys. If none of the subkeys are suitable
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/// for encryption, tries to use primary key. Returns `None` if the public
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/// key cannot be used for encryption.
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///
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/// TODO: take key flags and expiration dates into account
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fn select_pk_for_encryption(key: &SignedPublicKey) -> Option<SignedPublicKeyOrSubkey> {
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key.public_subkeys
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.iter()
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.find(|subkey| subkey.is_encryption_key())
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.map_or_else(
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|| {
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// No usable subkey found, try primary key
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if key.is_encryption_key() {
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Some(SignedPublicKeyOrSubkey::Key(key))
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} else {
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None
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}
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},
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|subkey| Some(SignedPublicKeyOrSubkey::Subkey(subkey)),
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)
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}
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/// Encrypts `plain` text using `public_keys_for_encryption`
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/// and signs it using `private_key_for_signing`.
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pub fn pk_encrypt(
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plain: &[u8],
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public_keys_for_encryption: &Keyring,
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private_key_for_signing: Option<&Key>,
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) -> Result<String> {
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let lit_msg = Message::new_literal_bytes("", plain);
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let pkeys: Vec<SignedPublicKeyOrSubkey> = public_keys_for_encryption
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.keys()
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.iter()
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.filter_map(|key| {
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key.as_ref()
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.try_into()
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.ok()
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.and_then(select_pk_for_encryption)
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})
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.collect();
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let pkeys_refs: Vec<&SignedPublicKeyOrSubkey> = pkeys.iter().collect();
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let mut rng = thread_rng();
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// TODO: measure time
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let encrypted_msg = if let Some(private_key) = private_key_for_signing {
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let skey: &SignedSecretKey = private_key
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.try_into()
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.map_err(|_| format_err!("Invalid private key"))?;
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lit_msg
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.sign(skey, || "".into(), Default::default())
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.and_then(|msg| msg.compress(CompressionAlgorithm::ZLIB))
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.and_then(|msg| msg.encrypt_to_keys(&mut rng, Default::default(), &pkeys_refs))
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} else {
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lit_msg.encrypt_to_keys(&mut rng, Default::default(), &pkeys_refs)
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};
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let msg = encrypted_msg?;
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let encoded_msg = msg.to_armored_string(None)?;
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Ok(encoded_msg)
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}
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#[allow(clippy::implicit_hasher)]
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pub fn pk_decrypt(
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ctext: &[u8],
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private_keys_for_decryption: &Keyring,
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public_keys_for_validation: &Keyring,
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ret_signature_fingerprints: Option<&mut HashSet<String>>,
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) -> Result<Vec<u8>> {
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let (msg, _) = Message::from_armor_single(Cursor::new(ctext))?;
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let skeys: Vec<&SignedSecretKey> = private_keys_for_decryption
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.keys()
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.iter()
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.filter_map(|key| {
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let k: &Key = &key;
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k.try_into().ok()
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})
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.collect();
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let (decryptor, _) = msg.decrypt(|| "".into(), || "".into(), &skeys[..])?;
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let msgs = decryptor.collect::<pgp::errors::Result<Vec<_>>>()?;
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ensure!(!msgs.is_empty(), "No valid messages found");
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let dec_msg = &msgs[0];
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if let Some(ret_signature_fingerprints) = ret_signature_fingerprints {
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if !public_keys_for_validation.keys().is_empty() {
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let pkeys: Vec<&SignedPublicKey> = public_keys_for_validation
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.keys()
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.iter()
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.filter_map(|key| {
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let k: &Key = &key;
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k.try_into().ok()
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})
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.collect();
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for pkey in &pkeys {
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if dec_msg.verify(&pkey.primary_key).is_ok() {
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let fp = hex::encode_upper(pkey.fingerprint());
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ret_signature_fingerprints.insert(fp);
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}
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}
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}
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}
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match dec_msg.get_content()? {
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Some(content) => Ok(content),
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None => bail!("Decrypted message is empty"),
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}
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}
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/// Symmetric encryption.
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pub fn symm_encrypt(passphrase: &str, plain: &[u8]) -> Result<String> {
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let mut rng = thread_rng();
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let lit_msg = Message::new_literal_bytes("", plain);
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let s2k = StringToKey::new_default(&mut rng);
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let msg =
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lit_msg.encrypt_with_password(&mut rng, s2k, Default::default(), || passphrase.into())?;
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let encoded_msg = msg.to_armored_string(None)?;
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Ok(encoded_msg)
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}
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/// Symmetric decryption.
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pub fn symm_decrypt<T: std::io::Read + std::io::Seek>(
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passphrase: &str,
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ctext: T,
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) -> Result<Vec<u8>> {
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let (enc_msg, _) = Message::from_armor_single(ctext)?;
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let decryptor = enc_msg.decrypt_with_password(|| passphrase.into())?;
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let msgs = decryptor.collect::<pgp::errors::Result<Vec<_>>>()?;
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ensure!(!msgs.is_empty(), "No valid messages found");
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match msgs[0].get_content()? {
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Some(content) => Ok(content),
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None => bail!("Decrypted message is empty"),
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use crate::test_utils::*;
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use lazy_static::lazy_static;
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#[test]
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fn test_split_armored_data_1() {
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let (typ, _headers, base64) = split_armored_data(
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b"-----BEGIN PGP MESSAGE-----\nNoVal:\n\naGVsbG8gd29ybGQ=\n-----END PGP MESSAGE----",
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)
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.unwrap();
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assert_eq!(typ, BlockType::Message);
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assert!(!base64.is_empty());
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assert_eq!(
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std::string::String::from_utf8(base64).unwrap(),
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"hello world"
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);
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}
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#[test]
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fn test_split_armored_data_2() {
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let (typ, headers, base64) = split_armored_data(
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b"-----BEGIN PGP PRIVATE KEY BLOCK-----\nAutocrypt-Prefer-Encrypt: mutual \n\naGVsbG8gd29ybGQ=\n-----END PGP PRIVATE KEY BLOCK-----"
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)
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.unwrap();
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assert_eq!(typ, BlockType::PrivateKey);
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assert!(!base64.is_empty());
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assert_eq!(headers.get(HEADER_AUTOCRYPT), Some(&"mutual".to_string()));
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}
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#[test]
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#[ignore] // is too expensive
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fn test_create_keypair() {
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let keypair0 = create_keypair(
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EmailAddress::new("foo@bar.de").unwrap(),
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KeyGenType::Default,
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)
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.unwrap();
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let keypair1 = create_keypair(
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EmailAddress::new("two@zwo.de").unwrap(),
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KeyGenType::Default,
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)
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.unwrap();
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assert_ne!(keypair0.public, keypair1.public);
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}
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/// [Key] objects to use in tests.
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struct TestKeys {
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alice_secret: Key,
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alice_public: Key,
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bob_secret: Key,
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bob_public: Key,
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}
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impl TestKeys {
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fn new() -> TestKeys {
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let alice = alice_keypair();
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let bob = bob_keypair();
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TestKeys {
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alice_secret: Key::from(alice.secret.clone()),
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alice_public: Key::from(alice.public.clone()),
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bob_secret: Key::from(bob.secret.clone()),
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bob_public: Key::from(bob.public.clone()),
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}
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}
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}
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/// The original text of [CTEXT_SIGNED]
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static CLEARTEXT: &[u8] = b"This is a test";
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lazy_static! {
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/// Initialised [TestKeys] for tests.
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static ref KEYS: TestKeys = TestKeys::new();
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/// A cyphertext encrypted to Alice & Bob, signed by Alice.
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static ref CTEXT_SIGNED: String = {
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let mut keyring = Keyring::default();
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keyring.add_owned(KEYS.alice_public.clone());
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keyring.add_ref(&KEYS.bob_public);
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pk_encrypt(CLEARTEXT, &keyring, Some(&KEYS.alice_secret)).unwrap()
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};
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/// A cyphertext encrypted to Alice & Bob, not signed.
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static ref CTEXT_UNSIGNED: String = {
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let mut keyring = Keyring::default();
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keyring.add_owned(KEYS.alice_public.clone());
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keyring.add_ref(&KEYS.bob_public);
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pk_encrypt(CLEARTEXT, &keyring, None).unwrap()
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};
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}
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#[test]
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fn test_encrypt_signed() {
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assert!(!CTEXT_SIGNED.is_empty());
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assert!(CTEXT_SIGNED.starts_with("-----BEGIN PGP MESSAGE-----"));
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}
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#[test]
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fn test_encrypt_unsigned() {
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assert!(!CTEXT_UNSIGNED.is_empty());
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assert!(CTEXT_UNSIGNED.starts_with("-----BEGIN PGP MESSAGE-----"));
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}
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#[test]
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fn test_decrypt_singed() {
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// Check decrypting as Alice
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let mut decrypt_keyring = Keyring::default();
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decrypt_keyring.add_ref(&KEYS.alice_secret);
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let mut sig_check_keyring = Keyring::default();
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sig_check_keyring.add_ref(&KEYS.alice_public);
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let mut valid_signatures: HashSet<String> = Default::default();
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let plain = pk_decrypt(
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CTEXT_SIGNED.as_bytes(),
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&decrypt_keyring,
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&sig_check_keyring,
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Some(&mut valid_signatures),
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)
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.map_err(|err| println!("{:?}", err))
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.unwrap();
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assert_eq!(plain, CLEARTEXT);
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assert_eq!(valid_signatures.len(), 1);
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// Check decrypting as Bob
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let mut decrypt_keyring = Keyring::default();
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decrypt_keyring.add_ref(&KEYS.bob_secret);
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let mut sig_check_keyring = Keyring::default();
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sig_check_keyring.add_ref(&KEYS.alice_public);
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let mut valid_signatures: HashSet<String> = Default::default();
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let plain = pk_decrypt(
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CTEXT_SIGNED.as_bytes(),
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&decrypt_keyring,
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||
&sig_check_keyring,
|
||
Some(&mut valid_signatures),
|
||
)
|
||
.map_err(|err| println!("{:?}", err))
|
||
.unwrap();
|
||
assert_eq!(plain, CLEARTEXT);
|
||
assert_eq!(valid_signatures.len(), 1);
|
||
}
|
||
|
||
#[test]
|
||
fn test_decrypt_no_sig_check() {
|
||
let mut keyring = Keyring::default();
|
||
keyring.add_ref(&KEYS.alice_secret);
|
||
let empty_keyring = Keyring::default();
|
||
let mut valid_signatures: HashSet<String> = Default::default();
|
||
let plain = pk_decrypt(
|
||
CTEXT_SIGNED.as_bytes(),
|
||
&keyring,
|
||
&empty_keyring,
|
||
Some(&mut valid_signatures),
|
||
)
|
||
.unwrap();
|
||
assert_eq!(plain, CLEARTEXT);
|
||
assert_eq!(valid_signatures.len(), 0);
|
||
}
|
||
|
||
#[test]
|
||
fn test_decrypt_signed_no_key() {
|
||
// The validation does not have the public key of the signer.
|
||
let mut decrypt_keyring = Keyring::default();
|
||
decrypt_keyring.add_ref(&KEYS.bob_secret);
|
||
let mut sig_check_keyring = Keyring::default();
|
||
sig_check_keyring.add_ref(&KEYS.bob_public);
|
||
let mut valid_signatures: HashSet<String> = Default::default();
|
||
let plain = pk_decrypt(
|
||
CTEXT_SIGNED.as_bytes(),
|
||
&decrypt_keyring,
|
||
&sig_check_keyring,
|
||
Some(&mut valid_signatures),
|
||
)
|
||
.unwrap();
|
||
assert_eq!(plain, CLEARTEXT);
|
||
assert_eq!(valid_signatures.len(), 0);
|
||
}
|
||
|
||
#[test]
|
||
fn test_decrypt_unsigned() {
|
||
let mut decrypt_keyring = Keyring::default();
|
||
decrypt_keyring.add_ref(&KEYS.bob_secret);
|
||
let sig_check_keyring = Keyring::default();
|
||
decrypt_keyring.add_ref(&KEYS.alice_public);
|
||
let mut valid_signatures: HashSet<String> = Default::default();
|
||
let plain = pk_decrypt(
|
||
CTEXT_UNSIGNED.as_bytes(),
|
||
&decrypt_keyring,
|
||
&sig_check_keyring,
|
||
Some(&mut valid_signatures),
|
||
)
|
||
.unwrap();
|
||
assert_eq!(plain, CLEARTEXT);
|
||
assert_eq!(valid_signatures.len(), 0);
|
||
}
|
||
|
||
#[test]
|
||
fn test_decrypt_signed_no_sigret() {
|
||
// Check decrypting signed cyphertext without providing the HashSet for signatures.
|
||
let mut decrypt_keyring = Keyring::default();
|
||
decrypt_keyring.add_ref(&KEYS.bob_secret);
|
||
let mut sig_check_keyring = Keyring::default();
|
||
sig_check_keyring.add_ref(&KEYS.alice_public);
|
||
let plain = pk_decrypt(
|
||
CTEXT_SIGNED.as_bytes(),
|
||
&decrypt_keyring,
|
||
&sig_check_keyring,
|
||
None,
|
||
)
|
||
.unwrap();
|
||
assert_eq!(plain, CLEARTEXT);
|
||
}
|
||
}
|