Refactor & simplify the handling of the packet stream and errors in
packet parsing & grammar validation.
This PR also makes the following observable changes:
- Packet parsing errors in not-yet-authenticated streams (i.e. SEIPDv1
with `allowUnauthenticatedStream: true`) get delayed until the
decrypted data stream is authenticated (i.e. the MDC has been
validated)
- Non-critical unknown packets get turned into `UnparseablePacket`
objects on the packet stream instead of being ignored
- The grammar validation internals are changed to a state machine where
each input packet is only checked once, for efficiency (before, the
entire partial packet sequence was checked for every packet)
Co-authored-by: larabr <larabr+github@protonmail.com>
It enforces a message structure as defined in
https://www.rfc-editor.org/rfc/rfc9580.html#section-10.3
(but slightly more permissive with Padding packets allowed in all cases).
Since we are unclear on whether this change might
impact handling of some messages in the wild, generated by
odd use-cases or non-conformant implementations, we
also add the option to disable the grammar check via
`config.enforceGrammar`.
GrammarErrors are only sensitive in the context of
unauthenticated decrypted streams.
In case of equal creation timestamps, pick the signing/encryption subkey
with the highest algorithm ID, on the assumption that that's the most
modern/secure algorithm.
Reverting commit ccb040ae96acd127a29161ffaf3b82b5b18c062f .
Firefox has fixed support in v132 (https://bugzilla.mozilla.org/show_bug.cgi?id=1918354)
usage of v130 and 131, which have a broken implementation, is now below 1%.
Also, Chrome has released support in v133.
To avoid issues with the lightweight build:
for now it works fine, but it could mess up chunking in the future,
and it already results in a circular import.
The existing md5 module brought in the util module,
which messed up the chunking structure in the lightweight build;
inlining those functions is an option, but the noble-hashes code
is also more modern and readable.
Every submodule under the 'crypto' directory was exported-imported
even if a handful of functions where actually needed.
We now only export entire modules behind default exports if it makes
sense for readability and if the different submodules would be
imported together anyway (e.g. `cipherMode` exports are all needed
by the SEIPD class).
We've also dropped exports that are not used outside of the crypto modules,
e.g. pkcs5 helpers.
This adds back support for decrypting password-protected messages which
were encrypted in OpenPGP.js v5 with custom config settings
`config.aeadProtect = true` together with
`config.preferredAEADAlgorithm = openpgp.enums.aead.experimentalGCM`.
Public-key-encrypted messages are affected if they were encrypted using the same config, while also providing `encryptionKeys` that declared `experimentalGCM` in their AEAD prefs.
Such keys could be generated in OpenPGP.js v5 by setting the aforementioned config values.
`experimentalGCM` should not be used anymore,
as a different a different algorithm ID was standardized
for GCM, and using the experimental value could give
interoperability issues with e.g. SEIPDv2 and AEAD-encrypted keys.
This affects the preferences of newly generated keys, which by default will
have SHA512 as first hash algo preference.
SHA512 will also be used when signing, as long as the recipient keys declare
support for the algorithm.
If given, the signature will be generated using the preferred hash algo from the recipient keys.
Otherwise, the signing key preferences are used (this was also the existing behavior).
Note: when signing through `openpgp.encrypt`, the `encryptionKeys` are automatically used as recipient keys.
In `openpgp.sign`, the signing key preferences are considered instead,
since no "recipient keys" are available.
The hash algo selection logic has been reworked as follows:
if `config.preferredHashAlgo` appears in the prefs of all recipients, we pick it;
otherwise, we use the strongest supported algo (note: SHA256 is always implicitly supported by all keys),
as long as it is compatible with the signing key (e.g. ECC keys require minimum digest sizes).
Previously, only the preferences of the signing key were used to determine the hash algo to use,
but this is in contrast to the RFC: https://www.rfc-editor.org/rfc/rfc9580.html#section-5.2.3.16-2 .
Also, an algo stronger than `config.preferredHashAlgo` would be used, if the signing key
declared it as first preference.
With this change, `config.preferredHashAlgo` is picked even if it's weaker than the
preferences of the recipient keys.
For v3 SKESK and PKESK packets, the session key algorithm is part of the payload,
so we can check the session key size on packet decryption.
This is helpful to catch errors early, when using e.g. `decryptSessionKeys`.
In v6 packets, the session key size check can only be done on SEIPDv2 decryption.
This is especially important for SEIPDv2 session keys,
as a key derivation step is run where the resulting key
will always match the expected cipher size,
but we want to ensure that the input key isn't e.g. too short.
Signature parsing would fail in case of unexpected payload sizes, causing key parsing to always throw
when processing e.g. an (unsupported) Curve448Legacy subkey instead of ignoring it.
To address this, we now throw on signature verification instead of parsing (as done for ECDSA).
NB: the bug and this fix are not relevant for the new Ed25519/Ed448 entities as standardized by the crypto-refresh.
These points do not pose a security threat in the context of OpenPGP ECDH,
and would simply result in an all-zero shared secret being generated.
However, they represent unexpected inputs, so we prefer to warn the user.
Due to missing support in WebKit and Chrome (without experimental flags),
and broken support in Firefox, for now we go back to using a JS implementation.
This change only affects encryption and decryption using X25519.
For signing and verification using Ed25519 we keep relying on
WebCrypto when available (namely in WebKit, Firefox, and Node).
Fixes regression from changes in #1782, as the spec mandates that
legacy x25519 store the secret scalar already clamped.
Keys generated using v6.0.0-beta.3 are still expected to be functional,
since the scalar is to be clamped before computing the ECDH shared secret.
To avoid returning dummy key packets, and improving error reporting.
This new behavior is also better aligned with that of `Key.getSigningKey()`.
This is a breaking change for apps that call `getDecryptionKeys()` directly.
The related error messages returned by `openpgp.decrypt` have also changed,
becoming more specific.
This change is also made in preparation of supporting private keys with
public key packets.
Asm.js has now been deprecated for many years, and no performance gain is
recorded for AES compared to vanilla JS.
The relevant AES fallback code is primarily used if the WebCrypto (resp.
NodeCrypto) implementation is not available.
Stick more closely to the algorithm preferences when creating an SEIPDv2
message, by trying additional combinations of the preferred symmetric algorithm
and the preferred AEAD algorithm. If one of them is supported but not the
other, we still use it (with the mandatory-to-implement algorithm for the other
one).
RFC9580 says that:
Argon2 is only used with AEAD (S2K usage octet 253). An
implementation MUST NOT create and MUST reject as malformed any
secret key packet where the S2K usage octet is not AEAD (253) and
the S2K specifier type is Argon2.
Therefore, we disallow reading and writing Argon2 keys without AEAD.
And:
[The Simple and Salted S2K methods] are used only for reading in
backwards compatibility mode.
Since v6 keys don't need backwards compatibility, we also disallow
reading Simple S2K there. We still allow reading Salted S2K since the
spec says it may be used "when [the password] is high entropy".
Parsing of v5 keys, v5 signatures and AEAD-encrypted data packets now requires turning on
the corresponding config flag.
The affected entities are non-standard, and in the crypto-refresh RFC they have been superseded by
v6 keys, v6 signatures and SEIPDv2 encrypted data, respectively.
However, generation of v5 entities was supported behind config flag in OpenPGP.js v5, and some other libraries,
hence parsing them might be necessary in some cases.
"Hard" revocations (i.e. key compromise, and unknown reasons) apply
at any time, even before the revocation was created.
Co-authored-by: larabr <larabr+github@protonmail.com>
