As specified in openpgp-crypto-refresh-09.
Instead of encoding the symmetric key algorithm in the PKESK ciphertext (requiring padding),
the symmetric key algorithm is left unencrypted.
Co-authored-by: Lukas Burkhalter <lukas.burkhalter@proton.ch>
The changes do not affect the public API:
`RandomBuffer` was used internally for secure randomness generation before
`crypto.getRandomValues` was made available to WebWorkers, requiring
generating randomness in the main thread.
As a result of the change, the internal `getRandomBytes()` and some functions
that use it are no longer async.
The relevant packets will be considered unsupported instead of malformed.
Hence, parsing them will succeed by default (based on
`config.ignoreUnsupportedPackets`).
Implement optional constant-time decryption flow to hinder Bleichenbacher-like
attacks against RSA- and ElGamal public-key encrypted session keys.
Changes:
- Add `config.constantTimePKCS1Decryption` to enable the constant-time
processing (defaults to `false`). The constant-time option is off by default
since it has measurable performance impact on message decryption, and it is
only helpful in specific application scenarios (more info below).
- Add `config.constantTimePKCS1DecryptionSupportedSymmetricAlgorithms`
(defaults to the AES algorithms). The set of supported ciphers is restricted by
default since the number of algorithms negatively affects performance.
Bleichenbacher-like attacks are of concern for applications where both of the
following conditions are met:
1. new/incoming messages are automatically decrypted (without user
interaction);
2. an attacker can determine how long it takes to decrypt each message (e.g.
due to decryption errors being logged remotely).
In several packet classes, we used to store string identifiers for public-key,
aead, cipher or hash algorithms. To make the code consistent and to avoid
having to convert to/from string values, we now always store integer values
instead, e.g. `enums.symmetric.aes128` is used instead of `'aes128'`.
This is not expected to be a breaking change for most library users. Note that
the type of `Key.getAlgorithmInfo()` and of the session key objects returned
and accepted by top-level functions remain unchanged.
Affected classes (type changes for some properties and method's arguments):
- `PublicKeyPacket`, `PublicSubkeyPacket`, `SecretKeyPacket`,
`SecretSubkeyPacket`
- `SymEncryptedIntegrityProtectedDataPacket`, `AEADEncryptedDataPacket`,
`SymmetricallyEncryptedDataPacket`
- `LiteralDataPacket`, `CompressedDataPacket`
- `PublicKeyEncryptedSessionKey`, `SymEncryptedSessionKeyPacket`
- `SignaturePacket`
Other potentially breaking changes:
- Removed property `AEADEncryptedDataPacket.aeadAlgo`, since it was redudant
given `.aeadAlgorithm`.
- Renamed `AEADEncryptedDataPacket.cipherAlgo` -> `.cipherAlgorithm`
- Use PascalCase for classes, with uppercase acronyms.
- Use camelCase for function and variables. First word/acronym is always
lowercase, otherwise acronyms are uppercase.
Also, make the packet classes' `tag` properties `static`.
Change session key parameter handling to mirror key parameters.
Parameters are stored as an object rather than an array. MPIs are
always stored as Uint8Arrays.
- Store private and public params separately and by name in objects,
instead of as an array
- Do not keep params in MPI form, but convert them to Uint8Arrays when
generating/parsing the key
- Modify low-level crypto functions to always accept and return
Uint8Arrays instead of BigIntegers
- Move PKCS1 padding to lower level functions
In the lightweight build, lazily load bn.js only when necessary.
Also, use Uint8Arrays instead of strings in PKCS1 padding functions, and
check that the leading zero is present when decoding EME-PKCS1 padding.
Also, when generating RSA keys in JS, generate them with p < q, as per
the spec.
Also, when generating RSA keys using Web Crypto or Node crypto, swap the
generated p and q around, so that will satisfy p < q in most browsers
(but not old Microsoft Edge, 50% of the time) and so that we can use the
generated u coefficient (p^-1 mod q in OpenPGP, q^-1 mod p in RFC3447).
Then, when signing and verifying, swap p and q again, so that the key
hopefully satisfies Safari's requirement that p > q, and so that we can
keep using u again.
So that uses of CFB other than sym_encrypted_integrity_protected.js
can benefit from them.
Also, implement CFB resync mode in terms of normal CFB rather than
separately (and duplicated).
So that uses of CFB other than sym_encrypted_integrity_protected.js
can benefit from them.
Also, implement CFB resync mode in terms of normal CFB rather than
separately (and duplicated).
