8d2416a602f2939c99423a2d6b112d04e8c34893
2
Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 jaap-jan
|
8d2416a602 |
Add the encrypted local cache and the sync client
Three new client projects, and the wire-contract fix they needed. DodoSSH.Client.Domain holds the decrypted item model and the three-way merge, with no I/O at all — so the suite that decides whether a credential can be lost runs in milliseconds with nothing to mock. Scalars defer to the server on a genuine clash so every replica resolves the same triple identically and two clients cannot ping-pong; directives merge per name so two people each adding one both keep theirs; the jump chain merges as a whole value because its order is the route. Whatever loses is returned rather than dropped. DodoSSH.Client.Storage is EF Core on SQLite, no SQLCipher: the rows are already ciphertext, so an encrypted file would protect protected bytes at the cost of a native dependency. It keeps the server's state and the outbox in separate tables, which is what preserves the common ancestor a merge needs. One pending operation per item, enforced by a unique index. DodoSSH.Client.Sync is the pull/apply/push loop. Pulling never decrypts — a change with no local work pending is plumbed as ciphertext — so a first sync of thousands of items does not run twice as many AEAD operations for nothing. Contracts: EncryptedPayload gains WrappedDataKey and DataKeyId. The specification has required a per-item data key since crypto.md §3, the columns have existed since the first migration and DshAad.ItemPayload binds the id, but this record had nowhere to put either — so a spec-compliant item could not be transmitted at all. Found by writing the client that has to produce one. Also closes a hole in AadResourceType, which had no value for the HostTag and HostCredential that SyncEntityType has always listed. Four bugs the tests found, not review: - SQLite refuses to order or compare its own DateTimeOffset mapping, and throws at execution rather than model build. Collecting tombstones and listing conflicts are both that shape, so this was a crash waiting for the first user with a deleted host. Timestamps are integers now, by convention so a later field cannot be the one left unconverted. - SQLitePCLRaw 2.1.11, which EF resolves, is covered by GHSA-2m69-gcr7-jv3q. Pinned forward as a family. - Resurrecting content from a remote deletion cleared the original before queueing the copy. Two transactions, so a crash between them lost the work; reversed, and the rescued id is derived from the tombstone so a replay coalesces instead of duplicating. - Several equality assertions went through Shouldly's ShouldBe, which compares IEnumerable element-wise and so tested nothing about the Equals these types exist to provide. Corrected; the falsification that caught it went from 2 failures to 6. The push response's cursor is deliberately ignored. It sits after this client's own writes, so adopting it skips anything another client committed at a lower sequence in the window between a pull and a push — permanently. Re-reading one's own writes is idempotent and costs a page. The Contracts doc that invited the shortcut now says so. 593 tests, up from 448. The delete-versus-edit rules, the ancestor retention, the fresh operation id on coalesce and the cursor safeguard were each verified by breaking them and watching the right test fail. |
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|
jaap-jan
|
e65d738912 |
Add the client key hierarchy: bundle, master key, vault and item keys
Everything crypto.md section 3 describes below the identity key, which is what the desktop client needs before it can enroll or store anything. DshAad gives every descriptor in the specification a named constructor. The AAD binding is the most valuable structural property in the design -- it is what stops a server holding every ciphertext from pasting one row's bytes onto another, rolling a row back to a superseded generation, or replaying a revoked grant -- and all of it depends on callers getting purpose, resource type and ids right at every single call site. Hand-constructing descriptors makes that a matter of care; picking a method name makes it a matter of spelling. UserSecretBundle holds private keys in libsodium's guarded, mlocked allocations rather than a byte[], so they are not paged out and do not land in a core dump. They are created exportable, deliberately: re-wrapping the same bundle for a passphrase change or a new device needs to re-encode it, and the alternative -- a long-lived managed array so the keys need not be exportable -- keeps the identical secret in strictly worse memory. Every export is into a buffer zeroed before the method returns. Two spec changes, both found by implementing it, which is the argument for writing code before calling a spec frozen: - MK is 64 bytes, not 32. Skipping HKDF-Extract is correct for an Argon2id output (RFC 5869 3.3), but it means MK *is* the PRK, and .NET's HKDF.Expand rejects a PRK shorter than the hash output -- so a 32-byte MK cannot be expanded with SHA-512 at all. Widening it keeps the specified primitive; the alternatives were dropping to SHA-256 or adding an Extract step that conditions nothing. - The bundle encoding is a fixed 92-byte layout rather than canonical CBOR. Canonicality is not load-bearing here -- unlike a key statement the bundle is never hashed or signed, only encrypted -- so CBOR's one advantage does not apply, while its canonicalisation rules are a real source of cross-implementation disagreement. It also costs a dependency System.Formats.Cbor is not in the shared framework. Safe to change now and not later: no bundle has ever been stored. 53 new tests. The encoding is checked against an independent codec written in the test rather than by round-tripping production code against itself -- a round trip passes just as happily when both directions are wrong the same way, and this format cannot change after one bundle is stored. The pinned 92-byte hex constant is the golden vector for the layout. Most of the rest are negative, because a binding is only demonstrated by the substitutions that fail: a wrap for another user, a grant from a superseded generation, a payload pasted onto another item, a metadata blob offered as a payload, a version rolled back. |