Public Access
Free the terminal from the Hosts screen, and fill the room it left
The WebView sat inside the Hosts grid, so navigating to Files or the keychain hid every open terminal and the strip that named them. A connection you had opened was invisible from four of the five screens. The window now has two surfaces rather than one: a nav rail that says which page you are on, and a terminal strip that is always there and switches the whole content area to a shell. Screen keeps meaning "which page" and never becomes a sixth kind of page, which is why this is two properties instead of one enum with a terminal member in it. Every screen lives inside one wrapper panel that collapses when a terminal is showing. That is not tidiness — the WebView hosts a Win32 child window that composites above everything Avalonia draws, so a screen left visible over its rectangle is a screen sliced in half, and this window has shipped that defect once already. One decision point, IsTerminalShowing, and a nested panel rather than five compound bindings nobody would remember to extend. The focus choreography is the part no test in this repo can see. Every reveal path now focuses in the same turn the WebView appeared, so all three of them post at DispatcherPriority.Loaded and let the native control re-push its bounds first. Going the other way had a real bug: the screen-changed branch called a bare Focus() where it had to release the keyboard from the native child, so switching from a terminal to Files silently ate the first keystrokes. Rare before this commit and the primary gesture after it. The tab strip grew a cross inside each tab, a plus that opens the quick-connect palette, and middle-click close. Nested buttons are correct here: Avalonia handles a left press on the cross and deliberately does not handle other buttons, which is exactly what lets middle-click bubble up from the cross as well as the tab. The test is PointerUpdateKind rather than IsMiddleButtonPressed, because the latter reports button state and is also true for a left press made while the middle button happens to be held. The handler is on the tab and not the strip, so the background closes nothing by construction. Plus opens the palette rather than a flyout, since a menu dropping into the WebView's rectangle may or may not composite above a child HWND and this repo does not make rendering claims it has not photographed. Everything a user reads now says keychain. The wire, the database and the cryptographic spec still say vault, deliberately: renaming those is a migration and a protocol change for a word. That split is written down rather than left to be rediscovered as an inconsistency. Four things that were squeezed into the keychain's category rail, or into nothing at all, now have screens. Pinned host keys get one, with fingerprints never truncated and a filter that matches them, because comparing what you have against what the operator published is the whole workflow; the approved date is read out of the item's UUIDv7 rather than added as a column, and says so, since it means first approval and not last use. Keys can be generated in the client, which needed the openssh-key-v1 container written by hand — there is no BCL or NSec helper, and the PKCS#8 route is unverified in the SSH library this uses. The armour carries no passphrase: encrypting it needs bcrypt_pbkdf, which is Blowfish with a swizzle, in a project whose crypto is otherwise entirely libsodium, for a protection the key's own remarks argue is redundant inside a vault. Generation fills the existing editor and stops, so SAVE stays the one thing that writes. ~/.ssh/config can be imported behind a preview that is ticked per row and writes nothing until the button; IdentityFile records the path and imports the key material only on an explicit opt-in, because reading somebody's private key into a vault is precisely the act this product exists to make deliberate. Match blocks and ProxyJump are reported rather than obeyed — one cannot be evaluated statically and the other has nothing behind it to route with, and a preview that implied otherwise would be worse than one that admits it. Files can be dragged in all four directions that are honestly available. Remote to Explorer does not ship and is not pretended to: the shell wants the bytes during the drop, which needs a virtual file and a native COM data object, outside what Avalonia offers. Note for the next person that Avalonia 12 replaced the drag model outright — DataObject and DataFormats are no-op stubs and IDataObject is not in the reference assembly, so every tutorial written for 11 does not compile here. Hosts can be grouped, flat and never nested. A parent id merged as a scalar lets two offline clients each re-parent A under B and B under A, producing a cycle inside an encrypted payload that no server can police and every reader would have to detect for ever. Membership lives in that payload rather than in the one plaintext concession ADR 0001 allows, whose test is that the relay cannot function without it — nothing on the server reads a group, so what plaintext would hand over is a clustering of the estate for nothing. The plaintext column reserved for it is dropped, provably always null, and the server now refuses a client that sends one; it was never populated, was copied on apply, and was not cleared on delete, so a group id would have outlived the host it described. Snippets insert through xterm rather than through the pump, because xterm is the only thing that knows whether the remote has bracketed paste on, and that is what makes a shell treat embedded newlines as text instead of as execute. The host process moves opaque bytes and never parses output, so it would have to guess, and guessing wrong runs every line. Running is off by default and the copy says the text goes into whatever is there — the terminal has no notion of being at a prompt, and may be in vi or at a password prompt with echo off, so the Enter the user presses themselves is the entire safety property. Connections and keychain changes are recorded as synced encrypted items, which is what makes them auditable by a team later and costs the server knowledge of connection rate and timing from row counts alone. ADR 0001 already concedes it cannot hide that class of metadata; the trade is now written into it rather than left implicit. A connection entry is written once, at close, which is what makes a synced log tractable: nothing to merge, one outbox row, no chance of colliding with itself. Live sessions come from memory, not from the log. The write is void by contract and posts to a bounded channel, because putting an encrypt-and-write on the teardown path of every session is how closing the application comes to take four seconds. A ticket opened before a lock still closes afterwards, since a shell outlives the vault. The activity log hooks the one generic repository every kind writes through, so it cannot miss a caller — which is also why the log kinds themselves declare they are not audited, or the first entry would write an entry about writing an entry. It records the names of the fields that changed and never their values; a log with an old password in it would be a plaintext credential store with no vault around it. Retention is 90 days or 5,000 entries, whichever bites first, pruned on the sync loop rather than on a second timer. That log traffic then broke the status line, which is worth recording because the fix is a shape and not a patch: background sync counted its own log rows as pushed items, so the quiet rule stopped being quiet and every action's message was overwritten a second later by a sync report. The report now separates log rows from user items and the rule reads the latter. S3 buckets appear as a remote in the file browser, behind the same interface an SFTP session implements, so the queue and both panes did not have to learn what they are talking to. Uploads go through a pipe, because the queue wants to write and the SDK wants to read; memory is then bounded by the part size instead of buffering a file to disk twice. Finally, the Windows device key store moved out of the session project, which was the one thing keeping it from being portable — everything else in it is platform-neutral, and a Windows CNG dependency in the middle of the vault code meant a second head could not reference it without dragging Windows along. The seam that made the move free was already there. docs/android-port.md is the audit behind that: what ports, what does not, in order of cost, the four decisions taken, and an inventory of every screen and state the interface has to carry, written so a design can be made from it directly. dotnet build, dotnet test and dotnet format --verify-no-changes are all clean: 1240 tests at zero warnings, including the end-to-end suite against real containers. The manual checks that headless Avalonia cannot make — the drag from Explorer, a generated key against a real host, twelve tabs at the minimum window width — are listed in docs/manual-checks.md and are still outstanding.
This commit is contained in:
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using System.Runtime.Versioning;
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using System.Security.Cryptography;
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using DodoSSH.Client.Session;
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namespace DodoSSH.Client.App.Platform;
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/// <summary>
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/// Picks the device key store this desktop machine can actually offer.
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/// </summary>
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/// <remarks>
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/// <para>
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/// One place decides, so nothing above has to carry a platform guard. A machine with no TPM, or one that
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/// is not Windows, gets <see cref="UnavailableDeviceKeyStore"/> and therefore keeps asking for the
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/// passphrase — which is the honest answer rather than a degraded one.
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/// </para>
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/// <para>
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/// <b>"Desktop", because the choice belongs to a head rather than to the session layer.</b> This file used
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/// to live in <c>DodoSSH.Client.Session</c>, which was the one thing keeping that project from being
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/// portable: everything else in it is platform-neutral, and a Windows CNG dependency in the middle of the
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/// vault code meant a second head could not reference it without dragging Windows along. The seam that
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/// makes the move free is <see cref="IDeviceKeyStore"/>, which was already there — the session takes a
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/// store and has never known which one. See <c>docs/android-port.md</c>.
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/// </para>
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/// </remarks>
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public static class DesktopDeviceKeyStores
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{
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/// <summary>The best store this machine supports.</summary>
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public static IDeviceKeyStore ForThisMachine(ClientPaths paths)
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{
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ArgumentNullException.ThrowIfNull(paths);
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return OperatingSystem.IsWindows() && WindowsDeviceKeyStore.IsSupported()
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? new WindowsDeviceKeyStore(paths)
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: new UnavailableDeviceKeyStore();
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}
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}
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/// <summary>
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/// Keeps the device key encrypted to a TPM-resident key whose use requires the user's consent.
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/// </summary>
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/// <remarks>
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/// <para>
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/// <b>The consent is enforced by CNG, not by this class</b>, and that distinction is the entire security
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/// value. A store that read a DPAPI blob after showing its own prompt would be trivially bypassed:
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/// malware running as the user would skip the prompt, read the file and call
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/// <c>CryptUnprotectData</c> itself. Here the unwrapping key lives in the TPM under
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/// <see cref="CngUIProtectionLevels.ProtectKey"/>, so the Windows consent dialog is a condition of
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/// <em>using</em> the key. Malware can ask; it cannot answer, and the attempt is visible.
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/// </para>
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/// <para>
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/// This is a refinement of what ADR 0007 describes, and stronger than it: the ADR reasoned about a
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/// gesture gating a protected blob and did not notice that a gate inside the process is not a gate. The
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/// mechanism recorded there has been corrected to match this.
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/// </para>
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/// <para>
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/// The TPM key is RSA rather than the ECDH one might expect, because it is used to encrypt 32 bytes and
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/// nothing else. OAEP over a 2048-bit key carries 190, so there is no need for an agreement step, and no
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/// need for the device key itself to be an algorithm the TPM understands — which is what keeps the DSH1
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/// device wrap unchanged at X25519. See ADR 0007 for why changing that is a separate decision.
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/// </para>
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/// <para>
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/// <b>Both ends prompt, and that was measured rather than assumed.</b> Encrypting uses only the public
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/// half, so it was reasonable to expect sealing to be silent — it is not. <c>CngKey.Create</c> with this
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/// UI policy blocks on a dialog at <em>creation</em>, because <c>ProtectKey</c> means "protect this key
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/// with a PIN", and Windows asks the user to set that up there and then. So registering a device shows one
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/// setup dialog and every unlock shows a consent dialog.
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/// </para>
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/// <para>
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/// That is the right shape for an opt-in feature, but it has two consequences worth knowing before
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/// touching this file. Every method except <see cref="IsSupported"/> and the empty case of
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/// <see cref="TryLoadAsync"/> needs an interactive desktop, so <b>none of them can be exercised by an
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/// automated test</b> — see <c>WindowsDeviceKeyStoreTests</c> for where that line falls. And a caller must
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/// treat <see cref="SaveAsync"/> as user-facing: it belongs on a UI thread, behind a button somebody
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/// pressed, never on a background pass.
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/// </para>
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/// </remarks>
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[SupportedOSPlatform("windows")]
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public sealed class WindowsDeviceKeyStore : IDeviceKeyStore
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{
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/// <remarks>
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/// Versioned, so a future change of algorithm or padding can create a new key beside the old one
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/// rather than failing to open blobs written by a previous build. A device that cannot be opened
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/// falls back to the passphrase, which is survivable — but silently, and a user would only notice
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/// their gesture had stopped working.
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/// </remarks>
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private const string KeyName = "DodoSSH.DeviceKey.v1";
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private const string PlatformProvider = "Microsoft Platform Crypto Provider";
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/// <remarks>Shown in the Windows consent dialog, so it has to read as a sentence to a person.</remarks>
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private const string ConsentPrompt = "Unlock your DodoSSH vault";
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private readonly ClientPaths paths;
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/// <summary>Creates the store.</summary>
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public WindowsDeviceKeyStore(ClientPaths paths)
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{
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ArgumentNullException.ThrowIfNull(paths);
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this.paths = paths;
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}
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/// <summary>
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/// Whether this machine has a TPM the platform provider will hold a key in.
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/// </summary>
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/// <remarks>
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/// Probed by creating a throwaway key and deleting it, rather than by asking the provider whether it
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/// exists. The provider is registered on machines with no usable TPM as well, and reports itself
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/// present right up to the point where creating a key fails — so the only honest test is the one that
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/// does the thing. No UI policy on the probe, so nothing prompts.
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/// </remarks>
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internal static bool IsSupported()
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{
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var probe = $"DodoSSH.Probe.{Guid.CreateVersion7():N}";
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try
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{
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using var key = CngKey.Create(
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CngAlgorithm.Rsa,
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probe,
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new CngKeyCreationParameters { Provider = new CngProvider(PlatformProvider) });
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key.Delete();
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return true;
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}
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catch (CryptographicException)
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{
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return false;
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}
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catch (PlatformNotSupportedException)
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{
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return false;
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}
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}
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/// <inheritdoc />
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public ValueTask<bool> IsAvailableAsync(CancellationToken cancellationToken) =>
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ValueTask.FromResult(IsSupported());
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/// <inheritdoc />
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public async ValueTask SaveAsync(
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ReadOnlyMemory<byte> devicePrivateKey,
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CancellationToken cancellationToken)
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{
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using var key = OpenOrCreate();
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using var rsa = new RSACng(key);
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var sealedKey = rsa.Encrypt(devicePrivateKey.Span, RSAEncryptionPadding.OaepSHA256);
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paths.EnsureCreated();
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await File.WriteAllBytesAsync(paths.DeviceKeyFile, sealedKey, cancellationToken)
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.ConfigureAwait(false);
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}
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/// <inheritdoc />
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public async ValueTask<byte[]?> TryLoadAsync(CancellationToken cancellationToken)
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{
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if (!File.Exists(paths.DeviceKeyFile))
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{
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return null;
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}
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var sealedKey = await File.ReadAllBytesAsync(paths.DeviceKeyFile, cancellationToken)
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.ConfigureAwait(false);
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return Unseal(sealedKey);
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}
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/// <inheritdoc />
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public ValueTask ForgetAsync(CancellationToken cancellationToken)
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{
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if (File.Exists(paths.DeviceKeyFile))
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{
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File.Delete(paths.DeviceKeyFile);
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}
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if (CngKey.Exists(KeyName, new CngProvider(PlatformProvider)))
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{
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using var key = CngKey.Open(KeyName, new CngProvider(PlatformProvider));
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key.Delete();
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}
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return ValueTask.CompletedTask;
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}
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/// <remarks>
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/// This is the call that prompts. Every failure becomes null, and the set is wider than it looks: the
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/// key may be gone, the user may have cancelled, the TPM may be locked out after too many wrong PINs,
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/// or the blob may predate a key that has since been replaced. None of them are distinguishable to a
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/// user and all have the same remedy, so none of them are worth telling apart here — see
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/// <c>UnlockStatus.DeviceKeyUnavailable</c>.
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/// </remarks>
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private static byte[]? Unseal(byte[] sealedKey)
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{
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try
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{
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if (!CngKey.Exists(KeyName, new CngProvider(PlatformProvider)))
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{
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return null;
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}
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using var key = CngKey.Open(KeyName, new CngProvider(PlatformProvider));
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using var rsa = new RSACng(key);
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return rsa.Decrypt(sealedKey, RSAEncryptionPadding.OaepSHA256);
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}
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catch (CryptographicException)
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{
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return null;
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}
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}
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/// <remarks>
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/// The UI policy is set at creation and cannot be added afterwards, which is why this opens an existing
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/// key rather than ever reconfiguring one: a key created without the policy would decrypt silently, and
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/// silently is the one behaviour this whole file exists to prevent.
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/// </remarks>
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private static CngKey OpenOrCreate()
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{
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var provider = new CngProvider(PlatformProvider);
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if (CngKey.Exists(KeyName, provider))
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{
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return CngKey.Open(KeyName, provider);
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}
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return CngKey.Create(
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CngAlgorithm.Rsa,
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KeyName,
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new CngKeyCreationParameters
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{
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Provider = provider,
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UIPolicy = new CngUIPolicy(CngUIProtectionLevels.ProtectKey, ConsentPrompt),
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// Machine-wide would put one key behind every account on the computer. This key stands for
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// "this user, on this machine", which is what a device wrap means.
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KeyCreationOptions = CngKeyCreationOptions.None,
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});
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}
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}
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