Internal
Public Access
ksmithandClaude Sonnet 5
e80fe7d634
Live testing against a real macOS Screen Sharing server surfaced two real bugs, independent of each other: 1. SessionTab::requestConnectOptions() never prompted for a password on VNC profiles (only SSH/RDP) -- every VNC connection went out with an empty password regardless of what the server needed. VNC now gets its own prompt; an empty password is allowed through (unlike RDP's hard requirement) since no-auth VNC servers exist and there's no way to know client-side before the security-type negotiation happens. 2. VncSessionBackend's Apple DH (type 30) response sent the client's public key before the encrypted credentials. Cross-checking against neatvnc's rfb-proto.h (an independent, authoritative reference: both the wire struct definitions and the full server-side verification code, matched field-by-field against this implementation) showed the correct order is credentials first, then public key -- exactly backwards from what was implemented. Fixed, with a new regression test that decrypts the credentials back out using the trailing public-key bytes to derive the shared secret, which would fail if the fields were swapped again. Also adds security type 33 (RSA + AES, src/vnc_apple_rsa_auth.h) as a fallback Apple auth scheme, sourced from the `asyncvnc` PyPI package. Preference when multiple are offered: None > AppleDH(30) > AppleRSA(33) > VNCAuth(2). Neither scheme has been gotten working live yet against the specific macOS Tahoe (26.6.2) server available for testing -- type 30's wire format is now verified correct byte-for-byte against the independent reference above, but the server still rejects it with a generic "Authentication or authorization failure"; type 33 is rejected even earlier, right after the initial host-key request. macOS Tahoe was released after this assistant's knowledge cutoff, so there may be a protocol or permission-model change specific to it that isn't reflected in either reference. Documented as an open issue in docs/PROGRESS.md rather than claimed as working. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
52 lines
2.3 KiB
C++
52 lines
2.3 KiB
C++
#ifndef ORBITHUB_VNC_APPLE_RSA_AUTH_H
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#define ORBITHUB_VNC_APPLE_RSA_AUTH_H
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#include <QByteArray>
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#include <QString>
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// Apple Screen Sharing's RSA-based authentication scheme (RFB security
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// type 33, sometimes called "MacAuthentication" or "ARD authentication").
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// Distinct from security type 30 (Diffie-Hellman + AES, see
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// vnc_apple_dh_auth.h): modern macOS advertises both, but empirically only
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// type 33 is actually functional -- type 30 appears to be vestigial.
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// Neither is part of RFC 6143; this wire format and crypto shape was
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// confirmed against the `asyncvnc` PyPI package's implementation (a real,
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// working, independently-maintained VNC client) rather than derived from
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// official Apple documentation, which doesn't exist for this scheme.
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//
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// Scheme: the server hands the client its RSA public key (DER-encoded
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// X.509 SubjectPublicKeyInfo); the client generates a random AES-128 key,
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// encrypts the username+password with it, then RSA-PKCS1v1.5-encrypts
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// that AES key with the server's public key and sends both back.
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namespace VncAppleRsaAuth {
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// Packs one credential string per the scheme's convention: UTF-8 bytes
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// followed by a single NUL terminator, then padded to exactly 64 bytes
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// with random bytes (or truncated to 64 if the NUL-terminated string is
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// already that long or longer). The NUL terminator is what lets the
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// server find the string's real end despite the random padding -- the
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// padding's specific value isn't otherwise significant. Exposed publicly
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// so it's independently unit-testable.
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QByteArray packCredential(const QString& text);
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struct Response {
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// Exactly 128 bytes on success (packCredential(username) +
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// packCredential(password), AES-128-ECB encrypted). Empty on failure.
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QByteArray encryptedCredentials;
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// RSA-modulus-length bytes on success (the random AES key,
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// PKCS1v1.5-encrypted with the server's public key). Empty on
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// failure.
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QByteArray encryptedAesKey;
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};
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// Computes the full type-33 response from the server's DER-encoded RSA
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// public key and the credentials to authenticate with. Returns a Response
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// with both fields empty on any failure (malformed key, an OpenSSL
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// operation failing).
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Response computeResponse(const QByteArray& hostKeyDer, const QString& username,
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const QString& password);
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}
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#endif
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