What HTTPS Can—and Cannot—Guarantee
The security of desktop software updates is the subject of this final judgment, and the title's question can now be answered directly. HTTPS can authenticate and protect a communication channel when certificate validation and endpoint handling are correct. It cannot, by itself, prove that the update plan was authorized, that the selected release is current, that the repository state is coherent, or that the installer will deploy the received bytes safely. UpdSight demonstrates why those distinctions matter in real closed-source clients; TUF shows how a distribution system can represent several of them as separate, verifiable responsibilities.
What a successful HTTPS connection actually tells us
An HTTPS handshake establishes a protected relationship between a client and an endpoint under the rules of the TLS implementation and its certificate validation. It can reduce eavesdropping and in-transit modification. It can help the updater reject a host that cannot prove control of the expected identity. Those are valuable properties, and weakening them through plaintext fallback or disabled certificate checks creates the first opening in many of the attack paths examined by UpdSight.
But the handshake does not answer the questions that begin after the connection succeeds. It does not tell the client whether the server selected the correct release. It does not make a version manifest authoritative merely because the manifest arrived over an encrypted channel. It does not say whether an older, genuine package should be rejected. It does not constrain the paths an archive may write or the privileges an installer may use.
The distinction is easiest to see by separating the endpoint from the statement. A server can be the expected endpoint and still return a stale, misconfigured, or semantically wrong update description. A content-delivery network can deliver the bytes the repository instructed it to deliver without becoming the authority that defines the release. A response can be encrypted in transit and still contain an unauthenticated URL, version, or checksum chosen by someone who should not control that field. Channel identity and update authority overlap, but they are not identical.
The same applies to a payload signature. A signature can show that an authorized party approved a set of bytes. It does not necessarily show that the bytes are the current release, that the metadata selecting them is current, or that the local deployment routine will handle them safely. The package may be genuine and still be the wrong answer to the update request. The archive may be genuine and still contain paths that a careless extractor should refuse.
A more complete question is therefore: what has been authenticated at each transition, and what policy makes that evidence sufficient for the next transition? HTTPS addresses one transition. Secure updating must preserve the answer through the rest.
What the desktop evidence makes impossible to ignore
The UpdSight study gives this distinction practical weight because it tests actual desktop clients under a network-adversary model. The attacker can intercept, modify, inject, or redirect update traffic, including through DNS redirection, but the study does not assume a compromised vendor build system, update server, or signing key. That boundary isolates the updater's own validation logic. It asks whether an ordinary hostile delivery position can cross the client's trust boundaries without already owning the vendor's strongest authorities.
The paper's four rules provide a compact way to state what HTTPS leaves open. Secure transport protects the route. Metadata integrity protects the update plan. Payload authenticity includes the connection between the received object and the authorized release, as well as freshness against rollback. Path integrity constrains what the installer or extractor may do locally. These properties form a chain, but they do not collapse into one another.
The cases show why.