Published on: 2017-02-16T15:10:46+00:00
On February 14th, 2017, a potential security vulnerability with Simplified Payment Verification (SPV) clients was highlighted by Jonas Schnelli via bitcoin-dev mailing list. He warned that using current SPV clients could expose a user's complete wallet content to any network observer between the user and the connected node. This means that coffee shop owners, ISPs, and cellphone providers could potentially correlate a user's wallet with their other internet behavior. To address this issue, Tom Zander suggested allowing trusted users to connect on a different, encrypted connection similar to RPC.There have been concerns raised about BIP150/151 and its "identity system". Some worry that BIP150 could partition the network, but most of these worries are unfounded. Users already filter and authenticate peers using IP tables, the 'addnode' command, peer banning in app-layer, and fast block relay. BIP150 allows for switching from IP-based authentication to a secure form of authentication with pre-shared keys (ECDH). While there are debates about whether identity is something desired in Bitcoin, BIP150 introduces optional authentication over an EC pubkey that can be changed per network interface and only revealed to peers who have proven knowledge of the user's identity.It has been suggested that BIP150/151 is not necessary as Tor and STunnel already exist. However, using Tor for a single secure channel may be excessive. Additionally, not many SPV users have encrypted channels to trusted nodes currently. The main focus of Tor is on onion routing and anonymity, rather than securing individual channels. Some feel that BIP151 provides a false sense of security and lacks MITM detection. Although BIP151 does not have MITM detection, it does add complexity to attacks. Without BIP151, anyone can intercept and read the stream, whereas with BIP151, an attacker needs to actively substitute ephemeral keys in both directions, accepting the risk of being detected.There is a debate regarding the encryption of Bitcoin traffic since it is inherently trustless. However, using current SPV clients exposes wallet content to network observers. Some suggest using a different channel to communicate with a full node than the p2p layer, but this may be undesirable for end users. Keeping users on the p2p layer allows for future changes where they can contribute to the network. Additionally, having a trusted connection through the p2p layer enables fallback to non-trusted nodes if the trusted node becomes unreachable.
Updated on: 2023-08-01T19:33:08.847167+00:00