github.com/pure-x-eth/consensus_tm@v0.0.0-20230502163723-e3c2ff987250/docs/tendermint-core/light-client.md (about) 1 --- 2 order: 13 3 --- 4 5 # Light Client 6 7 Light clients are an important part of the complete blockchain system for most 8 applications. Tendermint provides unique speed and security properties for 9 light client applications. 10 11 See our [light 12 package](https://pkg.go.dev/github.com/pure-x-eth/consensus_tm/light?tab=doc). 13 14 ## Overview 15 16 The objective of the light client protocol is to get a commit for a recent 17 block hash where the commit includes a majority of signatures from the last 18 known validator set. From there, all the application state is verifiable with 19 [merkle proofs](https://github.com/tendermint/spec/blob/953523c3cb99fdb8c8f7a2d21e3a99094279e9de/spec/blockchain/encoding.md#iavl-tree). 20 21 ## Properties 22 23 - You get the full collateralized security benefits of Tendermint; no 24 need to wait for confirmations. 25 - You get the full speed benefits of Tendermint; transactions 26 commit instantly. 27 - You can get the most recent version of the application state 28 non-interactively (without committing anything to the blockchain). For 29 example, this means that you can get the most recent value of a name from the 30 name-registry without worrying about fork censorship attacks, without posting 31 a commit and waiting for confirmations. It's fast, secure, and free! 32 33 ## Where to obtain trusted height & hash 34 35 [Trust Options](https://pkg.go.dev/github.com/pure-x-eth/consensus_tm/light?tab=doc#TrustOptions) 36 37 One way to obtain semi-trusted hash & height is to query multiple full nodes 38 and compare their hashes: 39 40 ```bash 41 $ curl -s https://233.123.0.140:26657:26657/commit | jq "{height: .result.signed_header.header.height, hash: .result.signed_header.commit.block_id.hash}" 42 { 43 "height": "273", 44 "hash": "188F4F36CBCD2C91B57509BBF231C777E79B52EE3E0D90D06B1A25EB16E6E23D" 45 } 46 ``` 47 48 ## Running a light client as an HTTP proxy server 49 50 Tendermint comes with a built-in `tendermint light` command, which can be used 51 to run a light client proxy server, verifying Tendermint RPC. All calls that 52 can be tracked back to a block header by a proof will be verified before 53 passing them back to the caller. Other than that, it will present the same 54 interface as a full Tendermint node. 55 56 You can start the light client proxy server by running `tendermint light <chainID>`, 57 with a variety of flags to specify the primary node, the witness nodes (which cross-check 58 the information provided by the primary), the hash and height of the trusted header, 59 and more. 60 61 For example: 62 63 ```bash 64 $ tendermint light supernova -p tcp://233.123.0.140:26657 \ 65 -w tcp://179.63.29.15:26657,tcp://144.165.223.135:26657 \ 66 --height=10 --hash=37E9A6DD3FA25E83B22C18835401E8E56088D0D7ABC6FD99FCDC920DD76C1C57 67 ``` 68 69 For additional options, run `tendermint light --help`.