Now supporting block builder submission with SSZ encoding

[metachris]

mev-boost-relay now supports block submissions in SSZ encoding (in addition to JSON). Also gzip is supported.

Implementation details:

• Allow SSZ builder submissions (also SSZ+GZIP) #388
• planned in October '22 :) feat: allow block builder submissions with ssz payload, and with json+gzip #209
• included in mev-boost-relay since v0.21

---

Request details

https://flashbots.github.io/relay-specs/#/Builder/submitBlock

POST /relay/v1/builder/blocks

Payload: capella.SubmitBlockRequest

https://github.com/attestantio/go-builder-client/blob/master/api/capella/submitblockrequest.go

{
    "message": {
        "slot": "5552306",
        "parent_hash": "0xbd3291854dc822b7ec585925cda0e18f06af28fa2886e15f52d52dd4b6f94ed6",
        "block_hash": "0x1bafdc454116b605005364976b134d761dd736cb4788d25c835783b46daeb121",
        "builder_pubkey": "0xb67a5148a03229926e34b190af81a82a81c4df66831c98c03a139778418dd09a3b542ced0022620d19f35781ece6dc36",
        "proposer_pubkey": "0x8559727ee65c295279332198029c939557f4d2aba0751fc55f71d0733b8aa17cd0301232a7f21a895f81eacf55c97ec4",
        "proposer_fee_recipient": "0x5cc0dde14e7256340cc820415a6022a7d1c93a35",
        "gas_limit": "30000000",
        "gas_used": "25875661",
        "value": "71177763439091815"
    },
    "execution_payload": {
        "parent_hash": "0xbd3291854dc822b7ec585925cda0e18f06af28fa2886e15f52d52dd4b6f94ed6",
        "fee_recipient": "0xb64a30399f7f6b0c154c2e7af0a3ec7b0a5b131a",
        "state_root": "0x74f74d15dcb00ba194901136f2019dd6be2d4c88c822786df90561a550193899",
        "receipts_root": "0xb410fa34a1312626db3c41d325545e9f24e903d5dd9b9c260882aadb4c28fa8e",
        "logs_bloom": "0x40f7484521e2f4f8001ed9b0810595c450380844af610944218104d21c220028aa6a150a86312b000040401909e548e71c6a05128a58607200103fc400346f6e9843c2e20c72a00d7bd8138a249a83208697c0d03d7633c18248a58fe88284240a0e43e782c6b0c1167a00ac9808be499950e8500228776980266490f21c9040b30a30b4922c3a7af850ba08f2000146ea850401e978038e1205094215025016ae8811166961477d68522c826c9a0d20228c822de2ac830503b13936b5e01b9f9532ec2322c70c491c1a21618533c284299b189207cf0e37f2c7a1930c6667815fd238290926265cc28095a0a0240234af3810928a962ad0264a4905018a02a1",
        "prev_randao": "0x9962816e9d0a39fd4c80935338a741dc916d1545694e41eb5a505e1a3098f9e4",
        "block_number": "8935900",
        "gas_limit": "30000000",
        "gas_used": "25875661",
        "timestamp": "1683135672",
        "extra_data": "0x496c6c756d696e61746520446d6f63726174697a6520447374726962757465",
        "base_fee_per_gas": "19075240703",
        "block_hash": "0x1bafdc454116b605005364976b134d761dd736cb4788d25c835783b46daeb121",
        "transactions": ["0x..."],
        "withdrawals": [
            {
                "index": "4466251",
                "validator_index": "418388",
                "address": "0x59b0d71688da01057c08e4c1baa8faa629819c2a",
                "amount": "1927254"
            }
        ]
    },
    "signature": "0xa2def54237bfeb1d9269365e853b5469f68b7f4ad51ca7877e406ca94bc8a94bba54c14024b2f9ed37d8690bb9fac52600b7ff52b96b843cd8529e9ecc2497a0ecd5db8372e2049156e0fa9334d5c1b0ef642f192675b586ecbe6fc381178f88"
}

---

HTTP Headers

HTTP headers to use for the different encodings:

Encoding	Content-Type	Content-Encoding
JSON
JSON+GZIP		gzip
SSZ	application/octet-stream
SSZ+GZIP	application/octet-stream	gzip

---

Relay support

All these encodings are supported by https://boost-relay.flashbots.net.

Asking for other relays to comment here once support is rolled out and confirmed ⭐

[michaelneuder]

confirmed it is available on ultra sound relay now

[MrKoberman]

confirmed it is available on securerpc relay now

[austonst]

SSZ block submissions should now be enabled on Aestus.