How is the FROM address known for historic transactions?

Question

The rlp encoded transaction that is stored in the ethereum database does not include the from address. How is the from address known and how is it associated to the rlp transaction data when retrieving a historic transaction ?

Answer 1

The encoded transaction when decoded has properties v, r and s.

{
  "nonce": "0x0",
  "maxFeePerGas": "0x1234",
  "maxPriorityFeePerGas": "0x1234",
  "gas": "0x55555",
  "to": "0x07a565b7ed7d7a678680a4c162885bedbb695fe0",
  "value": "0x1234",
  "input": "0xabcd",
  "v": "0x26",
  "r": "0x223a7c9bcf5531c99be5ea7082183816eb20cfe0bbc322e97cc5c7f71ab8b20e",
  "s": "0x2aadee6b34b45bb15bc42d9c09de4a6754e7000908da72d48cc7704971491663",
  "hash": "0xeba2df809e7a612a0a0d444ccfa5c839624bdc00dd29e3340d46df3870f8a30e"
}

From this you can compute the public key of the sender, and then the address.

To compute the public Key check this answer.