Understanding serialized unsigned raw transaction

Question

I'm currently learning about RLP (ethereum-under-the-hood-part-ii, wiki-eth-rlp) and Ethereum transaction structure, my goal is to create an unsigned raw tx and then sign it.

Right now I'm playing around with code snipped which I assume are working such as raw_tx_demo which produces:

• RLP-Encoded Tx: 0xe6808609184e72a0008303000094b0920c523d582040f2bcb1bd7fb1c7c1ecebdb3480801c8080
• Tx Hash: 0x3a2fd1a5ea9ffee477f449be53a49398533d2c006a5815023920d1c397298df3

Given ethereum tx structure, below what I extract from the RLP-Encoded Tx:

0x {e6} {80} {86 09 18 4e 72 a0 00} {83 03 00 00} {94 b0 92 0c 52 3d 58 20 40 f2 bc b1 bd 7f b1 c7 c1 ec eb db 34} {80} {80} {1c} {80} {80}

{e6} - ?: 230
{80} - nonce: 0
gasPrice: 10000000000000
gasLimit: 196608
to: "0xb0920c523d582040f2bcb1bd7fb1c7c1ecebdb34"
{80} - value: 0
{80} - data: 0
{1c} - v: 28
{80} - r: 0
{80} - s: 0 

From here, I got some questions:

• What the first byte 0xe6 or 230 is for ? How is it computed ?
• Why does the ChainId is 0x1c or 28 ? Given this list it don't understand.

Answer 1

Partial answer.

Why does the ChainId is 0x1c or 28 ? Given this list it don't understand.

The link you point to shows network ID, which isn't the same as chain ID.

Further, 28 isn't the chain ID, it's the v value. See EIP-155 for details of expected v values, and this answer for a definition of v, r, and s.

Answer 2

The byte 0xe6 was simply following the 3rd rule describing an rlp list serialized.

tx = new ethTx({});
console.log('RLP-Encoded Tx: 0x' + tx.serialize().toString('hex'))

Gives: 0x c9 808080808080808080 and as the payload 808080808080808080 is 9 bytes or 0x09 so below 55 bytes, serializing a rlp list is just 0xc0 + 0x09 -> 0xc9.

In my exemple, the payload was 38 bytes or 0x26 and 0xc0 + 0x26 -> 0xe6