Clarification on MPT Proof Structure and Node Encoding

[t-sorger]

Hi,

I am working with the trie-db crate and have been generating Merkle-Patricia Trie (MPT) proofs using the generate_proof function. I encountered a proof output that looks like this:

proof = [
    [128, 109, 246, 128, 40, 4, 143, 29, 173, 116, 217, 15, 202, 4, 160, 160, 243, 45, 95, 110, 28, 10, 153, 210, 113, 15, 3, 179, 233, 147, 5, 230, 153, 209, 209, 115, 128, 113, 191, 84, 118, 196, 215, 54, 25, 245, 52, 166, 200, 120, 122, 192, 104, 97, 253, 158, 24, 160, 177, 164, 114, 199, 9, 134, 60, 181, 222, 73, 243, 128, 136, 241, 139, 11, 150, 112, 108, 214, 87, 218, 133, 54, 61, 148, 207, 31, 88, 253, 222, 179, 177, 188, 198, 2, 133, 37, 168, 62, 129, 114, 253, 70, 128, 7, 163, 189, 250, 136, 142, 195, 195, 218, 59, 238, 243, 80, 253, 40, 152, 129, 165, 178, 131, 84, 196, 240, 8, 153, 237, 215, 189, 219, 47, 245, 58, 128, 11, 205, 1, 140, 183, 171, 19, 47, 147, 84, 153, 120, 73, 28, 170, 198, 246, 78, 95, 231, 36, 245, 98, 230, 117, 179, 163, 83, 179, 251, 184, 64, 0, 128, 48, 211, 8, 232, 219, 71, 172, 102, 249, 135, 136, 147, 93, 36, 70, 176, 85, 77, 95, 80, 246, 11, 121, 225, 79, 70, 115, 223, 48, 221, 117, 129, 128, 11, 242, 134, 219, 251, 72, 136, 31, 143, 118, 204, 30, 82, 119, 15, 192, 71, 77, 87, 3, 107, 161, 162, 237, 75, 19, 210, 7, 42, 15, 242, 195, 128, 9, 254, 94, 221, 144, 61, 92, 14, 157, 39, 103, 206, 173, 229, 219, 72, 95, 128, 151, 203, 214, 134, 216, 182, 96, 86, 108, 200, 86, 214, 110, 19, 128, 36, 255, 147, 74, 29, 85, 43, 167, 7, 132, 117, 60, 77, 200, 129, 26, 110, 25, 31, 16, 153, 7, 223, 150, 157, 184, 196, 37, 103, 57, 62, 105, 128, 175, 47, 204, 105, 72, 112, 255, 4, 235, 59, 5, 241, 155, 67, 73, 40, 194, 149, 151, 243, 142, 118, 139, 128, 140, 86, 180, 199, 167, 216, 121, 56],
    [128, 9, 0, 0, 128, 36, 25, 119, 113, 142, 246, 194, 73, 178, 154, 190, 114, 81, 232, 29, 114, 221, 10, 219, 104, 242, 170, 181, 114, 11, 19, 82, 255, 88, 163, 179, 197],
    [129, 5, 8, 32, 128, 152, 165, 197, 189, 19, 246, 122, 169, 52, 148, 27, 239, 143, 45, 182, 20, 157, 237, 67, 252, 163, 157, 162, 215, 192, 118, 168, 126, 248, 132, 182, 89, 0],
    [124, 101, 29, 221, 150, 105, 99, 28, 218, 101, 196, 107, 225, 80, 95, 11, 189, 109, 181, 202, 69, 33, 248, 233, 106, 239, 33, 148, 86, 180, 20, 0]
]

I understand that each Vec<u8> probably represents an encoded trie node, but I'm having trouble interpreting the structure and meaning of each node in the proof. I'm trying to understand:

• The type of each node (e.g., branch, extension, leaf).
• How these nodes collectively represent a proof of inclusion or exclusion for a particular key.

Could you please provide guidance or documentation on how to decode and interpret these proof nodes/values?

Thank you for your help!

(Mention to be pinged: @algomaster99, @javierron)