2.5 KiB
Block Witness Format
Each block witness consists of a header followed by a list of operators.
There is no length of witness specified anywhere, the code expects to just reach EOF
.
Witness: [HEADER, OP1, OP2, ..., OPn-1, OPn, EOF]
Encoding
Keys
key nibbles are encoded in a following way [FLAGS NIBBLE1+NIBBLE2 NIBBLE3+NIBBLE4 NIBBLE5... ]
FLAGS
- bit 0 -- 1 if the number of nibbles were odd
- bit 1 -- 1 if the nibbles end with 0x10
Header
format: version:byte
encoded as [ version ]
the current version is 1.
Operators
Each operator starts with an opcode (see witness_operators.go
for exact values).
Then it might contain some data.
OpEmptyRoot
puts empty trie root to on the stack
format: OpEmptyRoot
encoded as [ 0x06 ]
OpHash
puts a single hash on the stack
format: OpHash hash:[32]byte
encoded as [ 0x03 hash_byte_1 ... hash_byte_32 ]
OpBranch
pops N values from the stack and adds them as the children; pushes the result to the stack; N is the number of 1's in the mask field.
format: OpBranch mask:uint32
mask defines which children are present
(e.g. 0000000000001011
means that children 0, 1 and 3 are present and the other ones are not)
encoded as [ 0x02 CBOR(mask)...]
OpCode
pushes a code to the stack
format: OpCode code:[]byte
encoded as [ 0x04 CBOR(code)... ]
OpExtension
pushes an extension node with a specified key on the stack
format: OpExtension key:[]byte
encoded as [ 0x01 CBOR(key)... ]
OpLeaf
pushes a leaf with specified key and value to the stack
format: OpLeaf key:[]byte value:[]byte
encoded as [ 0x00 CBOR(key)... CBOR(value)... ]
OpAccountLeaf
pushes a leaf with specified parameters to the stack; if flags show, before that pops 1 or 2 values from the stack;
format: OpAccountLeaf key:[]byte flags [nonce:uint64] [balance:[]byte]
encoded as [ 0x05 CBOR(key|[]byte)... flags /CBOR(nonce).../ /CBOR(balance).../ ]
flags is a bitset encoded in a single bit (see witness_operators_test.go
to see flags in action).
- bit 0 defines if code is present; if set to 1 it assumes that either
OpCode
orOpHash
already put something on the stack; - bit 1 defines if storage is present; if set to 1, the operators preceeding
OpAccountLeaf
will reconstruct a storage trie; - bit 2 defines if nonce is not 0; if set to 0, nonce field is not encoded;
- bit 3 defines if balance is not 0; if set to 0, balance field is not encoded;