Block Header Binary Encoding

BlockHeader Binary Format For Chain Graphs of Degree Three

defined in Chainweb.BlockHeader

Size	Bytes	Value
8	0-7	nonce
8	8-15	time
32	16-47	parent
110	48-157	adjacents
32	158-189	target
32	190-221	payload
4	222-225	chain
32	226-257	weight
8	258-265	height
4	266-269	version
8	270-277	epoch start
32	278-309	hash

total: 302 bytes

Adjacent Parents Record (length 3):

Bytes	Value
0-1	length
2-107	adjacents

total: 110 bytes

Adjacent Parent:

Bytes	Value
0-3	chain
4-35	hash

total: 36 bytes

Fields

POW related values:

Arithmetic operations and comparisons on parent, target, weight, and hash interpret the value as unsigned 256 bit integral numbers in little endian encoding.

Time Stamps:

time and epoch start are a little endian twoth complement encoded integral numbers that counts SI microseconds since POSIX epoch. These numbers are always positive (highest bit is 0).

Numbers:

• height is a little endian encoded unsigned integral 64 bit number.
• length is a little endian encoded unsigned integral 16 bit number.

Version:

version identifies the chainweb version. It is a 32 bit value in little endian encoding. Values up to 0x0000FFFF are reserved for production versions (which includes Development and testnets).

value	version
0x00000001	Development
0x00000004	Testnet02

Other:

• nonce is any sequence of 8 bytes that is only compared for equality.
• chain is any sequence of 4 bytes that identifies a chain and can be compared for equality.
• payload is any sequence of 32 bytes that is a cryptographic hash of the payload associated with the block and can be compared for equality.