Basic Types

SSZ support two Basic Types:

1. Unisigned Integer

2. Boolean

Unsigned Integers

• Type:

  • uintN, where N can be: 8, 16, 32, 64, 128, 256.

• Aliases:

  • uint8 <-> byte
  • uint256 <-> root

• Default value:

  • 0

• Size:

  • size_of(uintN): N / 8

Serialization

The serialized form on any unsined integer is the Bytes representation of that integer.

The serialization of uintN is defined using the Python version of int.to_bytes, little-endian.

Merkleization

The integers, represented as bytes, are padded on the right side with zeroed bytes to a total of 32 bytes for merkleization. Note:

• Some complex types pack smaller integers together into 32 bytes, to reduce the merkleization cost.
• Because of the little-endianness and right-padding, equal integers of different bit-sizes all map to the same 32 bytes value.

Booleans

• Type: boolean

• Alias: bit

• Default value: False

• Size: 1

Serialization

Booleans have two possible values: True or False

The Boolean value false is serialized into a byte of value 0

The Boolean value true is serialized into a byte of value 1

Merkleization

The boolean represented as byte is merkleized exactly like byte, including the ability to pack (but only to byte precision, refer to bitfields for more efficient packing).