This repo has been archived!!!

Koinos now uses Protocol Buffers in koinos-proto.

Koinos Types

Koinos Types provides the canonical serialization of Koinos data structures. Using an IDL (Interface Definition Language) the Koinos Types program generates the corresponding API in each of the supported languages.

Base Types

Integer Types:

Network Byte Order (Big-Endian) for the fixed length integer size.

Signed/Unsigned types for 8, 16, 32, 64, 128, 160, and 256 bit length integers

Bool:

An 8 bit integer. For simplicity, only 0x00 and 0x01 are valid values when a bool is explicitly specified.

Varint:

Varint's can hold a maximum of 64 bits of data (increased from 32 for BitShares/Steem). The first bit of an octet signs if the varint continues or not (1 for continuation, 0 for stop). To encode signed varints, a transfomation to zigzag encoding (used by protobufs) is first applied (n<<1)^(n>>64) before encoding the now unsigned value as a varint. The max wire size of a varint can be 80 bits total.

Object:

Each field of the object is serialized inline according to the object definition.

Vector:

A varint size of the vector, followed by that many objects in the vector using their binary encoding.

Array<T,N>:

A fixed length container of N items serialized in their binary encoding.

Map<K,V>:

A varint size of the map followed by pairs serializing keys and values in the binary format.

Variant:

A varint key, followed by the binary encoding of whatever object is held by that key.

Optional:

A bool specifying if the optional is valid. If true, it is followed by the binary serialization of the contained type.

Multihash:

A varint hash function (key), followed by a varint digest size in bytes, followed by Network Byte Order hash for the specified length.

Multihash Vector:

A varint hash function (key), followed by a varint digest size in bytes, followed by a varint size of the vector, followed by that many digests each of the specified digest size.

Variable Length Blob:

Serialized as a vector

Fixed Length Blob:

The language specifies the fixed length of the blob, in which case it is simply a fixed number of bytes.

Other common types:

Array: A Fixed Length Blob

String: A Variable Length Blob

Timestamp: A signed 64 bit integer

Set: A vector where uniqueness is enforced in the language. For verifying correctness of a set, it should be deserialized, and serialized to check the signature rather than checking the signature directly against the incoming byte stream.