parameters.go

package mnemonikey

import (
	"time"
)

// EpochIncrement is the level of granularity available for the creation date of
// keys generated by mnemonikey.
const EpochIncrement = time.Second

// EpochStart is the start of the epoch after which key creation times are encoded
// in recovery phrases. It is exactly midnight in UTC time on the new year's eve
// between 2022 and 2023.
//
// In unix time, this epoch is exactly 1672531200 seconds after the unix epoch.
var EpochStart = time.Date(2023, 1, 1, 0, 0, 0, 0, time.UTC)

const (
	// MnemonicVersionLatest is the latest known mnemonikey version number. Backups encoded with versions higher
	// than this number will fail to decode.
	MnemonicVersionLatest MnemonicVersion = 1

	// EraLatest is the latest known mnemonikey era number.
	EraLatest Era = 0
)

const (
	// MnemonicVersionBitCount is the number of bits in the backup payload reserved for the version number.
	MnemonicVersionBitCount uint = 4

	// CreationOffsetBitCount is the number of bits used to represent a key creation offset.
	CreationOffsetBitCount uint = 31

	// ChecksumBitCount is the number of bits in the backup payload reserved for the checksum.
	ChecksumBitCount uint = 5

	// EntropyBitCount is the number of bits of entropy in the seed used to derive PGP keys.
	EntropyBitCount = 128

	// SaltBitCount is the number of bits of salt used for seed encryption keys.
	SaltBitCount uint = 19

	// EncSeedVerifyBitCount is the number of bits used for seed encryption key validation.
	EncSeedVerifyBitCount uint = 5
)

const (
	checksumMask      = (1 << ChecksumBitCount) - 1
	encSeedVerifyMask = (1 << EncSeedVerifyBitCount) - 1
)

// MaxCreationTime is the farthest point in the future that the mnemonikey recovery phrase
// encoding algorithm can represent key creation timestamps for.
var MaxCreationTime = EpochStart.Add(EpochIncrement * (time.Duration(1<<CreationOffsetBitCount) - 1))