tka

type AUM struct {
	MessageKind AUMKind `cbor:"1,keyasint"`
	PrevAUMHash []byte  `cbor:"2,keyasint"`

	// Key encodes a public key to be added to the key authority.
	// This field is used for AddKey AUMs.
	Key *Key `cbor:"3,keyasint,omitempty"`

	// KeyID references a public key which is part of the key authority.
	// This field is used for RemoveKey and UpdateKey AUMs.
	KeyID KeyID `cbor:"4,keyasint,omitempty"`

	// State describes the full state of the key authority.
	// This field is used for Checkpoint AUMs.
	State *State `cbor:"5,keyasint,omitempty"`

	// DisablementSecret is used to transmit a secret for disabling
	// the TKA.
	// This field is used for DisableNL AUMs.
	DisablementSecret []byte `cbor:"6,keyasint,omitempty"`

	// Votes and Meta describe properties of a key in the key authority.
	// These fields are used for UpdateKey AUMs.
	Votes *uint             `cbor:"7,keyasint,omitempty"`
	Meta  map[string]string `cbor:"8,keyasint,omitempty"`

	// Signatures lists the signatures over this AUM.
	// CBOR key 23 is the last key which can be encoded as a single byte.
	Signatures []Signature `cbor:"23,keyasint,omitempty"`
}

type AUMHash [blake2s.Size]byte

type AUMKind uint8

type AUMSigHash [blake2s.Size]byte

type Chonk interface {
	// AUM returns the AUM with the specified digest.
	//
	// If the AUM does not exist, then os.ErrNotExist is returned.
	AUM(hash AUMHash) (AUM, error)

	// ChildAUMs returns all AUMs with a specified previous
	// AUM hash.
	ChildAUMs(prevAUMHash AUMHash) ([]AUM, error)

	// CommitVerifiedAUMs durably stores the provided AUMs.
	// Callers MUST ONLY provide AUMs which are verified (specifically,
	// a call to aumVerify() must return a nil error).
	// as the implementation assumes that only verified AUMs are stored.
	CommitVerifiedAUMs(updates []AUM) error

	// Heads returns AUMs for which there are no children. In other
	// words, the latest AUM in all possible chains (the 'leaves').
	Heads() ([]AUM, error)

	// SetLastActiveAncestor is called to record the oldest-known AUM
	// that contributed to the current state. This value is used as
	// a hint on next startup to determine which chain to pick when computing
	// the current state, if there are multiple distinct chains.
	SetLastActiveAncestor(hash AUMHash) error

	// LastActiveAncestor returns the oldest-known AUM that was (in a
	// previous run) an ancestor of the current state. This is used
	// as a hint to pick the correct chain in the event that the Chonk stores
	// multiple distinct chains.
	LastActiveAncestor() (*AUMHash, error)
}

type FS struct {
	// contains filtered or unexported fields
}

type Key struct {
	Kind KeyKind `cbor:"1,keyasint"`

	// Votes describes the weight applied to signatures using this key.
	// Weighting is used to deterministically resolve branches in the AUM
	// chain (i.e. forks, where two AUMs exist with the same parent).
	Votes uint `cbor:"2,keyasint"`

	// Public encodes the public key of the key. For 25519 keys,
	// this is simply the point on the curve representing the public
	// key.
	Public []byte `cbor:"3,keyasint"`

	// Meta describes arbitrary metadata about the key. This could be
	// used to store the name of the key, for instance.
	Meta map[string]string `cbor:"12,keyasint,omitempty"`
}

type KeyID []byte

type KeyKind uint8

type Mem struct {
	// contains filtered or unexported fields
}

type Signature struct {
	KeyID     KeyID  `cbor:"1,keyasint"`
	Signature []byte `cbor:"2,keyasint"`
}

type State struct {
	// LastAUMHash is the blake2s digest of the last-applied AUM.
	// Because AUMs are strictly ordered and form a hash chain, we
	// check the previous AUM hash in an update we are applying
	// is the same as the LastAUMHash.
	LastAUMHash *AUMHash `cbor:"1,keyasint"`

	// DisablementSecrets are KDF-derived values which can be used
	// to turn off the TKA in the event of a consensus-breaking bug.
	// An AUM of type DisableNL should contain a secret when results
	// in one of these values when run through the disablement KDF.
	//
	// TODO(tom): This is an alpha feature, remove this mechanism once
	//            we have confidence in our implementation.
	DisablementSecrets [][]byte `cbor:"2,keyasint"`

	// Keys are the public keys currently trusted by the TKA.
	Keys []Key `cbor:"3,keyasint"`
}