A native Go implementation of macaroons
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Latest commit 77ef360 Aug 1, 2018

README.md

macaroon

-- import "gopkg.in/macaroon.v1"

The macaroon package implements macaroons as described in the paper "Macaroons: Cookies with Contextual Caveats for Decentralized Authorization in the Cloud" (http://theory.stanford.edu/~ataly/Papers/macaroons.pdf)

See the macaroon bakery packages at http://godoc.org/gopkg.in/macaroon-bakery.v0 for higher level services and operations that use macaroons.

Usage

type Caveat

type Caveat struct {
	Id       string
	Location string
}

type Macaroon

type Macaroon struct {
}

Macaroon holds a macaroon. See Fig. 7 of http://theory.stanford.edu/~ataly/Papers/macaroons.pdf for a description of the data contained within. Macaroons are mutable objects - use Clone as appropriate to avoid unwanted mutation.

func New

func New(rootKey []byte, id, loc string) (*Macaroon, error)

New returns a new macaroon with the given root key, identifier and location.

func (*Macaroon) AddFirstPartyCaveat

func (m *Macaroon) AddFirstPartyCaveat(caveatId string) error

AddFirstPartyCaveat adds a caveat that will be verified by the target service.

func (*Macaroon) AddThirdPartyCaveat

func (m *Macaroon) AddThirdPartyCaveat(rootKey []byte, caveatId string, loc string) error

AddThirdPartyCaveat adds a third-party caveat to the macaroon, using the given shared root key, caveat id and location hint. The caveat id should encode the root key in some way, either by encrypting it with a key known to the third party or by holding a reference to it stored in the third party's storage.

func (*Macaroon) Bind

func (m *Macaroon) Bind(sig []byte)

Bind prepares the macaroon for being used to discharge the macaroon with the given signature sig. This must be used before it is used in the discharges argument to Verify.

func (*Macaroon) Caveats

func (m *Macaroon) Caveats() []Caveat

Caveats returns the macaroon's caveats. This method will probably change, and it's important not to change the returned caveat.

func (*Macaroon) Clone

func (m *Macaroon) Clone() *Macaroon

Clone returns a copy of the receiving macaroon.

func (*Macaroon) Id

func (m *Macaroon) Id() string

Id returns the id of the macaroon. This can hold arbitrary information.

func (*Macaroon) Location

func (m *Macaroon) Location() string

Location returns the macaroon's location hint. This is not verified as part of the macaroon.

func (*Macaroon) MarshalBinary

func (m *Macaroon) MarshalBinary() ([]byte, error)

MarshalBinary implements encoding.BinaryMarshaler.

func (*Macaroon) MarshalJSON

func (m *Macaroon) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler.

func (*Macaroon) Signature

func (m *Macaroon) Signature() []byte

Signature returns the macaroon's signature.

func (*Macaroon) UnmarshalBinary

func (m *Macaroon) UnmarshalBinary(data []byte) error

UnmarshalBinary implements encoding.BinaryUnmarshaler.

func (*Macaroon) UnmarshalJSON

func (m *Macaroon) UnmarshalJSON(jsonData []byte) error

UnmarshalJSON implements json.Unmarshaler.

func (*Macaroon) Verify

func (m *Macaroon) Verify(rootKey []byte, check func(caveat string) error, discharges []*Macaroon) error

Verify verifies that the receiving macaroon is valid. The root key must be the same that the macaroon was originally minted with. The check function is called to verify each first-party caveat - it should return an error if the condition is not met.

The discharge macaroons should be provided in discharges.

Verify returns true if the verification succeeds; if returns (false, nil) if the verification fails, and (false, err) if the verification cannot be asserted (but may not be false).

TODO(rog) is there a possible DOS attack that can cause this function to infinitely recurse?

type Verifier

type Verifier interface {
	Verify(m *Macaroon, rootKey []byte) (bool, error)
}