104 lines
2.5 KiB
Go
104 lines
2.5 KiB
Go
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package nebula
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import (
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"crypto"
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"crypto/ed25519"
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"crypto/rand"
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"encoding/json"
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"errors"
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"fmt"
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"github.com/slackhq/nebula/cert"
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)
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// ErrInvalidSignature is returned from functions when a signature validation
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// fails.
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var ErrInvalidSignature = errors.New("invalid signature")
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func signCert(c *cert.NebulaCertificate, k SigningPrivateKey) error {
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return c.Sign(ed25519.PrivateKey(k))
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}
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// Signed wraps an arbitrary value with a signature which was generated using a
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// SigningPrivateKey. It can be JSON (un)marshaled while preserving all of its
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// properties.
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type Signed[T any] json.RawMessage
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type signed[T any] struct {
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Signature []byte
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Body json.RawMessage
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}
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// Sign will generate a Signed of the given value by first JSON marshaling it,
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// and then signing the resulting bytes.
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func Sign[T any](v T, k SigningPrivateKey) (Signed[T], error) {
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var res Signed[T]
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b, err := json.Marshal(v)
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if err != nil {
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return res, fmt.Errorf("json marshaling: %w", err)
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}
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sig, err := ed25519.PrivateKey(k).Sign(rand.Reader, b, crypto.Hash(0))
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if err != nil {
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return res, fmt.Errorf("generating signature: %w", err)
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}
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return json.Marshal(signed[T]{Signature: sig, Body: json.RawMessage(b)})
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}
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// MarshalJSON implements the json.Marshaler interface.
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func (s Signed[T]) MarshalJSON() ([]byte, error) {
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return []byte(s), nil
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}
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// UnmarshalJSON implements the json.Unmarshaler interface.
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func (s *Signed[T]) UnmarshalJSON(b []byte) error {
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*s = b
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return nil
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}
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// Unwrap produces the original value which Sign was called on, or returns
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// ErrInvalidSignature if the signature is not valid for the value and public
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// key.
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func (s Signed[T]) Unwrap(pubK SigningPublicKey) (T, error) {
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var (
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res T
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into signed[T]
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)
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if err := json.Unmarshal(s, &into); err != nil {
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return res, fmt.Errorf("json unmarshaling outer Signed: %w", err)
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}
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if !ed25519.Verify(
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ed25519.PublicKey(pubK), []byte(into.Body), into.Signature,
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) {
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return res, ErrInvalidSignature
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}
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if err := json.Unmarshal(into.Body, &res); err != nil {
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return res, fmt.Errorf("json unmarshaling: %w", err)
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}
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return res, nil
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}
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// UnwrapUnsafe is like Unwrap, but it will not check the signature.
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func (s Signed[T]) UnwrapUnsafe() (T, error) {
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var (
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res T
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into signed[T]
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)
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if err := json.Unmarshal(s, &into); err != nil {
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return res, fmt.Errorf("json unmarshaling outer Signed: %w", err)
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}
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if err := json.Unmarshal(into.Body, &res); err != nil {
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return res, fmt.Errorf("json unmarshaling: %w", err)
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}
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return res, nil
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}
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