move gotd fork into repo. (#111)

- update to latest telegram layer
- remove some references to fields in tg.Entities that don't exist in
the schema
- originally added here:
https://github.com/beeper/td/commit/820929062a2ba0104397bc01235ab58a9cff780e
  - referenced here
-
https://github.com/mautrix/telegramgo/commit/124f0967ed195b5a380c9bd02e170ada9710dde3
-
https://github.com/mautrix/telegramgo/commit/4205047aab2e0639217148b5d125bfaab668bd8e

pkg/gotd/crypto/key.go

@@ -0,0 +1,132 @@
+package crypto
+
+import (
+	"crypto/sha1" // #nosec
+	"encoding/binary"
+	"encoding/hex"
+	"fmt"
+
+	"github.com/go-faster/errors"
+	"github.com/go-faster/jx"
+	"go.uber.org/zap/zapcore"
+)
+
+// See https://core.telegram.org/mtproto/description#defining-aes-key-and-initialization-vector
+
+// Key represents 2048-bit authorization key value.
+type Key [256]byte
+
+func (k Key) String() string {
+	// Never print key.
+	return "(redacted)"
+}
+
+// Zero reports whether Key is zero value.
+func (k Key) Zero() bool {
+	return k == Key{}
+}
+
+// ID returns auth_key_id.
+func (k Key) ID() [8]byte {
+	raw := sha1.Sum(k[:]) // #nosec
+	var id [8]byte
+	copy(id[:], raw[12:])
+	return id
+}
+
+// AuxHash returns aux_hash value of key.
+func (k Key) AuxHash() [8]byte {
+	raw := sha1.Sum(k[:]) // #nosec
+	var id [8]byte
+	copy(id[:], raw[0:8])
+	return id
+}
+
+// WithID creates new AuthKey from Key.
+func (k Key) WithID() AuthKey {
+	return AuthKey{
+		Value: k,
+		ID:    k.ID(),
+	}
+}
+
+// AuthKey is a Key with cached id.
+type AuthKey struct {
+	Value Key
+	ID    [8]byte
+}
+
+// DecodeJSON decode AuthKey from object with base64-encoded key and integer ID.
+func (a *AuthKey) DecodeJSON(d *jx.Decoder) error {
+	return d.ObjBytes(func(d *jx.Decoder, key []byte) error {
+		switch string(key) {
+		case "value":
+			data, err := d.Base64()
+			if err != nil {
+				return errors.Wrap(err, "decode value")
+			}
+			copy(a.Value[:], data)
+		case "id":
+			id, err := d.Int64()
+			if err != nil {
+				return errors.Wrap(err, "decode id")
+			}
+			a.SetIntID(id)
+		default:
+			return d.Skip()
+		}
+
+		return nil
+	})
+}
+
+// UnmarshalJSON implements json.Unmarshaler.
+func (a *AuthKey) UnmarshalJSON(data []byte) error {
+	return a.DecodeJSON(jx.DecodeBytes(data))
+}
+
+// EncodeJSON encodes AuthKey as object with base64-encoded key and integer ID.
+func (a AuthKey) EncodeJSON(e *jx.Encoder) error {
+	e.ObjStart()
+	e.FieldStart("value")
+	e.Base64(a.Value[:])
+	e.FieldStart("id")
+	e.Int64(a.IntID())
+	e.ObjEnd()
+	return nil
+}
+
+// MarshalJSON implements json.Marshaler.
+func (a AuthKey) MarshalJSON() ([]byte, error) {
+	e := jx.GetEncoder()
+	if err := a.EncodeJSON(e); err != nil {
+		return nil, err
+	}
+	return e.Bytes(), nil
+}
+
+// Zero reports whether Key is zero value.
+func (a AuthKey) Zero() bool {
+	return a == AuthKey{}
+}
+
+// IntID returns key fingerprint (ID) as int64.
+func (a AuthKey) IntID() int64 {
+	return int64(binary.LittleEndian.Uint64(a.ID[:]))
+}
+
+// SetIntID sets key fingerprint (ID) as int64.
+func (a *AuthKey) SetIntID(v int64) {
+	binary.LittleEndian.PutUint64(a.ID[:], uint64(v))
+}
+
+// String implements fmt.Stringer.
+func (a AuthKey) String() string {
+	return fmt.Sprintf("Key(id: %x)", a.ID)
+}
+
+// MarshalLogObject implements zap.ObjectMarshaler.
+func (a AuthKey) MarshalLogObject(encoder zapcore.ObjectEncoder) error {
+	encoder.AddString("id", hex.EncodeToString(a.ID[:]))
+	return nil
+}