Try to add cbor support

internal/cbor/cbor.go

@@ -35,6 +35,10 @@ const (
 	additionalTypeEmbeddedJSON     uint16 = 262
 	additionalTypeTagHexString     uint16 = 263
 
+	// Expected later encoding for CBOR-to-JSON converters - from https://www.rfc-editor.org/rfc/rfc8949.html#section-3.4.5.2
+	additionalTypeTagBase64Standard byte = 22
+	additionalTypeTagBase64RawURL   byte = 23
+
 	// Unspecified number of elements.
 	additionalTypeInfiniteCount byte = 31
 )

internal/cbor/decode_stream.go

@@ -386,6 +386,17 @@ func decodeTagData(src *bufio.Reader) []byte {
 			}
 			src.UnreadByte()
 			return decodeStringToDataUrl(src, "application/cbor")
+		case additionalTypeTagBase64Standard, additionalTypeTagBase64RawURL:
+			data := decodeString(src, true)
+			enc := base64.StdEncoding
+			if byte(val) == additionalTypeTagBase64RawURL {
+				enc = base64.RawURLEncoding
+			}
+			output := make([]byte, enc.EncodedLen(len(data))+2)
+			output[0] = '"'
+			output[len(output)-1] = '"'
+			enc.Encode(output[1:len(output)-1], data)
+			return output
 		default:
 			panic(fmt.Errorf("Unsupported Additional Tag Type: %d in decodeTagData", val))
 		}

internal/cbor/types.go

@@ -1,6 +1,7 @@
 package cbor
 
 import (
+	"encoding/base64"
 	"fmt"
 	"math"
 	"net"
@@ -484,3 +485,19 @@ func (e Encoder) AppendHex(dst []byte, val []byte) []byte {
 	dst = append(dst, byte(additionalTypeTagHexString&0xff))
 	return e.AppendBytes(dst, val)
 }
+
+// AppendBase64 adds a TAG and inserts base64 bytes as a string.
+func (e Encoder) AppendBase64(enc *base64.Encoding, dst []byte, val []byte) []byte {
+	switch enc {
+	case base64.StdEncoding:
+		dst = append(dst, majorTypeTags|additionalTypeIntUint8)
+		dst = append(dst, additionalTypeTagBase64Standard)
+		return e.AppendBytes(dst, val)
+	case base64.RawURLEncoding:
+		dst = append(dst, majorTypeTags|additionalTypeIntUint8)
+		dst = append(dst, additionalTypeTagBase64RawURL)
+		return e.AppendBytes(dst, val)
+	default:
+		return e.AppendString(dst, enc.EncodeToString(val))
+	}
+}