1 // Copyright 2017 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // Package asn1 contains supporting types for parsing and building ASN.1 6 // messages with the cryptobyte package. 7 package asn1 // import "golang.org/x/crypto/cryptobyte/asn1" 8 9 // Tag represents an ASN.1 identifier octet, consisting of a tag number 10 // (indicating a type) and class (such as context-specific or constructed). 11 // 12 // Methods in the cryptobyte package only support the low-tag-number form, i.e. 13 // a single identifier octet with bits 7-8 encoding the class and bits 1-6 14 // encoding the tag number. 15 type Tag uint8 16 17 const ( 18 classConstructed = 0x20 19 classContextSpecific = 0x80 20 ) 21 22 // Constructed returns t with the constructed class bit set. 23 func (t Tag) Constructed() Tag { return t | classConstructed } 24 25 // ContextSpecific returns t with the context-specific class bit set. 26 func (t Tag) ContextSpecific() Tag { return t | classContextSpecific } 27 28 // The following is a list of standard tag and class combinations. 29 const ( 30 BOOLEAN = Tag(1) 31 INTEGER = Tag(2) 32 BIT_STRING = Tag(3) 33 OCTET_STRING = Tag(4) 34 NULL = Tag(5) 35 OBJECT_IDENTIFIER = Tag(6) 36 ENUM = Tag(10) 37 UTF8String = Tag(12) 38 SEQUENCE = Tag(16 | classConstructed) 39 SET = Tag(17 | classConstructed) 40 PrintableString = Tag(19) 41 T61String = Tag(20) 42 IA5String = Tag(22) 43 UTCTime = Tag(23) 44 GeneralizedTime = Tag(24) 45 GeneralString = Tag(27) 46 ) 47
