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SET

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A SET contains an unordered series of fields of one or more types. It is encoded into a TLV triplet that begins with a Tag byte of 0x31. The following example, adapted from the CMC Encoded ASN.1 topic, shows how a ClientId attribute is encoded in a SET data structure. The attribute can be specified by using the IX509AttributeClientId interface.

31 59                                     ; SET (59 Bytes)
   30 57                                  ; SEQUENCE (57 Bytes)
      06 09                               ; OBJECT_ID (9 Bytes)
      |  2b 06 01 04 01 82 37 15  14      ;   1.3.6.1.4.1.311.21.20 
      31 4a                               ; SET (4a Bytes)
         30 48                            ; SEQUENCE (48 Bytes)
            02 01                         ; INTEGER (1 Bytes)
            |  09
            0c 23                         ; UTF8_STRING (23 Bytes)
            |  76 69 63 68 33 64 2e 6a    ;   vich3d.j
            |  64 6f 6d 63 73 63 2e 6e    ;   domcsc.n
            |  74 74 65 73 74 2e 6d 69    ;   ttest.mi
            |  63 72 6f 73 6f 66 74 2e    ;   crosoft.
            |  63 6f 6d                   ;   com
            0c 15                         ; UTF8_STRING (15 Bytes)
            |  4a 44 4f 4d 43 53 43 5c    ;   JDOMCSC\
            |  61 64 6d 69 6e 69 73 74    ;   administ
            |  72 61 74 6f 72             ;   rator
            0c 07                         ; UTF8_STRING

If the SET contains fewer than 128 bytes, the Length field of the TLV triplet requires only one byte to specify the content length. If it is more than 127 bytes, bit 7 of the Length field is set to 1 and bits 6 through 0 specify the number of additional bytes used to identify the content length. For more information, see Encoded Length and Value Bytes.

ASN.1 Type System

DER Encoding of ASN.1 Types