UTF8String

The ASN.1 UTF8String data type is encoded into a TLV triplet that begins with a Tag byte of 0x0C. The following example, from the CMC Encoded ASN.1 topic, shows how the ClientId attribute is encoded as an integer and three UTF8String types. The object identifier for the attribute is 1.3.6.1.4.1.311.21.20. The information, which can be specified by using the IX509AttributeClientId interface, includes a client ID number, the Domain Name System (DNS) computer name, the Security Accounts Manager (SAM) user name, and the name of the application that created the certificate request.


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 (7 Bytes)
         63 65 72 74 72 65 71        ;   certreq

If the string contains fewer than 128 bytes, the Length field of the TLV triplet requires only one byte to specify the content length. If the string 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.

Related topics

ASN.1 Type System
DER Encoding of ASN.1 Types

 

 

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