Re: [ASN1] BER encoding of

[Lev Walkin]

Banibrata Dutta wrote:

Hi Lev,

Thanks for the clarification. Also, could you just give an example of what
would the BER encoded stream look like, if instead of SIZE(1) we had a
SIZE(2) SEQUENCE OF ? I am confused on whether it should be:-

[6] {
  SEQUENCE {
  }
  SEQUENCE {
  }
}

Yes.

Or be:-

[6] {
  SEQUENCE {
  }
}
[6] {
  SEQUENCE {
  }
}

No.

Thanks,
bdutta

-----Original Message-----

From: Lev Walkin [mailto:[EMAIL PROTECTED] Sent: Tuesday, June 14, 2005 11:27 PM

To: Banibrata Dutta
Cc: asn1@asn1.org
Subject: Re: [ASN1] BER encoding of

Banibrata Dutta wrote:

Hi,

Could someone please verify that for the following ASN.1 definitions
(snippet) :-

   contact [6] IMPLICIT SEQUENCE SIZE(1..5) OF SEQUENCE {
           name  [0] IMPLICIT Name OPTIONAL,
           url   [1] EXPLICIT Url OPTIONAL,
           value [2] IMPLICIT INTEGER OPTIONAL,
           delta [5] IMPLICIT INTEGER OPTIONAL
       } OPTIONAL,


Name ::= IA5String (SIZE(1..64))

Url ::= CHOICE {
   myUrl       [0] IMPLICIT SEQUENCE {
       user     [0] IMPLICIT IA5String (SIZE(1..16)) OPTIONAL,
       host     [1] IMPLICIT IA5String (SIZE(1..64)) OPTIONAL,
       port     [2] IMPLICIT INTEGER OPTIONAL,
       transport   [3] IMPLICIT ENUMERATED {
           udp(0),
           tcp(1),
       } OPTIONAL
   }

Is the following BER encoding of "contact" field is correct ?

 [6] {
   SEQUENCE {
     [0] (72 65 73 70 6F 6E 73 65 4F 4B)
     [2] (00)
   }

Yes, this is correct. It translates to a value of the
following:

        contact [6] IMPLICIT SEQUENCE SIZE(1) OF SEQUENCE {
                name [0] IMPLICIT IA5String (SIZE(10)),
                value [2] IMPLICIT INTEGER (0)
        }

and how about this ?

[6] {
   SEQUENCE {
     [1] {
       [0] {
         [1] (6C 61 76)
         [2] (16 44)
         [3] (00)
       }
     }
     [1] {
       [0] {
         [1] (6C 61 76)
         [2] (16 45)
         [3] (01)
       }
     }
   }
 }

This one is not correct. There are two tags [1] inside the SEQUENCE (which
is inside the outer SEQUENCE OF), which is wrong.

--
Lev Walkin
[EMAIL PROTECTED]

--
Lev Walkin
[EMAIL PROTECTED]
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