On Fri, 13 Apr 2001 [EMAIL PROTECTED] wrote:
> I have some problem in encoding of BER values for a particular ASN part.
>
> SEQUENCE
> {
> legID [2] CHOICE
> {
> sendingSideID [0] IMPLICIT OCTET STRING (SIZE (1)),
> receivingSideID [1] IMPLICIT OCTET STRING (SIZE (1))
> } OPTIONAL,
> dPSpecificCriteria [30] CHOICE
> {
> numberOfDigits [0] IMPLICIT INTEGER (1..255),
> applicationTimer [1] IMPLICIT INTEGER (0..2047)
> } OPTIONAL
> },
>
>
> I guess first the Type and Length for the Sequence will be specified.Can anyone
> tell
> me how the TLV format for the CHOICE will be specified while encoding.
> It will be of great help!!!!!!!!!
A CHOICE type is encoded as the chosen item. That is, there is no
difference in the BER encoding between cHosen and notChosen in the
examples below.
Choices ::= CHOICE { a INTEGER,
b BOOLEAN}
cHosen Choices ::= a: 15
NoChoice ::= INTEGER
notChosen NoChoice ::= 15
In your case, what remains from the [2] CHOICE is the tag [2],
and from the [30] CHOICE is the tag [30], thus, assuming the OPTIONAL
fields are present, you would have
T of the SEQUENCE
L
T [2]
L length of the 1st choice (3)
T either [0] or [1]
L 1
V the octet
T [30]
L length of the 2nd choice
T either [0] or [1]
L 1 if [0], 2 if [1]
V the integer
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