Specific decode choice ASN.1 - erlang

Question

I am using erlang ASN.1 compiler and I have the following ASN.1 definition:
DecryptedCertificate ::= SEQUENCE {
certificateProfileIdentifier INTEGER(0..255),
certificateAuthorityReference CertificateAuthority,
certificateHolderAuthorization CertificateHolderAuthorization,
endOfValidity TimeReal,
certificateHolderReference KeyIdentifier,
rsaPublicKey RsaPublicKey
}
KeyIdentifier ::= CHOICE {
extendedSerialNumber ExtendedSerialNumber,
certificateRequestID CertificateRequestID,
certificationAuthorityKID CertificationAuthorityKID
}
When I decode a binary, it always picks the CertificateRequestID choice, I would like to specify a specific choice for decoder, is that possible?
PS: I am using PER.
Edit:
I am including more information to make the question more clear
The CHOICE types are:
ExtendedSerialNumber ::= SEQUENCE {
serialNumber INTEGER(0..2^32-1)
monthYear BCDString(SIZE(2))
type OCTET STRING(SIZE(1))
manufacturerCode ManufacturerCode
}
CertificateRequestID ::= SEQUENCE {
requestSerialNumber INTEGER(0..2^32-1)
requestMonthYear BCDString(SIZE(2))
crIdentifier OCTET STRING(SIZE(1))
manufacturerCode ManufacturerCode
}
CertificationAuthorityKID ::= SEQUENCE {
nationNumeric NationNumeric
nationAlpha NationAlpha
keySerialNumber INTEGER(0..255)
additionalInfo OCTET STRING(SIZE(2))
caIdentifier OCTET STRING(SIZE(1))
}
ManufacturerCode ::= INTEGER(0..255)
NationNumeric ::= INTEGER(0..255)
NationAlpha ::= IA5String(SIZE(3))
There are some deterministic things like:
caIdentifier is always equal to 1;
crIdentifier is always equal to 0xFF.
I tried to specify the number by using: caIdentifier INTEGER(1) and crIdentifier INTEGER(255), however it always picks the first choice and throws parse error.

Answer 1

When I decode a binary, it always picks the CertificateRequestID choice, I would like to specify a specific choice for decoder, is that possible?
It's not possible to specify what is to be decoded. As you are decoding a particular binary message/record/PDU the decoder is going to pick whatever is contained in the binary according to the ASN.1 definitions and the UPER/APER encoding rules.
Somewhere in the binary there are two bits that determine what KeyIdentifier contains and if you are able to find and change them the decoder will try to decode a different field but then most probably is going to fail as your binary message actually contains a different field.
You could try to create a KeyIdentifier, fill whatever values you want and then encode it to get an idea what this different binary is going to look like.
UPDATE
PER format does not contain header for option types.
In the PER encoding CHOICE does contain an index (header) that specify the encoded type. See X.691 23 Encoding the choice type
23 Encoding the choice type
NOTE – (Tutorial) A choice type is encoded by encoding an index specifying the
chosen alternative. This is encoded as for a constrained integer (unless the
extension marker is present in the choice type, in which case it is a normally
small non-negative whole number) and would therefore typically occupy a fixed
length bit-field of the minimum number of bits needed to encode the index.
Although it could in principle be arbitrarily large.) This is followed by the
encoding of the chosen alternative, with alternatives that are extension
additions encoded as if they were the value of an open type field. Where the
choice has only one alternative, there is no encoding for the index.

Answer 2

It seems you are taking the wrong path to fix your problem: you must not modify an ASN.1 specification to fix it.
In your question, you should add more information about the erlang code you have written to decode the input.
Either erlang compiler has a bug or you are not using it properly ...
You can also use https://asn1.io/asn1playground/ as test to decode your PER data

Answer 3

After digging in Asn.1 Communication Between Heterogeneous Systems, I found a nice paragraph called Selecting a CHOICE alternative, which specify exactly what I was looking for:
The chosen type can be selected by the left angle bracket “ < ”
preceded by the alternative to be extracted and followed by a
reference to the CHOICE type
So the solution for my structure is to use:
DecryptedCertificate ::= SEQUENCE {
certificateProfileIdentifier INTEGER(0..255),
certificateAuthorityReference CertificateAuthority,
certificateHolderAuthorization CertificateHolderAuthorization,
endOfValidity TimeReal,
certificateHolderReference certificationAuthorityKID < KeyIdentifier,
rsaPublicKey RsaPublicKey
}
Of course I could have just hardcoded the type myself, however this is more flexible when it comes to specification modifications and more readable.