Function build_cmp_response 

pub fn build_cmp_response(
    req: &CmpRequest,
    response_type: CmpMessageType,
    body: &[u8],
) -> Result<Vec<u8>, KipukaError>

Build a DER-encoded CMP PKIMessage response.

Constructs a PKIMessage with:

• header: sender, recipient, transactionID, senderNonce, recipNonce
• body: the response content tagged with the response type
• protection: signature computed with the CA signing key
• extraCerts: CA certificate chain for validation

Errors

• KipukaError::BadRequest — empty transaction ID or body.
• KipukaError::Internal — ASN.1 encoding not yet implemented.