DLI Implementation and Reference Guide - Datalogics

15.6 DLI Implementation and Reference Guide
corresponding to the public key in the certificate. The RSA public-key algorithm with
a 1024-bit key length is used.
Concepts and Facilities: Guide to the DL Pager Composition System
The genPKCS7Cert callback is called by DLI during the dlpdfdocwritepdf
function call. The callback is supplied a binary data buffer of length maxLen. The
first 16 bytes of this buffer contain the MD5 checksum (in binary) for the PDF
document to sign. The callback must generate a PKCS #7 certificate as described
above, and fill the data buffer with the certificate, in binary. The callback function
must return the length to read from the data buffer, in bytes.
NOTE: maxLen bytes are set aside in the output PDF file for the PKCS #7
certificate, and will be written to the PDF file regardless of the actual certificate
length. Callers should pass length values which are close to the certificate length
if possible.
dlpdfsignaturesetdatacallback
This call is optional for clients using PKCS #7 certificates. A callback function is
supplied for the signature. The callback is called during the dlpdfdocwritepdf
function with binary information from the PDF file. This information will be in
sequential pieces, and may be used to generate the PDF document hash value. The
information is supplied as binary values in the character buffer; the length to read is
supplied as the second parameter. A length of 0 indicates that no further data is to be
read, and the hash may be finalized.
dlpdfpageplacesignature
This call associates a digital signature to a page in the PDF file generated by DLI. The
signature appearance must fit in the bounds supplied in imageBBox. This call is
required for all digital signatures, even invisible signatures. For invisible digital
signatures, the imageBBox is ignored and may be NULL.