You need to generate a hash in ClassicASP, which is equivalent to the following functions of PHP: $ hash = hash _ hmac ('sha256', $ message, pack ('h *', $ secret))；); $ message = ' stackoverflow$ secret = ' 1234567890 abcdef '； I tried many online methods, but none of them matched PHP.

And save it as a picture, put it in PDF, and I created an image (*; Png) from hexadecimal code (signature board generates hexadecimal number); The image seems good, but for some reason, it can't be put into PDF format through FPDF. But I can use FPDF to put any other image in my PDF; So I guess there is something wrong with my HEXtoImage.

This function is used to package the corresponding parameter ($args) into a binary string. The first parameter is $format.