Hi Pablo,
I mean, to get hash of the file attached to the document, I need to save the buffer for "context(utilities.sha2.hash256(io.loaddata(buffer)))".
But I don’t need to save the buffer to attach it to the PDF document.
My question is how to define \shabufferfile to avoid \savebuffer (only required to get the hash).
The SHA calculation isn't working properly because of a weird newline issue. Try this: \setupinteraction[state=start] \setupinteractionscreen[option={attachment}] \startbuffer[test] just a test and another one \stopbuffer \starttext \startluacode require("util-sha") function sha256(str) return utilities.sha2.hash256( str:gsub(string.char(0x0D), string.char(0x0A)) ) end \stopluacode \def\shabuffer#1% {\cldcontext{sha256(buffers.raw("#1"))}} \def\shafile#1% {\cldcontext{sha256(io.loaddata("#1"))}} \shabuffer{test} \savebuffer[test][temporary-αβγ, prefix=no] \shafile{temporary-αβγ} \attachment[buffer=test, name=\shabuffer{test}, method=hidden] \stoptext You can remove the "\savebuffer" and the "\shafile"; I just kept that in to show that the two hashes are now the same. -- Max