Cannot understand output of libgcrypt's hashing functions

Jacob Bachmeyer jcb62281 at
Mon Mar 25 01:39:36 CET 2024

megamind6155 via Gnupg-devel wrote:
> Hello,
> I'm trying to use libgcrypt to generate a hash. I'm pretty new to 
> programming so I'm just testing out the library.
> This is the code I've written:
> [...]
> As you can see I'm just trying to test out this function. Everything 
> runs but at the end the printf prints out jibberish which I'm unable 
> to interpret. How is the hash digest encoded?
That jibberish is almost certainly a binary MD5 digest of "hello\n".  
Try piping the output of your program through "hexdump -C" and compare 
the last bytes to the output of "echo hello | md5sum" at a shell prompt.

As for how to use this, try writing a simple routine to dump the hash 
value as hexadecimal instead of trying to print it as a string.

-- Jacob

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