pkce base64 url encoder

[wibed]

I am having issues with the base64.RawURLEncoder encoding the sha256 digest to check the challenge against the
code_verifier, in the pkce flow.

when I pass a random String:
dHB4ZWJqZXFwdW52bWJ1d2Vta3B1Z3JoZnl1Z3V0Ym8
and encode it with the rawUrl encoder option:
ZEhCNFpXSnFaWEZ3ZFc1MmJXSjFkMlZ0YTNCMVozSm9abmwxWjNWMFltOA

it checks out and encodes correctly (in the playground compared to my client)

but

when I sha256.hash above encoded random String:
c0f27a25520e25e9a4bc7c5b4bbe6039ae98850d07a355dda9839f337b22fa7e

even though when I fmt.Println("%x", hash.Sum(nil)) is equivalent the above hash
when I use the same base64 encoder producing the correct output, as showed above,

my client gets:
YzBmMjdhMjU1MjBlMjVlOWE0YmM3YzViNGJiZTYwMzlhZTk4ODUwZDA3YTM1NWRkYTk4MzlmMzM3YjIyZmE3ZQ

while base64.RawURLEncoder.EncodeToString(hash.Sum(nil)) results in:
wPJ6JVIOJemkvHxbS75gOa6YhQ0Ho1XdqYOfM3si-n4

why does it produce the exact same output on the first example, but an entirely different one
on the second?

I have tested it with third party options and none produces the same output as the go one, somehow

[vinckr]

Could you give me some pointers how to reproduce this?

[vinckr]

There was an older issue related to this:
#1572 (comment)

[wibed]

you were right.

I should have differentiated between the raw digest and the hex encoded one. the latter my sha256 has used implicitly.
I had to include a c library to get to the raw digest.

thank you for your help. greatly appreciated

[vinckr]

No problem, glad it got cleared up quickly!