Why cant I authenticate my infura project with my secret key?

im trying to authenticate my infura project through curl but its not working for no reason. Im doing this on powershell in windows.
curl --user :my-secret-key https://mainnet.infura.io/v3/myprojectID
the result I get is:
404 page not found
Not really much to work with. Looked around in the infura community and im not seeing any answers figured i’d ask here. By the way, Im actually using the real curl and not invoke-webrequest as aliased by windows on powershell. I turned it off and installed curl through choco.
their tutorial and their docs say i should be doing this exact same thing but its not working on my machine
I tried the same command on a debian machine and I got the same result, I dont think its a powershell/curl on windows issue.

If you are submitting that request as a GET request then the 404 means you are authenticating properly but there is no resources available via GET. Our API is JSON-RPC which expects a POST request. try that same curl but with a valid JSON-RPC API POST request and you should get data back. Sorry for the confusion. I will note it with our engineering team that we should add more detail to our documentation.

curl -u :[YOUR_PROJECT_SECRET]  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}' https://mainnet.infura.io/v3/[YOUR_PROJECT_ID]

Yeah I just tried that it gave me this
{"jsonrpc":"2.0","error":{"code":-32600,"message":"invalid json request"}}
There shouldn’t be any problems on my end as im just making a request correct? I should just be getting ‘answers’ or in this case the blocknumber in the terminal.

Yes you should be getting a hex number back as a response. That error means that you are sending invalid JSON in your data payload. Double check your data payload by pasting it at jsonlint.com and make sure there isn’t some utf-8 character or some other typo.

If you share you code or the full curl request we can take a look at it for you.

curl -u :MYSECRET  -d '{"jsonrpc":"2.0","method":"eth_blockNumber","params":[],"id":1}' https://mainnet.infura.io/v3/myid

I just used the line above as you said and replaced my credentials in the placeholders. I had already verified that my JSON was valid. Not really sure what the problem is here. If I deliberately mess up my secret or project ID I get an authentication error so at least I know its successfully attempting to connect the infura API.

Continuing the discussion from Why cant I authenticate my infura project with my secret key?:

I got it to work. Tested it on a third linux machine I got up and running and it worked. Somehow my windows and my first linux tests both failed for known reasons. Thanks for the help.