• Registered: 2021-02-18
  • Posts: 6

Topic: wolfSSL failed to load private key of self-generated cert

I created an issue ticket on GitHub, but I'm also asking it here.

Hi, I'm very new to wolfSSL, it's the most smooth experience I had with an SSL lib ever and thanks to wolfssl-examples smile
I want to use my own self-generated cert for my server, so I generated cert and private key with OpenSSL CLI util with

$ openssl req -x509 -newkey rsa:4096 -keyout key.pem -out cert.pem -days 365

and when I try to use these generated files on my implementation, I'm getting the following error

ERROR: Failed to load ./key.pem, please check the file.

from wolfSSL_CTX_use_PrivateKey_file function. I'm not sure what goes wrong, Can someone help me with this?
I'm using wolfSSL Release 4.7.0
My code example is from https://github.com/wolfSSL/wolfssl-exam … rver-tls.c

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  • From: Mobile, AL
  • Registered: 2013-12-11
  • Posts: 357

Re: wolfSSL failed to load private key of self-generated cert

Hello sapi01

Thanks for your kind words. We also think wolfSSL is the greatest.

I found a solution for this, but not a reason for why it works. If I use openSSL to open the key and simply write it out again using this command:

openssl rsa -inform pem -in server.key -outform pem -out server.key2

The new key (server.key2) will work in wolfSSL.

The certs and keys used in the examples are generated with this script:
https://github.com/wolfSSL/wolfssl/blob … ts.sh#L176

Maybe breaking up the openssl commands makes a difference?

Thanks,
Eric @ wolfSSL Support

embhorn's Website

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  • jeff
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  • Registered: 2020-09-14
  • Posts: 28

Re: wolfSSL failed to load private key of self-generated cert

Hi sapi01,

By default openSSL encrypts the key with a passphrase (which is a reasonable default) and wolfSSL doesn't have the passphrase.
To not protect the key file with a passphrase, the `-nodes` (that's no DES) can be used.

openssl req -x509 -nodes -newkey rsa:4096 -keyout key.pem -out cert.pem -days 365

Interestingly telling openssl to convert the RSA format as Eric showed, doesn't protect the key when output.

Hope that helps. Cheers,
Jeff

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4 Reply by jeff (edited by jeff 2021-02-18 11:46:15)

  • jeff
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  • Registered: 2020-09-14
  • Posts: 28

Re: wolfSSL failed to load private key of self-generated cert

To clarify wolfSSL does support passpharse protected keys.

In the main wolfSSL repo the server example supports this with a call to SSL_CTX_set_default_passwd_cb when configured with --enable-enckeys.

See the callback implementation here. wolfSSL_CTX_set_default_passwd_cb_userdata is also useful for supporting these keys.

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