testing/certutil: add support to RSA

[AndersonQ]

What does this PR do?

Enhance testing/certutil:

• add support to generate RSA certificates
• add -rsa cli to generate RSA certificates

Why is it important?

RSA keys are needed to test:

• Decrypt client TLS certificate key for Elastic Defend elastic-agent#5542

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works

How to test

the following should generate RSA keys:

cd testing/certutil/cmd
go run main.go --prefix rsa --pass rsa  --ips 10.80.40.42,127.0.0.1 -name localhost -rsa

verify the certificates with:

openssl x509 -in rsa-localhost.pem -text -noout | grep -E "Algorithm"

        Signature Algorithm: sha256WithRSAEncryption
            Public Key Algorithm: rsaEncryption
    Signature Algorithm: sha256WithRSAEncryption

the keys with:

openssl rsa -in rsa-ca_key.pem -text -noout

Private-Key: (2048 bit, 2 primes)
[...]

Related issues

• Relates Decrypt client TLS certificate key for Elastic Defend elastic-agent#5542

[AndersonQ]

/test

[mauri870]

LGTM, confirmed that it can generate valid rsa keys.

[AndersonQ]

good catch, it was a leftover from while I was refactoring. Also crypto.PrivateKey is any

[AndersonQ]

/test

[elasticmachine]

💚 Build Succeeded

• Buildkite Build
• Commit: 5d792b9

History

• 💚 Build #400 succeeded 27d7dcb
• 💚 Build #399 succeeded 162e7fc
• 💚 Build #398 succeeded 5e9fd64
• 💔 Build #397 failed b9f2de6
• 💔 Build #396 failed dcf177b
• 💔 Build #395 failed fcae5b8

cc @AndersonQ