DSN Format

[paragonie-scott]

Since we are using DSN-like strings for the constructor, we should decide how they behave.

• ":cipher=AES-256;mode=GCM" should use whatever driver allows aes-256-gcm or throw an exception if none are available
• "openssl:cipher=AES-256;mode=GCM" should use specifically openssl for aes-256-gcm, and throw an exception if openssl is not installed
• "libsodium" should use libsodium (or throw an exception if it's not installed) in the default configuration
• "openssl" should use openssl in a secure, sane default
• "openssl:cipher=AES-128;mode=ECB" should throw an exception because we do not allow secure modes
• "openssl:cipher=AES" should use aes-128-ctr with HMAC-SHA-256
• "openssl:cipher=AES-128;hash=SHA256" should use aes-128-ctr with HMAC-SHA-256

Thoughts or contrary positions are welcome.

[paragonie-scott]

$crypto = new \PCO\Asymmetric('openssl'); // should work, but
$crypto = new \PCO\Asymmetric('openssl:cipher=AES'); // should this fail?

[ircmaxell]

I would have it fail, if only for not specifying the variant of AES (should be openssl:cipher=AES-128)

[paragonie-scott]

I've updated the OP. That makes more sense than separating the keysize out as a second option.

$crypto = new \PCO\Asymmetric('openssl'); // should work, but
$crypto = new \PCO\Asymmetric('openssl:cipher=AES-128'); // should this fail?

[AshleyPinner]

@ircmaxell What about making it assume you want AES-128 and throw a notice?

[ircmaxell]

I wouldn't raise a notice. If we want to default to AES-128, that's fine. Just make that the default.

[paragonie-scott]

Updated the OP. I agree that AES should map to AES-128 since simply "openssl" is a sane default.