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libp2p / specs

Technical specifications for the libp2p networking stack
https://libp2p.io
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Handling unknown critical extensions #239

Open Demi-Marie opened 4 years ago

Demi-Marie commented 4 years ago

When TLS is used with libp2p, are unknown critical extensions still considered to be fatal errors?

Stebalien commented 4 years ago

Yes, but this should be documented. Would you mind updating the spec (tls/tls.md)?

Note: The go implementation, at least, should already reject certs with unknown critical extensions.

marten-seemann commented 4 years ago

RFC 5280 defines how unknown critical extensions are handled:

Each extension in a certificate is designated as either critical or non-critical. A certificate-using system MUST reject the certificate if it encounters a critical extension it does not recognize or a critical extension that contains information that it cannot process. A non-critical extension MAY be ignored if it is not recognized, but MUST be processed if it is recognized.

Do you think we need any text in addition to this?

Stebalien commented 4 years ago

Explicitly stating this in our spec can't hurt. It's something that TLS implementations might leave up to the application layer to enforce when the application layer is manually validating certificate chains (like we do).

Stebalien commented 4 years ago

(not critical, it just can't hurt if someone has the time)