Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

ODCID is a special for validating the server address #4344

Merged
merged 4 commits into from Nov 9, 2020
Merged

ODCID is a special for validating the server address #4344

Changes from 1 commit
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
b071df7
ODCID is a special for validating the server address
martinthomson Nov 9, 2020
c066481
Magic
martinthomson Nov 9, 2020
9f1c03c
Revert "Magic"
martinthomson Nov 9, 2020
da21152
More words on client validation of the server address
martinthomson Nov 9, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Jump to
Jump to file
Failed to load files.
Diff view
Diff view
7 changes: 4 additions & 3 deletions draft-ietf-quic-transport.md
View file
Open in desktop
Expand Up @@ -1928,9 +1928,10 @@ consider the peer address to have been validated.

Additionally, an endpoint MAY consider the peer address validated if the peer
uses a connection ID chosen by the endpoint and the connection ID contains at
least 64 bits of entropy. For the client, the value of the Destination
Connection ID field in its first Initial packet also fulfills this requirement,
such that successfully processing any packet validates the server address.
least 64 bits of entropy. A client can consider the server address validated on
successfully processing any packet received from the server, since for
Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Rather than "any packet", I think we might wan to say "Initial packet"? By stating as such, we can be clear that the receipt of Retry packets does not mean that the path has been validated. We do not need to be worried about Handshake or 1-RTT packets because processing an Initial packet is the prerequisite for obtaining keys necessary to decrypt Handshake and 1-RTT packets.

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

So any packet is correct, if we also say "successfully processed". Retry and VN both echo the Destination Connection ID field, and Initial packets use encryption. This is why I think that I will roll back Jana's proposed change - at least partly.

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@martinthomson Re Retry, I'm not sure if that is the case.

Section 17.2.5.1 specifies that a server MUST NOT echo the value of the DCID field of an Initial packet that it receives. Therefore, for a client, receiving a Retry packet does not mean that the server has received the Initial packet carrying the DCID that the client chose.

Copy link
Member Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Oh right. It's the authentication tag in Retry that provides that proof. Such a complicated, fiddly protocol.

Copy link
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Ah right. Receipt of Retry packets do validate the address using a different mechanism 🤦

encrypting its Initial packets, the server uses the Destination Connection ID
field from the client's first Initial packet; see Section 5.2 of {{QUIC-TLS}}.

Prior to validating the client address, servers MUST NOT send more than three
times as many bytes as the number of bytes they have received. This limits the
Expand Down