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Replaced WG Oblivious HTTP (ohttp)

WG Name Oblivious HTTP
Acronym ohttp
Area Security Area (sec)
State Replaced
Charter charter-ietf-ohttp-00-02 Replaced
Document dependencies
Personnel Chairs Alexey Melnikov, Richard Barnes
Area Director Francesca Palombini
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Charter for Working Group

In a number of different settings, interactions between clients and servers involve information that could be sensitive when associated with client identity. Client-server applications built on HTTP reveal aspects of client identity to servers through these interactions, especially source addresses. Even without client identity, a server might be able to build a profile of client activity by correlating requests from the same client over time.

In HTTP-based applications where the information included in requests does not need to be correlated, the Oblivious HTTP protocol allows a supporting server to accept requests via a proxy. The proxy ensures that the server cannot see source addressing information for clients, which prevents servers linking requests to the same client using such information. Encryption ensures that the proxy is unable to read requests or responses. However, if the proxy and server collude, then neither of these privacy properties hold.

Applications and use cases best suited for the Oblivious HTTP protocol are those that have discrete, transactional queries that might reveal small amounts of information over time. Examples include DNS queries, data or telemetry submission, and certificate revocation checking. In some of these application deployments, the relationship between client, server, and cooperating proxy is typically configured out-of-band.

General purpose HTTP applications such as web browsing are not in scope for the Oblivious HTTP protocol. Broad applicability is limited by multiple factors, including the need for explicit server support of the protocol. In contrast, transport-level proxies such as HTTP CONNECT or MASQUE are a more appropriate mechanism for those use cases, as they allow connecting to unmodified servers.

The OHTTP working group will define the Oblivious HTTP protocol, a method of encapsulating HTTP requests and responses that provides protected, low-latency exchanges. The working group will define any encryption scheme necessary and supporting data formats for carrying encapsulated requests and responses, plus any key configuration that might be needed to use the protocol.

The OHTTP working group will include an applicability statement that documents the limitations of this design and any usage constraints that are necessary to ensure that the protocol is secure. The working group will consider the operational impact as part of the protocol design and document operational considerations.

The working group will prioritize work on the core protocol elements as identified. In addition, the working group may work on other use cases and deployment models, including those that involve discovery of OHTTP proxies or servers and their key configurations.

The OHTTP working group will work closely with other groups that develop the tools that Oblivious HTTP depends on (HTTPbis for HTTP, CFRG for HPKE) or that might use Oblivious HTTP (DPRIVE and ADD for DNS over HTTPS).

The working group will use draft-thomson-http-oblivious as input.