OpenMLS validation status

Leaf Node Validation ¶

The validity of a LeafNode needs to be verified at the following stages:

When a LeafNode is downloaded in a KeyPackage, before it is used to add the client to the group
When a LeafNode is received by a group member in an Add, Update, or Commit message
When a client validates a ratchet tree, e.g., when joining a group or after processing a Commit

id	status	description	notes & code refs
valn0101 ¶	Unknown	Verify that the credential in the LeafNode is valid, as described in Section 5.3.1. ref	search code notes: maybe this should be an application-level check? no refs to code. no refs to tests.
valn0102 ¶	Partial	Verify that the signature on the LeafNode is valid using signature_key. ref	search code notes: todo: add test ref code refs: openmls::key_packages::KeyPackageIn::validate no refs to tests.
valn0103 ¶	Partial	Verify that the LeafNode is compatible with the group's parameters. If the GroupContext has a required_capabilities extension, then the required extensions, proposals, and credential types MUST be listed in the LeafNode's capabilities field. ref	search code notes: reported in https://github.com/xmtp/openmls/pull/19 We currently test this when an Add and Update proposal is being committed. no refs to code. test refs: openmls::group::tests_and_kats::tests::group_context_extensions::fail_insufficient_capabilities_add_valno103 openmls::group::tests_and_kats::tests::group_context_extensions::fail_insufficient_capabilities_update_valno103
valn0104 ¶	Partial	Verify that the credential type is supported by all members of the group, as specified by the capabilities field of each member's LeafNode, and that the capabilities field of this LeafNode indicates support for all the credential types currently in use by other members. ref	search code notes: todo: add test refs code refs: openmls::group::public_group::validation::validate_capabilities no refs to tests.
valn0105 ¶	Partial	Verify the `lifetime` field: If the LeafNode appears in a message being sent by the client, e.g., a Proposal or a Commit, then the client MUST verify that the current time is within the range of the lifetime field. ref ref	search code notes: probably only done for key packages, but these should be the only leaf nodes with lifetimes anyway todo: add test refs code refs: openmls::key_packages::KeyPackageIn::validate no refs to tests.
valn0106 ¶	Missing	Verify the `lifetime` field: If instead the LeafNode appears in a message being received by the client, e.g., a Proposal, a Commit, or a ratchet tree of the group the client is joining, it is RECOMMENDED that the client verifies that the current time is within the range of the lifetime field. (This check is not mandatory because the LeafNode might have expired in the time between when the message was sent and when it was received.) ref ref	search code no notes. no refs to code. no refs to tests.
valn0107 ¶	Partial	Verify that the extensions in the LeafNode are supported by checking that the ID for each extension in the extensions field is listed in the capabilities.extensions field of the LeafNode. ref	search code notes: todo: add test ref code refs: openmls::group::public_group::validation::validate_capabilities no refs to tests.
valn0108 ¶	Partial	Verify the `leaf_node_source` field: If the LeafNode appears in a KeyPackage, verify that leaf_node_source is set to key_package. ref ref	search code notes: todo: add test refs code refs: openmls::key_packages::KeyPackageIn::validate no refs to tests.
valn0109 ¶	Partial	Verify the `leaf_node_source` field: If the LeafNode appears in an Update proposal, verify that leaf_node_source is set to update and that encryption_key represents a different public key than the encryption_key in the leaf node being replaced by the Update proposal. ref ref	search code notes: we might be more restrictive here, because we don't accept colliding keys at all, not just in Update proposals todo: add test refs code refs: openmls::group::public_group::PublicGroup::validate_key_uniqueness no refs to tests.
valn0110 ¶	Partial	Verify the `leaf_node_source` field: If the LeafNode appears in the leaf_node value of the UpdatePath in a Commit, verify that leaf_node_source is set to commit. ref ref	search code notes: TODO: find and document where this is tested code refs: openmls::treesync::treekem::UpdatePathIn::into_verified no refs to tests.
valn0111 ¶	Partial	Verify that the following fields are unique among the members of the group: `signature_key` ref ref	search code notes: todo: add test ref code refs: openmls::group::public_group::validation::validate_key_uniqueness no refs to tests.
valn0112 ¶	Partial	Verify that the following fields are unique among the members of the group: `encryption_key` ref ref	search code notes: todo: add test ref code refs: openmls::group::public_group::validation::validate_key_uniqueness no refs to tests.

Key Package Validation ¶

The validity of a KeyPackage needs to be verified at a few stages:

When a KeyPackage is downloaded by a group member, before it is used to add the client to the group
When a KeyPackage is received by a group member in an Add message

ref

id	status	description	notes & code refs
valn0201 ¶	Complete	Verify that the cipher suite and protocol version of the KeyPackage match those in the GroupContext. ref	search code no notes. no refs to code. test refs: openmls::group::tests_and_kats::tests::group_context_extensions::fail_key_package_version_valno201
valn0202 ¶	Unknown	Verify that the leaf_node of the KeyPackage is valid for a KeyPackage according to Section 7.3. ref	search code notes: currently this is only done when processing adds in commit messages no refs to code. no refs to tests.
valn0203 ¶	Partial	Verify that the signature on the KeyPackage is valid using the public key in `leaf_node.credential`. ref	search code notes: this looks like a bug in the RFC. It should be signed using leaf_node.signature_key, but the credential can have opinions on whether that key is valid. code refs: openmls::key_packages::KeyPackageIn::validate no refs to tests.
valn0204 ¶	Partial	Verify that the value of `leaf_node.encryption_key` is different from the value of the `init_key` field. ref	search code notes: todo: add test ref code refs: openmls::key_packages::KeyPackageIn::validate no refs to tests.

Regular Commit Proposal List Validation ¶

A group member creating a `Commit` and a group member processing a `Commit` MUST verify that the list of committed proposals is valid using one of the following procedures, depending on whether the `Commit` is external or not. If the list of proposals is invalid, then the Commit message MUST be rejected as invalid.

For a regular, i.e., not external, Commit, the list is invalid if any of the following occurs:

id	status	description	notes & code refs
valn0301 ¶	Partial	It contains an individual proposal that is invalid as specified invalid Section 12.1. ref	search code notes: The use of the ? operator means that if any of the checks fails, the function returns an error todo: add test ref code refs: openmls::group::public_group::PublicGroup::validate_commit no refs to tests.
valn0302 ¶	Partial	It contains an Update proposal generated by the committer. ref	search code notes: todo: add tests ref code refs: openmls::group::public_group::PublicGroup::validate_commit no refs to tests.
valn0303 ¶	Partial	It contains a Remove proposal that removes the committer. ref	search code no notes. code refs: openmls::group::mls_group::MlsGroup::from_committed_proposals no refs to tests.
valn0304 ¶	Missing	It contains multiple Update and/or Remove proposals that apply to the same leaf. If the committer has received multiple such proposals they SHOULD prefer any Remove received, or the most recent Update if there are no Removes. ref	search code notes: reported in https://github.com/xmtp/openmls/pull/19 this check seems contradictory; if a forbidden thing happens, use this resolution strategy. We likely don't do the right thing, but it's also not clear what the right thing would be. no refs to code. no refs to tests.
valn0305 ¶	Missing	It contains multiple Add proposals that contain KeyPackages that represent the same client according to the application (for example, identical signature keys). ref	search code notes: reported in https://github.com/xmtp/openmls/pull/19 possibly an app-level concern, but then we at least need to give the app the tools to valiate this no refs to code. no refs to tests.
valn0306 ¶	Missing	It contains an Add proposal with a KeyPackage that represents a client already in the group according to the application, unless there is a Remove proposal in the list removing the matching client from the group. ref	search code notes: reported in https://github.com/xmtp/openmls/pull/19 possibly an app-level concern, but then we at least need to give the app the tools to valiate this no refs to code. no refs to tests.
valn0307 ¶	Partial	It contains multiple PreSharedKey proposals that reference then same PreSharedKeyID. ref	search code no notes. code refs: openmls::group::public_group::PublicGroup::validate_pre_shared_key_proposals no refs to tests.
valn0308 ¶	Complete	It contains multiple GroupContextExtension proposals. ref	search code no notes. code refs: openmls::group::public_group::validate_group_context_extensions_proposal test refs: openmls::group::tests_and_kats::tests::group_context_extensions::fail_3gce_proposals_1_commit_valno308
valn0309 ¶	Missing	It contains a ReInit proposal together with any other proposal. If the committer has received other proposals during the epoch, they SHOULD prefer them over the ReInit proposal, allowing the ReInit to be resent and applied in a subsequent epoch. ref	search code notes: reported in https://github.com/xmtp/openmls/pull/19 no refs to code. no refs to tests.
valn0310 ¶	Missing	It contains an ExternalInit proposal. ref	search code notes: reported in https://github.com/xmtp/openmls/pull/19 no refs to code. no refs to tests.
valn0311 ¶	Missing	It contains a Proposal with a non-default proposal type that is not supported by some members of the group that will process the Commit (i.e., members being added or removed by the Commit do not need to support the proposal type). ref	search code notes: reported in https://github.com/xmtp/openmls/pull/19 no refs to code. no refs to tests.
valn0312 ¶	Missing	After processing the Commit the ratchet tree is invalid, in particular, if it contains any leaf node that is invalid according to Section 7.3. ref	search code no notes. no refs to code. no refs to tests.

External Commit Proposal List Validation ¶

For an external Commit, the list is valid if it contains only the following proposals (not necessarily in this order):

id	status	description	notes & code refs
valn0401 ¶	Unknown	Exactly one ExternalInit ref	search code no notes. no refs to code. no refs to tests.
valn0402 ¶	Missing	At most one Remove proposal, with which the joiner removes an old version of themselves. If a Remove proposal is present, then the LeafNode in the path field of the external Commit MUST meet the same criteria as would the LeafNode in an Update for the removed leaf (see Section 12.1.2). In particular, the credential in the LeafNode MUST present a set of identifiers that is acceptable to the application for the removed participant. ref	search code notes: reported in https://github.com/xmtp/openmls/pull/19 no refs to code. no refs to tests.
valn0403 ¶	Unknown	Zero or more PreSharedKey proposals ref	search code no notes. no refs to code. no refs to tests.
valn0404 ¶	Unknown	No other proposals ref	search code no notes. no refs to code. no refs to tests.

id	status	description	notes & code refs
valn0501 ¶	Partial	An Add proposal is invalid if the KeyPackage is invalid according to Section 10.1. ref	search code notes: todo: add test refs code refs: openmls::messages::proposals_in::AddProposalIn::validate no refs to tests.

id	status	description	notes & code refs
valn0601 ¶	Partial	An Update proposal is invalid if the LeafNode is invalid for an Update proposal according to Section 7.3. ref	search code notes: todo: add test refs code refs: openmls::messages::proposals_in::UpdateProposalIn::validate no refs to tests.

id	status	description	notes & code refs
valn0701 ¶	Partial	A Remove proposal is invalid if the removed field does not identify a non-blank leaf node. ref	search code notes: the tests we have a are not great. The check and basic tests were added in PR https://github.com/openmls/openmls/pull/1655 code refs: openmls::group::PublicGroup::validate_remove_proposals no refs to tests.

PreSharedKey Proposal Validation ¶

A PreSharedKey proposal can be used to request that a pre-shared key be injected into the key schedule in the process of advancing the epoch.

A PreSharedKey proposal is invalid if any of the following is true:

id	status	description	notes & code refs
valn0801 ¶	Missing	The PreSharedKey proposal is not being processed as part of a reinitialization of the group (see Section 11.2), and the PreSharedKeyID has psktype set to resumption and usage set to reinit. ref	search code notes: PSK support not implemented no refs to code. no refs to tests.
valn0802 ¶	Missing	The PreSharedKey proposal is not being processed as part of a subgroup branching operation (see Section 11.3), and the PreSharedKeyID has psktype set to resumption and usage set to branch. ref	search code notes: PSK support not implemented no refs to code. no refs to tests.
valn0803 ¶	Partial	The psk_nonce is not of length KDF.Nh. ref	search code notes: todo: find test refs code refs: openmls::schedule::psk::PreSharedKeyId::validate_in_proposal no refs to tests.

status

description

notes & code refs

valn0801 ¶

Missing

The PreSharedKey proposal is not being processed as part of a reinitialization of the group (see Section 11.2), and the PreSharedKeyID has psktype set to resumption and usage set to reinit.

search code

notes:

PSK support not implemented

no refs to code.

no refs to tests.

valn0802 ¶

Missing

The PreSharedKey proposal is not being processed as part of a subgroup branching operation (see Section 11.3), and the PreSharedKeyID has psktype set to resumption and usage set to branch.

search code

notes:

PSK support not implemented

no refs to code.

no refs to tests.

valn0803 ¶

Partial

The psk_nonce is not of length KDF.Nh.

search code

notes:

todo: find test refs

code refs:

openmls::schedule::psk::PreSharedKeyId::validate_in_proposal

no refs to tests.

id	status	description	notes & code refs
valn0901 ¶	Unknown	A ReInit proposal is invalid if the version field is less than the version for the current group. ref	search code notes: this feature is not implemented no refs to code. no refs to tests.

id	status	description	notes & code refs
valn1001 ¶	Partial	A GroupContextExtensions proposal is invalid if it includes a required_capabilities extension and some members of the group do not support some of the required capabilities (including those added in the same Commit, and excluding those removed). ref	search code notes: currently, we only test for missing supported extension types, not proposal or proposal types. code refs: openmls::group::public_group::PublicGroup::validate_group_context_extensions_proposal test refs: openmls::group::tests_and_kats::tests::group_context_extensions::fail_unsupported_gces_add_valno1001

id	status	description	notes & code refs
valn1101 ¶	Partial	For each UpdatePathNode, the resolution of the corresponding copath node MUST exclude all new leaf nodes added as part of the current Commit. The length of the encrypted_path_secret vector MUST be equal to the length of the resolution of the copath node (excluding new leaf nodes), with each ciphertext being the encryption to the respective resolution node. ref	search code notes: todo: find test refs code refs: openmls::treesync::TreeSyncDiff::diff no refs to tests.

Processing a Commit ¶

A member of the group applies a Commit message by taking the following steps:

id	status	description	notes & code refs
valn1201 ¶	Partial	Verify that the epoch field of the enclosing FramedContent is equal to the epoch field of the current GroupContext object. ref	search code notes: todo: find test refs code refs: openmls::group::public_group::PublicGroup::validate_commit no refs to tests.
valn1202 ¶	Partial	Unprotect the Commit using the keys from the current epoch: If the message is encoded as PublicMessage, verify the membership MAC using the membership_key. ref ref	search code notes: todo: add test refs code refs: openmls::group::mls_group::MlsGroup::process_message openmls::group::public_group::PublicGroup::process_message no refs to tests.
valn1203 ¶	Partial	Verify the signature on the FramedContent message as described in Section 6.1. ref	search code notes: todo: find test refs code refs: openmls::group::mls_group::MlsGroup::process_unverified_message openmls::group::public_group::PublicGroup::process_unverified_message no refs to tests.
valn1204 ¶	Partial	Verify that the proposals vector is valid according to the rules in Section 12.2. ref	search code notes: todo: find test refs code refs: openmls::group::mls_group::MlsGroup::stage_commit openmls::group::public_group::PublicGroup::stage_commit no refs to tests.
valn1205 ¶	Unknown	Verify that all PreSharedKey proposals in the proposals vector are available. ref	search code notes: of course you need all the proposals and all the psks before being able to apply the commit... This is implicit in the code no refs to code. no refs to tests.
valn1206 ¶	Partial	Verify that the path value is populated if the proposals vector contains any Update or Remove proposals, or if it's empty. Otherwise, the path value MAY be omitted. ref	search code notes: todo: find test refs code refs: openmls::group::public_group::PublicGroup::stage_diff no refs to tests.
valn1207 ¶	Missing	If the path value is populated, validate it and apply it to the tree: Validate the LeafNode as specified in Section 7.3. The leaf_node_source field MUST be set to commit. ref ref	search code no notes. no refs to code. no refs to tests.
valn1208 ¶	Missing	If the path value is populated, validate it and apply it to the tree: Verify that the encryption_key value in the LeafNode is different from the committer's current leaf node. ref ref	search code no notes. no refs to code. no refs to tests.
valn1209 ¶	Partial	If the path value is populated, validate it and apply it to the tree: Verify that none of the public keys in the UpdatePath appear in any node of the new ratchet tree. ref ref	search code notes: todo: add test refs code refs: openmls::group::public_group::PublicGroup::validate_key_uniqueness no refs to tests.

Leaf Node Validation ¶

Key Package Validation ¶

Regular Commit Proposal List Validation ¶

External Commit Proposal List Validation ¶

Add Proposal Validation ¶

Update Proposal Validation ¶

Remove Proposal Validation ¶

PreSharedKey Proposal Validation ¶

ReInit Proposal Validation ¶

GroupContextExtensions Proposal Validation ¶

Update Path Validation ¶

Processing a Commit ¶