// Copyright 2016 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

syntax = "proto3";

// Key Transparency
//
// The Key Transparency API consists of a map of user names to public
// keys. Each user name also has a history of public keys that have been
// associated with it.
package google.keytransparency.v1;

option go_package = "github.com/google/keytransparency/core/api/v1/keytransparency_go_proto";

import "google/api/annotations.proto";
import "google/protobuf/empty.proto";
import "trillian.proto";
import "trillian_map_api.proto";
import "v1/admin.proto";

// Committed represents the data committed to in a cryptographic commitment.
// commitment = HMAC_SHA512_256(key, data)
message Committed {
  // key is the 16 byte random commitment key.
  bytes key = 1;
  // data is the data being committed to.
  bytes data = 2;
}

// EntryUpdate contains the user entry update(s).
// EntryUpdate will be placed in a Log of mutations.
message EntryUpdate {
  // user_id specifies the id for the user whose profile is being updated.
  string user_id = 1;
  // mutation authorizes the change to entry.
  SignedEntry mutation = 2;
  // committed contains the data committed to in mutation.commitment.
  Committed committed = 3;
}

//
// Verifiable Map Leaf Data and Mutation Data.
//

// Entry is a signed change to a map entry.
// Entry contains a commitment to profile and a set of authorized update keys.
// Entry is placed in the verifiable map as leaf data.
message Entry {
  // index is the location of this leaf in the sparse merkle tree.
  bytes index = 3;
  // commitment is a cryptographic commitment to arbitrary data.
  bytes commitment = 6;
  // authorized_keys is the tink keyset that validates the signatures on the next entry.
  bytes authorized_keyset = 9;
  // previous contains the SHA256 hash of SignedEntry.Entry the last time it was modified.
  bytes previous = 8;
  // Deprecated tag numbers, do not reuse.
  reserved 1, 2, 4, 5, 7;
}

// SignedEntry is a cryptographically signed Entry.
// SignedEntry will be storead as a trillian.Map leaf.
message SignedEntry {
  // entry contains a serialized Entry.
  bytes entry = 1;
  // signatures on entry. Must be signed by keys from both previous and
  // current revisions. The first proves ownership of new revision key, and the
  // second proves that the correct owner is making this change.
  // The signature scheme is specified by the authorized_keys tink.Keyset.
  repeated bytes signatures = 2;
}

// MutationProof contains the information necessary to compute the new leaf
// value. It contains a) the old leaf value with it's inclusion proof and b) the
// mutation. The new leaf value is computed via:
//       Mutate(leaf_value, mutation)
message MutationProof {
  // mutation contains the information needed to modify the old leaf.
  // The format of a mutation is specific to the particular Mutate function
  // being used.
  SignedEntry mutation = 1;
  // leaf_proof contains the leaf and its inclusion proof for a particular map
  // revision.
  trillian.MapLeafInclusion leaf_proof = 2;
}

// MapperMetadata tracks the mutations that have been mapped so far. It is
// embedded in the Trillian SignedMapHead.
message MapperMetadata {
  int64 highest_fully_completed_seq = 1;
}

// Gets the leaf entry for a user.
message GetUserRequest {
  // directory_id identifies the directory in which the user lives.
  string directory_id = 1;
  // user_id is the user identifier, the format for which is defined by the
  // application.
  string user_id = 2;
  // last_verified is the last log root the client verified.
  // Omitting this field will omit the log consistency proof from the response.
  LogRootRequest last_verified = 4;
  reserved 3;
}

// Leaf entry for a user.
message MapLeaf {
  // vrf_proof is the proof for the VRF on user_id.
  bytes vrf_proof = 1;
  // map_inclusion is an inclusion proof for the map leaf in an accompanying
  // trillian.SignedMapRoot. If the leaf is non-empty, its leaf.leaf_value
  // stores a serialized Entry proto.
  trillian.MapLeafInclusion map_inclusion = 2;
  // committed contains the data and nonce used to make a cryptographic
  // commitment, which is stored in the commitment field of the serialized Entry
  // proto from map_inclusion.
  // Note: committed can also be found serialized in
  // map_inclusion.leaf.extra_data.
  Committed committed = 3;
}

// Contains the leaf entry for a user at the most recently published revision.
message GetUserResponse {
  // revision is the most recently published revision.
  Revision revision = 1;
  // leaf is the leaf entry for the requested user.
  MapLeaf leaf = 2;
}

// BatchGetUserRequest contains multiple user_ids to fetch.
message BatchGetUserRequest {
  // directory_id identifies the directory in which the users live.
  string directory_id = 1;
  // user_ids are the user identifiers, the format for which is defined by the
  // application.
  repeated string user_ids = 2;
  // last_verified is the last log root the client verified.
  // Omitting this field will omit the log consistency proof from the response.
  LogRootRequest last_verified = 4;
  reserved 3;
}

// BatchGetUserIndexRequest identifies a set of users.
message BatchGetUserIndexRequest {
  // directory_id identifies the directory in which the users live.
  string directory_id = 1;
  // user_ids are the user identifiers
  repeated string user_ids = 2;
}

// BatchGetUserIndexRequest identifies a single user.
message BatchGetUserIndexResponse {
  // proofs is a map from user_id to its VRF proof.
  // Clients get the index by verifying the VRF proof.
  map<string, bytes> proofs = 1;
}

// BatchGetUserResponse contains the leaf entries for a set of users at the most
// recently published revision.
message BatchGetUserResponse {
  // revision is the most recently published revision.
  Revision revision = 1;
  // map_leaves_by_user_id is a map from user_id to the map leaf at the most
  // recently published revision.
  map<string, MapLeaf> map_leaves_by_user_id = 2;
}

// ListEntryHistoryRequest gets a list of historical keys for a user.
message ListEntryHistoryRequest {
  // directory_id identifies the directory in which the user lives.
  string directory_id = 6;
  // user_id is the user identifier.
  string user_id = 1;
  // start is the starting revision.
  int64 start = 2;
  // page_size is the maximum number of entries to return.
  // The server can return fewer entries than requested.
  int32 page_size = 3;
  // last_verified is the last log root the client verified.
  // Omitting this field will omit the log consistency proof from the response.
  LogRootRequest last_verified = 7;
  reserved 4, 5;
}

// ListEntryHistoryResponse requests a paginated history of keys for a user.
message ListEntryHistoryResponse {
  // values represents the list of keys this user_id has contained over time.
  repeated GetUserResponse values = 1;
  // next_start is the next page token to query for pagination.
  // next_start is 0 when there are no more results to fetch.
  int64 next_start = 2;
}

// ListUserRevisionsRequest gets a list of historical keys for a user.
message ListUserRevisionsRequest {
  // directory_id identifies the directory in which the user lives.
  string directory_id = 1;
  // user_id is the user identifier.
  string user_id = 2;
  // start_revision is the starting epoch.
  int64 start_revision = 3;
  // end_revision is the ending epoch.
  int64 end_revision = 4;
  // page_size is the maximum number of entries to return. If page_size is
  // unspecified, the server will decide how to paginate results.
  int32 page_size = 5;
  // page_token is a continuation token for paginating through results.
  string page_token = 6;
  // last_verified is the last log root the client verified.
  // Omitting this field will omit the log consistency proof from the response.
  LogRootRequest last_verified = 8;
  reserved 7;
}

// MapRevision contains a map leaf at a speific revision.
message MapRevision {
  // map_root contains the map root and its inclusion in the log.
  MapRoot map_root = 1;
  // map_leaf contains a leaf and its inclusion proof to map_root.
  MapLeaf map_leaf = 2;
}

// ListUserRevisionsResponse requests a paginated history of keys for a user.
message ListUserRevisionsResponse {
  // latest_log_root contains the latest log root and its consistency proof.
  LogRoot latest_log_root = 1;
  // map_revisions represents the list of keys this user_id has contained over
  // time. At most page_size results will be returned.
  repeated MapRevision map_revisions = 2;
  // next_page_token is a pagination token which will be set if more than
  // page_size results are available. Clients can pass this value as
  // the page_token in the next request in order to continue pagination.
  string next_page_token = 3;
}

// BatchListUserRevisionsRequest contains a list of users and a range of revisions.
message BatchListUserRevisionsRequest {
  // directory_id identifies the directory in which the users live.
  string directory_id = 1;
  // user_ids are the user identifiers.
  repeated string user_ids = 2;
  // start_revision is the starting revision.
  int64 start_revision = 3;
  // end_revision is the ending epoch.
  int64 end_revision = 4;
  // page_size is the maximum number of entries to return. If page_size is
  // unspecified, the server will decide how to paginate results.
  int32 page_size = 5;
  // page_token is a continuation token for paginating through results.
  string page_token = 6;
  // last_verified is the last log root the client verified.
  // Omitting this field will omit the log consistency proof from the response.
  LogRootRequest last_verified = 8;
  reserved 7;
}

// BatchMapRevision contains a set of map leaves at a speific revision.
message BatchMapRevision {
  // map_root contains the map root and its inclusion in the log.
  MapRoot map_root = 1;
  // map_leaves_by_user_id contains a mapping from user_id to the map leaf at
  // this revision.
  map<string, MapLeaf> map_leaves_by_user_id = 2;
}

// BatchListUserRevisionsResponse contains multiple map leaves across multiple revisions.
message BatchListUserRevisionsResponse {
  // latest_log_root contains the latest log root and its consistency proof.
  LogRoot latest_log_root = 1;
  // map_revisions is a list of map revisions.  At most page_size revisions will be returned.
  repeated BatchMapRevision map_revisions = 2;
}

// UpdateEntryRequest updates a user's profile.
message UpdateEntryRequest {
  // directory_id identifies the directory in which the user lives.
  string directory_id = 5;
  // Used to be user_id. user_id now lives in EntryUpdate.
  reserved 1;
  // Used to be app_id. Applications can define their own hierarchy for user_id
  // if desired.
  reserved 2;
  // Used to be first_tree_size. QueueEntryUpdate no longer returns any data.
  reserved 3;
  // entry_update contains the user submitted update.
  EntryUpdate entry_update = 4;
}

// BatchQueueUserUpdateRequest enqueues multiple changes to user profiles.
message BatchQueueUserUpdateRequest {
  // directory_id identifies the directory in which the users live.
  string directory_id = 1;
  // updates contains user updates.
  repeated EntryUpdate updates = 2;
}

// GetRevisionRequest identifies a particular revision.
message GetRevisionRequest {
  // directory_id is the directory for which revisions are being requested.
  string directory_id = 5;
  // revision specifies the revision number in which mutations will be returned.
  int64 revision = 1;
  // last_verified is the last log root the client verified.
  // Omitting this field will omit the log consistency proof from the response.
  LogRootRequest last_verified = 4;
  reserved 2, 3;
}

// GetLatestRevisionRequest identifies a particular revision.
message GetLatestRevisionRequest {
  // directory_id is the directory for which revisions are being requested.
  string directory_id = 1;
  // last_verified is the last log root the client verified.
  // Omitting this field will omit the log consistency proof from the response.
  LogRootRequest last_verified = 3;
  reserved 2;
}

// MapRoot contains the map root and its inclusion proof in the log.
message MapRoot {
  // map_root contains the signed map root for the sparse Merkle Tree.
  trillian.SignedMapRoot map_root = 1;
  // log_inclusion proves that map_root is part of log_root at
  // index=map_root.MapRevision.
  repeated bytes log_inclusion = 2;
}

// LogRootRequest contains the information needed to request and verify LogRoot.
message LogRootRequest {
  // root_hash is the root hash of the last log root the client verified.
  bytes root_hash = 1;
  // tree_size is the tree size of the last log root the client verified.
  int64 tree_size = 2;
}

// LogRoot contains the latest log root and its consistency proof.
message LogRoot {
  // log_root is the latest globally consistent log root.
  trillian.SignedLogRoot log_root = 1;
  // log_consistency proves that log_root is consistent with previously seen
  // roots.
  repeated bytes log_consistency = 2;
}

// Revision represents a snapshot of the entire key directory and
// a diff of what changed between this revision and the previous revision.
message Revision {
  // directory_id is the directory identifier.
  string directory_id = 1;
  // map_root contains the map root and its inclusion in the log.
  MapRoot map_root = 5;
  // latest_log_root contains the most recent log root and its consistency
  // proof to the client's last seen log root.
  LogRoot latest_log_root = 6;
  // Deprecated tag numbers, do not reuse.
  reserved 2, 3, 4;
}

// ListMutationsRequest requests the mutations that created a given revision.
message ListMutationsRequest {
  // directory_id is the directory identifier.
  string directory_id = 5;
  // revision specifies the revision number.
  int64 revision = 1;
  // page_token defines the starting point for pagination.
  // To request the next page, pass next_page_token from the previous response.
  // To start at the beginning, simply omit page_token from the request.
  string page_token = 3;
  // page_size is the maximum number of mutations to return in a single request.
  // The server may choose a smaller page_size than the one requested.
  int32 page_size = 4;
  // TODO(gbelvin): Add field mask.

}

// ListMutationsResponse contains the mutations that produced an revision.
message ListMutationsResponse {
  // mutations contains the mutation object and the leaf value it operated on.
  repeated MutationProof mutations = 6;
  // next_page_token is the next page token to query for pagination.
  // An empty value means there are no more results to fetch.
  string next_page_token = 7;
}

// The KeyTransparency API represents a directory of public keys.
//
// The API has a collection of directories:
// `/v1/directories/`
//  * Each directory has a single sparse merkle tree, append only log,
//    and other public key material that is needed to verify server responses.
//
// Each Directory has a collection of snapshots called revisions:
// `/v1/directories/*/revisions/`
//  * Each Revision contains the root of the sparse merkle tree and the changes
//  that
//    occurred that revision and the previous.
//
// Each Revision has a collection of mutations:
// `/v1/directories/*/revisions/*/mutations/`.
//  * Each mutation contains the leafvalue of the previous revision that it
//  operated on.
//  * The full set of mutations for an revision allows the receiver to compute the
//     Merkle Tree Root of this revision from the previous revision.
//
// Each Directory has a collection of Users:
// `/v1/directories/*/users/`
//  * Each User contains public key material, permissions for who is allowed to
//    change that user, and signatures indicating who made the last change.
//
// Each User also has a collection of historical values for user:
// `/v1/directories/*/users/*/history`
//
service KeyTransparency {
  // GetDirectory returns the information needed to verify the specified
  // directory.
  rpc GetDirectory(GetDirectoryRequest) returns (Directory) {
    option (google.api.http) = {
      get: "/v1/directories/{directory_id}"
    };
  }
  // GetRevision returns a SignedMapRoot by the by the requested revision number
  // along with its inclusion proof in the log and the log's consistency proofs.
  rpc GetRevision(GetRevisionRequest) returns (Revision) {
    option (google.api.http) = {
      get: "/v1/directories/{directory_id}/revisions/{revision}"
    };
  }
  // GetLatestRevision returns the latest SignedMapRoot along with its inclusion
  // proof in the log and the log's consistency proofs.
  rpc GetLatestRevision(GetLatestRevisionRequest) returns (Revision) {
    option (google.api.http) = {
      get: "/v1/directories/{directory_id}/revisions:latest"
    };
  }
  // GetRevisionStream streams new revisions from a requested starting point
  // and continues as new revisions are created.
  rpc GetRevisionStream(GetRevisionRequest) returns (stream Revision) {
    option (google.api.http) = {
      get: "/v1/directories/{directory_id}/revisions:stream"
    };
  }
  // ListMutations returns a list of mutations in a specific revision.
  rpc ListMutations(ListMutationsRequest) returns (ListMutationsResponse) {
    option (google.api.http) = {
      get: "/v1/directories/{directory_id}/revisions/{revision}/mutations"
    };
  }
  // ListMutationsStream is a streaming list of mutations in a specific revision.
  rpc ListMutationsStream(ListMutationsRequest) returns (stream MutationProof) {
    option (google.api.http) = {
      get: "/v1/directories/{directory_id}/revisions/{revision}/mutations:stream"
    };
  }
  // GetUser returns a user's leaf entry in the Merkle Tree.
  rpc GetUser(GetUserRequest) returns (GetUserResponse) {
    option (google.api.http) = {
      get: "/v1/directories/{directory_id}/users/{user_id}"
    };
  }
  // BatchGetUser returns a batch of user leaf entries in the Merkle tree at the same revision.
  rpc BatchGetUser(BatchGetUserRequest) returns (BatchGetUserResponse) {
    option (google.api.http) = {
      get: "/v1/directories/{directory_id}/users:batchGet"
    };
  }
  // BatchGetUserIndex returns the VRF proof for a set of userIDs.
  rpc BatchGetUserIndex(BatchGetUserIndexRequest) returns (BatchGetUserIndexResponse) {
    option (google.api.http) = {
      get: "/v1/directories/{directory_id}/users:batchGetIndex"
    };
  }
  // ListEntryHistory returns a list of historic GetUser values.
  //
  // Clients verify their account history by observing correct values for their
  // account over time.
  rpc ListEntryHistory(ListEntryHistoryRequest) returns (ListEntryHistoryResponse) {
    option (google.api.http) = {
      get: "/v1/directories/{directory_id}/users/{user_id}/history"
    };
  }
  // ListUserRevisions returns a list of historic leaf values for a user.
  //
  // Clients verify their account history by observing correct values for their
  // account over time.
  rpc ListUserRevisions(ListUserRevisionsRequest) returns (ListUserRevisionsResponse) {
    option (google.api.http) = {
      post: "/v1/directories/{directory_id}/users/{user_id}/revisions"
      body: "*"
    };
  }
  // BatchListUserRevisions returns a list of revisions for multiple users.
  rpc BatchListUserRevisions(BatchListUserRevisionsRequest) returns (BatchListUserRevisionsResponse) {
    option (google.api.http) = {
      post: "/v1/directories/{directory_id}/users:batchListRevisions"
      body: "*"
    };
  }
  // QueueUserUpdate enqueues an update to a user's profile.
  //
  // Clients should poll GetUser until the update appears, and retry if no
  // update appears after a timeout.
  rpc QueueEntryUpdate(UpdateEntryRequest) returns (google.protobuf.Empty) {
    option (google.api.http) = {
      post: "/v1/directories/{directory_id}/users/{entry_update.user_id}:queue"
      body: "entry_update"
    };
  }
  // BatchQueueUserUpdate enqueues a list of user profiles.
  rpc BatchQueueUserUpdate(BatchQueueUserUpdateRequest) returns (google.protobuf.Empty) {
    option (google.api.http) = {
      post: "/v1/directories/{directory_id}:batchQueueUpdate"
      body: "*"
    };
  }
}