diff options
| -rw-r--r-- | doc/api.md | 49 |
1 files changed, 26 insertions, 23 deletions
@@ -9,11 +9,12 @@ It can be found This is a work-in-progress document that may be moved or modified. ## Overview -The log implements an HTTP(S) API: +Logs implement an HTTP(S) API for accepting requests and sending +responses. - Input data in requests and output data in responses are expressed as ASCII-encoded key/value pairs. -- Requests with input data use POST to send the data to the log. +- Requests with input data use HTTP POST to send the data to a log. - Binary data is hex-encoded before being transmitted. The motivation for using a text based key/value format for request and @@ -27,12 +28,12 @@ wire-format in use by the Tor project. ## Primitives ### Cryptography -The log uses the same Merkle tree hash strategy as +Logs use the same Merkle tree hash strategy as [RFC 6962,ยง2](https://tools.ietf.org/html/rfc6962#section-2). The hash functions must be [SHA256](https://csrc.nist.gov/csrc/media/publications/fips/180/4/final/documents/fips180-4-draft-aug2014.pdf). -The log must sign tree heads using -[Ed25519](https://tools.ietf.org/html/rfc8032). The log's witnesses +Logs must sign tree heads using +[Ed25519](https://tools.ietf.org/html/rfc8032). Log witnesses must also sign tree heads using Ed25519. All other parts that are not Merkle tree related also use SHA256 as @@ -73,7 +74,7 @@ you may use it though. The main point of using Trunnel is that it makes a simple format explicit and unambiguous. #### Merkle tree head -Tree heads are signed by the log and its witnesses. It contains a +Tree heads are signed both by a log and its witnesses. It contains a timestamp, a tree size, and a root hash. The timestamp is included so that monitors can ensure _liveliness_. It is the time since the UNIX epoch (January 1, 1970 00:00 UTC) in seconds. The tree size @@ -93,7 +94,7 @@ not cosign a tree head if it is inconsistent with prior history or if the timestamp is backdated or future-dated more than 12 hours. #### Merkle tree leaf -The log supports a single leaf type. It contains a shard hint, a +Logs support a single leaf type. It contains a shard hint, a checksum over whatever the submitter wants to log a checksum for, a signature that the submitter computed over the shard hint and the checksum, and a hash of the submitter's public verification key, that @@ -113,8 +114,8 @@ struct tree_leaf { ``` `message` is composed of the `shard_hint`, chosen by the submitter to -match the shard interval for the log, and the submitter's `checksum` -to be logged. +match the shard interval for the log it's submitting to, and the +submitter's `checksum` to be logged. `signature_over_message` is a signature over `message`, using the submitter's verification key. It must be possible to verify the @@ -142,13 +143,13 @@ format as the input data, i.e. as ASCII key/value pairs on the format `Key=Value` The HTTP status code is 200 OK to indicate success. A different HTTP -status code is used to indicate failure, in which case the log should +status code is used to indicate failure, in which case a log should respond with a human-readable string describing what went wrong using the key `error`. Example: `error=Invalid signature.`. ### get-tree-head-cosigned Returns the latest cosigned tree head. Used together with -`get-proof-by-hash` and `get-consistency-proof` for verifying the log. +`get-proof-by-hash` and `get-consistency-proof` for verifying the tree. ``` GET <base url>/st/v0/get-tree-head-cosigned @@ -306,7 +307,7 @@ value in each list refers to the first leaf, the second value in each list refers to the second leaf, etc. The size of each list must match. -The log may return fewer leaves than requested. At least one leaf +A log may return fewer leaves than requested. At least one leaf must be returned on HTTP status code 200 OK. Example: `echo "start_size=42 @@ -340,11 +341,11 @@ match a hash over `verification_key`. The submission may also not be accepted if the second-level domain name exceeded its rate limit. By coupling every add-leaf request to -a second-level domain, it becomes more difficult to spam the log. You +a second-level domain, it becomes more difficult to spam logs. You would need an excessive number of domain names. This becomes costly if free domain names are rejected. -The log does not publish domain-name to key bindings because key +Logs don't publish domain-name to key bindings because key management is more complex than that. Public logging should not be assumed to have happened until an @@ -373,7 +374,7 @@ Input: Output on success: - None -`key_hash` can be used to identify which witness signed the log's tree +`key_hash` can be used to identify which witness signed the tree head. A key-hash, rather than the full verification key, is used to motivate verifiers to locate the appropriate key and make an explicit trust decision. @@ -382,11 +383,13 @@ Example: `echo "signature=d1b15061d0f287847d066630339beaa0915a6bbb77332c3e839a32 key_hash=662ce093682280f8fbea9939abe02fdba1f0dc39594c832b411ddafcffb75b1d" | curl --data-binary @- localhost/st/v0/add-cosignature` ## Summary of log parameters -- **Public key**: an Ed25519 verification key that can be used to - verify the log's tree head signatures. -- **Log identifier**: the hashed public verification key using SHA256. -- **Shard interval**: the time during which the log accepts logging - requests. The shard interval's start and end are inclusive and - expressed as the number of seconds since the UNIX epoch. -- **Base URL**: where the log can be reached over HTTP(S). It is the - prefix before a version-0 specific endpoint. +- **Public key**: The Ed25519 verification key to be used for + verifying tree head signatures. +- **Log identifier**: The public verification key `Public key` hashed + using SHA256. +- **Shard interval start**: The earliest time at which logging + requests are accepted as the number of seconds since the UNIX epoch. +- **Shard interval end**: The latest time at which logging + requests are accepted as the number of seconds since the UNIX epoch. +- **Base URL**: Where the log can be reached over HTTP(S). It is the + prefix to be used to construct a version 0 specific endpoint. |