diff options
| -rw-r--r-- | doc/formats.md | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/doc/formats.md b/doc/formats.md new file mode 100644 index 0000000..bffd05f --- /dev/null +++ b/doc/formats.md @@ -0,0 +1,160 @@ +# Formats +This document defines data structures and data formats. + +## Overview +Here we give an overview of our presentation language / serialization rules. + +All integers are represented by 64-bit unsigned integers in network byte order. + +Variable length lists have an integer specifying its length. Then each list +item is enumerated. + +TODO: fixme. + +## Items +Every item type start with a versioned format specifier. Protocol version 1 +uses format specifiers in the range 1--X. + +### Request data structures +Log endpoints that take input data use the following request data structures. + +#### `get_entries_v1` +``` +0 Format 8 16 24 ++----------+----------------+----------------+ +| 1 | Start Size | End Size | ++----------+----------------+----------------+ + uint64 uint64 uint64 +``` +- Format is always 1 for items of type `get_entries_v1`. +- Start size specifies the index of the first Merkle tree leaf to retrieve. +- End size specifies the index of the last Merkle tree leaf to retrieve. + +#### `get_proof_by_hash_v1` +``` +0 Format 8 16 48 ++----------+----------------+----------------+ +| 2 | Tree size | Leaf hash | ++----------+----------------+----------------+ + uint64 uint64 fixed byte array +``` +- Format is always 2 for items of type `get_proof_by_hash_v1`. +- Leaf hash is computed as described in [RFC 6962/bis, §2.1.1](https://tools.ietf.org/html/draft-ietf-trans-rfc6962-bis-35#section-2.1.1). +- Tree size specifies which Merkle tree root inclusion should be proven for. + +#### `get_consistency_proof_v1` +``` +0 Format 8 16 24 ++----------+----------------+----------------+ +| 3 | Old size | New size | ++----------+----------------+----------------+ + uint64 uint64 uint64 +``` +- Format is always 3 for items of type `get_consistency_proof_v1`. +- Old size specifies the tree size of an older Merkle tree head. +- New size specifies the tree size of a newer Merkle tree head. + +### Proof and log data structures +#### `inclusion_proof_v1` +``` + --zero or more node hashes--> +0 Format 8 48 56 64 72 72+Length ++----------+----------------+----------------+----------------+----------------+--------//--------+ +| 4 | Identifier | Tree size | Leaf index | Length | Node hashes | ++----------+----------------+----------------+----------------+----------------+--------//--------+ + uint64 ed25519_v1 uint64 uint64 uint64 list body +``` +- Format is always 4 for items of type `inclusion_proof_v1`. +- Identifier identifies the log uniquely as an `ed25519_v1` item. +- Tree size is the size of the Merkle tree that the proof is based on. +- Leaf index is a zero-based index of the log entry that the proof is based on. +- The remaining part is a list of node hashes. + - Length specifies the full byte size of the list. It must be `32 * m`, + where `m >= 0`. This means that an inclusion needs zero or more node + hashes to be well-formed. + - Node hash is a node hash in the Merkle tree that the proof is based on. + +Remark: the list of node hashes is generated and verified as in [RFC 6962/bis, +§2.1.3](https://tools.ietf.org/html/draft-ietf-trans-rfc6962-bis-35#section-2.1.3). + +#### `consistency_proof_v1` +``` + --zero or more node hashes--> +0 Format 8 48 56 64 72 72+Length ++----------+----------------+----------------+----------------+----------------+--------//--------+ +| 5 | Identifier | Old size | New size | Length | Node hashes | ++----------+----------------+----------------+----------------+----------------+--------//--------+ + uint64 ed25519_v1 uint64 uint64 uint64 list body +``` +- Format is always 5 for items of type `consistency_proof_v1`. +- Identifier identifies the log uniquely as an `ed25519_v1` item. +- Old size is the tree size of the older Merkle tree. +- New size is the tree size of the newer Merkle tree. +- The remaining part is a list of node hashes. + - Length specifies the full byte size of the list. It must be `32 * m`, + where `m >= 0`. This means that a consistenty proof needs zero or more node + hashes to be well-formed. + - Node hash is a node hash from the older or the newer Merkle tree. + +Remark: the list of node hashes is generated and verified as in [RFC 6962/bis, +§2.1.4](https://tools.ietf.org/html/draft-ietf-trans-rfc6962-bis-35#section-2.1.4). + +#### `signed_tree_head_v1` +``` + ----one or more signature-identifier pairs-------> +0 Format 8 16 24 56 64 128 168 64+Length ++----------+----------------+----------------+----------------+----------------+----------------+----------------+--//--+ +| 6 | Timestamp | Tree size | Root hash | Length | Signature | Identifier | .... | ++----------+----------------+----------------+----------------+----------------+----------------+----------------+--//--+ + uint64 uint64 uint64 fixed byte array uint64 fixed byte array ed25519_v1 cont. list body +``` +- Format is always 6 for items of type `signed_tree_head_v1`. +- Timestamp is the time since the UNIX epoch (January 1, 1970 00:00:00 UTC) in +milliseconds. +- Tree size is the number of leaves in the current Merkle tree. +- Root hash is the root hash of the current Merkle tree. +- The remaining part is a list of signature-identifier pairs. + - Length specifies the full byte size of the list. It must be `104 * m`, + where `m > 1`. This means that a signed tree head needs at least one + signature-identifier pair to be well-formed. + - Signature is an Ed25519 signature over bytes 0--56. The signature is + encodes as in [RFC 8032, §3.3](https://tools.ietf.org/html/rfc8032#section-3.3). + - Identifier identifies the signer uniquely as an `ed25519_v1` item. + +Remark: there may be multiple signature-identifier pairs if the log is cosigned. + +#### `signed_checksum32_ed25519_v1` +``` +0 Format 8 40 56 56+Length 120+Length 160+Length ++----------+----------------+----------------+-------//---------+----------------+--------//--------+ +| 7 | Checksum | Length | Identifier | Signature | Namespace | ++----------+----------------+----------------+-------//---------+----------------+--------//--------+ + uint64 fixed byte array uint64 byte array fixed byte array ed25519_v1 +``` +- Format is always 7 for items of type `signed_checksum32_ed25519_v1`. +- Checksum is a 32-byte checksum that represents a data item of opaque type. +- Length specified the full byte size of the following identifier. It must be +larger than zero and less than 128. +- Identifier identifies what the checksum represents. The aforementioned length +constraint means that the identifier cannot be omitted or exceed 128 bytes. +- Signature is an Ed25519 signature over bytes 0--56+Length. The signature is +encodes as in [RFC 8032, §3.3](https://tools.ietf.org/html/rfc8032#section-3.3). +- Namespace is an `ed25519_v1` item that identifies the signer uniquely. + +Remark: to keep this checksum entry as simple as possible it does not have a +variable length checksum or any agility with regards to the signing namespace. +This means that we need to have multiple leaf types that follow the pattern +`signed_checksum{32,64}_namespace_v1`. + +### Namespace data structures +#### `ed25519_v1` +``` +0 Format 8 40 ++----------+----------------+ +| 8 | public key | ++----------+----------------+ + uint64 fixed byte array +``` +- The format is always 8 for items of type `ed25519_v1`. +- The public Ed25519 verification key is always 32 bytes. See encoding in [RFC +8032, §3.2](https://tools.ietf.org/html/rfc8032#section-3.2). |