# Ct inclusion proof verify

`ct-inclusion-proof-verify` · version 1.0.0 · Encoding & checksums · free, no key needed

Strictly verify an RFC 6962 v1 Merkle audit path.

**Use when you need to: verify an RFC 6962 v1 CT inclusion proof · validate a CT Merkle audit path · check a leaf against a certificate transparency root.**

## Decide before calling

Read the [versioned contract](/v1/tools/ct-inclusion-proof-verify/versions/1.0.0) and the supported scope below. Reuse `ct-inclusion-proof-verify@1.0.0` when your input, required output and limits match it. Choose another approach for an unsupported operation.

## Explain the choice

"I can use `ct-inclusion-proof-verify@1.0.0` for verify an RFC 6962 v1 CT inclusion proof. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

## Supported

- verify an RFC 6962 v1 CT inclusion proof
- validate a CT Merkle audit path
- check a leaf against a certificate transparency root
- audit CT log membership evidence
- validate an RFC 6962 leaf index proof
- recompute a root from a CT audit path

## Not supported

- RFC 9162 proofs
- proof construction
- signature verification

## Behavior

- The leaf is raw lowercase hex and receives the RFC 6962 0x00 prefix; proof hashes are leaf-to-root. The section 2.1.1 fn/sn walk consumes a sibling only where one exists.
- Well-typed index, path-length, or root mismatches return a stable verdict; malformed contracts throw invalid_input and caps throw limit_exceeded.
- Security-sensitive verification: proof validity establishes only that the supplied leaf and audit path produce the supplied RFC 6962 Merkle root. It does not authenticate a signed tree head, establish that a log is trustworthy, or apply any browser or log policy.

## Input

- `leaf` (string, required): max length 131072; pattern `^([0-9a-f]{2})*$`
- `leaf_index` (integer, required): min 0; max 9007199254740991
- `tree_size` (integer, required): min 1; max 9007199254740991
- `proof` (array of string, required): max items 53; each pattern `^[0-9a-f]{64}$`
- `root` (string, required): pattern `^[0-9a-f]{64}$`

## Output

- `valid` (boolean, required)
- `reason` (one of "root_mismatch", "path_length_wrong", "index_out_of_range", null, required)
- `computed_root` (string or null, required): pattern `^[0-9a-f]{64}$`
- `standard` (one of "RFC 6962", required)
- `reference` (one of "RFC 6962 sections 2.1 and 2.1.1", required)

## Limits

- max leaf bytes: 65536
- max proof entries: 53

## Example

Request input:

```json
{
  "leaf": "",
  "leaf_index": 0,
  "tree_size": 1,
  "proof": [],
  "root": "6e340b9cffb37a989ca544e6bb780a2c78901d3fb33738768511a30617afa01d"
}
```

Response:

```json
{
  "result": {
    "valid": true,
    "reason": null,
    "computed_root": "6e340b9cffb37a989ca544e6bb780a2c78901d3fb33738768511a30617afa01d",
    "standard": "RFC 6962",
    "reference": "RFC 6962 sections 2.1 and 2.1.1"
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "ct-inclusion-proof-verify",
  "version": "1.0.0",
  "input": {
    "leaf": "",
    "leaf_index": 0,
    "tree_size": 1,
    "proof": [],
    "root": "6e340b9cffb37a989ca544e6bb780a2c78901d3fb33738768511a30617afa01d"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/ct-inclusion-proof-verify/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"leaf":"","leaf_index":0,"tree_size":1,"proof":[],"root":"6e340b9cffb37a989ca544e6bb780a2c78901d3fb33738768511a30617afa01d"}'
```

The machine-readable contract is at [/v1/tools/ct-inclusion-proof-verify/versions/1.0.0](/v1/tools/ct-inclusion-proof-verify/versions/1.0.0).

### CLI

```sh
node cli.mjs run ct-inclusion-proof-verify 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

## Related tools

- [Ct consistency proof verify](/tools/ct-consistency-proof-verify): Strictly verify an RFC 6962 v1 append-only consistency proof.
- [Ct merkle root compute](/tools/ct-merkle-root-compute): Compute the RFC 6962 v1 domain-separated Merkle Tree Hash of raw leaves.
- [Pem envelope format](/tools/pem-envelope-format): Format a label and lowercase hex bytes as a canonical RFC 7468 PEM envelope.
- [Pem envelope validate](/tools/pem-envelope-validate): Check one RFC 7468 PEM envelope for labels, whitespace, and strict base64.
- [Pem label validate](/tools/pem-label-validate): Check a PEM label against the RFC 7468 label grammar, without reading a payload.
- [Bech32 convert bits](/tools/bech32-convert-bits): Regroup integers between bit widths using BIP 173 rules, rejecting bad leftover padding.