Sri integrity compute

sri-integrity-compute · version 1.0.0 · Hashing & signatures · free, no key needed

Render one or more digests of content as a W3C Subresource Integrity 'integrity' attribute value.

Use when you need to: sri hash for a script tag · generate integrity attribute for a cdn link · sha384 sri value.

Decide before calling

Read the versioned contract and the supported scope below. Reuse sri-integrity-compute@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 sri-integrity-compute@1.0.0 for sri hash for a script tag. 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

• sri hash for a script tag
• generate integrity attribute for a cdn link
• sha384 sri value
• compute subresource integrity hash
• integrity= value for this file
• sri metadata for multiple algorithms

Not supported

• algorithms outside sha256/sha384/sha512 (md5 and sha1 are not W3C SRI algorithms)
• fetching or hashing a remote URL (content must be supplied directly)

Behavior

• algorithms defaults to ['sha384'] when omitted; order is preserved from the input, and duplicates are rejected, not silently deduplicated.
• Each token is "<algorithm>-<standard padded base64 of the raw digest bytes>" (RFC 4648 section 4, padded, never base64url).
• integrity is every token joined by a single ASCII space in the same order as algorithms; tokens reports the same digests as {algorithm, digest_base64} in that order.
• content is decoded from content_encoding (utf8 default); the raw decoded bytes are hashed with no normalization or byte-order-mark handling.

Input

• content (string, required): max length 262144
• content_encoding (one of "utf8", "hex", "base64", "base64url", optional): default "utf8"
• algorithms (array of one of "sha256", "sha384", "sha512", optional): min items 1; max items 3; default ["sha384"]

Output

• integrity (string, required): min length 1
• tokens (array of object, required): min items 1; max items 3

Limits

• max content bytes: 262144

Example

Request input:

{
  "content": "abc",
  "algorithms": [
    "sha256"
  ]
}

Response:

{
  "result": {
    "integrity": "sha256-ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0=",
    "tokens": [
      {
        "algorithm": "sha256",
        "digest_base64": "ungWv48Bz+pBQUDeXa4iI7ADYaOWF3qctBD/YfIAFa0="
      }
    ]
  }
}

How to call it

MCP

Connect https://computefirst.net/mcp (setup), then call execute with:

{
  "id": "sri-integrity-compute",
  "version": "1.0.0",
  "input": {
    "content": "abc",
    "algorithms": [
      "sha256"
    ]
  }
}

HTTP (no key)

curl -X POST https://computefirst.net/v1/tools/sri-integrity-compute/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"content":"abc","algorithms":["sha256"]}'

The machine-readable contract is at /v1/tools/sri-integrity-compute/versions/1.0.0.

CLI

node cli.mjs run sri-integrity-compute 1.0.0 --input input.json --base-url https://computefirst.net

Get the client at /clients/cli/.

Related tools

• Sri integrity verify: Parse an SRI integrity attribute, check content against its strongest digest, and report which tokens were used.
• Git object id compute: Compute the Git object id git itself would give a blob, tree, commit or tag under Git's exact object framing.
• Ipfs cid compute: Compute the CIDv0, CIDv1 dag-pb and CIDv1 raw content identifiers 'ipfs add' would give a single-chunk file.
• Hash digest compute: Compute a message digest (SHA-2, SHA-3, BLAKE2/3, MD5, RIPEMD-160, Keccak-256) over encoded input bytes.
• Hash noncrypto compute: Compute FNV-1/1a, MurmurHash3 or xxHash over encoded input bytes, with an optional seed for algorithms that take one.
• Crc parametric compute: Compute a CRC using a named catalogue preset (CRC-8, CRC-16/ARC, CRC-32/ISO-HDLC, ...) or an explicit Rocksoft model.