Verifying Reports

Every signed report can be checked at CallMeter's public verification page — no account required. Verification answers one question precisely: do these bytes match an unmodified, CallMeter-issued signed-report record, and has that record been revoked?

Verifying at the verification page

Go to /verify and upload the report PDF. CallMeter hashes the bytes you uploaded and matches that hash against its records — then checks the record's Ed25519 signature. The file is checked in your request and never stored.

The result is one of:

The page also shows the signing keyId and the report's details, so you can confirm you are looking at the report you expected.

Why you upload the file, not a code

Verification is deliberately file-only. A signed report's PDF prints a Report reference (an invoice-style identifier) on its cover and footer, but that reference is not a verification input — pasting it would prove nothing about the file in front of you. Anyone could alter a PDF and leave the printed reference untouched, so a reference-based check would happily "confirm" a tampered file. Only the bytes can prove the file is unmodified, so only an upload can verify one. The reference is there to identify a report in conversation or support, not to authenticate it.

What verification proves — and what it does not

Verification is record-anchored. A "verified" result means the bytes match a signed record CallMeter issued and has not changed. It is a strong integrity and origin check, and it is exactly that — not a legal attestation, notarization, or third-party certification. If you need a signature embedded inside the PDF that a desktop PDF reader validates on its own, that is a separate capability and is not what this check provides.

Checking a report independently

The signature is a standard Ed25519 signature, so anyone who has been given a report's public key and signature (for example, from the report's owner) can verify it without CallMeter in the loop. The signed message is domain-separated: the literal text callmeter-report-v1, a single newline, then the lowercase hex SHA-256 of the PDF bytes.

With Node.js:

const { createHash, createPublicKey, verify } = require("crypto");
const fs = require("fs");

const pdf = fs.readFileSync("report.pdf");
const sha256hex = createHash("sha256").update(pdf).digest("hex");

// Exact domain-separated payload: "callmeter-report-v1" + "\n" + sha256hex
const payload = Buffer.from("callmeter-report-v1\n" + sha256hex, "utf8");

const publicKey = createPublicKey({
  key: Buffer.from(PUBLIC_KEY_B64, "base64"), // base64 SPKI DER, from the report record
  format: "der",
  type: "spki",
});

const ok = verify(null, payload, publicKey, Buffer.from(SIGNATURE_B64, "base64"));
console.log(ok ? "VALID" : "INVALID");

The equivalent with OpenSSL:

# 1. Hash the PDF and build the exact signed payload (note the newline).
printf 'callmeter-report-v1\n%s' "$(sha256sum report.pdf | cut -d' ' -f1)" > payload.bin

# 2. Turn the base64 SPKI-DER public key into a PEM.
printf '%s' "$PUBLIC_KEY_B64" | base64 -d | openssl pkey -pubin -inform DER -out pub.pem

# 3. Decode the base64 signature, then verify (Ed25519 signs the raw message).
printf '%s' "$SIGNATURE_B64" | base64 -d > sig.bin
openssl pkeyutl -verify -pubin -inkey pub.pem -rawin -in payload.bin -sigfile sig.bin

If the payload prefix or the newline is wrong, verification fails — reproduce callmeter-report-v1\n exactly.

Key rotation

CallMeter can rotate its signing key. Because every signed report stores a snapshot of the public key that signed it, reports signed with an older key keep verifying forever — you always check a report against the key it was actually signed with, identified by its keyId. Rotating the key changes only which key signs new reports.

Related

• Signed Reports — what signing does and how to sign.
• Sharing Reports — send a signed report to someone logged out.