gchq/CyberChef · error · OperationError

Invalid hash

Error message

Invalid hash

What it means

Thrown by AnalyseHash.run when the input, after stripping all whitespace, does not match /^[a-f0-9]+$/i. The operation analyses a hash by its byte/bit length to suggest candidate algorithms, so it requires the input to be a contiguous hex string. Any non-hex character (a stray separator, a 0x prefix, a base64 hash, or trailing newline outside whitespace) causes rejection.

Source

Thrown at src/core/operations/AnalyseHash.mjs:44

        this.outputType = "string";
        this.args = [];
    }

    /**
     * @param {string} input
     * @param {Object[]} args
     * @returns {string}
     */
    run(input, args) {
        input = input.replace(/\s/g, "");

        let output = "",
            possibleHashFunctions = [];
        const byteLength = input.length / 2,
            bitLength = byteLength * 8;

        if (!/^[a-f0-9]+$/i.test(input)) {
            throw new OperationError("Invalid hash");
        }

        output += "Hash length: " + input.length + "\n" +
            "Byte length: " + byteLength + "\n" +
            "Bit length:  " + bitLength + "\n\n" +
            "Based on the length, this hash could have been generated by one of the following hashing functions:\n";

        switch (bitLength) {
            case 4:
                possibleHashFunctions = [
                    "Fletcher-4",
                    "Luhn algorithm",
                    "Verhoeff algorithm",
                ];
                break;
            case 8:
                possibleHashFunctions = [
                    "Fletcher-8",

View on GitHub (pinned to 4290ea7539)

Solutions

1. Provide the hash as a pure hexadecimal string (only 0-9 and a-f/A-F).
2. Remove any '0x' prefix, colons, dashes, or algorithm-name labels before the operation.
3. If the hash is base64 or raw bytes, first convert it to hex with a 'From Base64' or 'To Hex' operation.
4. Strip whitespace upstream; AnalyseHash already removes whitespace but will not remove other separators.

Example fix

// before
chef.analyseHash("sha256: e3b0c44298fc1c14...");

// after
chef.analyseHash("e3b0c44298fc1c14...");

function assertHexString(hash) {
  const clean = String(hash).replace(/\s/g, "");
  if (!/^[a-f0-9]+$/i.test(clean) || clean.length === 0) {
    throw new Error("Input must be a non-empty hex string");
  }
  return clean;
}
const hex = assertHexString(input);

function isHexString(s) {
  const clean = String(s).replace(/\s/g, "");
  return clean.length > 0 && /^[a-f0-9]+$/i.test(clean);
}

When it happens

Trigger: Input containing characters outside [0-9a-fA-F] after whitespace removal: a '0x' prefix, colons/dashes between byte groups, a base64-encoded hash, mixed-case with non-hex letters like 'g-z', or an empty string.

Common situations: Pasting a hash that includes separators (aa:bb:cc...), feeding a base64 or raw binary hash instead of hex, copying a hash with a leading label like 'sha256: ...', or an upstream operation emitting a non-hex digest.

Related errors

• Invalid UUID
• ${err.toString()}
• Incorrect hash length
• ${err}
• Error: Invalid Base64 input length (${data.length}). Cannot

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/361815efd2432bc7. Report an issue: GitHub.