gchq/CyberChef · error · OperationError

Failed to generate prime after ${maxAttempts} attempts. Try

Error message

Failed to generate prime after ${maxAttempts} attempts. Try a different bit length.

What it means

Thrown by GeneratePrime when the random-search loop exceeds maxAttempts (10000) iterations without finding a probable prime. Each iteration generates a fresh random bigint of the requested bit length and tests it with Miller-Rabin. Smaller bit lengths have denser prime distributions; failure here is statistically unlikely but possible, especially at edge bit lengths or with low-round (non-crypto-grade) testing.

Source

Thrown at src/core/operations/GeneratePrime.mjs:141

            throw new OperationError("Bit length must be at least 2");
        }

        if (bits > 4096) {
            throw new OperationError("Bit length limited to 4096 bits for performance reasons");
        }

        const rounds = cryptoGrade ? 40 : 7;
        let attempts = 0;
        const maxAttempts = 10000;

        let n = randBigInt(bits);

        while (!isProbablePrime(n, rounds)) {
            n = randBigInt(bits);
            attempts++;

            if (attempts > maxAttempts) {
                throw new OperationError(`Failed to generate prime after ${maxAttempts} attempts. Try a different bit length.`);
            }
        }

        // Return only the prime for pipeability
        if (outputFormat === "Hexadecimal") {
            return "0x" + n.toString(16);
        } else {
            return n.toString();
        }
    }
}

export default GeneratePrime;

View on GitHub (pinned to 4290ea7539)

Solutions

1. Retry the operation — failure is transient and statistical.
2. Try a different (typically larger or more standard) bit length such as a power of two.
3. Enable crypto-grade testing (more rounds) only if correctness matters; it does not reduce attempts but improves confidence.

for (let attempt = 0; attempt < 3; attempt++) {
  try {
    return generatePrime(bits, cryptoGrade, outputFormat);
  } catch (e) {
    if (!/Failed to generate prime/.test(e.message)) throw e;
  }
}
throw new Error("Prime generation failed after retries");

When it happens

Trigger: Statistically rare run of 10000 consecutive composites at the chosen bit length. More plausible at bit lengths where the random generator or rounding produces biased candidates.

Common situations: Unlucky RNG streak, or a faulty/rand-poor environment reducing prime density.

Related errors

• Failed to generate prime after ${maxAttempts} attempts. Try
• Bit length must be at least 2
• Bit length limited to 4096 bits for performance reasons
• Bit length must be at least 2
• Bit length limited to 4096 bits for performance reasons

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/64a5299eebfee8ca. Report an issue: GitHub.