hashicorp/nomad · error

error generating ECDSA private key: %s

Error message

error generating ECDSA private key: %s

What it means

GeneratePrivateKey creates an ECDSA P-256 key using crypto/ecdsa with rand.Reader. If the OS entropy source or the elliptic-curve key generation fails, the error is wrapped with this message. Failure here is rare and usually indicates a system-level crypto/entropy problem.

Source

Thrown at helper/tlsutil/generate.go:40

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// GenerateSerialNumber returns random bigint generated with crypto/rand
func GenerateSerialNumber() (*big.Int, error) {
	l := new(big.Int).Lsh(big.NewInt(1), 128)
	s, err := rand.Int(rand.Reader, l)
	if err != nil {
		return nil, err
	}
	return s, nil
}

// GeneratePrivateKey generates a new ecdsa private key
func GeneratePrivateKey() (crypto.Signer, string, error) {
	curve := elliptic.P256()

	pk, err := ecdsa.GenerateKey(curve, rand.Reader)
	if err != nil {
		return nil, "", fmt.Errorf("error generating ECDSA private key: %s", err)
	}

	bs, err := x509.MarshalECPrivateKey(pk)
	if err != nil {
		return nil, "", fmt.Errorf("error marshaling ECDSA private key: %s", err)
	}

	pemBlock, err := pemEncodeKey(bs, "EC PRIVATE KEY")
	if err != nil {
		return nil, "", err
	}

	return pk, pemBlock, nil
}

func pemEncodeKey(key []byte, blockType string) (string, error) {
	var buf bytes.Buffer

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Fix the underlying entropy source (ensure getrandom(2) or /dev/urandom works in the environment).
2. Retry the operation; entropy failures are often transient.
3. Run the workload on a platform/Go build with working crypto/rand support.

signer, pemKey, err := tlsutil.GeneratePrivateKey()
if err != nil {
    if strings.Contains(err.Error(), "error generating ECDSA private key") {
        // log underlying cause; entropy/system issue; retry or fix environment
        return fmt.Errorf("keygen failed: %w", err)
    }
    return err
}

When it happens

Trigger: ecdsa.GenerateKey(elliptic.P256(), rand.Reader) returns an error when GeneratePrivateKey is called (directly or via GenerateCA/GenerateCert).

Common situations: Running in a sandbox/VM where /dev/urandom or getrandom(2) is unavailable; heavily restricted containers; exotic platforms with broken crypto/rand.

Related errors

• Unsupported signature algorithm %T; RSA and ECDSA only are s
• error marshaling ECDSA private key: %s
• failed to generate key wrapper key: %w
• no PEM-encoded data found
• common name value not provided

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/318a217c76fcf373. Report an issue: GitHub.