nautechsystems/nautilus_trader · error

Failed to sign: {e}

Error message

Failed to sign: {e}

What it means

This error wraps a failure from the underlying ECDSA/K256 signing key when signing a Cosmos SignDoc transaction during dYdX credential signing. The library throws it whenever the cryptographic signing operation itself fails, before the signature can be returned as raw bytes. It indicates a problem with the signing key material or the signing operation, not with the transaction content.

Source

Thrown at crates/adapters/dydx/src/common/credential.rs:204

    }

    /// Signs a transaction SignDoc.
    ///
    /// This produces the signature bytes that will be included in the transaction.
    ///
    /// # Errors
    ///
    /// Returns an error if SignDoc serialization or signing fails.
    pub fn sign(&self, sign_doc: &SignDoc) -> anyhow::Result<Vec<u8>> {
        let sign_bytes = sign_doc
            .clone()
            .into_bytes()
            .map_err(|e| anyhow::anyhow!("Failed to serialize SignDoc: {e}"))?;

        let signature = self
            .signing_key
            .sign(&sign_bytes)
            .map_err(|e| anyhow::anyhow!("Failed to sign: {e}"))?;
        Ok(signature.to_bytes().to_vec())
    }

    /// Signs raw message bytes.
    ///
    /// Used for custom signing operations outside of standard transaction flow.
    ///
    /// # Errors
    ///
    /// Returns an error if signing fails.
    pub fn sign_bytes(&self, message: &[u8]) -> anyhow::Result<Vec<u8>> {
        let signature = self
            .signing_key
            .sign(message)
            .map_err(|e| anyhow::anyhow!("Failed to sign: {e}"))?;
        Ok(signature.to_bytes().to_vec())
    }

View on GitHub (pinned to 18893faf8b)

Solutions

  1. Verify the private key/mnemonic used to construct the credential is valid and derives a correct signing key
  2. Re-create the credential from the original mnemonic rather than a stored/serialized key
  3. Check that the SignDoc bytes are well-formed (serialize step succeeded immediately before this call)
  4. Update the k256/crypto dependencies if the failure is an internal library error

Example fix

// before
let cred = Credential::from_hex(&stale_hex_key)?;
let sig = cred.sign(sign_doc)?;
// after
let cred = Credential::from_mnemonic(MNEMONIC)?; // re-derive from source of truth
assert!(!sig.is_empty());
let sig = cred.sign(sign_doc)?;
Defensive patterns

Strategy: try-catch

Validate before calling

// Rust: check key derives before signing
let _pk = cred.public_key(); // construction failure would already surface; treat sign errors as key-material faults

Type guard

fn key_is_usable(cred: &Credential) -> bool { cred.public_key() != PublicKey::default() }

Try / catch

match cred.sign(&sign_doc) {
    Ok(sig) => sig,
    Err(e) => { log::error!("sign failed: {e}"); rebuild_credential_from_mnemonic()?.sign(&sign_doc)? }
}

Prevention

When it happens

Trigger: Calling `Credential::sign` with a SignDoc whose serialized bytes the `signing_key.sign(&sign_bytes)` call rejects — e.g. a corrupted, zeroed, or otherwise invalid signing key (k256 error) raised through `map_err(anyhow!)`.

Common situations: Mnemonic/private key was loaded incorrectly or truncated, a key derived from an invalid mnemonic, corrupted keyfile, or a dependency (k256/rust-crypto) returning an internal signing failure on malformed input bytes.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/101f1c369a29380c. Report an issue: GitHub.