nautechsystems/nautilus_trader · error · anyhow::Error

Invalid secp256k1 private key: {e}

Error message

Invalid secp256k1 private key: {e}

What it means

DydxWallet::from_private_key decodes the caller-supplied hex string and then validates it as a secp256k1 scalar via k256's SigningKey::from_slice. If the decoded bytes are not a valid private key (wrong length or out of the valid scalar range), the wallet cannot be constructed and this error is returned.

Source

Thrown at crates/adapters/dydx/src/execution/wallet.rs:95

}

impl Wallet {
    /// Create a wallet from a hex-encoded private key.
    ///
    /// The private key should be a 32-byte secp256k1 key encoded as hex,
    /// optionally with a `0x` prefix. Address and account ID are derived
    /// during construction.
    ///
    /// # Errors
    ///
    /// Returns an error if the private key is invalid hex or not a valid secp256k1 key.
    pub fn from_private_key(private_key_hex: &str) -> anyhow::Result<Self> {
        let key_bytes = hex::decode(private_key_hex.trim_start_matches("0x"))
            .context("Invalid hex private key")?;

        // Validate the key and derive address/account_id
        let signing_key = SigningKey::from_slice(&key_bytes)
            .map_err(|e| anyhow::anyhow!("Invalid secp256k1 private key: {e}"))?;

        let public_key = signing_key.public_key();
        let account_id = public_key
            .account_id(BECH32_PREFIX_DYDX)
            .map_err(|e| anyhow::anyhow!("Failed to derive account ID: {e}"))?;
        let address = account_id.to_string();

        Ok(Self {
            private_key_bytes: key_bytes.into_boxed_slice(),
            address,
            account_id,
        })
    }

    /// Get a dYdX account with zero account and sequence numbers.
    ///
    /// Creates an account using the pre-computed address/account_id.
    /// SigningKey is recreated from stored bytes (it doesn't implement Clone).

View on GitHub (pinned to 18893faf8b)

Solutions

1. Check the key is a 64-character hex string (32 bytes), with optional 0x prefix, representing a scalar in [1, n-1].
2. Re-export the key from the source wallet as a raw 32-byte hex private key (e.g. from a dYdX/Ethereum wallet's 'export private key' option).
3. Trim whitespace and any 0x prefix issues; the code trims '0x' but stray characters will already fail earlier at 'Invalid hex private key'.
4. Generate a fresh valid key for testing (e.g. k256::ecdsa::SigningKey::random or a known-good hex constant).

Example fix

// before
let wallet = DydxWallet::from_private_key("aabbcc")?; // 3 bytes -> invalid
// after
let wallet = DydxWallet::from_private_key("0x0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef")?; // 32 bytes

let key = private_key_hex.trim_start_matches("0x");
assert_eq!(key.len(), 64, "key must be 64 hex chars (32 bytes)");
let bytes = hex::decode(key)?;
assert!(!bytes.iter().all(|&b| b == 0), "zero key is invalid");

fn is_valid_hex_key(s: &str) -> bool {
    let k = s.trim_start_matches("0x");
    k.len() == 64 && hex::decode(k).map(|b| b.len() == 32 && !b.iter().all(|&x| x == 0)).unwrap_or(false)
}

match DydxWallet::from_private_key(hex) {
    Ok(w) => w,
    Err(e) if e.to_string().contains("Invalid secp256k1 private key") => {
        // fix key format/length before retry
        return Err(e);
    }
    Err(e) => return Err(e),
}

When it happens

Trigger: Calling DydxWallet::from_private_key(hex) where the hex decodes to bytes that k256 rejects: not exactly 32 bytes, or numerically >= the secp256k1 curve order, or all zeros.

Common situations: Typing or pasting a truncated key; exporting a key with an unexpected encoding (e.g. 33-byte compressed representation instead of the 32-byte scalar); passing a mnemonic phrase or an Ethereum keystore JSON instead of a raw hex scalar; hand-writing a test key that happens to be invalid.

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

• Failed to create signing key: {e}
• Failed to derive account ID: {e}
• No wallet credentials found: set wallet_address or private_k
• Signer private key in '{}' is not a valid secp256k1 private
• Failed to sign: {e}

AI-assisted analysis of nautechsystems/nautilus_trader@18893faf8b (2026-09-08). Data as JSON: /api/errors/abb21ef25319a269. Report an issue: GitHub.