Struct secp256k1::SecretKey

pub struct SecretKey(_);

Secret 256-bit key used as x in an ECDSA signature.

Side channel attacks

We have attempted to reduce the side channel attack surface by implementing a constant time eq method. For similar reasons we explicitly do not implement PartialOrd, Ord, or Hash on SecretKey. If you really want to order secrets keys then you can use AsRef to get at the underlying bytes and compare them - however this is almost certainly a bad idea.

Serde support

Implements de/serialization with the serde feature enabled. We treat the byte value as a tuple of 32 u8s for non-human-readable formats. This representation is optimal for for some formats (e.g. bincode) however other formats may be less optimal (e.g. cbor).

Examples

Basic usage:

use secp256k1::{rand, Secp256k1, SecretKey};

let secp = Secp256k1::new();
let secret_key = SecretKey::new(&mut rand::thread_rng());

Implementations

impl SecretKey

pub fn display_secret(&self) -> DisplaySecret

Formats the explicit byte value of the secret key kept inside the type as a little-endian hexadecimal string using the provided formatter.

This is the only method that outputs the actual secret key value, and, thus, should be used with extreme caution.

Examples

use secp256k1::SecretKey;
let key = SecretKey::from_str("0000000000000000000000000000000000000000000000000000000000000001").unwrap();

// Normal debug hides value (`Display` is not implemented for `SecretKey`).
// E.g., `format!("{:?}", key)` prints "SecretKey(#2518682f7819fb2d)".

// Here we explicitly display the secret value:
assert_eq!(
    "0000000000000000000000000000000000000000000000000000000000000001",
    format!("{}", key.display_secret())
);
// Also, we can explicitly display with `Debug`:
assert_eq!(
    format!("{:?}", key.display_secret()),
    format!("DisplaySecret(\"{}\")", key.display_secret())
);

impl SecretKey

pub fn new<R: Rng + ?Sized>(rng: &mut R) -> SecretKey

Available on crate feature rand only.

Generates a new random secret key.

Examples

use secp256k1::{rand, SecretKey};
let secret_key = SecretKey::new(&mut rand::thread_rng());

pub fn from_slice(data: &[u8]) -> Result<SecretKey, Error>

Converts a SECRET_KEY_SIZE-byte slice to a secret key.

Examples

use secp256k1::SecretKey;
let sk = SecretKey::from_slice(&[0xcd; 32]).expect("32 bytes, within curve order");

pub fn from_keypair(keypair: &KeyPair) -> Self

Creates a new secret key using data from BIP-340 KeyPair.

Examples

use secp256k1::{rand, Secp256k1, SecretKey, KeyPair};

let secp = Secp256k1::new();
let key_pair = KeyPair::new(&secp, &mut rand::thread_rng());
let secret_key = SecretKey::from_keypair(&key_pair);

pub fn from_hashed_data<H: ThirtyTwoByteHash + Hash>(data: &[u8]) -> Self

Available on crate feature bitcoin-hashes only.

Constructs a SecretKey by hashing data with hash algorithm H.

Requires the feature bitcoin_hashes to be enabled.

Examples

use secp256k1::hashes::{sha256, Hash};
use secp256k1::SecretKey;

let sk1 = SecretKey::from_hashed_data::<sha256::Hash>("Hello world!".as_bytes());
// is equivalent to
let sk2 = SecretKey::from(sha256::Hash::hash("Hello world!".as_bytes()));

assert_eq!(sk1, sk2);

pub fn secret_bytes(&self) -> [u8; 32]

Returns the secret key as a byte value.

pub fn negate(self) -> SecretKey

Negates the secret key.

pub fn add_tweak(self, tweak: &Scalar) -> Result<SecretKey, Error>

Tweaks a SecretKey by adding tweak modulo the curve order.

Errors

Returns an error if the resulting key would be invalid.

pub fn mul_tweak(self, tweak: &Scalar) -> Result<SecretKey, Error>

Tweaks a SecretKey by multiplying by tweak modulo the curve order.

Errors

Returns an error if the resulting key would be invalid.

pub fn sign_ecdsa(&self, msg: Message) -> Signature

Available on crate feature global-context only.

Constructs an ECDSA signature for msg using the global SECP256K1 context.

pub fn keypair<C: Signing>(&self, secp: &Secp256k1<C>) -> KeyPair

Returns the KeyPair for this SecretKey.

This is equivalent to using KeyPair::from_secret_key.

pub fn public_key<C: Signing>(&self, secp: &Secp256k1<C>) -> PublicKey

Returns the PublicKey for this SecretKey.

This is equivalent to using PublicKey::from_secret_key.

pub fn x_only_public_key<C: Signing>(
    &self,
    secp: &Secp256k1<C>
) -> (XOnlyPublicKey, Parity)

Returns the XOnlyPublicKey (and it’s Parity) for this SecretKey.

This is equivalent to XOnlyPublicKey::from_keypair(self.keypair(secp)).

Trait Implementations

impl AsRef<[u8; 32]> for SecretKey

fn as_ref(&self) -> &[u8; 32]

Gets a reference to the underlying array.

Side channel attacks

Using ordering functions (PartialOrd/Ord) on a reference to secret keys leaks data because the implementations are not constant time. Doing so will make your code vulnerable to side channel attacks. SecretKey::eq is implemented using a constant time algorithm, please consider using it to do comparisons of secret keys.

impl CPtr for SecretKey

type Target = u8

fn as_c_ptr(&self) -> *const Self::Target

fn as_mut_c_ptr(&mut self) -> *mut Self::Target

impl Clone for SecretKey

fn clone(&self) -> SecretKey

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SecretKey

Available on crate feature std only.

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for SecretKey

Available on crate feature serde only.

fn deserialize<D: Deserializer<'de>>(d: D) -> Result<Self, D::Error>

Deserialize this value from the given Serde deserializer.

impl<'a> From<&'a KeyPair> for SecretKey

fn from(pair: &'a KeyPair) -> Self

Converts to this type from the input type.

impl From<KeyPair> for SecretKey

fn from(pair: KeyPair) -> Self

Converts to this type from the input type.

impl From<SecretKey> for Scalar

fn from(value: SecretKey) -> Self

Converts to this type from the input type.

impl<T: ThirtyTwoByteHash> From<T> for SecretKey

fn from(t: T) -> SecretKey

Converts a 32-byte hash directly to a secret key without error paths.

impl FromStr for SecretKey

type Err = Error

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<SecretKey, Error>

Parses a string s to return a value of this type.

impl<I> Index<I> for SecretKeywhere
    [u8]: Index<I>,

type Output = <[u8] as Index<I>>::Output

The returned type after indexing.

fn index(&self, index: I) -> &Self::Output

Performs the indexing (container[index]) operation.

impl PartialEq<SecretKey> for SecretKey

fn eq(&self, other: &Self) -> bool

This implementation is designed to be constant time to help prevent side channel attacks.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for SecretKey

Available on crate feature serde only.

fn serialize<S: Serializer>(&self, s: S) -> Result<S::Ok, S::Error>

Serialize this value into the given Serde serializer.

impl Copy for SecretKey

impl Eq for SecretKey