Interface CryptoBackend

Low-level secp256k1 operations required by the signer layer.

Two concrete implementations ship with this package:

NobleBackend (pure JS, @noble/curves)
LegacyBackend (wraps tiny-secp256k1)

Third-party implementations must satisfy every non-optional method.

interface CryptoBackend {
    isPoint(p: Uint8Array): boolean;
    isPrivate(d: Uint8Array): boolean;
    isXOnlyPoint(p: Uint8Array): boolean;
    pointAddScalar(
        p: PublicKey,
        tweak: Bytes32,
        compressed?: boolean,
    ): PublicKey | null;
    pointCompress(p: PublicKey, compressed?: boolean): PublicKey;
    pointFromScalar(d: PrivateKey, compressed?: boolean): PublicKey | null;
    privateAdd(d: PrivateKey, tweak: Bytes32): PrivateKey | null;
    privateNegate(d: PrivateKey): PrivateKey;
    sign(
        hash: MessageHash,
        privateKey: PrivateKey,
        extraEntropy?: Uint8Array<ArrayBufferLike>,
    ): Signature;
    signSchnorr?(
        hash: MessageHash,
        privateKey: PrivateKey,
        extraEntropy?: Uint8Array<ArrayBufferLike>,
    ): SchnorrSignature;
    verify(
        hash: MessageHash,
        publicKey: PublicKey,
        signature: Signature,
    ): boolean;
    verifySchnorr?(
        hash: MessageHash,
        publicKey: XOnlyPublicKey,
        signature: SchnorrSignature,
    ): boolean;
    xOnlyPointAddTweak(
        p: XOnlyPublicKey,
        tweak: Bytes32,
    ): XOnlyPointAddTweakResult | null;
}

Implemented by

Index

Methods

isPoint isPrivate isXOnlyPoint pointAddScalar pointCompress pointFromScalar privateAdd privateNegate sign signSchnorr? verify verifySchnorr? xOnlyPointAddTweak

Methods

isPoint

isPoint(p: Uint8Array): boolean
Returns true if p is a valid SEC1-encoded secp256k1 point.
Parameters
- p: Uint8Array
  Compressed (33 bytes) or uncompressed (65 bytes) SEC1 encoding.
Returns boolean
- Defined in backend.ts:50

isPrivate

isPrivate(d: Uint8Array): boolean
Returns true if d is a valid secp256k1 private key (32 bytes, in range [1, n)).
Parameters
- d: Uint8Array
  Raw bytes to test.
Returns boolean
- Defined in backend.ts:44

isXOnlyPoint

isXOnlyPoint(p: Uint8Array): boolean
Returns true if p is a valid 32-byte x-only public key whose x-coordinate lies on the secp256k1 curve.
Parameters
- p: Uint8Array
  32-byte x-only encoding.
Returns boolean
- Defined in backend.ts:57

pointAddScalar

pointAddScalar(
    p: PublicKey,
    tweak: Bytes32,
    compressed?: boolean,
): PublicKey | null
Adds a scalar tweak to a public key point (P + tweak·G).
Parameters
- p: PublicKey
  Base public key.
- tweak: Bytes32
  32-byte scalar to add.
- Optionalcompressed: boolean
  Encoding of the returned point.
Returns PublicKey | null
The resulting point, or null if the result is the point at infinity.
- Defined in backend.ts:81

pointCompress

pointCompress(p: PublicKey, compressed?: boolean): PublicKey
Re-encodes a public key in the requested SEC1 form.
Parameters
- p: PublicKey
  Input public key in any SEC1 form.
- Optionalcompressed: boolean
  Target form. Defaults to compressed.
Returns PublicKey
- Defined in backend.ts:72

pointFromScalar

pointFromScalar(d: PrivateKey, compressed?: boolean): PublicKey | null
Derives the public key for a private key scalar.
Parameters
- d: PrivateKey
  Private key scalar.
- Optionalcompressed: boolean
  Return compressed (33 bytes) when true (default), uncompressed (65 bytes) when false.
Returns PublicKey | null
The public key, or null if d is invalid.
- Defined in backend.ts:65

privateAdd

privateAdd(d: PrivateKey, tweak: Bytes32): PrivateKey | null
Adds two private key scalars modulo the curve order ((d + tweak) mod n).
Parameters
- d: PrivateKey
  First scalar (private key).
- tweak: Bytes32
  Second scalar.
Returns PrivateKey | null
The sum, or null if the result is zero mod n.
- Defined in backend.ts:98

privateNegate

privateNegate(d: PrivateKey): PrivateKey
Negates a private key scalar modulo the curve order (n - d).
Parameters
- d: PrivateKey
  Scalar to negate.
Returns PrivateKey
- Defined in backend.ts:104

sign

sign(
    hash: MessageHash,
    privateKey: PrivateKey,
    extraEntropy?: Uint8Array<ArrayBufferLike>,
): Signature
Produces a compact (64-byte) ECDSA signature.
Parameters
- hash: MessageHash
  32-byte message hash.
- privateKey: PrivateKey
  Signing key.
- OptionalextraEntropy: Uint8Array<ArrayBufferLike>
  Optional additional randomness for RFC 6979.
Returns Signature
- Defined in backend.ts:112

`Optional`signSchnorr

signSchnorr?(
    hash: MessageHash,
    privateKey: PrivateKey,
    extraEntropy?: Uint8Array<ArrayBufferLike>,
): SchnorrSignature
Produces a 64-byte BIP-340 Schnorr signature.

Optional — backends that omit this method will cause ECPairSigner.signSchnorr to throw at runtime.
Parameters
- hash: MessageHash
  32-byte message hash.
- privateKey: PrivateKey
  Signing key.
- OptionalextraEntropy: Uint8Array<ArrayBufferLike>
  Optional auxiliary randomness.
Returns SchnorrSignature
- Defined in backend.ts:131

verify

verify(hash: MessageHash, publicKey: PublicKey, signature: Signature): boolean
Verifies a compact ECDSA signature.
Parameters
- hash: MessageHash
  32-byte message hash.
- publicKey: PublicKey
  Signer's public key.
- signature: Signature
  64-byte compact signature.
Returns boolean
- Defined in backend.ts:120

`Optional`verifySchnorr

verifySchnorr?(
    hash: MessageHash,
    publicKey: XOnlyPublicKey,
    signature: SchnorrSignature,
): boolean
Verifies a 64-byte BIP-340 Schnorr signature.

Optional — backends that omit this method will cause ECPairSigner.verifySchnorr to throw at runtime.
Parameters
- hash: MessageHash
  32-byte message hash.
- publicKey: XOnlyPublicKey
  32-byte x-only public key.
- signature: SchnorrSignature
  64-byte Schnorr signature.
Returns boolean
- Defined in backend.ts:146

xOnlyPointAddTweak

xOnlyPointAddTweak(
p: XOnlyPublicKey,
tweak: Bytes32,
): XOnlyPointAddTweakResult | null
Adds a scalar tweak to an x-only public key, returning the resulting x-only key together with its Y-coordinate parity.
Parameters
- p: XOnlyPublicKey
  32-byte x-only public key.
- tweak: Bytes32
  32-byte scalar.
Returns XOnlyPointAddTweakResult | null
Tweak result, or null on failure (infinity or invalid tweak).
- Defined in backend.ts:90

Interface CryptoBackend

Implemented by

Index

Methods

Methods

isPoint

Parameters

Returns boolean

isPrivate

Parameters

Returns boolean

isXOnlyPoint

Parameters

Returns boolean

pointAddScalar

Parameters

Returns PublicKey | null

pointCompress

Parameters

Returns PublicKey

pointFromScalar

Parameters

Returns PublicKey | null

privateAdd

Parameters

Returns PrivateKey | null

privateNegate

Parameters

Returns PrivateKey

sign

Parameters

Returns Signature

OptionalsignSchnorr

Parameters

Returns SchnorrSignature

verify

Parameters

Returns boolean

OptionalverifySchnorr

Parameters

Returns boolean

xOnlyPointAddTweak

Parameters

Returns XOnlyPointAddTweakResult | null

Settings

On This Page

`Optional`signSchnorr

`Optional`verifySchnorr