schnorr

Documentation

Index

• Constants
• func GenerateKey(rand io.Reader) (priv []byte, x, y *big.Int, err error)
• func ParsePubKey(pubKeyStr []byte) (key *secp256k1.PublicKey, err error)
• func RecoverPubkey(sig, msg []byte) (*secp256k1.PublicKey, bool, error)
• func Sign(priv *secp256k1.PrivateKey, hash []byte) (r, s *big.Int, err error)
• func Verify(pubkey *secp256k1.PublicKey, msg []byte, r *big.Int, s *big.Int) bool
• type Error
  • func (e Error) Error() string
  • func (e Error) GetCode() ErrorCode
• type ErrorCode
  • func (e ErrorCode) String() string
• type Signature
  • func NewSignature(r, s *big.Int) *Signature
  • func ParseSignature(sigStr []byte) (*Signature, error)
  • func (sig Signature) GetR() *big.Int
  • func (sig Signature) GetS() *big.Int
  • func (sig Signature) GetType() int
  • func (sig Signature) IsEqual(otherSig *Signature) bool
  • func (sig Signature) Serialize() []byte
  • func (sig Signature) Verify(msg []byte, pubkey *secp256k1.PublicKey) bool

Constants

const (
	// ErrBadInputSize indicates that input to a signature was of the wrong size.
	ErrBadInputSize = iota

	// ErrInputValue indicates that the value of an input was wrong (e.g. zero).
	ErrInputValue

	// ErrSchnorrHashValue indicates that the hash of (R || m) was too large
	// and so a new k value (nonce) should be used.
	ErrSchnorrHashValue

	// ErrPointNotOnCurve indicates that a point was not on the given
	// elliptic curve.
	ErrPointNotOnCurve

	// ErrBadSigRYValue indicates that the calculated Y value of R was odd,
	// which is not allowed.
	ErrBadSigRYValue

	// ErrBadSigRNotOnCurve indicates that the calculated or given point R for some
	// signature was not on the curve.
	ErrBadSigRNotOnCurve

	// ErrUnequalRValues indicates that the calculated point R for some
	// signature was not the same as the given R value for the signature.
	ErrUnequalRValues

	// ErrRegenerateRPoint indicates that a point could not be regenerated
	// from r.
	ErrRegenerateRPoint

	// ErrPubKeyOffCurve indicates that a regenerated pubkey was off the curve.
	ErrPubKeyOffCurve

	// ErrRegenSig indicates that a regenerated pubkey could not be validated
	// against the signature.
	ErrRegenSig

	// ErrBadNonce indicates that a generated nonce from some algorithm was
	// unusable.
	ErrBadNonce

	// ErrZeroSigS indicates a zero signature S value, which is invalid.
	ErrZeroSigS

	// ErrNonmatchingR indicates that all signatures to be combined in a
	// threshold signature failed to have a matching R value.
	ErrNonmatchingR
)

These constants are used to identify a specific RuleError.

const (
	PubKeyBytesLen = 33
)

These constants define the lengths of serialized public keys.

const SignatureSize = 64

SignatureSize is the size of an encoded Schnorr signature.

Functions

func GenerateKey

func GenerateKey(rand io.Reader) (priv []byte, x, y *big.Int, err error)

GenerateKey generates a key using a random number generator, returning the private scalar and the corresponding public key points.

func ParsePubKey

func ParsePubKey(pubKeyStr []byte) (key *secp256k1.PublicKey, err error)

ParsePubKey parses a public key for a koblitz curve from a bytestring into a ecdsa.Publickey, verifying that it is valid. It supports compressed signature formats only.

func RecoverPubkey

func RecoverPubkey(sig,
	msg []byte) (*secp256k1.PublicKey, bool, error)

RecoverPubkey is the exported and generalized version of schnorrRecover. It recovers a public key given a signature and a message, using BLAKE256 as the hashing function.

func Sign

func Sign(priv *secp256k1.PrivateKey, hash []byte) (r, s *big.Int, err error)

Sign is the exported version of sign. It uses RFC6979 and Blake256 to produce a Schnorr signature.

func Verify

func Verify(pubkey *secp256k1.PublicKey,
	msg []byte, r *big.Int, s *big.Int) bool

Verify is the generalized and exported function for the verification of a secp256k1 Schnorr signature. BLAKE256 is used as the hashing function.

Types

type Error

type Error struct {
	ErrorCode   ErrorCode // Describes the kind of error
	Description string    // Human readable description of the issue
}

Error identifies a violation.

func (Error) Error

func (e Error) Error() string

Error satisfies the error interface and prints human-readable errors.

func (Error) GetCode

func (e Error) GetCode() ErrorCode

GetCode satisfies the error interface and prints human-readable errors.

type ErrorCode

type ErrorCode int

ErrorCode identifies a kind of error.

func (ErrorCode) String

func (e ErrorCode) String() string

String returns the ErrorCode as a human-readable name.

type Signature

type Signature struct {
	R *big.Int
	S *big.Int
}

Signature is a type representing a Schnorr signature.

func NewSignature

func NewSignature(r, s *big.Int) *Signature

NewSignature instantiates a new signature given some R,S values.

func ParseSignature

func ParseSignature(sigStr []byte) (*Signature, error)

ParseSignature parses a signature in BER format for the curve type `curve' into a Signature type, performing some basic sanity checks.

func (Signature) GetR

func (sig Signature) GetR() *big.Int

GetR satisfies the chainec PublicKey interface.

func (Signature) GetS

func (sig Signature) GetS() *big.Int

GetS satisfies the chainec PublicKey interface.

func (Signature) GetType

func (sig Signature) GetType() int

GetType satisfies the chainec Signature interface.

func (Signature) IsEqual

func (sig Signature) IsEqual(otherSig *Signature) bool

IsEqual compares this Signature instance to the one passed, returning true if both Signatures are equivalent. A signature is equivalent to another, if they both have the same scalar value for R and S.

func (Signature) Serialize

func (sig Signature) Serialize() []byte

Serialize returns the Schnorr signature in the more strict format.

The signatures are encoded as

sig[0:32]  R, a point encoded as big endian
sig[32:64] S, scalar multiplication/addition results = (ab+c) mod l
  encoded also as big endian

func (Signature) Verify

func (sig Signature) Verify(msg []byte, pubkey *secp256k1.PublicKey) bool

Verify is the generalized and exported function for the verification of a secp256k1 Schnorr signature. BLAKE256 is used as the hashing function.