curve

Documentation

Index

• func CheckWIF(wif string) (valid bool, err error)
• func NAF(k []byte) ([]byte, []byte)
• func SignCompact(curve *KoblitzCurve, key *PrivateKey, hash []byte, isCompressedKey bool) ([]byte, error)
• type KoblitzCurve
  • func S256() *KoblitzCurve
  • func (curve *KoblitzCurve) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int)
  • func (curve *KoblitzCurve) DecompressPoint(x *big.Int, ybit bool) (*big.Int, error)
  • func (curve *KoblitzCurve) Double(x1, y1 *big.Int) (*big.Int, *big.Int)
  • func (curve *KoblitzCurve) IsOnCurve(x, y *big.Int) bool
  • func (curve *KoblitzCurve) Params() *elliptic.CurveParams
  • func (curve *KoblitzCurve) QPlus1Div4() *big.Int
  • func (curve *KoblitzCurve) ScalarBaseMult(k []byte) (*big.Int, *big.Int)
  • func (curve *KoblitzCurve) ScalarMult(Bx, By *big.Int, k []byte) (*big.Int, *big.Int)
• type PrivateKey
  • func NewPrivateKey(koblitzcurve elliptic.Curve) (*PrivateKey, error)
  • func (priv *PrivateKey) FromBytes(b []byte) (err error)
  • func (priv *PrivateKey) FromWIF(wif string) (err error)
  • func (p *PrivateKey) PubKey() *PublicKey
  • func (p *PrivateKey) Sign(hash []byte) (*Signature, error)
  • func (priv *PrivateKey) ToBytes() (b []byte)
  • func (p *PrivateKey) ToECDSA() *ecdsa.PrivateKey
  • func (priv *PrivateKey) ToWIF() (wif string)
  • func (priv *PrivateKey) ToWIFC() (wifc string)
• type PublicKey
  • func RecoverCompact(curve *KoblitzCurve, signature, hash []byte) (*PublicKey, bool, error)
  • func (pub *PublicKey) FromBytes(koblitzcurve *KoblitzCurve, b []byte) (err error)
  • func (pub *PublicKey) ToAddress() (address string)
  • func (pub *PublicKey) ToAddressUncompressed() (address string)
  • func (pub *PublicKey) ToBytes() (b []byte)
  • func (pub *PublicKey) ToBytesUncompressed() (b []byte)
  • func (p *PublicKey) ToECDSA() *ecdsa.PublicKey
• type Signature
  • func ParseDERSignature(sigStr []byte, curve elliptic.Curve) (*Signature, error)
  • func ParseSignature(sigStr []byte, curve elliptic.Curve) (*Signature, error)
  • func (sig *Signature) IsEqual(otherSig *Signature) bool
  • func (sig *Signature) Serialize() []byte
  • func (sig *Signature) Verify(hash []byte, pubKey *PublicKey) bool

Functions

func CheckWIF

func CheckWIF(wif string) (valid bool, err error)

CheckWIF checks that string wif is a valid Wallet Import Format or Wallet Import Format Compressed string. If it is not, err is populated with the reason.

func NAF

func NAF(k []byte) ([]byte, []byte)

NAF takes a positive integer k and returns the Non-Adjacent Form (NAF) as two byte slices. The first is where 1s will be. The second is where -1s will be. NAF is convenient in that on average, only 1/3rd of its values are non-zero. This is algorithm 3.30 from [GECC].

Essentially, this makes it possible to minimize the number of operations since the resulting ints returned will be at least 50% 0s.

func SignCompact

func SignCompact(curve *KoblitzCurve, key *PrivateKey,
	hash []byte, isCompressedKey bool) ([]byte, error)

SignCompact produces a compact signature of the data in hash with the given private key on the given koblitz curve. The isCompressed parameter should be used to detail if the given signature should reference a compressed public key or not. If successful the bytes of the compact signature will be returned in the format: <(byte of 27+public key solution)+4 if compressed >< padded bytes for signature R><padded bytes for signature S> where the R and S parameters are padde up to the bitlengh of the curve.

Types

type KoblitzCurve

type KoblitzCurve struct {
	*elliptic.CurveParams

	H int // cofactor of the curve.
	// contains filtered or unexported fields
}

KoblitzCurve supports a koblitz curve implementation that fits the ECC Curve interface from crypto/elliptic.

func S256

func S256() *KoblitzCurve

S256 returns a Curve which implements secp256k1.

func (*KoblitzCurve) Add

func (curve *KoblitzCurve) Add(x1, y1, x2, y2 *big.Int) (*big.Int, *big.Int)

Add returns the sum of (x1,y1) and (x2,y2). Part of the elliptic.Curve interface.

func (*KoblitzCurve) DecompressPoint

func (curve *KoblitzCurve) DecompressPoint(x *big.Int, ybit bool) (*big.Int, error)

DecompressPoint decompresses coordinate x and ylsb (y's least significant bit)

and returns the value of y source: https://github.com/btcsuite/btcd/blob/807d344fe97072efdf38ac3df053e07f26187a4f/btcec/pubkey.go#L27

func (*KoblitzCurve) Double

func (curve *KoblitzCurve) Double(x1, y1 *big.Int) (*big.Int, *big.Int)

Double returns 2*(x1,y1). Part of the elliptic.Curve interface.

func (*KoblitzCurve) IsOnCurve

func (curve *KoblitzCurve) IsOnCurve(x, y *big.Int) bool

IsOnCurve returns boolean if the point (x,y) is on the curve. Part of the elliptic.Curve interface. This function differs from the crypto/elliptic algorithm since a = 0 not -3.

func (*KoblitzCurve) Params

func (curve *KoblitzCurve) Params() *elliptic.CurveParams

Params returns the parameters for the curve.

func (*KoblitzCurve) QPlus1Div4

func (curve *KoblitzCurve) QPlus1Div4() *big.Int

QPlus1Div4 returns the Q+1/4 constant for the curve for use in calculating square roots via exponention.

func (*KoblitzCurve) ScalarBaseMult

func (curve *KoblitzCurve) ScalarBaseMult(k []byte) (*big.Int, *big.Int)

ScalarBaseMult returns k*G where G is the base point of the group and k is a big endian integer. Part of the elliptic.Curve interface.

func (*KoblitzCurve) ScalarMult

func (curve *KoblitzCurve) ScalarMult(Bx, By *big.Int, k []byte) (*big.Int, *big.Int)

ScalarMult returns k*(Bx, By) where k is a big endian integer. Part of the elliptic.Curve interface.

type PrivateKey

type PrivateKey ecdsa.PrivateKey

func NewPrivateKey

func NewPrivateKey(koblitzcurve elliptic.Curve) (*PrivateKey, error)

GenerateKey generate PublicKey/PrivateKey from KoblitzCurve

func (*PrivateKey) FromBytes

func (priv *PrivateKey) FromBytes(b []byte) (err error)

FromBytes converts a 32-byte byte slice to a Bitcoin private key and derives the corresponding public key.

func (*PrivateKey) FromWIF

func (priv *PrivateKey) FromWIF(wif string) (err error)

FromWIF converts a Wallet Import Format string to a Bitcoin private key and derives the corresponding public key.

func (*PrivateKey) PubKey

func (p *PrivateKey) PubKey() *PublicKey

PubKey returns the PublicKey corresponding to this private key.

func (*PrivateKey) Sign

func (p *PrivateKey) Sign(hash []byte) (*Signature, error)

Sign generates an ECDSA signature for the provided hash (which should be the result of hashing a larger message) using the private key. Produced signature is deterministic (same message and same key yield the same signature) and canonical in accordance with RFC6979 and BIP0062.

func (*PrivateKey) ToBytes

func (priv *PrivateKey) ToBytes() (b []byte)

ToBytes converts a Bitcoin private key to a 32-byte byte slice.

func (*PrivateKey) ToECDSA

func (p *PrivateKey) ToECDSA() *ecdsa.PrivateKey

ToECDSA returns the private key as a *ecdsa.PrivateKey.

func (*PrivateKey) ToWIF

func (priv *PrivateKey) ToWIF() (wif string)

ToWIF converts a Bitcoin private key to a Wallet Import Format string.

func (*PrivateKey) ToWIFC

func (priv *PrivateKey) ToWIFC() (wifc string)

ToWIFC converts a private key to a Wallet Import Format string with the public key compressed flag.

type PublicKey

type PublicKey ecdsa.PublicKey

func RecoverCompact

func RecoverCompact(curve *KoblitzCurve, signature,
	hash []byte) (*PublicKey, bool, error)

RecoverCompact verifies the compact signature "signature" of "hash" for the Koblitz curve in "curve". If the signature matches then the recovered public key will be returned as well as a boolen if the original key was compressed or not, else an error will be returned.

func (*PublicKey) FromBytes

func (pub *PublicKey) FromBytes(koblitzcurve *KoblitzCurve, b []byte) (err error)

TODO: Where is it used and what is it used for? FromBytes converts a byte slice (either with or without point compression) to a public key.

func (*PublicKey) ToAddress

func (pub *PublicKey) ToAddress() (address string)

ToAddress converts a public key to a compressed address string.

func (*PublicKey) ToAddressUncompressed

func (pub *PublicKey) ToAddressUncompressed() (address string)

ToAddressUncompressed converts a public key to an uncompressed address string.

func (*PublicKey) ToBytes

func (pub *PublicKey) ToBytes() (b []byte)

ToBytes converts a public key to a 33-byte byte slice with point compression.

func (*PublicKey) ToBytesUncompressed

func (pub *PublicKey) ToBytesUncompressed() (b []byte)

ToBytesUncompressed converts a public key to a 65-byte byte slice without point compression.

func (*PublicKey) ToECDSA

func (p *PublicKey) ToECDSA() *ecdsa.PublicKey

ToECDSA returns the public key as a *ecdsa.PublicKey.

type Signature

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

Signature is a type representing an ecdsa signature.

func ParseDERSignature

func ParseDERSignature(sigStr []byte, curve elliptic.Curve) (*Signature, error)

ParseDERSignature parses a signature in DER format for the curve type `curve` into a Signature type. If parsing according to the less strict BER format is needed, use ParseSignature.

func ParseSignature

func ParseSignature(sigStr []byte, curve elliptic.Curve) (*Signature, error)

ParseSignature parses a signature in BER format for the curve type `curve' into a Signature type, perfoming some basic sanity checks. If parsing according to the more strict DER format is needed, use ParseDERSignature.

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 ECDSA signature in the more strict DER format. Note that the serialized bytes returned do not include the appended hash type used in Bitcoin signature scripts.

encoding/asn1 is broken so we hand roll this output:

0x30 <length> 0x02 <length r> r 0x02 <length s> s

func (*Signature) Verify

func (sig *Signature) Verify(hash []byte, pubKey *PublicKey) bool

Verify calls ecdsa.Verify to verify the signature of hash using the public key. It returns true if the signature is valid, false otherwise.