go/src/crypto/ecdsa/ecdsa_legacy.go

func generateLegacy(c elliptic.Curve, rand io.Reader) (*PrivateKey, error) { … }

// hashToInt converts a hash value to an integer. Per FIPS 186-4, Section 6.4,
// we use the left-most bits of the hash to match the bit-length of the order of
// the curve. This also performs Step 5 of SEC 1, Version 2.0, Section 4.1.3.
func hashToInt(hash []byte, c elliptic.Curve) *big.Int { … }

var errZeroParam …

// Sign signs a hash (which should be the result of hashing a larger message)
// using the private key, priv. If the hash is longer than the bit-length of the
// private key's curve order, the hash will be truncated to that length. It
// returns the signature as a pair of integers. Most applications should use
// [SignASN1] instead of dealing directly with r, s.
func Sign(rand io.Reader, priv *PrivateKey, hash []byte) (r, s *big.Int, err error) { … }

func signLegacy(priv *PrivateKey, csprng io.Reader, hash []byte) (sig []byte, err error) { … }

// Verify verifies the signature in r, s of hash using the public key, pub. Its
// return value records whether the signature is valid. Most applications should
// use VerifyASN1 instead of dealing directly with r, s.
//
// The inputs are not considered confidential, and may leak through timing side
// channels, or if an attacker has control of part of the inputs.
func Verify(pub *PublicKey, hash []byte, r, s *big.Int) bool { … }

func verifyLegacy(pub *PublicKey, hash []byte, sig []byte) bool { … }

var one …

// randFieldElement returns a random element of the order of the given
// curve using the procedure given in FIPS 186-4, Appendix B.5.2.
func randFieldElement(c elliptic.Curve, rand io.Reader) (k *big.Int, err error) { … }