`package `**ecdsa**
Import Path
crypto/ecdsa* (on golang.org and go.dev)*
Dependency Relation
imports 11 packages, and imported by 2 packages
Involved Source Files
Package ecdsa implements the Elliptic Curve Digital Signature Algorithm, as
defined in FIPS 186-3.
This implementation derives the nonce from an AES-CTR CSPRNG keyed by:
SHA2-512(priv.D || entropy || hash)[:32]
The CSPRNG key is indifferentiable from a random oracle as shown in
[Coron], the AES-CTR stream is indifferentiable from a random oracle
under standard cryptographic assumptions (see [Larsson] for examples).
References:
[Coron]
https://cs.nyu.edu/~dodis/ps/merkle.pdf
[Larsson]
https://web.archive.org/web/20040719170906/https://www.nada.kth.se/kurser/kth/2D1441/semteo03/lecturenotes/assump.pdf
ecdsa_noasm.go
Code Examples
package main
import (
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/sha256"
"fmt"
)
func main() {
privateKey, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
if err != nil {
panic(err)
}
msg := "hello, world"
hash := sha256.Sum256([]byte(msg))
sig, err := ecdsa.SignASN1(rand.Reader, privateKey, hash[:])
if err != nil {
panic(err)
}
fmt.Printf("signature: %x\n", sig)
valid := ecdsa.VerifyASN1(&privateKey.PublicKey, hash[:], sig)
fmt.Println("signature verified:", valid)
}
Package-Level Type Names* (total 2)*
PrivateKey represents an ECDSA private key.
D **big.Int*
PublicKey *PublicKey*
PublicKey.Curve *elliptic.Curve*
PublicKey.X **big.Int*
PublicKey.Y **big.Int*
Add returns the sum of (x1,y1) and (x2,y2)
Double returns 2*(x,y)
Equal reports whether priv and x have the same value.
See PublicKey.Equal for details on how Curve is compared.
IsOnCurve reports whether the given (x,y) lies on the curve.
Params returns the parameters for the curve.
Public returns the public key corresponding to priv.
ScalarBaseMult returns k*G, where G is the base point of the group
and k is an integer in big-endian form.
ScalarMult returns k*(Bx,By) where k is a number in big-endian form.
Sign signs digest with priv, reading randomness from rand. The opts argument
is not currently used but, in keeping with the crypto.Signer interface,
should be the hash function used to digest the message.
This method implements crypto.Signer, which is an interface to support keys
where the private part is kept in, for example, a hardware module. Common
uses should use the Sign function in this package directly.
*T : crypto.Signer
T : crypto/elliptic.Curve
func GenerateKey(c elliptic.Curve, rand io.Reader) (***PrivateKey**, error)
func crypto/x509.ParseECPrivateKey(der []byte) (***PrivateKey**, error)
func Sign(rand io.Reader, priv ***PrivateKey**, hash []byte) (r, s *big.Int, err error)
func SignASN1(rand io.Reader, priv ***PrivateKey**, hash []byte) ([]byte, error)
func crypto/x509.MarshalECPrivateKey(key ***PrivateKey**) ([]byte, error)
PublicKey represents an ECDSA public key.
Curve *elliptic.Curve*
X **big.Int*
Y **big.Int*
Add returns the sum of (x1,y1) and (x2,y2)
Double returns 2*(x,y)
Equal reports whether pub and x have the same value.
Two keys are only considered to have the same value if they have the same Curve value.
Note that for example elliptic.P256() and elliptic.P256().Params() are different
values, as the latter is a generic not constant time implementation.
IsOnCurve reports whether the given (x,y) lies on the curve.
Params returns the parameters for the curve.
ScalarBaseMult returns k*G, where G is the base point of the group
and k is an integer in big-endian form.
ScalarMult returns k*(Bx,By) where k is a number in big-endian form.
T : crypto/elliptic.Curve
func Verify(pub ***PublicKey**, hash []byte, r, s *big.Int) bool
func VerifyASN1(pub ***PublicKey**, hash, sig []byte) bool
Package-Level Functions* (total 5)*
GenerateKey generates a public and private key pair.
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. The security of the private key
depends on the entropy of rand.
SignASN1 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 ASN.1 encoded signature. The security of the private key
depends on the entropy of rand.
Verify verifies the signature in r, s of hash using the public key, pub. Its
return value records whether the signature is valid.
VerifyASN1 verifies the ASN.1 encoded signature, sig, of hash using the
public key, pub. Its return value records whether the signature is valid.

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