golang 中的 ECDH - 椭圆/曲线解组失败

Question

不幸的是，没有内置的 Brainpool 支持，go所以我试图在keybase.

也许我在这里犯了一个新手错误，但通过代码，在第一个障碍处就跌倒了（即elliptic.Unmarshal返回零）？

package main

import (

 "fmt"

 "io/ioutil"

 "log"

"encoding/pem"

"crypto/ecdsa"

"crypto/rand"

"github.com/keybase/go-crypto/brainpool"

"crypto/elliptic"

"crypto/sha256"

)

func main() {

fmt.Println("Hello")

content, err := ioutil.ReadFile("/tmp/TEST.pem")

    if err != nil {

        log.Fatal(err)

    }

fmt.Printf("File contents: %s", content)

    block, _ := pem.Decode(content)

    if block == nil || block.Type != "PUBLIC KEY" {

        log.Fatal("failed to decode PEM")

    }

x,y := elliptic.Unmarshal(brainpool.P512r1(),block.Bytes)

if x == nil {

     log.Fatal("failed to unmarshal")

}

pubb := ecdsa.PublicKey {brainpool.P512r1(),x,y}

priva, _ := ecdsa.GenerateKey(brainpool.P512r1(), rand.Reader)

b, _ := pubb.Curve.ScalarMult(pubb.X, pubb.Y, priva.D.Bytes())

shared1 := sha256.Sum256(b.Bytes())

fmt.Printf("\nShared key %x\n",  shared1)

更新以显示测试密钥：

-----BEGIN PUBLIC KEY-----

MIGbMBQGByqGSM49AgEGCSskAwMCCAEBDQOBggAEM/zOLT7nMN374k902oTRZXnG

97DPzvqi8QQJaKXcq1BSrU/sNeUhOi6Y+hBcr7ZE+WZDYNoQkaMNrdhF+3x1XGx7

BTBFL3U1w2ENmkIPiDa2o0Q/wpSOLo/RFabdK5Q3/yvq0hoSdXlpKozE7UTre5cU

bJcUzjXvs9KDLEq54Fs=

-----END PUBLIC KEY-----

Answer 1

您正在尝试解组原始 ASN.1 消息，而不是公钥部分。您应该首先解组 ASN.1 块，然后解组 EC 数据。我的评论是错误的，Go 不支持 Brainpool 功能。因此，我从他们的 X509 包中借用了一些代码，为 Brainpool 包中的 6 条曲线构建了一个自定义解析器。游乐场：https://play.golang.org/p/i-Zd4mTugjUpackage mainimport (    "crypto/ecdsa"    "crypto/elliptic"    "crypto/rand"    "crypto/sha256"    "crypto/x509/pkix"    "encoding/asn1"    "encoding/pem"    "errors"    "fmt"    "log"    "math/big"    "github.com/keybase/go-crypto/brainpool")const ecKey = `-----BEGIN PUBLIC KEY-----MIGbMBQGByqGSM49AgEGCSskAwMCCAEBDQOBggAEM/zOLT7nMN374k902oTRZXnG97DPzvqi8QQJaKXcq1BSrU/sNeUhOi6Y+hBcr7ZE+WZDYNoQkaMNrdhF+3x1XGx7BTBFL3U1w2ENmkIPiDa2o0Q/wpSOLo/RFabdK5Q3/yvq0hoSdXlpKozE7UTre5cUbJcUzjXvs9KDLEq54Fs=-----END PUBLIC KEY-----`func main() {    block, _ := pem.Decode([]byte(ecKey))    if block == nil || block.Type != "PUBLIC KEY" {        log.Fatal("failed to decode PEM")    }    pub, err := parseBrainpoolPKIXPublicKey(block.Bytes)    if err != nil {        log.Fatalf("failed to parse key: %v", err)    }    pubb := ecdsa.PublicKey{Curve: brainpool.P512r1(), X: pub.X, Y: pub.Y}    priva, _ := ecdsa.GenerateKey(brainpool.P512r1(), rand.Reader)    b, _ := pubb.Curve.ScalarMult(pubb.X, pubb.Y, priva.D.Bytes())    shared1 := sha256.Sum256(b.Bytes())    fmt.Printf("\nShared key %x\n", shared1)}type publicKeyInfo struct {    Raw       asn1.RawContent    Algorithm pkix.AlgorithmIdentifier    PublicKey asn1.BitString}type pkcs1PublicKey struct {    N *big.Int    E int}var (    oidNamedCurveBrainpoolP256r1 = asn1.ObjectIdentifier{1, 3, 36, 3, 3, 2, 8, 1, 1, 7}    oidNamedCurveBrainpoolP256t1 = asn1.ObjectIdentifier{1, 3, 36, 3, 3, 2, 8, 1, 1, 8}    oidNamedCurveBrainpoolP384r1 = asn1.ObjectIdentifier{1, 3, 36, 3, 3, 2, 8, 1, 1, 11}    oidNamedCurveBrainpoolP384t1 = asn1.ObjectIdentifier{1, 3, 36, 3, 3, 2, 8, 1, 1, 12}    oidNamedCurveBrainpoolP512r1 = asn1.ObjectIdentifier{1, 3, 36, 3, 3, 2, 8, 1, 1, 13}    oidNamedCurveBrainpoolP512t1 = asn1.ObjectIdentifier{1, 3, 36, 3, 3, 2, 8, 1, 1, 14})func parseBrainpoolPKIXPublicKey(derBytes []byte) (pub *ecdsa.PublicKey, err error) {    var pki publicKeyInfo    if rest, err := asn1.Unmarshal(derBytes, &pki); err != nil {        if _, err := asn1.Unmarshal(derBytes, &pkcs1PublicKey{}); err == nil {            return nil, errors.New("failed to parse public key")        }        return nil, err    } else if len(rest) != 0 {        return nil, errors.New("trailing data after ASN.1 of public-key")    }    if !pki.Algorithm.Algorithm.Equal(asn1.ObjectIdentifier{1, 2, 840, 10045, 2, 1}) {        return nil, errors.New("not an ECDSA public key")    }    return parseBrainpoolPublicKey(&pki)}func parseBrainpoolPublicKey(keyData *publicKeyInfo) (*ecdsa.PublicKey, error) {    asn1Data := keyData.PublicKey.RightAlign()    paramsData := keyData.Algorithm.Parameters.FullBytes    namedCurveOID := new(asn1.ObjectIdentifier)    rest, err := asn1.Unmarshal(paramsData, namedCurveOID)    if err != nil {        return nil, errors.New("failed to parse ECDSA parameters as named curve")    }    if len(rest) != 0 {        return nil, errors.New("trailing data after ECDSA parameters")    }    namedCurve := namedCurveFromOID(*namedCurveOID)    if namedCurve == nil {        return nil, errors.New("unsupported elliptic curve")    }    x, y := elliptic.Unmarshal(namedCurve, asn1Data)    if x == nil {        return nil, errors.New("failed to unmarshal elliptic curve point")    }    pub := &ecdsa.PublicKey{        Curve: namedCurve,        X:     x,        Y:     y,    }    return pub, nil}func namedCurveFromOID(oid asn1.ObjectIdentifier) elliptic.Curve {    switch {    case oid.Equal(oidNamedCurveBrainpoolP256r1):        return brainpool.P256r1()    case oid.Equal(oidNamedCurveBrainpoolP256t1):        return brainpool.P256t1()    case oid.Equal(oidNamedCurveBrainpoolP384r1):        return brainpool.P384r1()    case oid.Equal(oidNamedCurveBrainpoolP384t1):        return brainpool.P384t1()    case oid.Equal(oidNamedCurveBrainpoolP512r1):        return brainpool.P512r1()    case oid.Equal(oidNamedCurveBrainpoolP512t1):        return brainpool.P512t1()    }    return nil}