246 lines
7.2 KiB
Go
246 lines
7.2 KiB
Go
/*
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Copyright 2014 The Kubernetes Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package cert
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import (
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"bytes"
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"crypto/ecdsa"
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"crypto/elliptic"
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cryptorand "crypto/rand"
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"crypto/rsa"
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"crypto/x509"
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"crypto/x509/pkix"
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"encoding/pem"
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"errors"
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"fmt"
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"math"
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"math/big"
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"net"
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"time"
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)
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const (
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rsaKeySize = 2048
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duration365d = time.Hour * 24 * 365
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)
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// Config contains the basic fields required for creating a certificate
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type Config struct {
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CommonName string
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Organization []string
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AltNames AltNames
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Usages []x509.ExtKeyUsage
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}
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// AltNames contains the domain names and IP addresses that will be added
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// to the API Server's x509 certificate SubAltNames field. The values will
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// be passed directly to the x509.Certificate object.
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type AltNames struct {
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DNSNames []string
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IPs []net.IP
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}
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// NewPrivateKey creates an RSA private key
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func NewPrivateKey() (*rsa.PrivateKey, error) {
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return rsa.GenerateKey(cryptorand.Reader, rsaKeySize)
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}
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// NewSelfSignedCACert creates a CA certificate
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func NewSelfSignedCACert(cfg Config, key *rsa.PrivateKey) (*x509.Certificate, error) {
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now := time.Now()
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tmpl := x509.Certificate{
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SerialNumber: new(big.Int).SetInt64(0),
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Subject: pkix.Name{
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CommonName: cfg.CommonName,
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Organization: cfg.Organization,
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},
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NotBefore: now.UTC(),
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NotAfter: now.Add(duration365d * 10).UTC(),
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KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
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BasicConstraintsValid: true,
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IsCA: true,
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}
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certDERBytes, err := x509.CreateCertificate(cryptorand.Reader, &tmpl, &tmpl, key.Public(), key)
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if err != nil {
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return nil, err
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}
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return x509.ParseCertificate(certDERBytes)
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}
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// NewSignedCert creates a signed certificate using the given CA certificate and key
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func NewSignedCert(cfg Config, key *rsa.PrivateKey, caCert *x509.Certificate, caKey *rsa.PrivateKey) (*x509.Certificate, error) {
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serial, err := cryptorand.Int(cryptorand.Reader, new(big.Int).SetInt64(math.MaxInt64))
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if err != nil {
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return nil, err
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}
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if len(cfg.CommonName) == 0 {
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return nil, errors.New("must specify a CommonName")
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}
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if len(cfg.Usages) == 0 {
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return nil, errors.New("must specify at least one ExtKeyUsage")
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}
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certTmpl := x509.Certificate{
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Subject: pkix.Name{
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CommonName: cfg.CommonName,
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Organization: cfg.Organization,
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},
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DNSNames: cfg.AltNames.DNSNames,
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IPAddresses: cfg.AltNames.IPs,
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SerialNumber: serial,
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NotBefore: caCert.NotBefore,
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NotAfter: time.Now().Add(duration365d).UTC(),
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KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
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ExtKeyUsage: cfg.Usages,
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}
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certDERBytes, err := x509.CreateCertificate(cryptorand.Reader, &certTmpl, caCert, key.Public(), caKey)
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if err != nil {
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return nil, err
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}
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return x509.ParseCertificate(certDERBytes)
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}
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// MakeEllipticPrivateKeyPEM creates an ECDSA private key
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func MakeEllipticPrivateKeyPEM() ([]byte, error) {
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privateKey, err := ecdsa.GenerateKey(elliptic.P256(), cryptorand.Reader)
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if err != nil {
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return nil, err
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}
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derBytes, err := x509.MarshalECPrivateKey(privateKey)
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if err != nil {
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return nil, err
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}
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privateKeyPemBlock := &pem.Block{
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Type: ECPrivateKeyBlockType,
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Bytes: derBytes,
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}
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return pem.EncodeToMemory(privateKeyPemBlock), nil
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}
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// GenerateSelfSignedCertKey creates a self-signed certificate and key for the given host.
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// Host may be an IP or a DNS name
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// You may also specify additional subject alt names (either ip or dns names) for the certificate
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func GenerateSelfSignedCertKey(host string, alternateIPs []net.IP, alternateDNS []string) ([]byte, []byte, error) {
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caKey, err := rsa.GenerateKey(cryptorand.Reader, 2048)
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if err != nil {
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return nil, nil, err
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}
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caTemplate := x509.Certificate{
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SerialNumber: big.NewInt(1),
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Subject: pkix.Name{
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CommonName: fmt.Sprintf("%s-ca@%d", host, time.Now().Unix()),
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},
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NotBefore: time.Now(),
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NotAfter: time.Now().Add(time.Hour * 24 * 365),
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KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign,
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BasicConstraintsValid: true,
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IsCA: true,
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}
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caDERBytes, err := x509.CreateCertificate(cryptorand.Reader, &caTemplate, &caTemplate, &caKey.PublicKey, caKey)
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if err != nil {
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return nil, nil, err
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}
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caCertificate, err := x509.ParseCertificate(caDERBytes)
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if err != nil {
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return nil, nil, err
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}
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priv, err := rsa.GenerateKey(cryptorand.Reader, 2048)
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if err != nil {
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return nil, nil, err
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}
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template := x509.Certificate{
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SerialNumber: big.NewInt(2),
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Subject: pkix.Name{
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CommonName: fmt.Sprintf("%s@%d", host, time.Now().Unix()),
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},
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NotBefore: time.Now(),
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NotAfter: time.Now().Add(time.Hour * 24 * 365),
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KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
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ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
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BasicConstraintsValid: true,
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}
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if ip := net.ParseIP(host); ip != nil {
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template.IPAddresses = append(template.IPAddresses, ip)
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} else {
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template.DNSNames = append(template.DNSNames, host)
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}
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template.IPAddresses = append(template.IPAddresses, alternateIPs...)
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template.DNSNames = append(template.DNSNames, alternateDNS...)
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derBytes, err := x509.CreateCertificate(cryptorand.Reader, &template, caCertificate, &priv.PublicKey, caKey)
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if err != nil {
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return nil, nil, err
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}
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// Generate cert, followed by ca
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certBuffer := bytes.Buffer{}
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if err := pem.Encode(&certBuffer, &pem.Block{Type: CertificateBlockType, Bytes: derBytes}); err != nil {
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return nil, nil, err
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}
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if err := pem.Encode(&certBuffer, &pem.Block{Type: CertificateBlockType, Bytes: caDERBytes}); err != nil {
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return nil, nil, err
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}
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// Generate key
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keyBuffer := bytes.Buffer{}
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if err := pem.Encode(&keyBuffer, &pem.Block{Type: RSAPrivateKeyBlockType, Bytes: x509.MarshalPKCS1PrivateKey(priv)}); err != nil {
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return nil, nil, err
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}
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return certBuffer.Bytes(), keyBuffer.Bytes(), nil
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}
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// FormatBytesCert receives byte array certificate and formats in human-readable format
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func FormatBytesCert(cert []byte) (string, error) {
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block, _ := pem.Decode(cert)
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c, err := x509.ParseCertificate(block.Bytes)
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if err != nil {
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return "", fmt.Errorf("failed to parse certificate [%v]", err)
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}
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return FormatCert(c), nil
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}
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// FormatCert receives certificate and formats in human-readable format
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func FormatCert(c *x509.Certificate) string {
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var ips []string
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for _, ip := range c.IPAddresses {
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ips = append(ips, ip.String())
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}
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altNames := append(ips, c.DNSNames...)
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res := fmt.Sprintf(
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"Issuer: CN=%s | Subject: CN=%s | CA: %t\n",
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c.Issuer.CommonName, c.Subject.CommonName, c.IsCA,
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)
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res += fmt.Sprintf("Not before: %s Not After: %s", c.NotBefore, c.NotAfter)
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if len(altNames) > 0 {
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res += fmt.Sprintf("\nAlternate Names: %v", altNames)
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}
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return res
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}
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