75 lines
2.0 KiB
Go
75 lines
2.0 KiB
Go
package certificate
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import (
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"bytes"
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"fmt"
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"strconv"
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"time"
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"crypto/rand"
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"crypto/x509"
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"crypto/x509/pkix"
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"encoding/pem"
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"math/big"
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)
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func SignCert(caCertPem, caPrivKeyPem, csrPem string) (string, error) {
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caCertData, _ := pem.Decode([]byte(caCertPem))
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caCert, err := x509.ParseCertificate(caCertData.Bytes)
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if err != nil {
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return "", fmt.Errorf("parse cert %v", err)
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}
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pemKey, _ := pem.Decode([]byte(caPrivKeyPem))
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if pemKey == nil || pemKey.Type != "RSA PRIVATE KEY" {
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return "", fmt.Errorf("failed to decode PEM block containing private key")
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}
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keyPair, err := x509.ParsePKCS1PrivateKey(pemKey.Bytes)
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if err != nil {
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return "", fmt.Errorf("private key %v", err)
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}
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csrData, _ := pem.Decode([]byte(csrPem))
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csr, err := x509.ParseCertificateRequest(csrData.Bytes)
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if err != nil {
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return "", fmt.Errorf("parse csr %v", err)
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}
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serial, _ := strconv.ParseInt(time.Now().Format("20060102150405"), 10, 64)
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certTemplate := x509.Certificate{
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SerialNumber: big.NewInt(serial + 1),
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Issuer: caCert.Issuer,
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Subject: pkix.Name{
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Organization: []string{"Kubernetes Mutating Webserver"},
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Country: csr.Subject.Country,
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Province: []string{"Cluster Service"},
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Locality: []string{"Cluster Local"},
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StreetAddress: csr.Subject.StreetAddress,
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PostalCode: csr.Subject.PostalCode,
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},
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NotBefore: time.Now(),
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NotAfter: time.Now().AddDate(1, 6, 0),
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KeyUsage: x509.KeyUsageDigitalSignature,
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ExtKeyUsage: []x509.ExtKeyUsage{
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x509.ExtKeyUsageClientAuth,
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x509.ExtKeyUsageServerAuth,
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},
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DNSNames: csr.DNSNames,
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Signature: csr.Signature,
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SignatureAlgorithm: csr.SignatureAlgorithm,
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PublicKey: csr.PublicKey,
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PublicKeyAlgorithm: csr.PublicKeyAlgorithm,
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}
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certBytes, err := x509.CreateCertificate(rand.Reader, &certTemplate, caCert, csr.PublicKey, keyPair)
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if err != nil {
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return "", fmt.Errorf("sign %v", err)
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}
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c := new(bytes.Buffer)
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pem.Encode(c, &pem.Block{
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Type: "CERTIFICATE",
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Bytes: certBytes,
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})
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return c.String(), nil
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}
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