certificates/cas/cloudcas/certificate.go

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package cloudcas
import (
"crypto"
"crypto/ecdsa"
"crypto/rsa"
"crypto/x509"
"crypto/x509/pkix"
"encoding/asn1"
"encoding/pem"
"fmt"
"github.com/pkg/errors"
kmsapi "github.com/smallstep/certificates/kms/apiv1"
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pb "google.golang.org/genproto/googleapis/cloud/security/privateca/v1"
)
var (
oidExtensionSubjectKeyID = []int{2, 5, 29, 14}
oidExtensionKeyUsage = []int{2, 5, 29, 15}
oidExtensionExtendedKeyUsage = []int{2, 5, 29, 37}
oidExtensionAuthorityKeyID = []int{2, 5, 29, 35}
oidExtensionBasicConstraints = []int{2, 5, 29, 19}
oidExtensionSubjectAltName = []int{2, 5, 29, 17}
oidExtensionCRLDistributionPoints = []int{2, 5, 29, 31}
oidExtensionCertificatePolicies = []int{2, 5, 29, 32}
oidExtensionAuthorityInfoAccess = []int{1, 3, 6, 1, 5, 5, 7, 1, 1}
)
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var extraExtensions = [...]asn1.ObjectIdentifier{
oidExtensionSubjectKeyID, // Added by CAS
oidExtensionKeyUsage, // Added in CertificateConfig.ReusableConfig
oidExtensionExtendedKeyUsage, // Added in CertificateConfig.ReusableConfig
oidExtensionAuthorityKeyID, // Added by CAS
oidExtensionBasicConstraints, // Added in CertificateConfig.ReusableConfig
oidExtensionSubjectAltName, // Added in CertificateConfig.SubjectConfig.SubjectAltName
oidExtensionCRLDistributionPoints, // Added by CAS
oidExtensionCertificatePolicies, // Added in CertificateConfig.ReusableConfig
oidExtensionAuthorityInfoAccess, // Added in CertificateConfig.ReusableConfig and by CAS
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}
var (
oidExtKeyUsageAny = asn1.ObjectIdentifier{2, 5, 29, 37, 0}
oidExtKeyUsageIPSECEndSystem = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 5}
oidExtKeyUsageIPSECTunnel = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 6}
oidExtKeyUsageIPSECUser = asn1.ObjectIdentifier{1, 3, 6, 1, 5, 5, 7, 3, 7}
oidExtKeyUsageMicrosoftServerGatedCrypto = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 10, 3, 3}
oidExtKeyUsageNetscapeServerGatedCrypto = asn1.ObjectIdentifier{2, 16, 840, 1, 113730, 4, 1}
oidExtKeyUsageMicrosoftCommercialCodeSigning = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 2, 1, 22}
oidExtKeyUsageMicrosoftKernelCodeSigning = asn1.ObjectIdentifier{1, 3, 6, 1, 4, 1, 311, 61, 1, 1}
)
const (
nameTypeEmail = 1
nameTypeDNS = 2
nameTypeURI = 6
nameTypeIP = 7
)
func createCertificateConfig(tpl *x509.Certificate) (*pb.Certificate_Config, error) {
pk, err := createPublicKey(tpl.PublicKey)
if err != nil {
return nil, err
}
config := &pb.CertificateConfig{
SubjectConfig: &pb.CertificateConfig_SubjectConfig{
Subject: createSubject(tpl),
SubjectAltName: createSubjectAlternativeNames(tpl),
},
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X509Config: createX509Parameters(tpl),
PublicKey: pk,
}
return &pb.Certificate_Config{
Config: config,
}, nil
}
func createPublicKey(key crypto.PublicKey) (*pb.PublicKey, error) {
switch key := key.(type) {
case *ecdsa.PublicKey:
asn1Bytes, err := x509.MarshalPKIXPublicKey(key)
if err != nil {
return nil, errors.Wrap(err, "error marshaling public key")
}
return &pb.PublicKey{
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Format: pb.PublicKey_PEM,
Key: pem.EncodeToMemory(&pem.Block{
Type: "PUBLIC KEY",
Bytes: asn1Bytes,
}),
}, nil
case *rsa.PublicKey:
return &pb.PublicKey{
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Format: pb.PublicKey_PEM,
Key: pem.EncodeToMemory(&pem.Block{
Type: "RSA PUBLIC KEY",
Bytes: x509.MarshalPKCS1PublicKey(key),
}),
}, nil
default:
return nil, errors.Errorf("unsupported public key type: %T", key)
}
}
func createSubject(cert *x509.Certificate) *pb.Subject {
sub := cert.Subject
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ret := &pb.Subject{
CommonName: sub.CommonName,
}
if len(sub.Country) > 0 {
ret.CountryCode = sub.Country[0]
}
if len(sub.Organization) > 0 {
ret.Organization = sub.Organization[0]
}
if len(sub.OrganizationalUnit) > 0 {
ret.OrganizationalUnit = sub.OrganizationalUnit[0]
}
if len(sub.Locality) > 0 {
ret.Locality = sub.Locality[0]
}
if len(sub.Province) > 0 {
ret.Province = sub.Province[0]
}
if len(sub.StreetAddress) > 0 {
ret.StreetAddress = sub.StreetAddress[0]
}
if len(sub.PostalCode) > 0 {
ret.PostalCode = sub.PostalCode[0]
}
return ret
}
func createSubjectAlternativeNames(cert *x509.Certificate) *pb.SubjectAltNames {
ret := new(pb.SubjectAltNames)
ret.DnsNames = cert.DNSNames
ret.EmailAddresses = cert.EmailAddresses
if n := len(cert.IPAddresses); n > 0 {
ret.IpAddresses = make([]string, n)
for i, ip := range cert.IPAddresses {
ret.IpAddresses[i] = ip.String()
}
}
if n := len(cert.URIs); n > 0 {
ret.Uris = make([]string, n)
for i, u := range cert.URIs {
ret.Uris[i] = u.String()
}
}
// Add extra SANs coming from the extensions
if ext, ok := findExtraExtension(cert, oidExtensionSubjectAltName); ok {
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var rawValues []asn1.RawValue
if _, err := asn1.Unmarshal(ext.Value, &rawValues); err == nil {
var newValues []asn1.RawValue
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for _, v := range rawValues {
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if v.Class == asn1.ClassContextSpecific {
switch v.Tag {
case nameTypeDNS:
if len(ret.DnsNames) == 0 {
newValues = append(newValues, v)
}
case nameTypeEmail:
if len(ret.EmailAddresses) == 0 {
newValues = append(newValues, v)
}
case nameTypeIP:
if len(ret.IpAddresses) == 0 {
newValues = append(newValues, v)
}
case nameTypeURI:
if len(ret.Uris) == 0 {
newValues = append(newValues, v)
}
default:
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newValues = append(newValues, v)
}
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} else {
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newValues = append(newValues, v)
}
}
if len(newValues) > 0 {
if b, err := asn1.Marshal(newValues); err == nil {
ret.CustomSans = []*pb.X509Extension{{
ObjectId: createObjectID(ext.Id),
Critical: ext.Critical,
Value: b,
}}
}
}
}
}
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return ret
}
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func createX509Parameters(cert *x509.Certificate) *pb.X509Parameters {
var unknownEKUs []*pb.ObjectId
var ekuOptions = &pb.KeyUsage_ExtendedKeyUsageOptions{}
for _, eku := range cert.ExtKeyUsage {
switch eku {
case x509.ExtKeyUsageAny:
unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageAny))
case x509.ExtKeyUsageServerAuth:
ekuOptions.ServerAuth = true
case x509.ExtKeyUsageClientAuth:
ekuOptions.ClientAuth = true
case x509.ExtKeyUsageCodeSigning:
ekuOptions.CodeSigning = true
case x509.ExtKeyUsageEmailProtection:
ekuOptions.EmailProtection = true
case x509.ExtKeyUsageIPSECEndSystem:
unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageIPSECEndSystem))
case x509.ExtKeyUsageIPSECTunnel:
unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageIPSECTunnel))
case x509.ExtKeyUsageIPSECUser:
unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageIPSECUser))
case x509.ExtKeyUsageTimeStamping:
ekuOptions.TimeStamping = true
case x509.ExtKeyUsageOCSPSigning:
ekuOptions.OcspSigning = true
case x509.ExtKeyUsageMicrosoftServerGatedCrypto:
unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageMicrosoftServerGatedCrypto))
case x509.ExtKeyUsageNetscapeServerGatedCrypto:
unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageNetscapeServerGatedCrypto))
case x509.ExtKeyUsageMicrosoftCommercialCodeSigning:
unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageMicrosoftCommercialCodeSigning))
case x509.ExtKeyUsageMicrosoftKernelCodeSigning:
unknownEKUs = append(unknownEKUs, createObjectID(oidExtKeyUsageMicrosoftKernelCodeSigning))
}
}
for _, oid := range cert.UnknownExtKeyUsage {
unknownEKUs = append(unknownEKUs, createObjectID(oid))
}
var policyIDs []*pb.ObjectId
for _, oid := range cert.PolicyIdentifiers {
policyIDs = append(policyIDs, createObjectID(oid))
}
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var caOptions *pb.X509Parameters_CaOptions
if cert.BasicConstraintsValid {
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caOptions = new(pb.X509Parameters_CaOptions)
var maxPathLength int32
switch {
case cert.MaxPathLenZero:
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maxPathLength = 0
caOptions.MaxIssuerPathLength = &maxPathLength
case cert.MaxPathLen > 0:
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maxPathLength = int32(cert.MaxPathLen)
caOptions.MaxIssuerPathLength = &maxPathLength
}
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caOptions.IsCa = &cert.IsCA
}
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var extraExtensions []*pb.X509Extension
for _, ext := range cert.ExtraExtensions {
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if isExtraExtension(ext.Id) {
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extraExtensions = append(extraExtensions, &pb.X509Extension{
ObjectId: createObjectID(ext.Id),
Critical: ext.Critical,
Value: ext.Value,
})
}
}
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return &pb.X509Parameters{
KeyUsage: &pb.KeyUsage{
BaseKeyUsage: &pb.KeyUsage_KeyUsageOptions{
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DigitalSignature: cert.KeyUsage&x509.KeyUsageDigitalSignature > 0,
ContentCommitment: cert.KeyUsage&x509.KeyUsageContentCommitment > 0,
KeyEncipherment: cert.KeyUsage&x509.KeyUsageKeyEncipherment > 0,
DataEncipherment: cert.KeyUsage&x509.KeyUsageDataEncipherment > 0,
KeyAgreement: cert.KeyUsage&x509.KeyUsageKeyAgreement > 0,
CertSign: cert.KeyUsage&x509.KeyUsageCertSign > 0,
CrlSign: cert.KeyUsage&x509.KeyUsageCRLSign > 0,
EncipherOnly: cert.KeyUsage&x509.KeyUsageEncipherOnly > 0,
DecipherOnly: cert.KeyUsage&x509.KeyUsageDecipherOnly > 0,
},
ExtendedKeyUsage: ekuOptions,
UnknownExtendedKeyUsages: unknownEKUs,
},
CaOptions: caOptions,
PolicyIds: policyIDs,
AiaOcspServers: cert.OCSPServer,
AdditionalExtensions: extraExtensions,
}
}
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// isExtraExtension returns true if the extension oid is not managed in a
// different way.
func isExtraExtension(oid asn1.ObjectIdentifier) bool {
for _, id := range extraExtensions {
if id.Equal(oid) {
return false
}
}
return true
}
func createObjectID(oid asn1.ObjectIdentifier) *pb.ObjectId {
ret := make([]int32, len(oid))
for i, v := range oid {
ret[i] = int32(v)
}
return &pb.ObjectId{
ObjectIdPath: ret,
}
}
func findExtraExtension(cert *x509.Certificate, oid asn1.ObjectIdentifier) (pkix.Extension, bool) {
for _, ext := range cert.ExtraExtensions {
if ext.Id.Equal(oid) {
return ext, true
}
}
return pkix.Extension{}, false
}
func createKeyVersionSpec(alg kmsapi.SignatureAlgorithm, bits int) (*pb.CertificateAuthority_KeyVersionSpec, error) {
switch alg {
case kmsapi.UnspecifiedSignAlgorithm, kmsapi.ECDSAWithSHA256:
return &pb.CertificateAuthority_KeyVersionSpec{
KeyVersion: &pb.CertificateAuthority_KeyVersionSpec_Algorithm{
Algorithm: pb.CertificateAuthority_EC_P256_SHA256,
},
}, nil
case kmsapi.ECDSAWithSHA384:
return &pb.CertificateAuthority_KeyVersionSpec{
KeyVersion: &pb.CertificateAuthority_KeyVersionSpec_Algorithm{
Algorithm: pb.CertificateAuthority_EC_P384_SHA384,
},
}, nil
case kmsapi.SHA256WithRSA:
algo, err := getRSAPKCS1Algorithm(bits)
if err != nil {
return nil, err
}
return &pb.CertificateAuthority_KeyVersionSpec{
KeyVersion: &pb.CertificateAuthority_KeyVersionSpec_Algorithm{
Algorithm: algo,
},
}, nil
case kmsapi.SHA256WithRSAPSS:
algo, err := getRSAPSSAlgorithm(bits)
if err != nil {
return nil, err
}
return &pb.CertificateAuthority_KeyVersionSpec{
KeyVersion: &pb.CertificateAuthority_KeyVersionSpec_Algorithm{
Algorithm: algo,
},
}, nil
default:
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return nil, fmt.Errorf("unknown or unsupported signature algorithm '%s'", alg)
}
}
func getRSAPKCS1Algorithm(bits int) (pb.CertificateAuthority_SignHashAlgorithm, error) {
switch bits {
case 0, 3072:
return pb.CertificateAuthority_RSA_PKCS1_3072_SHA256, nil
case 2048:
return pb.CertificateAuthority_RSA_PKCS1_2048_SHA256, nil
case 4096:
return pb.CertificateAuthority_RSA_PKCS1_4096_SHA256, nil
default:
return 0, fmt.Errorf("unsupported RSA PKCS #1 key size '%d'", bits)
}
}
func getRSAPSSAlgorithm(bits int) (pb.CertificateAuthority_SignHashAlgorithm, error) {
switch bits {
case 0, 3072:
return pb.CertificateAuthority_RSA_PSS_3072_SHA256, nil
case 2048:
return pb.CertificateAuthority_RSA_PSS_2048_SHA256, nil
case 4096:
return pb.CertificateAuthority_RSA_PSS_4096_SHA256, nil
default:
return 0, fmt.Errorf("unsupported RSA-PSS key size '%d'", bits)
}
}