certificates/authority/provisioner/scep.go

164 lines
5.2 KiB
Go

package provisioner
import (
"context"
"time"
"github.com/pkg/errors"
"github.com/smallstep/certificates/policy"
)
// SCEP is the SCEP provisioner type, an entity that can authorize the
// SCEP provisioning flow
type SCEP struct {
*base
ID string `json:"-"`
Type string `json:"type"`
Name string `json:"name"`
ForceCN bool `json:"forceCN,omitempty"`
ChallengePassword string `json:"challenge,omitempty"`
Capabilities []string `json:"capabilities,omitempty"`
// IncludeRoot makes the provisioner return the CA root in addition to the
// intermediate in the GetCACerts response
IncludeRoot bool `json:"includeRoot,omitempty"`
// MinimumPublicKeyLength is the minimum length for public keys in CSRs
MinimumPublicKeyLength int `json:"minimumPublicKeyLength,omitempty"`
// Numerical identifier for the ContentEncryptionAlgorithm as defined in github.com/mozilla-services/pkcs7
// at https://github.com/mozilla-services/pkcs7/blob/33d05740a3526e382af6395d3513e73d4e66d1cb/encrypt.go#L63
// Defaults to 0, being DES-CBC
EncryptionAlgorithmIdentifier int `json:"encryptionAlgorithmIdentifier,omitempty"`
Options *Options `json:"options,omitempty"`
Claims *Claims `json:"claims,omitempty"`
claimer *Claimer
x509Policy policy.X509NamePolicyEngine
secretChallengePassword string
encryptionAlgorithm int
}
// GetID returns the provisioner unique identifier.
func (s *SCEP) GetID() string {
if s.ID != "" {
return s.ID
}
return s.GetIDForToken()
}
// GetIDForToken returns an identifier that will be used to load the provisioner
// from a token.
func (s *SCEP) GetIDForToken() string {
return "scep/" + s.Name
}
// GetName returns the name of the provisioner.
func (s *SCEP) GetName() string {
return s.Name
}
// GetType returns the type of provisioner.
func (s *SCEP) GetType() Type {
return TypeSCEP
}
// GetEncryptedKey returns the base provisioner encrypted key if it's defined.
func (s *SCEP) GetEncryptedKey() (string, string, bool) {
return "", "", false
}
// GetTokenID returns the identifier of the token.
func (s *SCEP) GetTokenID(ott string) (string, error) {
return "", errors.New("scep provisioner does not implement GetTokenID")
}
// GetOptions returns the configured provisioner options.
func (s *SCEP) GetOptions() *Options {
return s.Options
}
// DefaultTLSCertDuration returns the default TLS cert duration enforced by
// the provisioner.
func (s *SCEP) DefaultTLSCertDuration() time.Duration {
return s.claimer.DefaultTLSCertDuration()
}
// Init initializes and validates the fields of a SCEP type.
func (s *SCEP) Init(config Config) (err error) {
switch {
case s.Type == "":
return errors.New("provisioner type cannot be empty")
case s.Name == "":
return errors.New("provisioner name cannot be empty")
}
// Update claims with global ones
if s.claimer, err = NewClaimer(s.Claims, config.Claims); err != nil {
return err
}
// Mask the actual challenge value, so it won't be marshaled
s.secretChallengePassword = s.ChallengePassword
s.ChallengePassword = "*** redacted ***"
// Default to 2048 bits minimum public key length (for CSRs) if not set
if s.MinimumPublicKeyLength == 0 {
s.MinimumPublicKeyLength = 2048
}
if s.MinimumPublicKeyLength%8 != 0 {
return errors.Errorf("%d bits is not exactly divisible by 8", s.MinimumPublicKeyLength)
}
s.encryptionAlgorithm = s.EncryptionAlgorithmIdentifier // TODO(hs): we might want to upgrade the default security to AES-CBC?
if s.encryptionAlgorithm < 0 || s.encryptionAlgorithm > 4 {
return errors.New("only encryption algorithm identifiers from 0 to 4 are valid")
}
// TODO: add other, SCEP specific, options?
// Initialize the x509 allow/deny policy engine
if s.x509Policy, err = newX509PolicyEngine(s.Options.GetX509Options()); err != nil {
return err
}
return err
}
// AuthorizeSign does not do any verification, because all verification is handled
// in the SCEP protocol. This method returns a list of modifiers / constraints
// on the resulting certificate.
func (s *SCEP) AuthorizeSign(ctx context.Context, token string) ([]SignOption, error) {
return []SignOption{
// modifiers / withOptions
newProvisionerExtensionOption(TypeSCEP, s.Name, ""),
newForceCNOption(s.ForceCN),
profileDefaultDuration(s.claimer.DefaultTLSCertDuration()),
// validators
newPublicKeyMinimumLengthValidator(s.MinimumPublicKeyLength),
newValidityValidator(s.claimer.MinTLSCertDuration(), s.claimer.MaxTLSCertDuration()),
newX509NamePolicyValidator(s.x509Policy),
}, nil
}
// GetChallengePassword returns the challenge password
func (s *SCEP) GetChallengePassword() string {
return s.secretChallengePassword
}
// GetCapabilities returns the CA capabilities
func (s *SCEP) GetCapabilities() []string {
return s.Capabilities
}
// ShouldIncludeRootInChain indicates if the CA should
// return its intermediate, which is currently used for
// both signing and decryption, as well as the root in
// its chain.
func (s *SCEP) ShouldIncludeRootInChain() bool {
return s.IncludeRoot
}
// GetContentEncryptionAlgorithm returns the numeric identifier
// for the pkcs7 package encryption algorithm to use.
func (s *SCEP) GetContentEncryptionAlgorithm() int {
return s.encryptionAlgorithm
}