create option to return all certs from signer in SCEP response

authority/provisioner/scep.go

@@ -41,6 +41,10 @@ type SCEP struct {
 	// GetCACerts response
 	ExcludeIntermediate bool `json:"excludeIntermediate,omitempty"`
 
+	// ReturnEntireCertChain makes the provisioner return the full certificate chain
+	// provided by the CA rather than just the leaf certificate
+	ReturnEntireCertChain bool `json:"returnEntireCertChain,omitempty"`
+
 	// MinimumPublicKeyLength is the minimum length for public keys in CSRs
 	MinimumPublicKeyLength int `json:"minimumPublicKeyLength,omitempty"`
 
@@ -447,6 +451,13 @@ func (s *SCEP) ShouldIncludeIntermediateInChain() bool {
 	return !s.ExcludeIntermediate
 }
 
+// ShouldReturnEntireCertChain indicates if the
+// CA should return the entire chain of certificates in the SCEP
+// PKIOperation response rather than just the leaf certificate.
+func (s *SCEP) ShouldReturnEntireCertChain() bool {
+	return s.ReturnEntireCertChain
+}
+
 // GetContentEncryptionAlgorithm returns the numeric identifier
 // for the pkcs7 package encryption algorithm to use.
 func (s *SCEP) GetContentEncryptionAlgorithm() int {

scep/authority.go

@@ -363,10 +363,16 @@ func (a *Authority) SignCSR(ctx context.Context, csr *x509.CertificateRequest, m
 		return nil, err
 	}
 
-	// add the certificate into the signed data type
-	// this cert must be added before the signedData because the recipient will expect it
-	// as the first certificate in the array
-	signedData.AddCertificate(cert)
+	// add the certificate chain into the signed data type if specified
+	// otherwise just return the leaf cert. the ordering of the added signed data is important
+	// because the recipient will expect the leaf as the first certificate
+	if p.ShouldReturnEntireCertChain() {
+		for _, c := range certChain {
+			signedData.AddCertificate(c)
+		}
+	} else {
+		signedData.AddCertificate(cert)
+	}
 
 	signerCert, signer, err := a.selectSigner(ctx)
 	if err != nil {

scep/provisioner.go

@@ -17,6 +17,7 @@ type Provisioner interface {
 	GetCapabilities() []string
 	ShouldIncludeRootInChain() bool
 	ShouldIncludeIntermediateInChain() bool
+	ShouldReturnEntireCertChain() bool
 	GetDecrypter() (*x509.Certificate, crypto.Decrypter)
 	GetSigner() (*x509.Certificate, crypto.Signer)
 	GetContentEncryptionAlgorithm() int