1 files changed, 264 insertions, 0 deletions
diff --git a/vendor/go.mozilla.org/pkcs7/verify.go b/vendor/go.mozilla.org/pkcs7/verify.go
new file mode 100644
index 000000000..c8ead2362
--- /dev/null
+++ b/vendor/go.mozilla.org/pkcs7/verify.go
@@ -0,0 +1,264 @@
+package pkcs7
+
+import (
+	"crypto/subtle"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/asn1"
+	"errors"
+	"fmt"
+	"time"
+)
+
+// Verify is a wrapper around VerifyWithChain() that initializes an empty
+// trust store, effectively disabling certificate verification when validating
+// a signature.
+func (p7 *PKCS7) Verify() (err error) {
+	return p7.VerifyWithChain(nil)
+}
+
+// VerifyWithChain checks the signatures of a PKCS7 object.
+// If truststore is not nil, it also verifies the chain of trust of the end-entity
+// signer cert to one of the root in the truststore.
+func (p7 *PKCS7) VerifyWithChain(truststore *x509.CertPool) (err error) {
+	if len(p7.Signers) == 0 {
+		return errors.New("pkcs7: Message has no signers")
+	}
+	for _, signer := range p7.Signers {
+		if err := verifySignature(p7, signer, truststore); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func verifySignature(p7 *PKCS7, signer signerInfo, truststore *x509.CertPool) (err error) {
+	signedData := p7.Content
+	ee := getCertFromCertsByIssuerAndSerial(p7.Certificates, signer.IssuerAndSerialNumber)
+	if ee == nil {
+		return errors.New("pkcs7: No certificate for signer")
+	}
+	signingTime := time.Now().UTC()
+	if len(signer.AuthenticatedAttributes) > 0 {
+		// TODO(fullsailor): First check the content type match
+		var digest []byte
+		err := unmarshalAttribute(signer.AuthenticatedAttributes, OIDAttributeMessageDigest, &digest)
+		if err != nil {
+			return err
+		}
+		hash, err := getHashForOID(signer.DigestAlgorithm.Algorithm)
+		if err != nil {
+			return err
+		}
+		h := hash.New()
+		h.Write(p7.Content)
+		computed := h.Sum(nil)
+		if subtle.ConstantTimeCompare(digest, computed) != 1 {
+			return &MessageDigestMismatchError{
+				ExpectedDigest: digest,
+				ActualDigest:   computed,
+			}
+		}
+		signedData, err = marshalAttributes(signer.AuthenticatedAttributes)
+		if err != nil {
+			return err
+		}
+		err = unmarshalAttribute(signer.AuthenticatedAttributes, OIDAttributeSigningTime, &signingTime)
+		if err == nil {
+			// signing time found, performing validity check
+			if signingTime.After(ee.NotAfter) || signingTime.Before(ee.NotBefore) {
+				return fmt.Errorf("pkcs7: signing time %q is outside of certificate validity %q to %q",
+					signingTime.Format(time.RFC3339),
+					ee.NotBefore.Format(time.RFC3339),
+					ee.NotBefore.Format(time.RFC3339))
+			}
+		}
+	}
+	if truststore != nil {
+		_, err = verifyCertChain(ee, p7.Certificates, truststore, signingTime)
+		if err != nil {
+			return err
+		}
+	}
+	sigalg, err := getSignatureAlgorithm(signer.DigestEncryptionAlgorithm, signer.DigestAlgorithm)
+	if err != nil {
+		return err
+	}
+	return ee.CheckSignature(sigalg, signedData, signer.EncryptedDigest)
+}
+
+// GetOnlySigner returns an x509.Certificate for the first signer of the signed
+// data payload. If there are more or less than one signer, nil is returned
+func (p7 *PKCS7) GetOnlySigner() *x509.Certificate {
+	if len(p7.Signers) != 1 {
+		return nil
+	}
+	signer := p7.Signers[0]
+	return getCertFromCertsByIssuerAndSerial(p7.Certificates, signer.IssuerAndSerialNumber)
+}
+
+// UnmarshalSignedAttribute decodes a single attribute from the signer info
+func (p7 *PKCS7) UnmarshalSignedAttribute(attributeType asn1.ObjectIdentifier, out interface{}) error {
+	sd, ok := p7.raw.(signedData)
+	if !ok {
+		return errors.New("pkcs7: payload is not signedData content")
+	}
+	if len(sd.SignerInfos) < 1 {
+		return errors.New("pkcs7: payload has no signers")
+	}
+	attributes := sd.SignerInfos[0].AuthenticatedAttributes
+	return unmarshalAttribute(attributes, attributeType, out)
+}
+
+func parseSignedData(data []byte) (*PKCS7, error) {
+	var sd signedData
+	asn1.Unmarshal(data, &sd)
+	certs, err := sd.Certificates.Parse()
+	if err != nil {
+		return nil, err
+	}
+	// fmt.Printf("--> Signed Data Version %d\n", sd.Version)
+
+	var compound asn1.RawValue
+	var content unsignedData
+
+	// The Content.Bytes maybe empty on PKI responses.
+	if len(sd.ContentInfo.Content.Bytes) > 0 {
+		if _, err := asn1.Unmarshal(sd.ContentInfo.Content.Bytes, &compound); err != nil {
+			return nil, err
+		}
+	}
+	// Compound octet string
+	if compound.IsCompound {
+		if compound.Tag == 4 {
+			if _, err = asn1.Unmarshal(compound.Bytes, &content); err != nil {
+				return nil, err
+			}
+		} else {
+			content = compound.Bytes
+		}
+	} else {
+		// assuming this is tag 04
+		content = compound.Bytes
+	}
+	return &PKCS7{
+		Content:      content,
+		Certificates: certs,
+		CRLs:         sd.CRLs,
+		Signers:      sd.SignerInfos,
+		raw:          sd}, nil
+}
+
+// verifyCertChain takes an end-entity certs, a list of potential intermediates and a
+// truststore, and built all potential chains between the EE and a trusted root.
+//
+// When verifying chains that may have expired, currentTime can be set to a past date
+// to allow the verification to pass. If unset, currentTime is set to the current UTC time.
+func verifyCertChain(ee *x509.Certificate, certs []*x509.Certificate, truststore *x509.CertPool, currentTime time.Time) (chains [][]*x509.Certificate, err error) {
+	intermediates := x509.NewCertPool()
+	for _, intermediate := range certs {
+		intermediates.AddCert(intermediate)
+	}
+	verifyOptions := x509.VerifyOptions{
+		Roots:         truststore,
+		Intermediates: intermediates,
+		KeyUsages:     []x509.ExtKeyUsage{x509.ExtKeyUsageAny},
+		CurrentTime:   currentTime,
+	}
+	chains, err = ee.Verify(verifyOptions)
+	if err != nil {
+		return chains, fmt.Errorf("pkcs7: failed to verify certificate chain: %v", err)
+	}
+	return
+}
+
+// MessageDigestMismatchError is returned when the signer data digest does not
+// match the computed digest for the contained content
+type MessageDigestMismatchError struct {
+	ExpectedDigest []byte
+	ActualDigest   []byte
+}
+
+func (err *MessageDigestMismatchError) Error() string {
+	return fmt.Sprintf("pkcs7: Message digest mismatch\n\tExpected: %X\n\tActual  : %X", err.ExpectedDigest, err.ActualDigest)
+}
+
+func getSignatureAlgorithm(digestEncryption, digest pkix.AlgorithmIdentifier) (x509.SignatureAlgorithm, error) {
+	switch {
+	case digestEncryption.Algorithm.Equal(OIDDigestAlgorithmECDSASHA1):
+		return x509.ECDSAWithSHA1, nil
+	case digestEncryption.Algorithm.Equal(OIDDigestAlgorithmECDSASHA256):
+		return x509.ECDSAWithSHA256, nil
+	case digestEncryption.Algorithm.Equal(OIDDigestAlgorithmECDSASHA384):
+		return x509.ECDSAWithSHA384, nil
+	case digestEncryption.Algorithm.Equal(OIDDigestAlgorithmECDSASHA512):
+		return x509.ECDSAWithSHA512, nil
+	case digestEncryption.Algorithm.Equal(OIDEncryptionAlgorithmRSA),
+		digestEncryption.Algorithm.Equal(OIDEncryptionAlgorithmRSASHA1),
+		digestEncryption.Algorithm.Equal(OIDEncryptionAlgorithmRSASHA256),
+		digestEncryption.Algorithm.Equal(OIDEncryptionAlgorithmRSASHA384),
+		digestEncryption.Algorithm.Equal(OIDEncryptionAlgorithmRSASHA512):
+		switch {
+		case digest.Algorithm.Equal(OIDDigestAlgorithmSHA1):
+			return x509.SHA1WithRSA, nil
+		case digest.Algorithm.Equal(OIDDigestAlgorithmSHA256):
+			return x509.SHA256WithRSA, nil
+		case digest.Algorithm.Equal(OIDDigestAlgorithmSHA384):
+			return x509.SHA384WithRSA, nil
+		case digest.Algorithm.Equal(OIDDigestAlgorithmSHA512):
+			return x509.SHA512WithRSA, nil
+		default:
+			return -1, fmt.Errorf("pkcs7: unsupported digest %q for encryption algorithm %q",
+				digest.Algorithm.String(), digestEncryption.Algorithm.String())
+		}
+	case digestEncryption.Algorithm.Equal(OIDDigestAlgorithmDSA),
+		digestEncryption.Algorithm.Equal(OIDDigestAlgorithmDSASHA1):
+		switch {
+		case digest.Algorithm.Equal(OIDDigestAlgorithmSHA1):
+			return x509.DSAWithSHA1, nil
+		case digest.Algorithm.Equal(OIDDigestAlgorithmSHA256):
+			return x509.DSAWithSHA256, nil
+		default:
+			return -1, fmt.Errorf("pkcs7: unsupported digest %q for encryption algorithm %q",
+				digest.Algorithm.String(), digestEncryption.Algorithm.String())
+		}
+	case digestEncryption.Algorithm.Equal(OIDEncryptionAlgorithmECDSAP256),
+		digestEncryption.Algorithm.Equal(OIDEncryptionAlgorithmECDSAP384),
+		digestEncryption.Algorithm.Equal(OIDEncryptionAlgorithmECDSAP521):
+		switch {
+		case digest.Algorithm.Equal(OIDDigestAlgorithmSHA1):
+			return x509.ECDSAWithSHA1, nil
+		case digest.Algorithm.Equal(OIDDigestAlgorithmSHA256):
+			return x509.ECDSAWithSHA256, nil
+		case digest.Algorithm.Equal(OIDDigestAlgorithmSHA384):
+			return x509.ECDSAWithSHA384, nil
+		case digest.Algorithm.Equal(OIDDigestAlgorithmSHA512):
+			return x509.ECDSAWithSHA512, nil
+		default:
+			return -1, fmt.Errorf("pkcs7: unsupported digest %q for encryption algorithm %q",
+				digest.Algorithm.String(), digestEncryption.Algorithm.String())
+		}
+	default:
+		return -1, fmt.Errorf("pkcs7: unsupported algorithm %q",
+			digestEncryption.Algorithm.String())
+	}
+}
+
+func getCertFromCertsByIssuerAndSerial(certs []*x509.Certificate, ias issuerAndSerial) *x509.Certificate {
+	for _, cert := range certs {
+		if isCertMatchForIssuerAndSerial(cert, ias) {
+			return cert
+		}
+	}
+	return nil
+}
+
+func unmarshalAttribute(attrs []attribute, attributeType asn1.ObjectIdentifier, out interface{}) error {
+	for _, attr := range attrs {
+		if attr.Type.Equal(attributeType) {
+			_, err := asn1.Unmarshal(attr.Value.Bytes, out)
+			return err
+		}
+	}
+	return errors.New("pkcs7: attribute type not in attributes")
+}