/**
* Validate the signature on the attribute certificate in this holder.
*
* @param verifierProvider a ContentVerifierProvider that can generate a verifier for the
* signature.
* @return true if the signature is valid, false otherwise.
* @throws CertException if the signature cannot be processed or is inappropriate.
*/
public boolean isSignatureValid(ContentVerifierProvider verifierProvider) throws CertException {
AttributeCertificateInfo acinfo = attrCert.getAcinfo();
if (!CertUtils.isAlgIdEqual(acinfo.getSignature(), attrCert.getSignatureAlgorithm())) {
throw new CertException("signature invalid - algorithm identifier mismatch");
}
ContentVerifier verifier;
try {
verifier = verifierProvider.get((acinfo.getSignature()));
OutputStream sOut = verifier.getOutputStream();
DEROutputStream dOut = new DEROutputStream(sOut);
dOut.writeObject(acinfo);
sOut.close();
} catch (Exception e) {
throw new CertException("unable to process signature: " + e.getMessage(), e);
}
return verifier.verify(attrCert.getSignatureValue().getBytes());
}
private boolean doVerify(SignerInformationVerifier verifier) throws CMSException {
String digestName = CMSSignedHelper.INSTANCE.getDigestAlgName(this.getDigestAlgOID());
String encName = CMSSignedHelper.INSTANCE.getEncryptionAlgName(this.getEncryptionAlgOID());
String signatureName = digestName + "with" + encName;
try {
if (digestCalculator != null) {
resultDigest = digestCalculator.getDigest();
} else {
DigestCalculator calc = verifier.getDigestCalculator(this.getDigestAlgorithmID());
if (content != null) {
OutputStream digOut = calc.getOutputStream();
content.write(digOut);
digOut.close();
} else if (signedAttributeSet == null) {
// TODO Get rid of this exception and just treat content==null as empty not missing?
throw new CMSException("data not encapsulated in signature - use detached constructor.");
}
resultDigest = calc.getDigest();
}
} catch (IOException e) {
throw new CMSException("can't process mime object to create signature.", e);
} catch (NoSuchAlgorithmException e) {
throw new CMSException("can't find algorithm: " + e.getMessage(), e);
} catch (OperatorCreationException e) {
throw new CMSException("can't create digest calculator: " + e.getMessage(), e);
}
// RFC 3852 11.1 Check the content-type attribute is correct
{
DERObject validContentType =
getSingleValuedSignedAttribute(CMSAttributes.contentType, "content-type");
if (validContentType == null) {
if (!isCounterSignature && signedAttributeSet != null) {
throw new CMSException(
"The content-type attribute type MUST be present whenever signed attributes are present in signed-data");
}
} else {
if (isCounterSignature) {
throw new CMSException(
"[For counter signatures,] the signedAttributes field MUST NOT contain a content-type attribute");
}
if (!(validContentType instanceof DERObjectIdentifier)) {
throw new CMSException(
"content-type attribute value not of ASN.1 type 'OBJECT IDENTIFIER'");
}
DERObjectIdentifier signedContentType = (DERObjectIdentifier) validContentType;
if (!signedContentType.equals(contentType)) {
throw new CMSException("content-type attribute value does not match eContentType");
}
}
}
// RFC 3852 11.2 Check the message-digest attribute is correct
{
DERObject validMessageDigest =
getSingleValuedSignedAttribute(CMSAttributes.messageDigest, "message-digest");
if (validMessageDigest == null) {
if (signedAttributeSet != null) {
throw new CMSException(
"the message-digest signed attribute type MUST be present when there are any signed attributes present");
}
} else {
if (!(validMessageDigest instanceof ASN1OctetString)) {
throw new CMSException("message-digest attribute value not of ASN.1 type 'OCTET STRING'");
}
ASN1OctetString signedMessageDigest = (ASN1OctetString) validMessageDigest;
if (!Arrays.constantTimeAreEqual(resultDigest, signedMessageDigest.getOctets())) {
throw new CMSSignerDigestMismatchException(
"message-digest attribute value does not match calculated value");
}
}
}
// RFC 3852 11.4 Validate countersignature attribute(s)
{
AttributeTable signedAttrTable = this.getSignedAttributes();
if (signedAttrTable != null
&& signedAttrTable.getAll(CMSAttributes.counterSignature).size() > 0) {
throw new CMSException("A countersignature attribute MUST NOT be a signed attribute");
}
AttributeTable unsignedAttrTable = this.getUnsignedAttributes();
if (unsignedAttrTable != null) {
ASN1EncodableVector csAttrs = unsignedAttrTable.getAll(CMSAttributes.counterSignature);
for (int i = 0; i < csAttrs.size(); ++i) {
Attribute csAttr = (Attribute) csAttrs.get(i);
if (csAttr.getAttrValues().size() < 1) {
throw new CMSException(
"A countersignature attribute MUST contain at least one AttributeValue");
}
// Note: We don't recursively validate the countersignature value
}
}
}
try {
ContentVerifier contentVerifier =
verifier.getContentVerifier(sigAlgFinder.find(signatureName));
OutputStream sigOut = contentVerifier.getOutputStream();
if (signedAttributeSet == null) {
if (digestCalculator != null) {
if (contentVerifier instanceof RawContentVerifier) {
RawContentVerifier rawVerifier = (RawContentVerifier) contentVerifier;
if (encName.equals("RSA")) {
DigestInfo digInfo = new DigestInfo(digestAlgorithm, resultDigest);
return rawVerifier.verify(digInfo.getDEREncoded(), this.getSignature());
}
return rawVerifier.verify(resultDigest, this.getSignature());
}
throw new CMSException("verifier unable to process raw signature");
} else if (content != null) {
// TODO Use raw signature of the hash value instead
content.write(sigOut);
}
} else {
sigOut.write(this.getEncodedSignedAttributes());
}
sigOut.close();
return contentVerifier.verify(this.getSignature());
} catch (IOException e) {
throw new CMSException("can't process mime object to create signature.", e);
} catch (OperatorCreationException e) {
throw new CMSException("can't create content verifier: " + e.getMessage(), e);
}
}