private String getNameFromCert(TrustAnchor rootAuthority)
throws PaymentRequestException.PkiVerificationException {
org.spongycastle.asn1.x500.X500Name name =
new X500Name(rootAuthority.getTrustedCert().getSubjectX500Principal().getName());
String commonName = null, org = null, location = null, country = null;
for (RDN rdn : name.getRDNs()) {
AttributeTypeAndValue pair = rdn.getFirst();
String val = ((ASN1String) pair.getValue()).getString();
if (pair.getType().equals(RFC4519Style.cn)) commonName = val;
else if (pair.getType().equals(RFC4519Style.o)) org = val;
else if (pair.getType().equals(RFC4519Style.l)) location = val;
else if (pair.getType().equals(RFC4519Style.c)) country = val;
}
if (org != null && location != null && country != null) {
return org + ", " + location + ", " + country;
} else {
if (commonName == null)
throw new PaymentRequestException.PkiVerificationException(
"Could not find any identity info for root CA");
return commonName;
}
}
/**
* Uses the provided PKI method to find the corresponding public key and verify the provided
* signature. Returns null if no PKI method was specified in the {@link Protos.PaymentRequest}.
*/
public @Nullable PkiVerificationData verifyPki() throws PaymentRequestException {
try {
if (pkiVerificationData != null) return pkiVerificationData;
if (paymentRequest.getPkiType().equals("none"))
// Nothing to verify. Everything is fine. Move along.
return null;
String algorithm;
if (paymentRequest.getPkiType().equals("x509+sha256")) algorithm = "SHA256withRSA";
else if (paymentRequest.getPkiType().equals("x509+sha1")) algorithm = "SHA1withRSA";
else
throw new PaymentRequestException.InvalidPkiType(
"Unsupported PKI type: " + paymentRequest.getPkiType());
Protos.X509Certificates protoCerts =
Protos.X509Certificates.parseFrom(paymentRequest.getPkiData());
if (protoCerts.getCertificateCount() == 0)
throw new PaymentRequestException.InvalidPkiData(
"No certificates provided in message: server config error");
// Parse the certs and turn into a certificate chain object. Cert factories can parse both DER
// and base64.
// The ordering of certificates is defined by the payment protocol spec to be the same as what
// the Java
// crypto API requires - convenient!
CertificateFactory certificateFactory = CertificateFactory.getInstance("X.509");
List<X509Certificate> certs = Lists.newArrayList();
for (ByteString bytes : protoCerts.getCertificateList())
certs.add((X509Certificate) certificateFactory.generateCertificate(bytes.newInput()));
CertPath path = certificateFactory.generateCertPath(certs);
// Retrieves the most-trusted CAs from keystore.
PKIXParameters params = new PKIXParameters(createKeyStore(trustStorePath));
// Revocation not supported in the current version.
params.setRevocationEnabled(false);
// Now verify the certificate chain is correct and trusted. This let's us get an identity
// linked pubkey.
CertPathValidator validator = CertPathValidator.getInstance("PKIX");
PKIXCertPathValidatorResult result =
(PKIXCertPathValidatorResult) validator.validate(path, params);
PublicKey publicKey = result.getPublicKey();
// OK, we got an identity, now check it was used to sign this message.
Signature signature = Signature.getInstance(algorithm);
// Note that we don't use signature.initVerify(certs.get(0)) here despite it being the most
// obvious
// way to set it up, because we don't care about the constraints specified on the
// certificates: any
// cert that links a key to a domain name or other identity will do for us.
signature.initVerify(publicKey);
Protos.PaymentRequest.Builder reqToCheck = paymentRequest.toBuilder();
reqToCheck.setSignature(ByteString.EMPTY);
signature.update(reqToCheck.build().toByteArray());
if (!signature.verify(paymentRequest.getSignature().toByteArray()))
throw new PaymentRequestException.PkiVerificationException(
"Invalid signature, this payment request is not valid.");
// Signature verifies, get the names from the identity we just verified for presentation to
// the user.
X500Principal principal = certs.get(0).getSubjectX500Principal();
// At this point the Java crypto API falls flat on its face and dies - there's no clean way to
// get the
// different parts of the certificate name except for parsing the string. That's hard because
// of various
// custom escaping rules and the usual crap. So, use Bouncy Castle to re-parse the string into
// binary form
// again and then look for the names we want. Fail!
org.spongycastle.asn1.x500.X500Name name = new X500Name(principal.getName());
String entityName = null, orgName = null;
for (RDN rdn : name.getRDNs()) {
AttributeTypeAndValue pair = rdn.getFirst();
if (pair.getType().equals(RFC4519Style.cn))
entityName = ((ASN1String) pair.getValue()).getString();
else if (pair.getType().equals(RFC4519Style.o))
orgName = ((ASN1String) pair.getValue()).getString();
}
if (entityName == null && orgName == null)
throw new PaymentRequestException.PkiVerificationException(
"Invalid certificate, no CN or O fields");
// Everything is peachy. Return some useful data to the caller.
PkiVerificationData data =
new PkiVerificationData(entityName, orgName, publicKey, result.getTrustAnchor());
// Cache the result so we don't have to re-verify if this method is called again.
pkiVerificationData = data;
return data;
} catch (InvalidProtocolBufferException e) {
// Data structures are malformed.
throw new PaymentRequestException.InvalidPkiData(e);
} catch (CertificateException e) {
// The X.509 certificate data didn't parse correctly.
throw new PaymentRequestException.PkiVerificationException(e);
} catch (NoSuchAlgorithmException e) {
// Should never happen so don't make users have to think about it. PKIX is always present.
throw new RuntimeException(e);
} catch (InvalidAlgorithmParameterException e) {
throw new RuntimeException(e);
} catch (CertPathValidatorException e) {
// The certificate chain isn't known or trusted, probably, the server is using an SSL root we
// don't
// know about and the user needs to upgrade to a new version of the software (or import a root
// cert).
throw new PaymentRequestException.PkiVerificationException(e);
} catch (InvalidKeyException e) {
// Shouldn't happen if the certs verified correctly.
throw new PaymentRequestException.PkiVerificationException(e);
} catch (SignatureException e) {
// Something went wrong during hashing (yes, despite the name, this does not mean the sig was
// invalid).
throw new PaymentRequestException.PkiVerificationException(e);
} catch (IOException e) {
throw new PaymentRequestException.PkiVerificationException(e);
} catch (KeyStoreException e) {
throw new RuntimeException(e);
}
}
