public static DecryptOutcome decryptAndValidateSubmission(
Document doc, PrivateKey rsaPrivateKey, File instanceDir, File unEncryptedDir)
throws ParsingException, FileSystemException, CryptoException {
Element rootElement = doc.getRootElement();
String base64EncryptedSymmetricKey;
String instanceIdMetadata = null;
List<String> mediaNames = new ArrayList<String>();
String encryptedSubmissionFile;
String base64EncryptedElementSignature;
{
Element base64Key = null;
Element base64Signature = null;
Element encryptedXml = null;
for (int i = 0; i < rootElement.getChildCount(); ++i) {
if (rootElement.getType(i) == Node.ELEMENT) {
Element child = rootElement.getElement(i);
String name = child.getName();
if (name.equals("base64EncryptedKey")) {
base64Key = child;
} else if (name.equals("base64EncryptedElementSignature")) {
base64Signature = child;
} else if (name.equals("encryptedXmlFile")) {
encryptedXml = child;
} else if (name.equals("media")) {
Element media = child;
for (int j = 0; j < media.getChildCount(); ++j) {
if (media.getType(j) == Node.ELEMENT) {
Element mediaChild = media.getElement(j);
String mediaFileElementName = mediaChild.getName();
if (mediaFileElementName.equals("file")) {
String mediaName = XFormParser.getXMLText(mediaChild, true);
if (mediaName == null || mediaName.length() == 0) {
mediaNames.add(null);
} else {
mediaNames.add(mediaName);
}
}
}
}
}
}
}
// verify base64Key
if (base64Key == null) {
throw new ParsingException("Missing base64EncryptedKey element in encrypted form.");
}
base64EncryptedSymmetricKey = XFormParser.getXMLText(base64Key, true);
// get instanceID out of OpenRosa meta block
instanceIdMetadata = XmlManipulationUtils.getOpenRosaInstanceId(rootElement);
if (instanceIdMetadata == null) {
throw new ParsingException("Missing instanceID within meta block of encrypted form.");
}
// get submission filename
if (encryptedXml == null) {
throw new ParsingException("Missing encryptedXmlFile element in encrypted form.");
}
encryptedSubmissionFile = XFormParser.getXMLText(encryptedXml, true);
if (base64Signature == null) {
throw new ParsingException(
"Missing base64EncryptedElementSignature element in encrypted form.");
}
base64EncryptedElementSignature = XFormParser.getXMLText(base64Signature, true);
}
if (instanceIdMetadata == null
|| base64EncryptedSymmetricKey == null
|| base64EncryptedElementSignature == null
|| encryptedSubmissionFile == null) {
throw new ParsingException("Missing one or more required elements of encrypted form.");
}
FormInstanceMetadata fim;
try {
fim = XmlManipulationUtils.getFormInstanceMetadata(rootElement);
} catch (ParsingException e) {
e.printStackTrace();
throw new ParsingException(
"Unable to extract form instance medatadata from submission manifest. Cause: "
+ e.toString());
}
if (!instanceIdMetadata.equals(fim.instanceId)) {
throw new ParsingException(
"InstanceID within metadata does not match that on top level element.");
}
boolean isValidated =
FileSystemUtils.decryptSubmissionFiles(
base64EncryptedSymmetricKey,
fim,
mediaNames,
encryptedSubmissionFile,
base64EncryptedElementSignature,
rsaPrivateKey,
instanceDir,
unEncryptedDir);
// and change doc to be the decrypted submission document
File decryptedSubmission = new File(unEncryptedDir, "submission.xml");
doc = XmlManipulationUtils.parseXml(decryptedSubmission);
if (doc == null) {
return null;
}
// verify that the metadata matches between the manifest and the submission
rootElement = doc.getRootElement();
FormInstanceMetadata sim = XmlManipulationUtils.getFormInstanceMetadata(rootElement);
if (!fim.xparam.equals(sim.xparam)) {
throw new ParsingException(
"FormId or version in decrypted submission does not match that in manifest!");
}
if (!fim.instanceId.equals(sim.instanceId)) {
throw new ParsingException(
"InstanceId in decrypted submission does not match that in manifest!");
}
return new DecryptOutcome(doc, isValidated);
}
private static boolean decryptSubmissionFiles(
String base64EncryptedSymmetricKey,
FormInstanceMetadata fim,
List<String> mediaNames,
String encryptedSubmissionFile,
String base64EncryptedElementSignature,
PrivateKey rsaPrivateKey,
File instanceDir,
File unencryptedDir)
throws FileSystemException, CryptoException, ParsingException {
EncryptionInformation ei =
new EncryptionInformation(base64EncryptedSymmetricKey, fim.instanceId, rsaPrivateKey);
byte[] elementDigest;
try {
// construct the base64-encoded RSA-encrypted symmetric key
Cipher pkCipher;
pkCipher = Cipher.getInstance(ASYMMETRIC_ALGORITHM);
// extract digest
pkCipher.init(Cipher.DECRYPT_MODE, rsaPrivateKey);
byte[] encryptedElementSignature = Base64.decodeBase64(base64EncryptedElementSignature);
elementDigest = pkCipher.doFinal(encryptedElementSignature);
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
throw new CryptoException(
"Error decrypting base64EncryptedElementSignature Cause: " + e.toString());
} catch (NoSuchPaddingException e) {
e.printStackTrace();
throw new CryptoException(
"Error decrypting base64EncryptedElementSignature Cause: " + e.toString());
} catch (InvalidKeyException e) {
e.printStackTrace();
throw new CryptoException(
"Error decrypting base64EncryptedElementSignature Cause: " + e.toString());
} catch (IllegalBlockSizeException e) {
e.printStackTrace();
throw new CryptoException(
"Error decrypting base64EncryptedElementSignature Cause: " + e.toString());
} catch (BadPaddingException e) {
e.printStackTrace();
throw new CryptoException(
"Error decrypting base64EncryptedElementSignature Cause: " + e.toString());
}
// NOTE: will decrypt only the files in the media list, plus the encryptedSubmissionFile
File[] allFiles = instanceDir.listFiles();
List<File> filesToProcess = new ArrayList<File>();
for (File f : allFiles) {
if (mediaNames.contains(f.getName())) {
filesToProcess.add(f);
} else if (encryptedSubmissionFile.equals(f.getName())) {
filesToProcess.add(f);
}
}
// should have all media files plus one submission.xml.enc file
if (filesToProcess.size() != mediaNames.size() + 1) {
// figure out what we're missing...
int lostFileCount = 0;
List<String> missing = new ArrayList<String>();
for (String name : mediaNames) {
if (name == null) {
// this was lost due to an pre-ODK Aggregate 1.4.5 mark-as-complete action
++lostFileCount;
continue;
}
File f = new File(instanceDir, name);
if (!filesToProcess.contains(f)) {
missing.add(name);
}
}
StringBuilder b = new StringBuilder();
for (String name : missing) {
b.append(" ").append(name);
}
if (!filesToProcess.contains(new File(instanceDir, encryptedSubmissionFile))) {
b.append(" ").append(encryptedSubmissionFile);
throw new FileSystemException(
"Error decrypting: " + instanceDir.getName() + " Missing files:" + b.toString());
} else {
// ignore the fact that we don't have the lost files
if (filesToProcess.size() + lostFileCount != mediaNames.size() + 1) {
throw new FileSystemException(
"Error decrypting: " + instanceDir.getName() + " Missing files:" + b.toString());
}
}
}
// decrypt the media files IN ORDER.
for (String mediaName : mediaNames) {
String displayedName = (mediaName == null) ? "<missing .enc file>" : mediaName;
File f = (mediaName == null) ? null : new File(instanceDir, mediaName);
try {
decryptFile(ei, f, unencryptedDir);
} catch (InvalidKeyException e) {
e.printStackTrace();
throw new CryptoException("Error decrypting:" + displayedName + " Cause: " + e.toString());
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
throw new CryptoException("Error decrypting:" + displayedName + " Cause: " + e.toString());
} catch (InvalidAlgorithmParameterException e) {
e.printStackTrace();
throw new CryptoException("Error decrypting:" + displayedName + " Cause: " + e.toString());
} catch (NoSuchPaddingException e) {
e.printStackTrace();
throw new CryptoException("Error decrypting:" + displayedName + " Cause: " + e.toString());
} catch (IOException e) {
e.printStackTrace();
throw new FileSystemException(
"Error decrypting:" + displayedName + " Cause: " + e.toString());
}
}
// decrypt the submission file
File f = new File(instanceDir, encryptedSubmissionFile);
try {
decryptFile(ei, f, unencryptedDir);
} catch (InvalidKeyException e) {
e.printStackTrace();
throw new CryptoException("Error decrypting:" + f.getName() + " Cause: " + e.toString());
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
throw new CryptoException("Error decrypting:" + f.getName() + " Cause: " + e.toString());
} catch (InvalidAlgorithmParameterException e) {
e.printStackTrace();
throw new CryptoException("Error decrypting:" + f.getName() + " Cause: " + e.toString());
} catch (NoSuchPaddingException e) {
e.printStackTrace();
throw new CryptoException("Error decrypting:" + f.getName() + " Cause: " + e.toString());
} catch (IOException e) {
e.printStackTrace();
throw new FileSystemException("Error decrypting:" + f.getName() + " Cause: " + e.toString());
}
// get the FIM for the decrypted submission file
File submissionFile =
new File(
unencryptedDir,
encryptedSubmissionFile.substring(0, encryptedSubmissionFile.lastIndexOf(".enc")));
FormInstanceMetadata submissionFim;
try {
Document subDoc = XmlManipulationUtils.parseXml(submissionFile);
submissionFim = XmlManipulationUtils.getFormInstanceMetadata(subDoc.getRootElement());
} catch (ParsingException e) {
e.printStackTrace();
throw new FileSystemException(
"Error decrypting: " + submissionFile.getName() + " Cause: " + e.toString());
} catch (FileSystemException e) {
e.printStackTrace();
throw new FileSystemException(
"Error decrypting: " + submissionFile.getName() + " Cause: " + e.getMessage());
}
boolean same = submissionFim.xparam.formId.equals(fim.xparam.formId);
if (!same) {
throw new FileSystemException(
"Error decrypting:"
+ unencryptedDir.getName()
+ " Cause: form instance metadata differs from that in manifest");
}
// Construct the element signature string
StringBuilder b = new StringBuilder();
appendElementSignatureSource(b, fim.xparam.formId);
if (fim.xparam.modelVersion != null) {
appendElementSignatureSource(b, Long.toString(fim.xparam.modelVersion));
}
appendElementSignatureSource(b, base64EncryptedSymmetricKey);
appendElementSignatureSource(b, fim.instanceId);
boolean missingFile = false;
for (String encFilename : mediaNames) {
if (encFilename == null) {
missingFile = true;
continue;
}
File decryptedFile =
new File(unencryptedDir, encFilename.substring(0, encFilename.lastIndexOf(".enc")));
if (decryptedFile.getName().endsWith(".missing")) {
// this is a missing file -- we will not be able to
// confirm the signature of the submission.
missingFile = true;
continue;
}
String md5 = FileSystemUtils.getMd5Hash(decryptedFile);
appendElementSignatureSource(b, decryptedFile.getName() + "::" + md5);
}
String md5 = FileSystemUtils.getMd5Hash(submissionFile);
appendElementSignatureSource(b, submissionFile.getName() + "::" + md5);
// compute the digest of the element signature string
byte[] messageDigest;
try {
MessageDigest md = MessageDigest.getInstance("MD5");
md.update(b.toString().getBytes("UTF-8"));
messageDigest = md.digest();
} catch (NoSuchAlgorithmException e) {
e.printStackTrace();
throw new CryptoException("Error computing xml signature Cause: " + e.toString());
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
throw new CryptoException("Error computing xml signature Cause: " + e.toString());
}
same = true;
for (int i = 0; i < messageDigest.length; ++i) {
if (messageDigest[i] != elementDigest[i]) {
same = false;
break;
}
}
return same;
}
