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Add support for non-ASCII passwords #66

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Add support for non-ASCII passwords #66

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24 changes: 21 additions & 3 deletions src/org/nick/abe/AndroidBackup.java
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Original file line number Diff line number Diff line change
Expand Up @@ -121,8 +121,7 @@ public static void extractAsTar(String backupFilename, String filename,

// decrypt the master key blob
Cipher c = Cipher.getInstance(ENCRYPTION_MECHANISM);
// XXX we don't support non-ASCII passwords
SecretKey userKey = buildPasswordKey(password, userSalt, rounds, false);
SecretKey userKey = buildPasswordKey(password, userSalt, rounds, true);
byte[] IV = hexToByteArray(userIvHex);
IvParameterSpec ivSpec = new IvParameterSpec(IV);
c.init(Cipher.DECRYPT_MODE,
Expand Down Expand Up @@ -153,6 +152,25 @@ public static void extractAsTar(String backupFilename, String filename,
System.err.println("MK checksum: " + toHex(mkChecksum));
}

// checking pkcs5 padding (of length 13 or even 8) is enough to determine a wrong password
c = Cipher.getInstance("AES/CBC/NoPadding");
userKey = buildPasswordKey(password, userSalt, rounds, true);
byte[] IVCheck = hexToByteArray(userIvHex);
ivSpec = new IvParameterSpec(IVCheck);
c.init(Cipher.DECRYPT_MODE,
new SecretKeySpec(userKey.getEncoded(), "AES"), ivSpec);
mkCipher = hexToByteArray(masterKeyBlobHex);
byte[] mkBlobCheck = c.doFinal(mkCipher);
int pad_byte = mkBlobCheck[mkBlobCheck.length - 1];
if (pad_byte < 8) {
System.err.println("PKCS5Padding is not correct, wrong password?");
} else {
c = Cipher.getInstance(ENCRYPTION_MECHANISM);
ivSpec = new IvParameterSpec(IV);
c.init(Cipher.DECRYPT_MODE, new SecretKeySpec(mk, "AES"), ivSpec);
cipherStream = new CipherInputStream(rawInStream, c);
}
/*
// now validate the decrypted master key against the checksum
// first try the algorithm matching the archive version
boolean useUtf = version >= BACKUP_FILE_V2;
Expand All @@ -172,7 +190,7 @@ public static void extractAsTar(String backupFilename, String filename,
// Only if all of the above worked properly will 'result' be
// assigned
cipherStream = new CipherInputStream(rawInStream, c);
}
} */
}

if (isEncrypted && cipherStream == null) {
Expand Down