Display HOTP code if password contains HOTP secret, unify HOTP and TOTP code (#413)

* Display HOTP code if password contains HOTP secret, unify HOTP and TOTP code

* Add ability to show HOTP instead of showing every decrypt

* Fix off by 1 error

* fix return intent logic so that edits and HOTP increments are properly committed

* fix linting errors

* Fix broken logic for case when a password is created

* add ability to choose if password entry will be updated on HOTP code calculation

1 files changed, 5 insertions, 6 deletions

diff --git a/app/src/main/java/com/zeapo/pwdstore/utils/Totp.java b/app/src/main/java/com/zeapo/pwdstore/utils/Otp.java
index 5e4326e2..44e2aa64 100644
--- a/app/src/main/java/com/zeapo/pwdstore/utils/Totp.java
+++ b/app/src/main/java/com/zeapo/pwdstore/utils/Otp.java
@@ -13,18 +13,18 @@ import java.util.Arrays;
 import javax.crypto.Mac;
 import javax.crypto.spec.SecretKeySpec;
 
-public class Totp {
+public class Otp {
+    public static final int TIME_WINDOW = 30;
 
     private static final String ALGORITHM = "HmacSHA1";
-    private static final int TIME_WINDOW = 30;
     private static final int CODE_DIGITS = 6;
 
     private static final Base32 BASE_32 = new Base32();
 
-    private Totp() {
+    private Otp() {
     }
 
-    public static String calculateCode(String secret, long epochSeconds) {
+    public static String calculateCode(String secret, long counter) {
         SecretKeySpec signingKey = new SecretKeySpec(BASE_32.decode(secret), ALGORITHM);
 
         Mac mac = null;
@@ -39,8 +39,7 @@ public class Totp {
             return null;
         }
 
-        long time = epochSeconds / TIME_WINDOW;
-        byte[] digest = mac.doFinal(ByteBuffer.allocate(8).putLong(time).array());
+        byte[] digest = mac.doFinal(ByteBuffer.allocate(8).putLong(counter).array());
         int offset = digest[digest.length - 1] & 0xf;
         byte[] code = Arrays.copyOfRange(digest, offset, offset + 4);
         code[0] = (byte) (0x7f & code[0]);