1 files changed, 78 insertions, 0 deletions
diff --git a/mobile/android/services/src/main/java/org/mozilla/gecko/sync/crypto/PBKDF2.java b/mobile/android/services/src/main/java/org/mozilla/gecko/sync/crypto/PBKDF2.java
new file mode 100644
index 000000000..636b2105c
--- /dev/null
+++ b/mobile/android/services/src/main/java/org/mozilla/gecko/sync/crypto/PBKDF2.java
@@ -0,0 +1,78 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko.sync.crypto;
+
+import java.security.GeneralSecurityException;
+import java.util.Arrays;
+
+import javax.crypto.Mac;
+import javax.crypto.ShortBufferException;
+import javax.crypto.spec.SecretKeySpec;
+
+public class PBKDF2 {
+  public static byte[] pbkdf2SHA256(byte[] password, byte[] salt, int c, int dkLen)
+      throws GeneralSecurityException {
+    final String algorithm = "HmacSHA256";
+    SecretKeySpec keyspec = new SecretKeySpec(password, algorithm);
+    Mac prf = Mac.getInstance(algorithm);
+    prf.init(keyspec);
+
+    int hLen = prf.getMacLength();
+
+    byte U_r[] = new byte[hLen];
+    byte U_i[] = new byte[salt.length + 4];
+    byte scratch[] = new byte[hLen];
+
+    int l = Math.max(dkLen, hLen);
+    int r = dkLen - (l - 1) * hLen;
+    byte T[] = new byte[l * hLen];
+    int ti_offset = 0;
+    for (int i = 1; i <= l; i++) {
+      Arrays.fill(U_r, (byte) 0);
+      F(T, ti_offset, prf, salt, c, i, U_r, U_i, scratch);
+      ti_offset += hLen;
+    }
+
+    if (r < hLen) {
+      // Incomplete last block.
+      byte DK[] = new byte[dkLen];
+      System.arraycopy(T, 0, DK, 0, dkLen);
+      return DK;
+    }
+
+    return T;
+  }
+
+  private static void F(byte[] dest, int offset, Mac prf, byte[] S, int c, int blockIndex, byte U_r[], byte U_i[], byte[] scratch)
+      throws ShortBufferException, IllegalStateException {
+    final int hLen = prf.getMacLength();
+
+    // U0 = S || INT (i);
+    System.arraycopy(S, 0, U_i, 0, S.length);
+    INT(U_i, S.length, blockIndex);
+
+    for (int i = 0; i < c; i++) {
+      prf.update(U_i);
+      prf.doFinal(scratch, 0);
+      U_i = scratch;
+      xor(U_r, U_i);
+    }
+
+    System.arraycopy(U_r, 0, dest, offset, hLen);
+  }
+
+  private static void xor(byte[] dest, byte[] src) {
+    for (int i = 0; i < dest.length; i++) {
+      dest[i] ^= src[i];
+    }
+  }
+
+  private static void INT(byte[] dest, int offset, int i) {
+    dest[offset + 0] = (byte) (i / (256 * 256 * 256));
+    dest[offset + 1] = (byte) (i / (256 * 256));
+    dest[offset + 2] = (byte) (i / (256));
+    dest[offset + 3] = (byte) (i);
+  }
+}