1 files changed, 5 insertions, 28 deletions
diff --git a/source/crypto/Kdf.mc b/source/crypto/Kdf.mc
index 5bace1c..e64c8ff 100644
--- a/source/crypto/Kdf.mc
+++ b/source/crypto/Kdf.mc
@@ -1,5 +1,5 @@
 // Author:  cirakg & claude ai
-// Summary: Key derivation: resumable PBKDF2-HMAC-SHA256 (RFC 8018) with calibration, and HKDF-SHA256 (RFC 5869).
+// Summary: PIN key derivation: resumable PBKDF2-HMAC-SHA256 (RFC 8018) with calibration.
 //
 // PBKDF2 turns the PIN into a key (README 7.2). It runs as a Jobs.Job, a
 // bounded number of iterations per step, because the iteration count is
@@ -7,11 +7,11 @@
 // watchdog budget. It uses the native HMAC-SHA256: the object keeps the key
 // and digest() resets it, so each iteration is one native call.
 //
-// HKDF splits one master key into separate encryption and MAC keys
-// (README 7.3).
+// HKDF, which splits one master key into separate encryption and MAC keys
+// (README 7.3), is in Hkdf.mc (the glance needs it, but not PBKDF2).
 //
-// Verified with RFC 7914 section 11 (PBKDF2) and RFC 5869 A.1-A.3 (HKDF),
-// plus seeded vectors from Python's hashlib (test/crypto/KdfTest.mc).
+// Verified with RFC 7914 section 11 (PBKDF2) plus seeded vectors from
+// Python's hashlib (test/crypto/KdfAesTest.mc).
 
 import Toybox.Cryptography;
 import Toybox.Lang;
@@ -191,27 +191,4 @@ module Kdf {
         }
         return estimate > MAX_ITERATIONS ? MAX_ITERATIONS : estimate.toNumber();
     }
-
-    // HKDF-SHA256 (RFC 5869): extract with salt (empty means 32 zero bytes),
-    // then expand to `length` bytes with info. length <= 255 * 32.
-    function hkdf(ikm as ByteArray, salt as ByteArray, info as ByteArray, length as Number) as ByteArray {
-        if (length < 1 || length > 255 * SHA256_BYTES) {
-            throw new Lang.InvalidValueException("HKDF: bad key length");
-        }
-        var prk = Hmac.nativeSha256(salt.size() > 0 ? salt : new [SHA256_BYTES]b, ikm);
-        var okm = new [0]b;
-        var block = new [0]b;
-        for (var counter = 1; okm.size() < length; counter++) {
-            var input = Bytes.concat(block, info);
-            input.add(counter);
-            Bytes.wipe(block);
-            block = Hmac.nativeSha256(prk, input);
-            okm.addAll(block);
-        }
-        Bytes.wipe(prk);
-        Bytes.wipe(block);
-        var key = okm.slice(0, length);
-        Bytes.wipe(okm);
-        return key;
-    }
 }