diff --git a/src/main/java/com/ledger/u2f/U2FApplet.java b/src/main/java/com/ledger/u2f/U2FApplet.java
index 0ff8942..4e50410 100644
--- a/src/main/java/com/ledger/u2f/U2FApplet.java
+++ b/src/main/java/com/ledger/u2f/U2FApplet.java
@@ -190,18 +190,19 @@ private void handleEnroll(APDU apdu) throws ISOException {
         attestationSignature.update(scratch, SCRATCH_KEY_HANDLE_OFFSET, keyHandleLength);
         attestationSignature.update(scratch, SCRATCH_PUBLIC_KEY_OFFSET, (short)65);
         outOffset = (short)(ENROLL_PUBLIC_KEY_OFFSET + 65 + 1 + keyHandleLength);
+        short signatureSize = attestationSignature.sign(buffer, (short)0, (short)0, scratch, SCRATCH_SIGNATURE_OFFSET);
+
         if (extendedLength) {
             // If using extended length, the message can be completed and sent immediately
             scratch[SCRATCH_TRANSPORT_STATE] = TRANSPORT_EXTENDED;
-            outOffset = Util.arrayCopyNonAtomic(scratch, SCRATCH_PAD, buffer, (short)0, outOffset);
-            outOffset = Util.arrayCopyNonAtomic(attestationCertificate, (short)0, buffer, outOffset, (short)attestationCertificate.length);
-            short signatureSize = attestationSignature.sign(buffer, (short)0, (short)0, buffer, outOffset);
-            outOffset += signatureSize;
-            apdu.setOutgoingAndSend((short)0, outOffset);
+            apdu.setOutgoing();
+            apdu.setOutgoingLength((short)(outOffset + attestationCertificate.length + signatureSize));
+            apdu.sendBytesLong(scratch, SCRATCH_PAD, outOffset);
+            apdu.sendBytesLong(attestationCertificate, (short)0, (short)attestationCertificate.length);
+            apdu.sendBytesLong(scratch, SCRATCH_SIGNATURE_OFFSET, signatureSize);
         }
         else {
             // Otherwise, keep the signature and proceed to send the first chunk
-            short signatureSize = attestationSignature.sign(buffer, (short)0, (short)0, scratch, SCRATCH_SIGNATURE_OFFSET);
             scratch[SCRATCH_TRANSPORT_STATE] = TRANSPORT_NOT_EXTENDED;
             Util.setShort(scratch, SCRATCH_CURRENT_OFFSET, (short)0);
             Util.setShort(scratch, SCRATCH_SIGNATURE_LENGTH, signatureSize);
@@ -285,8 +286,9 @@ private void handleSign(APDU apdu) throws ISOException {
         if (extendedLength) {
             // If using extended length, the message can be completed and sent immediately
             scratch[SCRATCH_TRANSPORT_STATE] = TRANSPORT_EXTENDED;
-            Util.arrayCopyNonAtomic(scratch, SCRATCH_PAD, buffer, (short)0, outOffset);
-            apdu.setOutgoingAndSend((short)0, (short)(outOffset - SCRATCH_PAD));
+            apdu.setOutgoing();
+            apdu.setOutgoingLength((short)(outOffset - SCRATCH_PAD));
+            apdu.sendBytesLong(scratch, SCRATCH_PAD, (short)(outOffset - SCRATCH_PAD));
         }
         else {
             // Otherwise send the first chunk