From 22add1d5151e199101750fe0bf4b8cc7fcd437be Mon Sep 17 00:00:00 2001
From: Dusan Klinec <dusan.klinec@gmail.com>
Date: Fri, 2 Nov 2018 14:17:53 +0100
Subject: [PATCH] xmr: full mlsag simplified

---
 src/apps/monero/signing/step_09_sign_input.py | 19 +++++------
 src/apps/monero/xmr/mlsag.py                  | 33 +++++++------------
 2 files changed, 19 insertions(+), 33 deletions(-)

diff --git a/src/apps/monero/signing/step_09_sign_input.py b/src/apps/monero/signing/step_09_sign_input.py
index 8d4249545b..73c7566eb4 100644
--- a/src/apps/monero/signing/step_09_sign_input.py
+++ b/src/apps/monero/signing/step_09_sign_input.py
@@ -134,14 +134,14 @@ async def sign_input(
     )
 
     state.mem_trace(4, True)
-    mg_buffer = []
 
     from apps.monero.xmr import mlsag
 
-    if state.rct_type == RctType.Simple:
-        ring_pubkeys = [x.key for x in src_entr.outputs]
-        src_entr = None
+    mg_buffer = []
+    ring_pubkeys = [x.key for x in src_entr.outputs]
+    del src_entr
 
+    if state.rct_type == RctType.Simple:
         mlsag.generate_mlsag_simple(
             state.full_message,
             ring_pubkeys,
@@ -153,18 +153,15 @@ async def sign_input(
             mg_buffer,
         )
 
-        del (ring_pubkeys, input_secret_key, pseudo_out_alpha, pseudo_out_c)
+        del (input_secret_key, pseudo_out_alpha, pseudo_out_c)
 
     else:
         # Full RingCt, only one input
         txn_fee_key = crypto.scalarmult_h(state.fee)
-        ring_pubkeys = [[x.key] for x in src_entr.outputs]
-        src_entr = None
-
         mlsag.generate_mlsag_full(
             state.full_message,
             ring_pubkeys,
-            [input_secret_key],
+            input_secret_key,
             state.output_sk_masks,
             state.output_pk_commitments,
             kLRki,
@@ -173,9 +170,9 @@ async def sign_input(
             mg_buffer,
         )
 
-        del (ring_pubkeys, input_secret_key, txn_fee_key)
+        del (input_secret_key, txn_fee_key)
 
-    del (mlsag, src_entr)
+    del (mlsag, ring_pubkeys)
     state.mem_trace(5, True)
 
     from trezor.messages.MoneroTransactionSignInputAck import (
diff --git a/src/apps/monero/xmr/mlsag.py b/src/apps/monero/xmr/mlsag.py
index 944c1b8afe..06b47fd1b9 100644
--- a/src/apps/monero/xmr/mlsag.py
+++ b/src/apps/monero/xmr/mlsag.py
@@ -63,22 +63,12 @@ def generate_mlsag_full(
     cols = len(pubs)
     if cols == 0:
         raise ValueError("Empty pubs")
-    rows = len(pubs[0])
-    if rows == 0:
-        raise ValueError("Empty pub row")
-    for i in range(cols):
-        if len(pubs[i]) != rows:
-            raise ValueError("pub is not rectangular")
-
-    if len(in_sk) != rows:
-        raise ValueError("Bad inSk size")
+    rows = 1  # Monero uses only one row
     if len(out_sk_mask) != len(out_pk_commitments):
         raise ValueError("Bad outsk/putpk size")
 
     sk = _key_vector(rows + 1)
     M = _key_matrix(rows + 1, cols)
-    for i in range(rows + 1):
-        sk[i] = crypto.sc_0()
 
     tmp_mi_rows = crypto.new_point(None)
     tmp_pt = crypto.new_point(None)
@@ -86,13 +76,13 @@ def generate_mlsag_full(
     for i in range(cols):
         crypto.identity_into(tmp_mi_rows)  # M[i][rows]
 
-        for j in range(rows):
-            M[i][j] = pubs[i][j].dest
-            crypto.point_add_into(
-                tmp_mi_rows,
-                tmp_mi_rows,
-                crypto.decodepoint_into(tmp_pt, pubs[i][j].commitment),
-            )
+        # Should iterate over rows, simplified as rows == 1
+        M[i][0] = pubs[i].dest
+        crypto.point_add_into(
+            tmp_mi_rows,
+            tmp_mi_rows,
+            crypto.decodepoint_into(tmp_pt, pubs[i].commitment),
+        )
         pubs[i] = None
 
         for j in range(len(out_pk_commitments)):
@@ -106,10 +96,9 @@ def generate_mlsag_full(
         crypto.point_sub_into(tmp_mi_rows, tmp_mi_rows, txn_fee_key)
         M[i][rows] = crypto.encodepoint(tmp_mi_rows)
 
-    sk[rows] = crypto.sc_0()
-    for j in range(rows):
-        sk[j] = in_sk[j].dest
-        crypto.sc_add_into(sk[rows], sk[rows], in_sk[j].mask)  # add masks in last row
+    # Simplified as rows == 1
+    sk[0] = in_sk.dest
+    sk[rows] = in_sk.mask  # originally: sum of all in_sk[0..rows] in sk[rows]
 
     for j in range(len(out_pk_commitments)):
         crypto.sc_sub_into(