Merge pull request #394 from ph4r05/xmr-mg

xmr: MLSAG computation optimized

src/apps/monero/signing/step_09_sign_input.py

@@ -10,7 +10,7 @@ from .state import State
 
 from apps.monero.layout import confirms
 from apps.monero.signing import RctType
-from apps.monero.xmr import crypto, serialize
+from apps.monero.xmr import crypto
 
 if False:
     from trezor.messages.MoneroTransactionSourceEntry import (
@@ -40,8 +40,6 @@ async def sign_input(
     :param spend_enc: one time address spending private key. Encrypted.
     :return: Generated signature MGs[i]
     """
-    from apps.monero.signing import offloading_keys
-
     await confirms.transaction_step(
         state.ctx, state.STEP_SIGN, state.current_input_index + 1, state.input_count
     )
@@ -57,8 +55,11 @@ async def sign_input(
         raise ValueError("Two and more inputs must imply SimpleRCT")
 
     input_position = state.source_permutation[state.current_input_index]
+    mods = utils.unimport_begin()
 
     # Check input's HMAC
+    from apps.monero.signing import offloading_keys
+
     vini_hmac_comp = await offloading_keys.gen_hmac_vini(
         state.key_hmac, src_entr, vini_bin, input_position
     )
@@ -66,7 +67,9 @@ async def sign_input(
         raise ValueError("HMAC is not correct")
 
     gc.collect()
-    state.mem_trace(1)
+    state.mem_trace(1, True)
+
+    from apps.monero.xmr.crypto import chacha_poly
 
     if state.rct_type == RctType.Simple:
         # both pseudo_out and its mask were offloaded so we need to
@@ -78,10 +81,7 @@ async def sign_input(
         if not crypto.ct_equals(pseudo_out_hmac_comp, pseudo_out_hmac):
             raise ValueError("HMAC is not correct")
 
-        gc.collect()
-        state.mem_trace(2)
-
-        from apps.monero.xmr.crypto import chacha_poly
+        state.mem_trace(2, True)
 
         pseudo_out_alpha = crypto.decodeint(
             chacha_poly.decrypt_pack(
@@ -92,9 +92,6 @@ async def sign_input(
         pseudo_out_c = crypto.decodepoint(pseudo_out)
 
     # Spending secret
-    from apps.monero.xmr.crypto import chacha_poly
-    from apps.monero.xmr.serialize_messages.ct_keys import CtKey
-
     spend_key = crypto.decodeint(
         chacha_poly.decrypt_pack(
             offloading_keys.enc_key_spend(state.key_enc, input_position),
@@ -102,8 +99,18 @@ async def sign_input(
         )
     )
 
-    gc.collect()
-    state.mem_trace(3)
+    del (
+        offloading_keys,
+        chacha_poly,
+        pseudo_out,
+        pseudo_out_hmac,
+        pseudo_out_alpha_enc,
+        spend_enc,
+    )
+    utils.unimport_end(mods)
+    state.mem_trace(3, True)
+
+    from apps.monero.xmr.serialize_messages.ct_keys import CtKey
 
     # Basic setup, sanity check
     index = src_entr.real_output
@@ -126,14 +133,16 @@ async def sign_input(
         "Real source entry's mask does not equal spend key's",
     )
 
-    gc.collect()
-    state.mem_trace(4)
+    state.mem_trace(4, True)
 
     from apps.monero.xmr import mlsag
 
+    mg_buffer = []
+    ring_pubkeys = [x.key for x in src_entr.outputs]
+    del src_entr
+
     if state.rct_type == RctType.Simple:
-        ring_pubkeys = [x.key for x in src_entr.outputs]
-        mg = mlsag.generate_mlsag_simple(
+        mlsag.generate_mlsag_simple(
             state.full_message,
             ring_pubkeys,
             input_secret_key,
@@ -141,52 +150,33 @@ async def sign_input(
             pseudo_out_c,
             kLRki,
             index,
+            mg_buffer,
         )
 
+        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]
-        mg = mlsag.generate_mlsag_full(
+        mlsag.generate_mlsag_full(
             state.full_message,
             ring_pubkeys,
-            [input_secret_key],
+            input_secret_key,
             state.output_sk_masks,
             state.output_pk_commitments,
             kLRki,
             index,
             txn_fee_key,
+            mg_buffer,
         )
 
-    gc.collect()
-    state.mem_trace(5)
+        del (input_secret_key, txn_fee_key)
 
-    # Encode
-    mgs = _recode_msg([mg])
-
-    gc.collect()
-    state.mem_trace(6)
+    del (mlsag, ring_pubkeys)
+    state.mem_trace(5, True)
 
     from trezor.messages.MoneroTransactionSignInputAck import (
         MoneroTransactionSignInputAck,
     )
 
-    return MoneroTransactionSignInputAck(
-        signature=serialize.dump_msg_gc(mgs[0], preallocate=488)
-    )
-
-
-def _recode_msg(mgs):
-    """
-    Recodes MGs signatures from raw forms to bytearrays so it works with serialization
-    """
-    for idx in range(len(mgs)):
-        mgs[idx].cc = crypto.encodeint(mgs[idx].cc)
-        if hasattr(mgs[idx], "II") and mgs[idx].II:
-            for i in range(len(mgs[idx].II)):
-                mgs[idx].II[i] = crypto.encodepoint(mgs[idx].II[i])
-
-        for i in range(len(mgs[idx].ss)):
-            for j in range(len(mgs[idx].ss[i])):
-                mgs[idx].ss[i][j] = crypto.encodeint(mgs[idx].ss[i][j])
-    return mgs
+    return MoneroTransactionSignInputAck(signature=mg_buffer)

src/apps/monero/xmr/crypto/__init__.py

@@ -107,6 +107,7 @@ def sc_init_into(r, x):
     return tcry.init256_modm(r, x)
 
 
+sc_copy = tcry.init256_modm
 sc_get64 = tcry.get256_modm
 sc_check = tcry.check256_modm
 check_sc = tcry.check256_modm

src/apps/monero/xmr/mlsag.py

@@ -42,63 +42,76 @@ and `sk` is equal to:
 Mostly ported from official Monero client, but also inspired by Mininero.
 Author: Dusan Klinec, ph4r05, 2018
 """
+
+import gc
+
 from apps.monero.xmr import crypto
+from apps.monero.xmr.serialize import int_serialize
 
 
 def generate_mlsag_full(
-    message, pubs, in_sk, out_sk_mask, out_pk_commitments, kLRki, index, txn_fee_key
+    message,
+    pubs,
+    in_sk,
+    out_sk_mask,
+    out_pk_commitments,
+    kLRki,
+    index,
+    txn_fee_key,
+    mg_buff,
 ):
     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)
 
     for i in range(cols):
-        M[i][rows] = crypto.identity()
-        for j in range(rows):
-            M[i][j] = crypto.decodepoint(pubs[i][j].dest)
-            M[i][rows] = crypto.point_add(
-                M[i][rows], crypto.decodepoint(pubs[i][j].commitment)
-            )
+        crypto.identity_into(tmp_mi_rows)  # M[i][rows]
 
-    sk[rows] = crypto.sc_0()
-    for j in range(rows):
-        sk[j] = in_sk[j].dest
-        sk[rows] = crypto.sc_add(sk[rows], in_sk[j].mask)  # add masks in last row
+        # 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 i in range(cols):
         for j in range(len(out_pk_commitments)):
-            M[i][rows] = crypto.point_sub(
-                M[i][rows], crypto.decodepoint(out_pk_commitments[j])
+            crypto.point_sub_into(
+                tmp_mi_rows,
+                tmp_mi_rows,
+                crypto.decodepoint_into(tmp_pt, out_pk_commitments[j]),
             )  # subtract output Ci's in last row
 
         # Subtract txn fee output in last row
-        M[i][rows] = crypto.point_sub(M[i][rows], txn_fee_key)
+        crypto.point_sub_into(tmp_mi_rows, tmp_mi_rows, txn_fee_key)
+        M[i][rows] = crypto.encodepoint(tmp_mi_rows)
+
+    # 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)):
-        sk[rows] = crypto.sc_sub(
-            sk[rows], out_sk_mask[j]
+        crypto.sc_sub_into(
+            sk[rows], sk[rows], out_sk_mask[j]
         )  # subtract output masks in last row
 
-    return generate_mlsag(message, M, sk, kLRki, index, rows)
+    del (pubs, tmp_mi_rows, tmp_pt)
+    gc.collect()
 
+    return generate_mlsag(message, M, sk, kLRki, index, rows, mg_buff)
 
-def generate_mlsag_simple(message, pubs, in_sk, a, cout, kLRki, index):
+
+def generate_mlsag_simple(message, pubs, in_sk, a, cout, kLRki, index, mg_buff):
     """
     MLSAG for RctType.Simple
     :param message: the full message to be signed (actually its hash)
@@ -108,7 +121,7 @@ def generate_mlsag_simple(message, pubs, in_sk, a, cout, kLRki, index):
     :param cout: pseudo output commitment; point, decoded; better name: pseudo_out_c
     :param kLRki: used only in multisig, currently not implemented
     :param index: specifies corresponding public key to the `in_sk` in the pubs array
-    :return: MgSig
+    :param mg_buff: buffer to store the signature to
     """
     # Monero signs inputs separately, so `rows` always equals 2 (pubkey, commitment)
     # and `dsRows` is always 1 (denotes where the pubkeys "end")
@@ -123,12 +136,21 @@ def generate_mlsag_simple(message, pubs, in_sk, a, cout, kLRki, index):
 
     sk[0] = in_sk.dest
     sk[1] = crypto.sc_sub(in_sk.mask, a)
+    tmp_pt = crypto.new_point()
 
     for i in range(cols):
-        M[i][0] = crypto.decodepoint(pubs[i].dest)
-        M[i][1] = crypto.point_sub(crypto.decodepoint(pubs[i].commitment), cout)
+        crypto.point_sub_into(
+            tmp_pt, crypto.decodepoint_into(tmp_pt, pubs[i].commitment), cout
+        )
+
+        M[i][0] = pubs[i].dest
+        M[i][1] = crypto.encodepoint(tmp_pt)
+        pubs[i] = None
+
+    del (pubs)
+    gc.collect()
 
-    return generate_mlsag(message, M, sk, kLRki, index, dsRows)
+    return generate_mlsag(message, M, sk, kLRki, index, dsRows, mg_buff)
 
 
 def gen_mlsag_assert(pk, xx, kLRki, index, dsRows):
@@ -159,13 +181,10 @@ def gen_mlsag_assert(pk, xx, kLRki, index, dsRows):
     return rows, cols
 
 
-def generate_first_c_and_key_images(
-    message, rv, pk, xx, kLRki, index, dsRows, rows, cols
-):
+def generate_first_c_and_key_images(message, pk, xx, kLRki, index, dsRows, rows, cols):
     """
     MLSAG computation - the part with secret keys
     :param message: the full message to be signed (actually its hash)
-    :param rv: MgSig
     :param pk: matrix of public keys and commitments
     :param xx: input secret array composed of a private key and commitment mask
     :param kLRki: used only in multisig, currently not implemented
@@ -174,18 +193,19 @@ def generate_first_c_and_key_images(
     :param rows: total number of rows
     :param cols: size of ring
     """
-    Ip = _key_vector(dsRows)
-    rv.II = _key_vector(dsRows)
+    II = _key_vector(dsRows)
     alpha = _key_vector(rows)
-    rv.ss = _key_matrix(rows, cols)
 
     tmp_buff = bytearray(32)
+    Hi = crypto.new_point()
+    aGi = crypto.new_point()
+    aHPi = crypto.new_point()
     hasher = _hasher_message(message)
 
     for i in range(dsRows):
         # this is somewhat extra as compared to the Ring Confidential Tx paper
         # see footnote in From Zero to Monero section 3.3
-        hasher.update(crypto.encodepoint(pk[index][i]))
+        hasher.update(pk[index][i])
         if kLRki:
             raise NotImplementedError("Multisig not implemented")
             # alpha[i] = kLRki.k
@@ -194,36 +214,34 @@ def generate_first_c_and_key_images(
             # hash_point(hasher, kLRki.R, tmp_buff)
 
         else:
-            Hi = crypto.hash_to_point(crypto.encodepoint(pk[index][i]))
+            crypto.hash_to_point_into(Hi, pk[index][i])
             alpha[i] = crypto.random_scalar()
             # L = alpha_i * G
-            aGi = crypto.scalarmult_base(alpha[i])
+            crypto.scalarmult_base_into(aGi, alpha[i])
             # Ri = alpha_i * H(P_i)
-            aHPi = crypto.scalarmult(Hi, alpha[i])
+            crypto.scalarmult_into(aHPi, Hi, alpha[i])
             # key image
-            rv.II[i] = crypto.scalarmult(Hi, xx[i])
+            II[i] = crypto.scalarmult(Hi, xx[i])
             _hash_point(hasher, aGi, tmp_buff)
             _hash_point(hasher, aHPi, tmp_buff)
 
-        Ip[i] = rv.II[i]
-
     for i in range(dsRows, rows):
         alpha[i] = crypto.random_scalar()
         # L = alpha_i * G
-        aGi = crypto.scalarmult_base(alpha[i])
+        crypto.scalarmult_base_into(aGi, alpha[i])
         # for some reasons we omit calculating R here, which seems
         # contrary to the paper, but it is in the Monero official client
         # see https://github.com/monero-project/monero/blob/636153b2050aa0642ba86842c69ac55a5d81618d/src/ringct/rctSigs.cpp#L191
-        _hash_point(hasher, pk[index][i], tmp_buff)
+        hasher.update(pk[index][i])
         _hash_point(hasher, aGi, tmp_buff)
 
     # the first c
     c_old = hasher.digest()
     c_old = crypto.decodeint(c_old)
-    return c_old, Ip, alpha
+    return c_old, II, alpha
 
 
-def generate_mlsag(message, pk, xx, kLRki, index, dsRows):
+def generate_mlsag(message, pk, xx, kLRki, index, dsRows, mg_buff):
     """
     Multilayered Spontaneous Anonymous Group Signatures (MLSAG signatures)
 
@@ -233,56 +251,89 @@ def generate_mlsag(message, pk, xx, kLRki, index, dsRows):
     :param kLRki: used only in multisig, currently not implemented
     :param index: specifies corresponding public key to the `xx`'s private key in the `pk` array
     :param dsRows: separates pubkeys from commitment
-    :return MgSig
+    :param mg_buff: mg signature buffer
     """
-    from apps.monero.xmr.serialize_messages.tx_full import MgSig
-
     rows, cols = gen_mlsag_assert(pk, xx, kLRki, index, dsRows)
+    rows_b_size = int_serialize.uvarint_size(rows)
+
+    # Preallocation of the chunked buffer, len + cols + cc
+    for _ in range(1 + cols + 1):
+        mg_buff.append(None)
 
-    rv = MgSig()
-    c, L, R, Hi = 0, None, None, None
+    mg_buff[0] = int_serialize.dump_uvarint_b(cols)
+    cc = crypto.new_scalar()  # rv.cc
+    c = crypto.new_scalar()
+    L = crypto.new_point()
+    R = crypto.new_point()
+    Hi = crypto.new_point()
 
     # calculates the "first" c, key images and random scalars alpha
-    c_old, Ip, alpha = generate_first_c_and_key_images(
-        message, rv, pk, xx, kLRki, index, dsRows, rows, cols
+    c_old, II, alpha = generate_first_c_and_key_images(
+        message, pk, xx, kLRki, index, dsRows, rows, cols
     )
 
     i = (index + 1) % cols
     if i == 0:
-        rv.cc = c_old
+        crypto.sc_copy(cc, c_old)
 
+    ss = [crypto.new_scalar() for _ in range(rows)]
     tmp_buff = bytearray(32)
+
     while i != index:
-        rv.ss[i] = _generate_random_vector(rows)
         hasher = _hasher_message(message)
 
+        # Serialize size of the row
+        mg_buff[i + 1] = bytearray(rows_b_size + 32 * rows)
+        int_serialize.dump_uvarint_b_into(rows, mg_buff[i + 1])
+
+        for x in ss:
+            crypto.random_scalar(x)
+
         for j in range(dsRows):
             # L = rv.ss[i][j] * G + c_old * pk[i][j]
-            L = crypto.add_keys2(rv.ss[i][j], c_old, pk[i][j])
-            Hi = crypto.hash_to_point(crypto.encodepoint(pk[i][j]))
+            crypto.add_keys2_into(
+                L, ss[j], c_old, crypto.decodepoint_into(Hi, pk[i][j])
+            )
+            crypto.hash_to_point_into(Hi, pk[i][j])
+
             # R = rv.ss[i][j] * H(pk[i][j]) + c_old * Ip[j]
-            R = crypto.add_keys3(rv.ss[i][j], Hi, c_old, rv.II[j])
-            _hash_point(hasher, pk[i][j], tmp_buff)
+            crypto.add_keys3_into(R, ss[j], Hi, c_old, II[j])
+
+            hasher.update(pk[i][j])
             _hash_point(hasher, L, tmp_buff)
             _hash_point(hasher, R, tmp_buff)
 
         for j in range(dsRows, rows):
             # again, omitting R here as discussed above
-            L = crypto.add_keys2(rv.ss[i][j], c_old, pk[i][j])
-            _hash_point(hasher, pk[i][j], tmp_buff)
+            crypto.add_keys2_into(
+                L, ss[j], c_old, crypto.decodepoint_into(Hi, pk[i][j])
+            )
+            hasher.update(pk[i][j])
             _hash_point(hasher, L, tmp_buff)
 
-        c = crypto.decodeint(hasher.digest())
-        c_old = c
+        for si in range(rows):
+            crypto.encodeint_into(mg_buff[i + 1], ss[si], rows_b_size + 32 * si)
+
+        crypto.decodeint_into(c, hasher.digest())
+        crypto.sc_copy(c_old, c)
+        pk[i] = None
         i = (i + 1) % cols
 
         if i == 0:
-            rv.cc = c_old
+            crypto.sc_copy(cc, c_old)
+        gc.collect()
+
+    del II
 
+    # Finalizing rv.ss by processing rv.ss[index]
+    mg_buff[index + 1] = bytearray(rows_b_size + 32 * rows)
+    int_serialize.dump_uvarint_b_into(rows, mg_buff[index + 1])
     for j in range(rows):
-        rv.ss[index][j] = crypto.sc_mulsub(c, xx[j], alpha[j])
+        crypto.sc_mulsub_into(ss[j], c, xx[j], alpha[j])
+        crypto.encodeint_into(mg_buff[index + 1], ss[j], rows_b_size + 32 * j)
 
-    return rv
+    # rv.cc
+    mg_buff[-1] = crypto.encodeint(cc)
 
 
 def _key_vector(rows):

src/apps/monero/xmr/serialize_messages/tx_full.py

@@ -1,11 +0,0 @@
-from apps.monero.xmr.serialize.message_types import MessageType
-from apps.monero.xmr.serialize_messages.base import ECKey
-from apps.monero.xmr.serialize_messages.ct_keys import KeyM
-
-
-class MgSig(MessageType):
-    __slots__ = ("ss", "cc", "II")
-
-    @classmethod
-    def f_specs(cls):
-        return (("ss", KeyM), ("cc", ECKey))

src/protobuf.py

@@ -275,6 +275,11 @@ async def dump_message(writer, msg, fields=None):
             elif ftype is BoolType:
                 await dump_uvarint(writer, int(svalue))
 
+            elif ftype is BytesType and is_chunked(svalue):
+                await dump_uvarint(writer, len_list_bytes(svalue))
+                for sub_svalue in svalue:
+                    await writer.awrite(sub_svalue)
+
             elif ftype is BytesType:
                 await dump_uvarint(writer, len(svalue))
                 await writer.awrite(svalue)
@@ -329,7 +334,9 @@ def count_message(msg, fields=None):
 
         elif ftype is BytesType:
             for svalue in fvalue:
-                svalue = len(svalue)
+                svalue = (
+                    len(svalue) if not is_chunked(svalue) else len_list_bytes(svalue)
+                )
                 nbytes += count_uvarint(svalue)
                 nbytes += svalue
 
@@ -351,3 +358,18 @@ def count_message(msg, fields=None):
             raise TypeError
 
     return nbytes
+
+
+def is_chunked(svalue):
+    return (
+        isinstance(svalue, list)
+        and len(svalue) > 0
+        and not isinstance(svalue[0], (int, bool))
+    )
+
+
+def len_list_bytes(svalue):
+    res = 0
+    for x in svalue:
+        res += len(x)
+    return res