def create_contract_variable(cname: str) -> StateVariableDeclaration:
"""Create a public constant state variable with which contract with name 'cname' can be accessed"""
inst_idf = Identifier(cfg.get_contract_var_name(cname))
c_type = ContractTypeName([Identifier(cname)])
cast_0_to_c = PrimitiveCastExpr(c_type, NumberLiteralExpr(0))
var_decl = StateVariableDeclaration(AnnotatedTypeName(c_type), ['public', 'constant'], inst_idf.clone(), cast_0_to_c)
return var_decl
def split_into_external_and_internal_fct(self, f: ConstructorOrFunctionDefinition, original_params: List[Parameter],
global_owners: List[PrivacyLabelExpr]) -> Tuple[ConstructorOrFunctionDefinition,
ConstructorOrFunctionDefinition]:
"""
Take public function f and split it into an internal function and an external wrapper function.
:param f: [SIDE EFFECT] function to split (at least requires_verification_if_external)
:param original_params: list of transformed function parameters without additional parameters added due to transformation
:param global_owners: list of static labels (me + final address state variable identifiers)
:return: Tuple of newly created external and internal function definitions
"""
assert f.requires_verification_when_external
# Create new empty function with same parameters as original -> external wrapper
if f.is_function:
new_modifiers = ['external']
original_params = [deep_copy(p, with_types=True).with_changed_storage('memory', 'calldata') for p in original_params]
else:
new_modifiers = ['public']
if f.is_payable:
new_modifiers.append('payable')
requires_proof = True
if not f.has_side_effects:
requires_proof = False
new_modifiers.append('view')
new_f = ConstructorOrFunctionDefinition(f.idf, original_params, new_modifiers, f.return_parameters, Block([]))
# Make original function internal
f.idf = Identifier(cfg.get_internal_name(f))
f.modifiers = ['internal' if mod == 'public' else mod for mod in f.modifiers if mod != 'payable']
f.requires_verification_when_external = False
# Create new circuit for external function
circuit = self.create_circuit_helper(new_f, global_owners, self.circuits[f])
if not f.requires_verification:
del self.circuits[f]
self.circuits[new_f] = circuit
# Set meta attributes and populate body
new_f.requires_verification = True
new_f.requires_verification_when_external = True
new_f.called_functions = f.called_functions
new_f.called_functions[f] = None
new_f.used_crypto_backends = f.used_crypto_backends
new_f.body = self.create_external_wrapper_body(f, circuit, original_params, requires_proof)
# Add out and proof parameter to external wrapper
storage_loc = 'calldata' if new_f.is_function else 'memory'
new_f.add_param(Array(AnnotatedTypeName.uint_all()), Identifier(cfg.zk_out_name), storage_loc)
if requires_proof:
new_f.add_param(AnnotatedTypeName.proof_type(), Identifier(cfg.proof_param_name), storage_loc)
return new_f, f
def test_assignment_statement(self):
i = Identifier('x')
lhs = IdentifierExpr(i)
rhs = BooleanLiteralExpr(True)
a = AssignmentStatement(lhs, rhs)
self.assertIsNotNone(a)
self.assertEqual(str(a), 'x = true;')
self.assertEqual(a.children(), [lhs, rhs])
self.assertDictEqual(a.names, {})
self.assertIsNone(a.parent)
def import_contract(cname: str, su: SourceUnit, corresponding_circuit: Optional[CircuitHelper] = None):
"""
Import contract 'vname' into the given source unit.
:param cname: contract name (.sol filename stem must match contract type name)
:param su: [SIDE EFFECT] source unit where contract should be imported
:param corresponding_circuit: [SIDE EFFECT] if contract is a verification contract, this should be the corresponding circuit helper
"""
import_filename = f'./{cname}.sol'
su.used_contracts.append(import_filename)
if corresponding_circuit is not None:
c_type = ContractTypeName([Identifier(cname)])
corresponding_circuit.register_verification_contract_metadata(c_type, import_filename)
class GlobalVars:
msg: StateVariableDeclaration = StateVariableDeclaration(
AnnotatedTypeName.all(
StructTypeName([GlobalDefs.msg_struct.idf],
GlobalDefs.msg_struct)), [], Identifier('msg'),
None)
msg.idf.parent = msg
block: StateVariableDeclaration = StateVariableDeclaration(
AnnotatedTypeName.all(
StructTypeName([GlobalDefs.block_struct.idf],
GlobalDefs.block_struct)), [], Identifier('block'),
None)
block.idf.parent = block
tx: StateVariableDeclaration = StateVariableDeclaration(
AnnotatedTypeName.all(
StructTypeName([GlobalDefs.tx_struct.idf], GlobalDefs.tx_struct)),
[], Identifier('tx'), None)
tx.idf.parent = tx
now: StateVariableDeclaration = StateVariableDeclaration(
AnnotatedTypeName.uint_all(), [], Identifier('now'), None)
now.idf.parent = now
def get_loc_value(self, arr: Identifier, indices: List[str]) -> str:
"""Get the location of the given identifier/array element."""
if isinstance(
arr, HybridArgumentIdf
) and arr.arg_type == HybridArgType.PRIV_CIRCUIT_VAL and not arr.name.startswith(
'tmp'):
# Private circuit values are located in private value dictionary
return self.get_priv_value(arr.name)
elif isinstance(arr, HybridArgumentIdf
) and arr.arg_type == HybridArgType.PUB_CIRCUIT_ARG:
# Public circuit inputs are in the zk_data dict
return self.visit(arr.get_loc_expr())
else:
idxvals = ''.join([f'[{idx}]' for idx in indices])
return f'{self.visit(arr)}{idxvals}'
def get_value(self, idf: IdentifierExpr, indices: List[str]):
"""
Get code corresponding to the rvalue location of an identifier or index expression.
e.g. idf = x and indices = [some_addr, 5] corresponds to x[some_addr][5]
State variable values are downloaded from the chain if their value is not yet present in the local state variable dict.
"""
if self.is_special_var(idf.idf):
return self.get_loc_value(idf.idf, indices)
elif isinstance(idf.target, StateVariableDeclaration):
# If a state variable appears as an rvalue, the value may need to be requested from the blockchain
indices = f', {", ".join(indices)}' if indices else ''
return f'self.state["{idf.idf.name}"{indices}]'
else:
name = idf.idf
if isinstance(idf.target,
VariableDeclaration) and not self.inside_circuit:
# Local variables are stored in locals dict
name = Identifier(f'self.locals["{idf.idf.name}"]')
return self.get_loc_value(name, indices)
def visitMemberAccessExpr(self, ast: MemberAccessExpr):
assert not isinstance(
ast.target,
StateVariableDeclaration), "State member accesses not handled"
if isinstance(ast.expr.target, EnumDefinition):
return f'{self.visit_list(ast.expr.target.qualified_name, sep=".")}.{self.visit(ast.member)}'
if ast.member.name == 'length' and isinstance(
ast.expr.target.annotated_type.type_name, Array):
return f'len({self.visit(ast.expr)})'
if self.current_index:
indices = list(reversed(self.current_index))
self.current_index, self.current_index_t = [], None
indices = [self.visit(idx) for idx in indices]
else:
indices = []
if isinstance(ast.member, HybridArgumentIdf):
e = f'{self.visit(ast.expr)}["{ast.member.name}"]'
else:
e = super().visitMemberAccessExpr(ast)
return self.get_loc_value(Identifier(e), indices)
class GlobalDefs:
# gasleft: FunctionDefinition = FunctionDefinition(
# idf=Identifier('gasleft'),
# parameters=[],
# modifiers=[],
# return_parameters=[Parameter([], annotated_type=AnnotatedTypeName.uint_all(), idf=Identifier(''))],
# body=Block([])
# )
# gasleft.idf.parent = gasleft
address_struct: StructDefinition = StructDefinition(
Identifier('<address>'), [
VariableDeclaration([], AnnotatedTypeName.uint_all(),
Identifier('balance'))
])
set_parents(address_struct)
address_payable_struct: StructDefinition = StructDefinition(
Identifier('<address_payable>'), [
VariableDeclaration([], AnnotatedTypeName.uint_all(),
Identifier('balance')),
ConstructorOrFunctionDefinition(
Identifier('send'),
[Parameter([], AnnotatedTypeName.uint_all(), Identifier(''))],
['public'],
[Parameter([], AnnotatedTypeName.bool_all(), Identifier(''))],
Block([])),
ConstructorOrFunctionDefinition(
Identifier('transfer'),
[Parameter([], AnnotatedTypeName.uint_all(), Identifier(''))],
['public'], [], Block([])),
])
address_payable_struct.members[1].can_be_private = False
address_payable_struct.members[2].can_be_private = False
set_parents(address_payable_struct)
msg_struct: StructDefinition = StructDefinition(Identifier('<msg>'), [
VariableDeclaration([],
AnnotatedTypeName(TypeName.address_payable_type()),
Identifier('sender')),
VariableDeclaration([], AnnotatedTypeName.uint_all(),
Identifier('value')),
])
set_parents(msg_struct)
block_struct: StructDefinition = StructDefinition(Identifier('<block>'), [
VariableDeclaration([],
AnnotatedTypeName(TypeName.address_payable_type()),
Identifier('coinbase')),
VariableDeclaration([], AnnotatedTypeName.uint_all(),
Identifier('difficulty')),
VariableDeclaration([], AnnotatedTypeName.uint_all(),
Identifier('gaslimit')),
VariableDeclaration([], AnnotatedTypeName.uint_all(),
Identifier('number')),
VariableDeclaration([], AnnotatedTypeName.uint_all(),
Identifier('timestamp')),
])
set_parents(block_struct)
tx_struct: StructDefinition = StructDefinition(Identifier('<tx>'), [
VariableDeclaration([], AnnotatedTypeName.uint_all(),
Identifier('gasprice')),
VariableDeclaration([],
AnnotatedTypeName(TypeName.address_payable_type()),
Identifier('origin')),
])
set_parents(tx_struct)
# BUILTIN SPECIAL TYPE DEFINITIONS
from zkay.zkay_ast.ast import AnnotatedTypeName, FunctionTypeName, Parameter, Identifier, StructDefinition, \
VariableDeclaration, TypeName, StateVariableDeclaration, UserDefinedTypeName, StructTypeName, Block, ConstructorOrFunctionDefinition
from zkay.zkay_ast.pointers.parent_setter import set_parents
array_length_member = VariableDeclaration([], AnnotatedTypeName.uint_all(),
Identifier('length'))
class GlobalDefs:
# gasleft: FunctionDefinition = FunctionDefinition(
# idf=Identifier('gasleft'),
# parameters=[],
# modifiers=[],
# return_parameters=[Parameter([], annotated_type=AnnotatedTypeName.uint_all(), idf=Identifier(''))],
# body=Block([])
# )
# gasleft.idf.parent = gasleft
address_struct: StructDefinition = StructDefinition(
Identifier('<address>'), [
VariableDeclaration([], AnnotatedTypeName.uint_all(),
Identifier('balance'))
])
set_parents(address_struct)
address_payable_struct: StructDefinition = StructDefinition(
Identifier('<address_payable>'), [
VariableDeclaration([], AnnotatedTypeName.uint_all(),
Identifier('balance')),
ConstructorOrFunctionDefinition(
def evaluate_stmt_in_circuit(self, ast: Statement) -> AssignmentStatement:
"""
Evaluate an entire statement privately.
This works by turning the statement into an assignment statement where the
* lhs is a tuple of all external locations (defined outside statement), which are modified inside the statement
* rhs is the return value of an inlined function call expression to a virtual function where body = the statement + return statement \
which returns a tuple of the most recent SSA version of all modified locations
Note: Modifying external locations which are not owned by @me inside the statement is illegal (would leak information).
Note: At the moment, this is only used for if statements with a private condition.
:param ast: the statement to evaluate inside the circuit
:return: AssignmentStatement as described above
"""
astmt = ExpressionStatement(NumberLiteralExpr(0))
for var in ast.modified_values:
if var.in_scope_at(ast):
astmt = AssignmentStatement(None, None)
break
astmt.before_analysis = ast.before_analysis
# External values written inside statement -> function return values
ret_params = []
for var in ast.modified_values:
if var.in_scope_at(ast):
# side effect affects location outside statement and has privacy @me
assert ast.before_analysis.same_partition(
var.privacy, Expression.me_expr())
assert isinstance(
var.target,
(Parameter, VariableDeclaration, StateVariableDeclaration))
t = var.target.annotated_type.zkay_type
if not t.type_name.is_primitive_type():
raise NotImplementedError(
'Reference types inside private if statements are not supported'
)
ret_t = AnnotatedTypeName(t.type_name, Expression.me_expr(),
t.homomorphism) # t, but @me
ret_param = IdentifierExpr(var.target.idf.clone(),
ret_t).override(target=var.target)
ret_param.statement = astmt
ret_params.append(ret_param)
# Build the imaginary function
fdef = ConstructorOrFunctionDefinition(
Identifier('<stmt_fct>'), [], ['private'], [
Parameter([], ret.annotated_type, ret.target.idf)
for ret in ret_params
], Block([ast, ReturnStatement(TupleExpr(ret_params))]))
fdef.original_body = fdef.body
fdef.body.parent = fdef
fdef.parent = ast
# inline "Call" to the imaginary function
fcall = FunctionCallExpr(
IdentifierExpr('<stmt_fct>').override(target=fdef), [])
fcall.statement = astmt
ret_args = self.inline_function_call_into_circuit(fcall)
# Move all return values out of the circuit
if not isinstance(ret_args, TupleExpr):
ret_args = TupleExpr([ret_args])
for ret_arg in ret_args.elements:
ret_arg.statement = astmt
ret_arg_outs = [
self._get_circuit_output_for_private_expression(
ret_arg, Expression.me_expr(),
ret_param.annotated_type.homomorphism)
for ret_param, ret_arg in zip(ret_params, ret_args.elements)
]
# Create assignment statement
if ret_params:
astmt.lhs = TupleExpr(
[ret_param.clone() for ret_param in ret_params])
astmt.rhs = TupleExpr(ret_arg_outs)
return astmt
else:
assert isinstance(astmt, ExpressionStatement)
return astmt
def create_external_wrapper_body(int_fct: ConstructorOrFunctionDefinition, ext_circuit: CircuitHelper,
original_params: List[Parameter], requires_proof: bool) -> Block:
"""
Return Block with external wrapper function body.
:param int_fct: corresponding internal function
:param ext_circuit: [SIDE EFFECT] circuit helper of the external wrapper function
:param original_params: list of transformed function parameters without additional parameters added due to transformation
:return: body with wrapper code
"""
priv_args = [p for p in original_params if p.annotated_type.is_cipher()]
args_backends = OrderedDict.fromkeys([p.annotated_type.type_name.crypto_params for p in priv_args])
stmts = []
for crypto_params in args_backends:
assert crypto_params in int_fct.used_crypto_backends
# If there are any private arguments with homomorphism 'hom', we need the public key for that crypto backend
ext_circuit._require_public_key_for_label_at(None, Expression.me_expr(), crypto_params)
for crypto_params in cfg.all_crypto_params():
if crypto_params.is_symmetric_cipher():
if (MeExpr(), crypto_params) in ext_circuit.requested_global_keys or crypto_params in args_backends:
# Make sure msg.sender's key pair is available in the circuit
stmts += ext_circuit.request_private_key(crypto_params)
# Verify that out parameter has correct size
stmts += [RequireStatement(IdentifierExpr(cfg.zk_out_name).dot('length').binop('==', NumberLiteralExpr(ext_circuit.out_size_trans)))]
# IdentifierExpr for array var holding serialized public circuit inputs
in_arr_var = IdentifierExpr(cfg.zk_in_name).as_type(Array(AnnotatedTypeName.uint_all()))
# Request static public keys
offset = 0
key_req_stmts = []
me_key_idx: Dict[CryptoParams, int] = {}
if ext_circuit.requested_global_keys:
# Ensure that me public key is stored starting at in[0]
keys = [key for key in ext_circuit.requested_global_keys]
tmp_keys = {}
for crypto_params in int_fct.used_crypto_backends:
tmp_key_var = Identifier(f'_tmp_key_{crypto_params.identifier_name}')
key_req_stmts.append(tmp_key_var.decl_var(AnnotatedTypeName.key_type(crypto_params)))
tmp_keys[crypto_params] = tmp_key_var
for (key_owner, crypto_params) in keys:
tmp_key_var = tmp_keys[crypto_params]
idf, assignment = ext_circuit.request_public_key(crypto_params, key_owner, ext_circuit.get_glob_key_name(key_owner, crypto_params))
assignment.lhs = IdentifierExpr(tmp_key_var.clone())
key_req_stmts.append(assignment)
# Remember me-keys for later use in symmetrically encrypted keys
if key_owner == MeExpr():
assert crypto_params not in me_key_idx
me_key_idx[crypto_params] = offset
# Manually add to circuit inputs
key_len = crypto_params.key_len
key_req_stmts.append(in_arr_var.slice(offset, key_len).assign(IdentifierExpr(tmp_key_var.clone()).slice(0, key_len)))
offset += key_len
assert offset == ext_circuit.in_size
# Check encrypted parameters
param_stmts = []
for p in original_params:
""" * of T_e rule 8 """
if p.annotated_type.is_cipher():
cipher_payload_len = p.annotated_type.type_name.crypto_params.cipher_payload_len
assign_stmt = in_arr_var.slice(offset, cipher_payload_len).assign(IdentifierExpr(p.idf.clone()).slice(0, cipher_payload_len))
ext_circuit.ensure_parameter_encryption(assign_stmt, p)
# Manually add to circuit inputs
param_stmts.append(assign_stmt)
offset += cipher_payload_len
# Populate sender field of parameters encrypted with a symmetric cipher
copy_stmts = []
for p in original_params:
if p.annotated_type.is_cipher():
c = p.annotated_type.type_name
assert isinstance(c, CipherText)
if c.crypto_params.is_symmetric_cipher():
sender_key = in_arr_var.index(me_key_idx[c.crypto_params])
idf = IdentifierExpr(p.idf.clone()).as_type(p.annotated_type.clone())
cipher_payload_len = cfg.get_crypto_params(p.annotated_type.homomorphism).cipher_payload_len
lit = ArrayLiteralExpr([idf.clone().index(i) for i in range(cipher_payload_len)] + [sender_key])
copy_stmts.append(VariableDeclarationStatement(VariableDeclaration([], p.annotated_type.clone(), p.idf.clone(), 'memory'), lit))
if copy_stmts:
param_stmts += [Comment(), Comment('Copy from calldata to memory and set sender field')] + copy_stmts
# Declare in array
new_in_array_expr = NewExpr(AnnotatedTypeName(TypeName.dyn_uint_array()), [NumberLiteralExpr(ext_circuit.in_size_trans)])
in_var_decl = in_arr_var.idf.decl_var(TypeName.dyn_uint_array(), new_in_array_expr)
stmts.append(in_var_decl)
stmts.append(Comment())
stmts += Comment.comment_wrap_block('Request static public keys', key_req_stmts)
stmts += Comment.comment_wrap_block('Backup private arguments for verification', param_stmts)
# Call internal function
args = [IdentifierExpr(param.idf.clone()) for param in original_params]
internal_call = FunctionCallExpr(IdentifierExpr(int_fct.idf.clone()).override(target=int_fct), args)
internal_call.sec_start_offset = ext_circuit.priv_in_size
if int_fct.requires_verification:
ext_circuit.call_function(internal_call)
args += [in_arr_var.clone(), NumberLiteralExpr(ext_circuit.in_size),
IdentifierExpr(cfg.zk_out_name), NumberLiteralExpr(ext_circuit.out_size)]
if int_fct.return_parameters:
stmts += Comment.comment_list("Declare return variables", [VariableDeclarationStatement(deep_copy(vd)) for vd in int_fct.return_var_decls])
in_call = TupleExpr([IdentifierExpr(vd.idf.clone()) for vd in int_fct.return_var_decls]).assign(internal_call)
else:
in_call = ExpressionStatement(internal_call)
stmts.append(Comment("Call internal function"))
stmts.append(in_call)
stmts.append(Comment())
# Call verifier
if requires_proof and not cfg.disable_verification:
verifier = IdentifierExpr(cfg.get_contract_var_name(ext_circuit.verifier_contract_type.code()))
verifier_args = [IdentifierExpr(cfg.proof_param_name), IdentifierExpr(cfg.zk_in_name), IdentifierExpr(cfg.zk_out_name)]
verify = ExpressionStatement(verifier.call(cfg.verification_function_name, verifier_args))
stmts.append(StatementList([Comment('Verify zk proof of execution'), verify], excluded_from_simulation=True))
# Add return statement at the end if necessary
if int_fct.return_parameters:
stmts.append(ReturnStatement(TupleExpr([IdentifierExpr(vd.idf.clone()) for vd in int_fct.return_var_decls])))
return Block(stmts)
def create_internal_verification_wrapper(self, ast: ConstructorOrFunctionDefinition):
"""
Add the necessary additional parameters and boiler plate code for verification support to the given function.
:param ast: [SIDE EFFECT] Internal function which requires verification
"""
circuit = self.circuits[ast]
stmts = []
symmetric_cipher_used = any([backend.is_symmetric_cipher() for backend in ast.used_crypto_backends])
if symmetric_cipher_used and 'pure' in ast.modifiers:
# Symmetric trafo requires msg.sender access -> change from pure to view
ast.modifiers = ['view' if mod == 'pure' else mod for mod in ast.modifiers]
# Add additional params
ast.add_param(Array(AnnotatedTypeName.uint_all()), cfg.zk_in_name)
ast.add_param(AnnotatedTypeName.uint_all(), f'{cfg.zk_in_name}_start_idx')
ast.add_param(Array(AnnotatedTypeName.uint_all()), cfg.zk_out_name)
ast.add_param(AnnotatedTypeName.uint_all(), f'{cfg.zk_out_name}_start_idx')
# Verify that in/out parameters have correct size
out_start_idx, in_start_idx = IdentifierExpr(f'{cfg.zk_out_name}_start_idx'), IdentifierExpr(f'{cfg.zk_in_name}_start_idx')
out_var, in_var = IdentifierExpr(cfg.zk_out_name), IdentifierExpr(cfg.zk_in_name).as_type(Array(AnnotatedTypeName.uint_all()))
stmts.append(RequireStatement(out_start_idx.binop('+', NumberLiteralExpr(circuit.out_size_trans)).binop('<=', out_var.dot('length'))))
stmts.append(RequireStatement(in_start_idx.binop('+', NumberLiteralExpr(circuit.in_size_trans)).binop('<=', in_var.dot('length'))))
# Declare zk_data struct var (if needed)
if circuit.requires_zk_data_struct():
zk_struct_type = StructTypeName([Identifier(circuit.zk_data_struct_name)])
stmts += [Identifier(cfg.zk_data_var_name).decl_var(zk_struct_type), BlankLine()]
# Declare return variable if necessary
if ast.return_parameters:
stmts += Comment.comment_list("Declare return variables", [VariableDeclarationStatement(vd) for vd in ast.return_var_decls])
# Find all me-keys in the in array
me_key_idx: Dict[CryptoParams, int] = {}
offset = 0
for (key_owner, crypto_params) in circuit.requested_global_keys:
if key_owner == MeExpr():
assert crypto_params not in me_key_idx
me_key_idx[crypto_params] = offset
offset += crypto_params.key_len
# Deserialize out array (if any)
deserialize_stmts = []
offset = 0
for s in circuit.output_idfs:
deserialize_stmts.append(s.deserialize(cfg.zk_out_name, out_start_idx, offset))
if isinstance(s.t, CipherText) and s.t.crypto_params.is_symmetric_cipher():
# Assign sender field to user-encrypted values if necessary
# Assumption: s.t.crypto_params.key_len == 1 for all symmetric ciphers
assert s.t.crypto_params in me_key_idx, "Symmetric cipher but did not request me key"
key_idx = me_key_idx[s.t.crypto_params]
sender_key = in_var.index(key_idx)
cipher_payload_len = s.t.crypto_params.cipher_payload_len
deserialize_stmts.append(s.get_loc_expr().index(cipher_payload_len).assign(sender_key))
offset += s.t.size_in_uints
if deserialize_stmts:
stmts.append(StatementList(Comment.comment_wrap_block("Deserialize output values", deserialize_stmts), excluded_from_simulation=True))
# Include original transformed function body
stmts += ast.body.statements
# Serialize in parameters to in array (if any)
serialize_stmts = []
offset = 0
for s in circuit.input_idfs:
serialize_stmts += [s.serialize(cfg.zk_in_name, in_start_idx, offset)]
offset += s.t.size_in_uints
if offset:
stmts.append(Comment())
stmts += Comment.comment_wrap_block('Serialize input values', serialize_stmts)
# Add return statement at the end if necessary
# (was previously replaced by assignment to return_var by ZkayStatementTransformer)
if circuit.has_return_var:
stmts.append(ReturnStatement(TupleExpr([IdentifierExpr(vd.idf.clone()).override(target=vd) for vd in ast.return_var_decls])))
ast.body.statements[:] = stmts
def transform_contract(self, su: SourceUnit, c: ContractDefinition) -> ContractDefinition:
"""
Transform an entire zkay contract into a public solidity contract.
This:
* transforms state variables, function bodies and signatures
* import verification contracts
* adds zk_data structs for each function with verification \
(to store circuit I/O, to bypass solidity stack limit and allow for easy assignment of array variables),
* creates external wrapper functions for all public functions which require verification
* adds circuit IO serialization/deserialization code from/to zk_data struct to all functions which require verification.
:param su: [SIDE EFFECTS] Source unit of which this contract is part of
:param c: [SIDE EFFECTS] The contract to transform
:return: The contract itself
"""
all_fcts = c.constructor_definitions + c.function_definitions
# Get list of static owner labels for this contract
global_owners = [Expression.me_expr()]
for var in c.state_variable_declarations:
if var.annotated_type.is_address() and (var.is_final or var.is_constant):
global_owners.append(var.idf)
# Backup untransformed function bodies
for fct in all_fcts:
fct.original_body = deep_copy(fct.body, with_types=True, with_analysis=True)
# Transform types of normal state variables
c.state_variable_declarations = self.var_decl_trafo.visit_list(c.state_variable_declarations)
# Split into functions which require verification and those which don't need a circuit helper
req_ext_fcts = {}
new_fcts, new_constr = [], []
for fct in all_fcts:
assert isinstance(fct, ConstructorOrFunctionDefinition)
if fct.requires_verification or fct.requires_verification_when_external:
self.circuits[fct] = self.create_circuit_helper(fct, global_owners)
if fct.requires_verification_when_external:
req_ext_fcts[fct] = fct.parameters[:]
elif fct.is_constructor:
new_constr.append(fct)
else:
new_fcts.append(fct)
# Add constant state variables for external contracts and field prime
field_prime_decl = StateVariableDeclaration(AnnotatedTypeName.uint_all(), ['public', 'constant'],
Identifier(cfg.field_prime_var_name),
NumberLiteralExpr(bn128_scalar_field))
contract_var_decls = self.include_verification_contracts(su, c)
c.state_variable_declarations = [field_prime_decl, Comment()]\
+ Comment.comment_list('Helper Contracts', contract_var_decls)\
+ [Comment('User state variables')]\
+ c.state_variable_declarations
# Transform signatures
for f in all_fcts:
f.parameters = self.var_decl_trafo.visit_list(f.parameters)
for f in c.function_definitions:
f.return_parameters = self.var_decl_trafo.visit_list(f.return_parameters)
f.return_var_decls = self.var_decl_trafo.visit_list(f.return_var_decls)
# Transform bodies
for fct in all_fcts:
gen = self.circuits.get(fct, None)
fct.body = ZkayStatementTransformer(gen).visit(fct.body)
# Transform (internal) functions which require verification (add the necessary additional parameters and boilerplate code)
fcts_with_verification = [fct for fct in all_fcts if fct.requires_verification]
compute_transitive_circuit_io_sizes(fcts_with_verification, self.circuits)
transform_internal_calls(fcts_with_verification, self.circuits)
for f in fcts_with_verification:
circuit = self.circuits[f]
assert circuit.requires_verification()
if circuit.requires_zk_data_struct():
# Add zk data struct for f to contract
zk_data_struct = StructDefinition(Identifier(circuit.zk_data_struct_name), [
VariableDeclaration([], AnnotatedTypeName(idf.t), idf.clone(), '')
for idf in circuit.output_idfs + circuit.input_idfs
])
c.struct_definitions.append(zk_data_struct)
self.create_internal_verification_wrapper(f)
# Create external wrapper functions where necessary
for f, params in req_ext_fcts.items():
ext_f, int_f = self.split_into_external_and_internal_fct(f, params, global_owners)
if ext_f.is_function:
new_fcts.append(ext_f)
else:
new_constr.append(ext_f)
new_fcts.append(int_f)
c.constructor_definitions = new_constr
c.function_definitions = new_fcts
return c
def create_external_wrapper_body(int_fct: ConstructorOrFunctionDefinition,
ext_circuit: CircuitHelper,
original_params: List[Parameter],
requires_proof: bool) -> Block:
"""
Return Block with external wrapper function body.
:param int_fct: corresponding internal function
:param ext_circuit: [SIDE EFFECT] circuit helper of the external wrapper function
:param original_params: list of transformed function parameters without additional parameters added due to transformation
:return: body with wrapper code
"""
has_priv_args = any(
[p.annotated_type.is_cipher() for p in original_params])
stmts = []
if has_priv_args:
ext_circuit._require_public_key_for_label_at(
None, Expression.me_expr())
if cfg.is_symmetric_cipher():
# Make sure msg.sender's key pair is available in the circuit
assert any(isinstance(k, MeExpr) for k in ext_circuit.requested_global_keys) \
or has_priv_args, "requires verification => both sender keys required"
stmts += ext_circuit.request_private_key()
# Verify that out parameter has correct size
stmts += [
RequireStatement(
IdentifierExpr(cfg.zk_out_name).dot('length').binop(
'==', NumberLiteralExpr(ext_circuit.out_size_trans)))
]
# IdentifierExpr for array var holding serialized public circuit inputs
in_arr_var = IdentifierExpr(cfg.zk_in_name).as_type(
Array(AnnotatedTypeName.uint_all()))
# Find index of me's public key in requested_global_keys
glob_me_key_index = -1
for idx, e in enumerate(ext_circuit.requested_global_keys):
if isinstance(e, MeExpr):
glob_me_key_index = idx
break
# Request static public keys
offset = 0
key_req_stmts = []
if ext_circuit.requested_global_keys:
# Ensure that me public key is stored starting at in[0]
keys = [key for key in ext_circuit.requested_global_keys]
if glob_me_key_index != -1:
(keys[0], keys[glob_me_key_index]) = (keys[glob_me_key_index],
keys[0])
tmp_key_var = Identifier('_tmp_key')
key_req_stmts.append(
tmp_key_var.decl_var(AnnotatedTypeName.key_type()))
for key_owner in keys:
idf, assignment = ext_circuit.request_public_key(
key_owner, ext_circuit.get_glob_key_name(key_owner))
assignment.lhs = IdentifierExpr(tmp_key_var.clone())
key_req_stmts.append(assignment)
# Manually add to circuit inputs
key_req_stmts.append(
in_arr_var.slice(offset, cfg.key_len).assign(
IdentifierExpr(tmp_key_var.clone()).slice(
0, cfg.key_len)))
offset += cfg.key_len
assert offset == ext_circuit.in_size
# Check encrypted parameters
param_stmts = []
for p in original_params:
""" * of T_e rule 8 """
if p.annotated_type.is_cipher():
assign_stmt = in_arr_var.slice(
offset, cfg.cipher_payload_len).assign(
IdentifierExpr(p.idf.clone()).slice(
0, cfg.cipher_payload_len))
ext_circuit.ensure_parameter_encryption(assign_stmt, p)
# Manually add to circuit inputs
param_stmts.append(assign_stmt)
offset += cfg.cipher_payload_len
if cfg.is_symmetric_cipher():
# Populate sender field of encrypted parameters
copy_stmts = []
for p in original_params:
if p.annotated_type.is_cipher():
sender_key = in_arr_var.index(0)
idf = IdentifierExpr(p.idf.clone()).as_type(
p.annotated_type.clone())
lit = ArrayLiteralExpr([
idf.clone().index(i)
for i in range(cfg.cipher_payload_len)
] + [sender_key])
copy_stmts.append(
VariableDeclarationStatement(
VariableDeclaration([], p.annotated_type.clone(),
p.idf.clone(), 'memory'), lit))
if copy_stmts:
param_stmts += [
Comment(),
Comment(
'Copy from calldata to memory and set sender field')
] + copy_stmts
assert glob_me_key_index != -1, "Symmetric cipher but did not request me key"
# Declare in array
new_in_array_expr = NewExpr(
AnnotatedTypeName(TypeName.dyn_uint_array()),
[NumberLiteralExpr(ext_circuit.in_size_trans)])
in_var_decl = in_arr_var.idf.decl_var(TypeName.dyn_uint_array(),
new_in_array_expr)
stmts.append(in_var_decl)
stmts.append(Comment())
stmts += Comment.comment_wrap_block('Request static public keys',
key_req_stmts)
stmts += Comment.comment_wrap_block(
'Backup private arguments for verification', param_stmts)
# Call internal function
args = [IdentifierExpr(param.idf.clone()) for param in original_params]
internal_call = FunctionCallExpr(
IdentifierExpr(int_fct.idf.clone()).override(target=int_fct), args)
internal_call.sec_start_offset = ext_circuit.priv_in_size
if int_fct.requires_verification:
ext_circuit.call_function(internal_call)
args += [
in_arr_var.clone(),
NumberLiteralExpr(ext_circuit.in_size),
IdentifierExpr(cfg.zk_out_name),
NumberLiteralExpr(ext_circuit.out_size)
]
if int_fct.return_parameters:
stmts += Comment.comment_list("Declare return variables", [
VariableDeclarationStatement(deep_copy(vd))
for vd in int_fct.return_var_decls
])
in_call = TupleExpr([
IdentifierExpr(vd.idf.clone())
for vd in int_fct.return_var_decls
]).assign(internal_call)
else:
in_call = ExpressionStatement(internal_call)
stmts.append(Comment("Call internal function"))
stmts.append(in_call)
stmts.append(Comment())
# Call verifier
if requires_proof:
verifier = IdentifierExpr(
cfg.get_contract_var_name(
ext_circuit.verifier_contract_type.code()))
verifier_args = [
IdentifierExpr(cfg.proof_param_name),
IdentifierExpr(cfg.zk_in_name),
IdentifierExpr(cfg.zk_out_name)
]
verify = ExpressionStatement(
verifier.call(cfg.verification_function_name, verifier_args))
stmts.append(
StatementList(
[Comment('Verify zk proof of execution'), verify],
excluded_from_simulation=True))
# Add return statement at the end if necessary
if int_fct.return_parameters:
stmts.append(
ReturnStatement(
TupleExpr([
IdentifierExpr(vd.idf.clone())
for vd in int_fct.return_var_decls
])))
return Block(stmts)
def visitIndexExpr(self, ast: IndexExpr):
assert isinstance(ast.arr, LocationExpr), "Function call return value indexing not yet supported"
source_t = ast.arr.target.annotated_type.type_name
ast.target = VariableDeclaration([], source_t.value_type, Identifier(''))