/
deposit_contract.sol
178 lines (156 loc) · 9.2 KB
/
deposit_contract.sol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
// ┏━━━┓━┏┓━┏┓━━┏━━━┓━━┏━━━┓━━━━┏━━━┓━━━━━━━━━━━━━━━━━━━┏┓━━━━━┏━━━┓━━━━━━━━━┏┓━━━━━━━━━━━━━━┏┓━
// ┃┏━━┛┏┛┗┓┃┃━━┃┏━┓┃━━┃┏━┓┃━━━━┗┓┏┓┃━━━━━━━━━━━━━━━━━━┏┛┗┓━━━━┃┏━┓┃━━━━━━━━┏┛┗┓━━━━━━━━━━━━┏┛┗┓
// ┃┗━━┓┗┓┏┛┃┗━┓┗┛┏┛┃━━┃┃━┃┃━━━━━┃┃┃┃┏━━┓┏━━┓┏━━┓┏━━┓┏┓┗┓┏┛━━━━┃┃━┗┛┏━━┓┏━┓━┗┓┏┛┏━┓┏━━┓━┏━━┓┗┓┏┛
// ┃┏━━┛━┃┃━┃┏┓┃┏━┛┏┛━━┃┃━┃┃━━━━━┃┃┃┃┃┏┓┃┃┏┓┃┃┏┓┃┃━━┫┣┫━┃┃━━━━━┃┃━┏┓┃┏┓┃┃┏┓┓━┃┃━┃┏┛┗━┓┃━┃┏━┛━┃┃━
// ┃┗━━┓━┃┗┓┃┃┃┃┃┃┗━┓┏┓┃┗━┛┃━━━━┏┛┗┛┃┃┃━┫┃┗┛┃┃┗┛┃┣━━┃┃┃━┃┗┓━━━━┃┗━┛┃┃┗┛┃┃┃┃┃━┃┗┓┃┃━┃┗┛┗┓┃┗━┓━┃┗┓
// ┗━━━┛━┗━┛┗┛┗┛┗━━━┛┗┛┗━━━┛━━━━┗━━━┛┗━━┛┃┏━┛┗━━┛┗━━┛┗┛━┗━┛━━━━┗━━━┛┗━━┛┗┛┗┛━┗━┛┗┛━┗━━━┛┗━━┛━┗━┛
// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┃┃━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
// ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┗┛━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
// SPDX-License-Identifier: CC0-1.0
pragma solidity 0.6.11;
// This interface is designed to be compatible with the Vyper version.
/// @notice This is the Ethereum 2.0 deposit contract interface.
/// For more information see the Phase 0 specification under https://github.com/ethereum/eth2.0-specs
interface IDepositContract {
/// @notice A processed deposit event.
event DepositEvent(
bytes pubkey,
bytes withdrawal_credentials,
bytes amount,
bytes signature,
bytes index
);
/// @notice Submit a Phase 0 DepositData object.
/// @param pubkey A BLS12-381 public key.
/// @param withdrawal_credentials Commitment to a public key for withdrawals.
/// @param signature A BLS12-381 signature.
/// @param deposit_data_root The SHA-256 hash of the SSZ-encoded DepositData object.
/// Used as a protection against malformed input.
function deposit(
bytes calldata pubkey,
bytes calldata withdrawal_credentials,
bytes calldata signature,
bytes32 deposit_data_root
) external payable;
/// @notice Query the current deposit root hash.
/// @return The deposit root hash.
function get_deposit_root() external view returns (bytes32);
/// @notice Query the current deposit count.
/// @return The deposit count encoded as a little endian 64-bit number.
function get_deposit_count() external view returns (bytes memory);
}
// Based on official specification in https://eips.ethereum.org/EIPS/eip-165
interface ERC165 {
/// @notice Query if a contract implements an interface
/// @param interfaceId The interface identifier, as specified in ERC-165
/// @dev Interface identification is specified in ERC-165. This function
/// uses less than 30,000 gas.
/// @return `true` if the contract implements `interfaceId` and
/// `interfaceId` is not 0xffffffff, `false` otherwise
function supportsInterface(bytes4 interfaceId) external pure returns (bool);
}
// This is a rewrite of the Vyper Eth2.0 deposit contract in Solidity.
// It tries to stay as close as possible to the original source code.
/// @notice This is the Ethereum 2.0 deposit contract interface.
/// For more information see the Phase 0 specification under https://github.com/ethereum/eth2.0-specs
contract DepositContract is IDepositContract, ERC165 {
uint constant DEPOSIT_CONTRACT_TREE_DEPTH = 32;
// NOTE: this also ensures `deposit_count` will fit into 64-bits
uint constant MAX_DEPOSIT_COUNT = 2**DEPOSIT_CONTRACT_TREE_DEPTH - 1;
bytes32[DEPOSIT_CONTRACT_TREE_DEPTH] branch;
uint256 deposit_count;
bytes32[DEPOSIT_CONTRACT_TREE_DEPTH] zero_hashes;
constructor() public {
// Compute hashes in empty sparse Merkle tree
for (uint height = 0; height < DEPOSIT_CONTRACT_TREE_DEPTH - 1; height++)
zero_hashes[height + 1] = sha256(abi.encodePacked(zero_hashes[height], zero_hashes[height]));
}
function get_deposit_root() override external view returns (bytes32) {
bytes32 node;
uint size = deposit_count;
for (uint height = 0; height < DEPOSIT_CONTRACT_TREE_DEPTH; height++) {
if ((size & 1) == 1)
node = sha256(abi.encodePacked(branch[height], node));
else
node = sha256(abi.encodePacked(node, zero_hashes[height]));
size /= 2;
}
return sha256(abi.encodePacked(
node,
to_little_endian_64(uint64(deposit_count)),
bytes24(0)
));
}
function get_deposit_count() override external view returns (bytes memory) {
return to_little_endian_64(uint64(deposit_count));
}
function deposit(
bytes calldata pubkey,
bytes calldata withdrawal_credentials,
bytes calldata signature,
bytes32 deposit_data_root
) override external payable {
// Extended ABI length checks since dynamic types are used.
require(pubkey.length == 48, "DepositContract: invalid pubkey length");
require(withdrawal_credentials.length == 32, "DepositContract: invalid withdrawal_credentials length");
require(signature.length == 96, "DepositContract: invalid signature length");
// Check deposit amount
require(msg.value >= 1 ether, "DepositContract: deposit value too low");
require(msg.value % 1 gwei == 0, "DepositContract: deposit value not multiple of gwei");
uint deposit_amount = msg.value / 1 gwei;
require(deposit_amount <= type(uint64).max, "DepositContract: deposit value too high");
// Emit `DepositEvent` log
bytes memory amount = to_little_endian_64(uint64(deposit_amount));
emit DepositEvent(
pubkey,
withdrawal_credentials,
amount,
signature,
to_little_endian_64(uint64(deposit_count))
);
// Compute deposit data root (`DepositData` hash tree root)
bytes32 pubkey_root = sha256(abi.encodePacked(pubkey, bytes16(0)));
bytes32 signature_root = sha256(abi.encodePacked(
sha256(abi.encodePacked(signature[:64])),
sha256(abi.encodePacked(signature[64:], bytes32(0)))
));
bytes32 node = sha256(abi.encodePacked(
sha256(abi.encodePacked(pubkey_root, withdrawal_credentials)),
sha256(abi.encodePacked(amount, bytes24(0), signature_root))
));
// Verify computed and expected deposit data roots match
require(node == deposit_data_root, "DepositContract: reconstructed DepositData does not match supplied deposit_data_root");
// Avoid overflowing the Merkle tree (and prevent edge case in computing `branch`)
require(deposit_count < MAX_DEPOSIT_COUNT, "DepositContract: merkle tree full");
// Add deposit data root to Merkle tree (update a single `branch` node)
deposit_count += 1;
uint size = deposit_count;
for (uint height = 0; height < DEPOSIT_CONTRACT_TREE_DEPTH; height++) {
if ((size & 1) == 1) {
branch[height] = node;
return;
}
node = sha256(abi.encodePacked(branch[height], node));
size /= 2;
}
// As the loop should always end prematurely with the `return` statement,
// this code should be unreachable. We assert `false` just to be safe.
assert(false);
}
function supportsInterface(bytes4 interfaceId) override external pure returns (bool) {
return interfaceId == type(ERC165).interfaceId || interfaceId == type(IDepositContract).interfaceId;
}
function to_little_endian_64(uint64 value) internal pure returns (bytes memory ret) {
ret = new bytes(8);
bytes8 bytesValue = bytes8(value);
// Byteswapping during copying to bytes.
ret[0] = bytesValue[7];
ret[1] = bytesValue[6];
ret[2] = bytesValue[5];
ret[3] = bytesValue[4];
ret[4] = bytesValue[3];
ret[5] = bytesValue[2];
ret[6] = bytesValue[1];
ret[7] = bytesValue[0];
}
}