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
179
180
181
182

// This file is part of Substrate.

// Copyright (C) 2017-2020 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// 	http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Hash utilities.

use codec::Codec;
use sp_std::prelude::Vec;
use sp_io::hashing::{blake2_128, blake2_256, twox_64, twox_128, twox_256};

// This trait must be kept coherent with frame-support-procedural HasherKind usage
pub trait Hashable: Sized {
	fn blake2_128(&self) -> [u8; 16];
	fn blake2_256(&self) -> [u8; 32];
	fn blake2_128_concat(&self) -> Vec<u8>;
	fn twox_128(&self) -> [u8; 16];
	fn twox_256(&self) -> [u8; 32];
	fn twox_64_concat(&self) -> Vec<u8>;
	fn identity(&self) -> Vec<u8>;
}

impl<T: Codec> Hashable for T {
	fn blake2_128(&self) -> [u8; 16] {
		self.using_encoded(blake2_128)
	}
	fn blake2_256(&self) -> [u8; 32] {
		self.using_encoded(blake2_256)
	}
	fn blake2_128_concat(&self) -> Vec<u8> {
		self.using_encoded(Blake2_128Concat::hash)
	}
	fn twox_128(&self) -> [u8; 16] {
		self.using_encoded(twox_128)
	}
	fn twox_256(&self) -> [u8; 32] {
		self.using_encoded(twox_256)
	}
	fn twox_64_concat(&self) -> Vec<u8> {
		self.using_encoded(Twox64Concat::hash)
	}
	fn identity(&self) -> Vec<u8> { self.encode() }
}

/// Hasher to use to hash keys to insert to storage.
pub trait StorageHasher: 'static {
	type Output: AsRef<[u8]>;
	fn hash(x: &[u8]) -> Self::Output;
}

/// Hasher to use to hash keys to insert to storage.
///
/// Reversible hasher store the encoded key after the hash part.
pub trait ReversibleStorageHasher: StorageHasher {
	/// Split the hash part out of the input.
	///
	/// I.e. for input `&[hash ++ key ++ some]` returns `&[key ++ some]`
	fn reverse(x: &[u8]) -> &[u8];
}

/// Store the key directly.
pub struct Identity;
impl StorageHasher for Identity {
	type Output = Vec<u8>;
	fn hash(x: &[u8]) -> Vec<u8> {
		x.to_vec()
	}
}
impl ReversibleStorageHasher for Identity {
	fn reverse(x: &[u8]) -> &[u8] {
		x
	}
}

/// Hash storage keys with `concat(twox64(key), key)`
pub struct Twox64Concat;
impl StorageHasher for Twox64Concat {
	type Output = Vec<u8>;
	fn hash(x: &[u8]) -> Vec<u8> {
		twox_64(x)
			.iter()
			.chain(x.into_iter())
			.cloned()
			.collect::<Vec<_>>()
	}
}
impl ReversibleStorageHasher for Twox64Concat {
	fn reverse(x: &[u8]) -> &[u8] {
		if x.len() < 8 {
			crate::debug::error!("Invalid reverse: hash length too short");
			return &[]
		}
		&x[8..]
	}
}

/// Hash storage keys with `concat(blake2_128(key), key)`
pub struct Blake2_128Concat;
impl StorageHasher for Blake2_128Concat {
	type Output = Vec<u8>;
	fn hash(x: &[u8]) -> Vec<u8> {
		blake2_128(x)
			.iter()
			.chain(x.into_iter())
			.cloned()
			.collect::<Vec<_>>()
	}
}
impl ReversibleStorageHasher for Blake2_128Concat {
	fn reverse(x: &[u8]) -> &[u8] {
		if x.len() < 16 {
			crate::debug::error!("Invalid reverse: hash length too short");
			return &[]
		}
		&x[16..]
	}
}

/// Hash storage keys with blake2 128
pub struct Blake2_128;
impl StorageHasher for Blake2_128 {
	type Output = [u8; 16];
	fn hash(x: &[u8]) -> [u8; 16] {
		blake2_128(x)
	}
}

/// Hash storage keys with blake2 256
pub struct Blake2_256;
impl StorageHasher for Blake2_256 {
	type Output = [u8; 32];
	fn hash(x: &[u8]) -> [u8; 32] {
		blake2_256(x)
	}
}

/// Hash storage keys with twox 128
pub struct Twox128;
impl StorageHasher for Twox128 {
	type Output = [u8; 16];
	fn hash(x: &[u8]) -> [u8; 16] {
		twox_128(x)
	}
}

/// Hash storage keys with twox 256
pub struct Twox256;
impl StorageHasher for Twox256 {
	type Output = [u8; 32];
	fn hash(x: &[u8]) -> [u8; 32] {
		twox_256(x)
	}
}

#[cfg(test)]
mod tests {
	use super::*;

	#[test]
	fn test_twox_64_concat() {
		let r = Twox64Concat::hash(b"foo");
		assert_eq!(r.split_at(8), (&twox_128(b"foo")[..8], &b"foo"[..]))
	}

	#[test]
	fn test_blake2_128_concat() {
		let r = Blake2_128Concat::hash(b"foo");
		assert_eq!(r.split_at(16), (&blake2_128(b"foo")[..], &b"foo"[..]))
	}
}