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/**
* Copyright 2010 - 2022 JetBrains s.r.o.
*
* 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
*
* https://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.
*/
package jetbrains.exodus.crypto
/**
* Crypts byte array in-place by blocks of length `alignment`.
* Can be applied only to byte arrays which cannot be re-used for reading.
*/
fun cryptBlocksMutable(cipherProvider: StreamCipherProvider,
cipherKey: ByteArray,
basicIV: Long,
address: Long,
bytes: ByteArray,
offset: Int,
length: Int,
alignment: Int) {
cryptBlocksImpl(cipherProvider, cipherKey, basicIV, address, bytes, offset, length, bytes, offset, alignment)
}
/**
* Crypts immutable byte array by blocks of length `alignment`.
*/
fun cryptBlocksImmutable(cipherProvider: StreamCipherProvider,
cipherKey: ByteArray,
basicIV: Long,
address: Long,
bytes: ByteArray,
offset: Int,
length: Int,
alignment: Int): ByteArray {
return ByteArray(length).also {
cryptBlocksImpl(cipherProvider, cipherKey, basicIV, address, bytes, offset, length, it, 0, alignment)
}
}
/**
* Crypts byte array by blocks of length `alignment`.
*/
private fun cryptBlocksImpl(cipherProvider: StreamCipherProvider,
cipherKey: ByteArray,
basicIV: Long,
address: Long,
input: ByteArray,
inputOffset: Int,
length: Int,
output: ByteArray,
outputOffset: Int,
alignment: Int) {
var iv = basicIV + ((address + inputOffset) / alignment)
var inputOff = inputOffset
var len = length
var outputOff = outputOffset
while (len > 0) {
val offsetInBlock = inputOff % alignment
val blockLen = minOf(alignment - offsetInBlock, len)
val cipher = cipherProvider.newCipher().apply {
init(cipherKey, iv.asHashedIV())
}
// if offset is not the left bound of a block then the cipher should skip some bytes
if (offsetInBlock > 0) {
repeat(offsetInBlock) {
cipher.crypt(0)
}
}
repeat(blockLen) {
output[outputOff++] = cipher.crypt(input[inputOff++])
}
++iv
len -= blockLen
}
}
// Donald Knuth's 64-bit linear congruent generator (https://en.wikipedia.org/wiki/Linear_congruential_generator)
fun Long.asHashedIV() = this * 6364136223846793005 + 1442695040888963407
