/* SPDX-License-Identifier: Apache-2.0 OR BSD-2-Clause */
//
// This file is dual-licensed, meaning that you can use it under your
// choice of either of the following two licenses:
//
// Copyright 2023 The OpenSSL Project Authors. All Rights Reserved.
//
// Licensed under the Apache License 2.0 (the "License"). You can obtain
// a copy in the file LICENSE in the source distribution or at
// https://www.openssl.org/source/license.html
//
// or
//
// Copyright (c) 2023, Jerry Shih <jerry.shih@sifive.com>
// Copyright 2024 Google LLC
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
// The generated code of this file depends on the following RISC-V extensions:
// - RV64I
// - RISC-V Vector ('V') with VLEN >= 128
// - RISC-V Vector Cryptography Bit-manipulation extension ('Zvkb')
// void chacha_zvkb(struct chacha_state *state, const u8 *in, u8 *out,
// size_t nblocks, int nrounds);
//
// |nblocks| is the number of 64-byte blocks to process, and must be nonzero.
//
// |state| gives the ChaCha state matrix, including the 32-bit counter in
// state->x[12] following the RFC7539 convention; note that this differs from
// the original Salsa20 paper which uses a 64-bit counter in state->x[12..13].
// The updated 32-bit counter is written back to state->x[12] before returning.
SYM_FUNC_START(chacha_zvkb)
addi sp, sp, -96
sd s0, 0(sp)
sd s1, 8(sp)
sd s2, 16(sp)
sd s3, 24(sp)
sd s4, 32(sp)
sd s5, 40(sp)
sd s6, 48(sp)
sd s7, 56(sp)
sd s8, 64(sp)
sd s9, 72(sp)
sd s10, 80(sp)
sd s11, 88(sp)
.Lblock_loop:
// Set vl to the number of blocks to process in this iteration.
vsetvli VL, NBLOCKS, e32, m1, ta, ma
// Set up the initial state matrix for the next VL blocks in v0-v15.
// v{i} holds the i'th 32-bit word of the state matrix for all blocks.
// Note that only the counter word, at index 12, differs across blocks.
vmv.v.x v0, CONSTS0
vmv.v.x v1, CONSTS1
vmv.v.x v2, CONSTS2
vmv.v.x v3, CONSTS3
vmv.v.x v4, KEY0
vmv.v.x v5, KEY1
vmv.v.x v6, KEY2
vmv.v.x v7, KEY3
vmv.v.x v8, KEY4
vmv.v.x v9, KEY5
vmv.v.x v10, KEY6
vmv.v.x v11, KEY7
vid.v v12
vadd.vx v12, v12, COUNTER
vmv.v.x v13, NONCE0
vmv.v.x v14, NONCE1
vmv.v.x v15, NONCE2
// Load the first half of the input data for each block into v16-v23.
// v{16+i} holds the i'th 32-bit word for all blocks.
vlsseg8e32.v v16, (INP), STRIDE
// Load the second half of the input data for each block into v24-v31.
// v{24+i} holds the {8+i}'th 32-bit word for all blocks.
addi TMP, INP, 32
vlsseg8e32.v v24, (TMP), STRIDE
// Finalize the first half of the keystream for each block.
vadd.vx v0, v0, CONSTS0
vadd.vx v1, v1, CONSTS1
vadd.vx v2, v2, CONSTS2
vadd.vx v3, v3, CONSTS3
vadd.vx v4, v4, KEY0
vadd.vx v5, v5, KEY1
vadd.vx v6, v6, KEY2
vadd.vx v7, v7, KEY3
// Encrypt/decrypt the first half of the data for each block.
vxor.vv v16, v16, v0
vxor.vv v17, v17, v1
vxor.vv v18, v18, v2
vxor.vv v19, v19, v3
vxor.vv v20, v20, v4
vxor.vv v21, v21, v5
vxor.vv v22, v22, v6
vxor.vv v23, v23, v7
// Store the first half of the output data for each block.
vssseg8e32.v v16, (OUTP), STRIDE
// Finalize the second half of the keystream for each block.
vadd.vx v8, v8, KEY4
vadd.vx v9, v9, KEY5
vadd.vx v10, v10, KEY6
vadd.vx v11, v11, KEY7
vid.v v0
vadd.vx v12, v12, COUNTER
vadd.vx v13, v13, NONCE0
vadd.vx v14, v14, NONCE1
vadd.vx v15, v15, NONCE2
vadd.vv v12, v12, v0
// Encrypt/decrypt the second half of the data for each block.
vxor.vv v24, v24, v8
vxor.vv v25, v25, v9
vxor.vv v26, v26, v10
vxor.vv v27, v27, v11
vxor.vv v29, v29, v13
vxor.vv v28, v28, v12
vxor.vv v30, v30, v14
vxor.vv v31, v31, v15
// Store the second half of the output data for each block.
addi TMP, OUTP, 32
vssseg8e32.v v24, (TMP), STRIDE
// Update the counter, the remaining number of blocks, and the input and
// output pointers according to the number of blocks processed (VL).
add COUNTER, COUNTER, VL sub NBLOCKS, NBLOCKS, VL
slli TMP, VL, 6
add OUTP, OUTP, TMP
add INP, INP, TMP
bnez NBLOCKS, .Lblock_loop
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