// SPDX-License-Identifier: GPL-2.0-or-later/* * The "hash function" used as the core of the ChaCha stream cipher (RFC7539) * * Copyright (C) 2015 Martin Willi */ #include <linux/kernel.h>#include <linux/export.h>#include <linux/bitops.h>#include <linux/cryptohash.h>#include <asm/unaligned.h>#include <crypto/chacha.h> static void chacha_permute(u32 *x, int nrounds){	int i; 	/* whitelist the allowed round counts */	WARN_ON_ONCE(nrounds != 20 && nrounds != 12); 	for (i = 0; i < nrounds; i += 2) {		x[0]  += x[4];    x[12] = rol32(x[12] ^ x[0],  16);		x[1]  += x[5];    x[13] = rol32(x[13] ^ x[1],  16);		x[2]  += x[6];    x[14] = rol32(x[14] ^ x[2],  16);		x[3]  += x[7];    x[15] = rol32(x[15] ^ x[3],  16); 		x[8]  += x[12];   x[4]  = rol32(x[4]  ^ x[8],  12);		x[9]  += x[13];   x[5]  = rol32(x[5]  ^ x[9],  12);		x[10] += x[14];   x[6]  = rol32(x[6]  ^ x[10], 12);		x[11] += x[15];   x[7]  = rol32(x[7]  ^ x[11], 12); 		x[0]  += x[4];    x[12] = rol32(x[12] ^ x[0],   8);		x[1]  += x[5];    x[13] = rol32(x[13] ^ x[1],   8);		x[2]  += x[6];    x[14] = rol32(x[14] ^ x[2],   8);		x[3]  += x[7];    x[15] = rol32(x[15] ^ x[3],   8); 		x[8]  += x[12];   x[4]  = rol32(x[4]  ^ x[8],   7);		x[9]  += x[13];   x[5]  = rol32(x[5]  ^ x[9],   7);		x[10] += x[14];   x[6]  = rol32(x[6]  ^ x[10],  7);		x[11] += x[15];   x[7]  = rol32(x[7]  ^ x[11],  7); 		x[0]  += x[5];    x[15] = rol32(x[15] ^ x[0],  16);		x[1]  += x[6];    x[12] = rol32(x[12] ^ x[1],  16);		x[2]  += x[7];    x[13] = rol32(x[13] ^ x[2],  16);		x[3]  += x[4];    x[14] = rol32(x[14] ^ x[3],  16); 		x[10] += x[15];   x[5]  = rol32(x[5]  ^ x[10], 12);		x[11] += x[12];   x[6]  = rol32(x[6]  ^ x[11], 12);		x[8]  += x[13];   x[7]  = rol32(x[7]  ^ x[8],  12);		x[9]  += x[14];   x[4]  = rol32(x[4]  ^ x[9],  12); 		x[0]  += x[5];    x[15] = rol32(x[15] ^ x[0],   8);		x[1]  += x[6];    x[12] = rol32(x[12] ^ x[1],   8);		x[2]  += x[7];    x[13] = rol32(x[13] ^ x[2],   8);		x[3]  += x[4];    x[14] = rol32(x[14] ^ x[3],   8); 		x[10] += x[15];   x[5]  = rol32(x[5]  ^ x[10],  7);		x[11] += x[12];   x[6]  = rol32(x[6]  ^ x[11],  7);		x[8]  += x[13];   x[7]  = rol32(x[7]  ^ x[8],   7);		x[9]  += x[14];   x[4]  = rol32(x[4]  ^ x[9],   7);	}} /** * chacha_block - generate one keystream block and increment block counter * @state: input state matrix (16 32-bit words) * @stream: output keystream block (64 bytes) * @nrounds: number of rounds (20 or 12; 20 is recommended) * * This is the ChaCha core, a function from 64-byte strings to 64-byte strings. * The caller has already converted the endianness of the input.  This function * also handles incrementing the block counter in the input matrix. */void chacha_block(u32 *state, u8 *stream, int nrounds){	u32 x[16];	int i; 	memcpy(x, state, 64); 	chacha_permute(x, nrounds); 	for (i = 0; i < ARRAY_SIZE(x); i++)		put_unaligned_le32(x[i] + state[i], &stream[i * sizeof(u32)]); 	state[12]++;}EXPORT_SYMBOL(chacha_block); /** * hchacha_block - abbreviated ChaCha core, for XChaCha * @in: input state matrix (16 32-bit words) * @out: output (8 32-bit words) * @nrounds: number of rounds (20 or 12; 20 is recommended) * * HChaCha is the ChaCha equivalent of HSalsa and is an intermediate step * towards XChaCha (see https://cr.yp.to/snuffle/xsalsa-20081128.pdf).  HChaCha * skips the final addition of the initial state, and outputs only certain words * of the state.  It should not be used for streaming directly. */void hchacha_block(const u32 *in, u32 *out, int nrounds){	u32 x[16]; 	memcpy(x, in, 64); 	chacha_permute(x, nrounds); 	memcpy(&out[0], &x[0], 16);	memcpy(&out[4], &x[12], 16);}EXPORT_SYMBOL(hchacha_block);