mirror of
https://xff.cz/git/u-boot/
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144 lines
3.9 KiB
C
144 lines
3.9 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (c) 2011 The Chromium OS Authors.
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* (C) Copyright 2010 - 2011 NVIDIA Corporation <www.nvidia.com>
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*/
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#include <common.h>
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#include <log.h>
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#include <linux/errno.h>
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#include "crypto.h"
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#include "uboot_aes.h"
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static u8 zero_key[16];
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#define AES_CMAC_CONST_RB 0x87 /* from RFC 4493, Figure 2.2 */
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enum security_op {
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SECURITY_SIGN = 1 << 0, /* Sign the data */
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SECURITY_ENCRYPT = 1 << 1, /* Encrypt the data */
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};
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/**
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* Shift a vector left by one bit
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*
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* \param in Input vector
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* \param out Output vector
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* \param size Length of vector in bytes
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*/
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static void left_shift_vector(u8 *in, u8 *out, int size)
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{
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int carry = 0;
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int i;
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for (i = size - 1; i >= 0; i--) {
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out[i] = (in[i] << 1) | carry;
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carry = in[i] >> 7; /* get most significant bit */
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}
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}
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/**
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* Sign a block of data, putting the result into dst.
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*
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* \param key Input AES key, length AES128_KEY_LENGTH
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* \param key_schedule Expanded key to use
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* \param src Source data of length 'num_aes_blocks' blocks
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* \param dst Destination buffer, length AES128_KEY_LENGTH
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* \param num_aes_blocks Number of AES blocks to encrypt
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*/
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static void sign_object(u8 *key, u8 *key_schedule, u8 *src, u8 *dst,
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u32 num_aes_blocks)
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{
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u8 tmp_data[AES128_KEY_LENGTH];
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u8 iv[AES128_KEY_LENGTH] = {0};
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u8 left[AES128_KEY_LENGTH];
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u8 k1[AES128_KEY_LENGTH];
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u8 *cbc_chain_data;
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unsigned i;
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cbc_chain_data = zero_key; /* Convenient array of 0's for IV */
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/* compute K1 constant needed by AES-CMAC calculation */
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for (i = 0; i < AES128_KEY_LENGTH; i++)
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tmp_data[i] = 0;
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aes_cbc_encrypt_blocks(AES128_KEY_LENGTH, key_schedule, iv,
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tmp_data, left, 1);
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left_shift_vector(left, k1, sizeof(left));
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if ((left[0] >> 7) != 0) /* get MSB of L */
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k1[AES128_KEY_LENGTH - 1] ^= AES_CMAC_CONST_RB;
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/* compute the AES-CMAC value */
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for (i = 0; i < num_aes_blocks; i++) {
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/* Apply the chain data */
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aes_apply_cbc_chain_data(cbc_chain_data, src, tmp_data);
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/* for the final block, XOR K1 into the IV */
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if (i == num_aes_blocks - 1)
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aes_apply_cbc_chain_data(tmp_data, k1, tmp_data);
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/* encrypt the AES block */
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aes_encrypt(AES128_KEY_LENGTH, tmp_data,
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key_schedule, dst);
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debug("sign_obj: block %d of %d\n", i, num_aes_blocks);
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/* Update pointers for next loop. */
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cbc_chain_data = dst;
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src += AES128_KEY_LENGTH;
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}
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}
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/**
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* Encrypt and sign a block of data (depending on security mode).
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*
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* \param key Input AES key, length AES128_KEY_LENGTH
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* \param oper Security operations mask to perform (enum security_op)
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* \param src Source data
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* \param length Size of source data
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* \param sig_dst Destination address for signature, AES128_KEY_LENGTH bytes
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*/
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static int encrypt_and_sign(u8 *key, enum security_op oper, u8 *src,
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u32 length, u8 *sig_dst)
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{
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u32 num_aes_blocks;
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u8 key_schedule[AES128_EXPAND_KEY_LENGTH];
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u8 iv[AES128_KEY_LENGTH] = {0};
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debug("encrypt_and_sign: length = %d\n", length);
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/*
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* The only need for a key is for signing/checksum purposes, so
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* if not encrypting, expand a key of 0s.
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*/
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aes_expand_key(oper & SECURITY_ENCRYPT ? key : zero_key,
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AES128_KEY_LENGTH, key_schedule);
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num_aes_blocks = (length + AES128_KEY_LENGTH - 1) / AES128_KEY_LENGTH;
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if (oper & SECURITY_ENCRYPT) {
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/* Perform this in place, resulting in src being encrypted. */
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debug("encrypt_and_sign: begin encryption\n");
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aes_cbc_encrypt_blocks(AES128_KEY_LENGTH, key_schedule, iv, src,
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src, num_aes_blocks);
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debug("encrypt_and_sign: end encryption\n");
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}
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if (oper & SECURITY_SIGN) {
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/* encrypt the data, overwriting the result in signature. */
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debug("encrypt_and_sign: begin signing\n");
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sign_object(key, key_schedule, src, sig_dst, num_aes_blocks);
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debug("encrypt_and_sign: end signing\n");
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}
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return 0;
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}
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int sign_data_block(u8 *source, unsigned length, u8 *signature)
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{
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return encrypt_and_sign(zero_key, SECURITY_SIGN, source,
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length, signature);
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}
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