LXR uboot/arch/arm/mach-tegra/tegra20/crypto.c

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * Copyright (c) 2011 The Chromium OS Authors.
   4 * (C) Copyright 2010 - 2011 NVIDIA Corporation <www.nvidia.com>
   5 */
   6
   7#include <common.h>
   8#include <linux/errno.h>
   9#include "crypto.h"
  10#include "uboot_aes.h"
  11
  12static u8 zero_key[16];
  13
  14#define AES_CMAC_CONST_RB 0x87  /* from RFC 4493, Figure 2.2 */
  15
  16enum security_op {
  17        SECURITY_SIGN           = 1 << 0,       /* Sign the data */
  18        SECURITY_ENCRYPT        = 1 << 1,       /* Encrypt the data */
  19};
  20
  21/**
  22 * Shift a vector left by one bit
  23 *
  24 * \param in    Input vector
  25 * \param out   Output vector
  26 * \param size  Length of vector in bytes
  27 */
  28static void left_shift_vector(u8 *in, u8 *out, int size)
  29{
  30        int carry = 0;
  31        int i;
  32
  33        for (i = size - 1; i >= 0; i--) {
  34                out[i] = (in[i] << 1) | carry;
  35                carry = in[i] >> 7;     /* get most significant bit */
  36        }
  37}
  38
  39/**
  40 * Sign a block of data, putting the result into dst.
  41 *
  42 * \param key                   Input AES key, length AES_KEY_LENGTH
  43 * \param key_schedule          Expanded key to use
  44 * \param src                   Source data of length 'num_aes_blocks' blocks
  45 * \param dst                   Destination buffer, length AES_KEY_LENGTH
  46 * \param num_aes_blocks        Number of AES blocks to encrypt
  47 */
  48static void sign_object(u8 *key, u8 *key_schedule, u8 *src, u8 *dst,
  49                        u32 num_aes_blocks)
  50{
  51        u8 tmp_data[AES_KEY_LENGTH];
  52        u8 iv[AES_KEY_LENGTH] = {0};
  53        u8 left[AES_KEY_LENGTH];
  54        u8 k1[AES_KEY_LENGTH];
  55        u8 *cbc_chain_data;
  56        unsigned i;
  57
  58        cbc_chain_data = zero_key;      /* Convenient array of 0's for IV */
  59
  60        /* compute K1 constant needed by AES-CMAC calculation */
  61        for (i = 0; i < AES_KEY_LENGTH; i++)
  62                tmp_data[i] = 0;
  63
  64        aes_cbc_encrypt_blocks(key_schedule, iv, tmp_data, left, 1);
  65
  66        left_shift_vector(left, k1, sizeof(left));
  67
  68        if ((left[0] >> 7) != 0) /* get MSB of L */
  69                k1[AES_KEY_LENGTH-1] ^= AES_CMAC_CONST_RB;
  70
  71        /* compute the AES-CMAC value */
  72        for (i = 0; i < num_aes_blocks; i++) {
  73                /* Apply the chain data */
  74                aes_apply_cbc_chain_data(cbc_chain_data, src, tmp_data);
  75
  76                /* for the final block, XOR K1 into the IV */
  77                if (i == num_aes_blocks - 1)
  78                        aes_apply_cbc_chain_data(tmp_data, k1, tmp_data);
  79
  80                /* encrypt the AES block */
  81                aes_encrypt(tmp_data, key_schedule, dst);
  82
  83                debug("sign_obj: block %d of %d\n", i, num_aes_blocks);
  84
  85                /* Update pointers for next loop. */
  86                cbc_chain_data = dst;
  87                src += AES_KEY_LENGTH;
  88        }
  89}
  90
  91/**
  92 * Encrypt and sign a block of data (depending on security mode).
  93 *
  94 * \param key           Input AES key, length AES_KEY_LENGTH
  95 * \param oper          Security operations mask to perform (enum security_op)
  96 * \param src           Source data
  97 * \param length        Size of source data
  98 * \param sig_dst       Destination address for signature, AES_KEY_LENGTH bytes
  99 */
 100static int encrypt_and_sign(u8 *key, enum security_op oper, u8 *src,
 101                            u32 length, u8 *sig_dst)
 102{
 103        u32 num_aes_blocks;
 104        u8 key_schedule[AES_EXPAND_KEY_LENGTH];
 105        u8 iv[AES_KEY_LENGTH] = {0};
 106
 107        debug("encrypt_and_sign: length = %d\n", length);
 108
 109        /*
 110         * The only need for a key is for signing/checksum purposes, so
 111         * if not encrypting, expand a key of 0s.
 112         */
 113        aes_expand_key(oper & SECURITY_ENCRYPT ? key : zero_key, key_schedule);
 114
 115        num_aes_blocks = (length + AES_KEY_LENGTH - 1) / AES_KEY_LENGTH;
 116
 117        if (oper & SECURITY_ENCRYPT) {
 118                /* Perform this in place, resulting in src being encrypted. */
 119                debug("encrypt_and_sign: begin encryption\n");
 120                aes_cbc_encrypt_blocks(key_schedule, iv, src, src,
 121                                       num_aes_blocks);
 122                debug("encrypt_and_sign: end encryption\n");
 123        }
 124
 125        if (oper & SECURITY_SIGN) {
 126                /* encrypt the data, overwriting the result in signature. */
 127                debug("encrypt_and_sign: begin signing\n");
 128                sign_object(key, key_schedule, src, sig_dst, num_aes_blocks);
 129                debug("encrypt_and_sign: end signing\n");
 130        }
 131
 132        return 0;
 133}
 134
 135int sign_data_block(u8 *source, unsigned length, u8 *signature)
 136{
 137        return encrypt_and_sign(zero_key, SECURITY_SIGN, source,
 138                                length, signature);
 139}
 140