LXR uboot/arch/arm/cpu/tegra20-common/crypto.c

   1/*
   2 * Copyright (c) 2011 The Chromium OS Authors.
   3 * (C) Copyright 2010 - 2011 NVIDIA Corporation <www.nvidia.com>
   4 *
   5 * SPDX-License-Identifier:     GPL-2.0+
   6 */
   7
   8#include <common.h>
   9#include <asm/errno.h>
  10#include "crypto.h"
  11#include "aes.h"
  12
  13static u8 zero_key[16];
  14
  15#define AES_CMAC_CONST_RB 0x87  /* from RFC 4493, Figure 2.2 */
  16
  17enum security_op {
  18        SECURITY_SIGN           = 1 << 0,       /* Sign the data */
  19        SECURITY_ENCRYPT        = 1 << 1,       /* Encrypt the data */
  20};
  21
  22/**
  23 * Shift a vector left by one bit
  24 *
  25 * \param in    Input vector
  26 * \param out   Output vector
  27 * \param size  Length of vector in bytes
  28 */
  29static void left_shift_vector(u8 *in, u8 *out, int size)
  30{
  31        int carry = 0;
  32        int i;
  33
  34        for (i = size - 1; i >= 0; i--) {
  35                out[i] = (in[i] << 1) | carry;
  36                carry = in[i] >> 7;     /* get most significant bit */
  37        }
  38}
  39
  40/**
  41 * Sign a block of data, putting the result into dst.
  42 *
  43 * \param key                   Input AES key, length AES_KEY_LENGTH
  44 * \param key_schedule          Expanded key to use
  45 * \param src                   Source data of length 'num_aes_blocks' blocks
  46 * \param dst                   Destination buffer, length AES_KEY_LENGTH
  47 * \param num_aes_blocks        Number of AES blocks to encrypt
  48 */
  49static void sign_object(u8 *key, u8 *key_schedule, u8 *src, u8 *dst,
  50                        u32 num_aes_blocks)
  51{
  52        u8 tmp_data[AES_KEY_LENGTH];
  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, 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
 106        debug("encrypt_and_sign: length = %d\n", length);
 107
 108        /*
 109         * The only need for a key is for signing/checksum purposes, so
 110         * if not encrypting, expand a key of 0s.
 111         */
 112        aes_expand_key(oper & SECURITY_ENCRYPT ? key : zero_key, key_schedule);
 113
 114        num_aes_blocks = (length + AES_KEY_LENGTH - 1) / AES_KEY_LENGTH;
 115
 116        if (oper & SECURITY_ENCRYPT) {
 117                /* Perform this in place, resulting in src being encrypted. */
 118                debug("encrypt_and_sign: begin encryption\n");
 119                aes_cbc_encrypt_blocks(key_schedule, src, src, num_aes_blocks);
 120                debug("encrypt_and_sign: end encryption\n");
 121        }
 122
 123        if (oper & SECURITY_SIGN) {
 124                /* encrypt the data, overwriting the result in signature. */
 125                debug("encrypt_and_sign: begin signing\n");
 126                sign_object(key, key_schedule, src, sig_dst, num_aes_blocks);
 127                debug("encrypt_and_sign: end signing\n");
 128        }
 129
 130        return 0;
 131}
 132
 133int sign_data_block(u8 *source, unsigned length, u8 *signature)
 134{
 135        return encrypt_and_sign(zero_key, SECURITY_SIGN, source,
 136                                length, signature);
 137}
 138