--- /dev/null
+/*
+ * Copyright (c) 2011 The Chromium OS Authors.
+ * (C) Copyright 2010 - 2011 NVIDIA Corporation <www.nvidia.com>
+ *
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <common.h>
+#include <asm/errno.h>
+#include "crypto.h"
+#include "aes.h"
+
+static u8 zero_key[16];
+
+#define AES_CMAC_CONST_RB 0x87 /* from RFC 4493, Figure 2.2 */
+
+enum security_op {
+ SECURITY_SIGN = 1 << 0, /* Sign the data */
+ SECURITY_ENCRYPT = 1 << 1, /* Encrypt the data */
+};
+
+static void debug_print_vector(char *name, u32 num_bytes, u8 *data)
+{
+ u32 i;
+
+ debug("%s [%d] @0x%08x", name, num_bytes, (u32)data);
+ for (i = 0; i < num_bytes; i++) {
+ if (i % 16 == 0)
+ debug(" = ");
+ debug("%02x", data[i]);
+ if ((i+1) % 16 != 0)
+ debug(" ");
+ }
+ debug("\n");
+}
+
+/**
+ * Apply chain data to the destination using EOR
+ *
+ * Each array is of length AES_AES_KEY_LENGTH.
+ *
+ * \param cbc_chain_data Chain data
+ * \param src Source data
+ * \param dst Destination data, which is modified here
+ */
+static void apply_cbc_chain_data(u8 *cbc_chain_data, u8 *src, u8 *dst)
+{
+ int i;
+
+ for (i = 0; i < 16; i++)
+ *dst++ = *src++ ^ *cbc_chain_data++;
+}
+
+/**
+ * Encrypt some data with AES.
+ *
+ * \param key_schedule Expanded key to use
+ * \param src Source data to encrypt
+ * \param dst Destination buffer
+ * \param num_aes_blocks Number of AES blocks to encrypt
+ */
+static void encrypt_object(u8 *key_schedule, u8 *src, u8 *dst,
+ u32 num_aes_blocks)
+{
+ u8 tmp_data[AES_KEY_LENGTH];
+ u8 *cbc_chain_data;
+ u32 i;
+
+ cbc_chain_data = zero_key; /* Convenient array of 0's for IV */
+
+ for (i = 0; i < num_aes_blocks; i++) {
+ debug("encrypt_object: block %d of %d\n", i, num_aes_blocks);
+ debug_print_vector("AES Src", AES_KEY_LENGTH, src);
+
+ /* Apply the chain data */
+ apply_cbc_chain_data(cbc_chain_data, src, tmp_data);
+ debug_print_vector("AES Xor", AES_KEY_LENGTH, tmp_data);
+
+ /* encrypt the AES block */
+ aes_encrypt(tmp_data, key_schedule, dst);
+ debug_print_vector("AES Dst", AES_KEY_LENGTH, dst);
+
+ /* Update pointers for next loop. */
+ cbc_chain_data = dst;
+ src += AES_KEY_LENGTH;
+ dst += AES_KEY_LENGTH;
+ }
+}
+
+/**
+ * Shift a vector left by one bit
+ *
+ * \param in Input vector
+ * \param out Output vector
+ * \param size Length of vector in bytes
+ */
+static void left_shift_vector(u8 *in, u8 *out, int size)
+{
+ int carry = 0;
+ int i;
+
+ for (i = size - 1; i >= 0; i--) {
+ out[i] = (in[i] << 1) | carry;
+ carry = in[i] >> 7; /* get most significant bit */
+ }
+}
+
+/**
+ * Sign a block of data, putting the result into dst.
+ *
+ * \param key Input AES key, length AES_KEY_LENGTH
+ * \param key_schedule Expanded key to use
+ * \param src Source data of length 'num_aes_blocks' blocks
+ * \param dst Destination buffer, length AES_KEY_LENGTH
+ * \param num_aes_blocks Number of AES blocks to encrypt
+ */
+static void sign_object(u8 *key, u8 *key_schedule, u8 *src, u8 *dst,
+ u32 num_aes_blocks)
+{
+ u8 tmp_data[AES_KEY_LENGTH];
+ u8 left[AES_KEY_LENGTH];
+ u8 k1[AES_KEY_LENGTH];
+ u8 *cbc_chain_data;
+ unsigned i;
+
+ cbc_chain_data = zero_key; /* Convenient array of 0's for IV */
+
+ /* compute K1 constant needed by AES-CMAC calculation */
+ for (i = 0; i < AES_KEY_LENGTH; i++)
+ tmp_data[i] = 0;
+
+ encrypt_object(key_schedule, tmp_data, left, 1);
+ debug_print_vector("AES(key, nonce)", AES_KEY_LENGTH, left);
+
+ left_shift_vector(left, k1, sizeof(left));
+ debug_print_vector("L", AES_KEY_LENGTH, left);
+
+ if ((left[0] >> 7) != 0) /* get MSB of L */
+ k1[AES_KEY_LENGTH-1] ^= AES_CMAC_CONST_RB;
+ debug_print_vector("K1", AES_KEY_LENGTH, k1);
+
+ /* compute the AES-CMAC value */
+ for (i = 0; i < num_aes_blocks; i++) {
+ /* Apply the chain data */
+ apply_cbc_chain_data(cbc_chain_data, src, tmp_data);
+
+ /* for the final block, XOR K1 into the IV */
+ if (i == num_aes_blocks - 1)
+ apply_cbc_chain_data(tmp_data, k1, tmp_data);
+
+ /* encrypt the AES block */
+ aes_encrypt(tmp_data, key_schedule, dst);
+
+ debug("sign_obj: block %d of %d\n", i, num_aes_blocks);
+ debug_print_vector("AES-CMAC Src", AES_KEY_LENGTH, src);
+ debug_print_vector("AES-CMAC Xor", AES_KEY_LENGTH, tmp_data);
+ debug_print_vector("AES-CMAC Dst", AES_KEY_LENGTH, dst);
+
+ /* Update pointers for next loop. */
+ cbc_chain_data = dst;
+ src += AES_KEY_LENGTH;
+ }
+
+ debug_print_vector("AES-CMAC Hash", AES_KEY_LENGTH, dst);
+}
+
+/**
+ * Encrypt and sign a block of data (depending on security mode).
+ *
+ * \param key Input AES key, length AES_KEY_LENGTH
+ * \param oper Security operations mask to perform (enum security_op)
+ * \param src Source data
+ * \param length Size of source data
+ * \param sig_dst Destination address for signature, AES_KEY_LENGTH bytes
+ */
+static int encrypt_and_sign(u8 *key, enum security_op oper, u8 *src,
+ u32 length, u8 *sig_dst)
+{
+ u32 num_aes_blocks;
+ u8 key_schedule[AES_EXPAND_KEY_LENGTH];
+
+ debug("encrypt_and_sign: length = %d\n", length);
+ debug_print_vector("AES key", AES_KEY_LENGTH, key);
+
+ /*
+ * The only need for a key is for signing/checksum purposes, so
+ * if not encrypting, expand a key of 0s.
+ */
+ aes_expand_key(oper & SECURITY_ENCRYPT ? key : zero_key, key_schedule);
+
+ num_aes_blocks = (length + AES_KEY_LENGTH - 1) / AES_KEY_LENGTH;
+
+ if (oper & SECURITY_ENCRYPT) {
+ /* Perform this in place, resulting in src being encrypted. */
+ debug("encrypt_and_sign: begin encryption\n");
+ encrypt_object(key_schedule, src, src, num_aes_blocks);
+ debug("encrypt_and_sign: end encryption\n");
+ }
+
+ if (oper & SECURITY_SIGN) {
+ /* encrypt the data, overwriting the result in signature. */
+ debug("encrypt_and_sign: begin signing\n");
+ sign_object(key, key_schedule, src, sig_dst, num_aes_blocks);
+ debug("encrypt_and_sign: end signing\n");
+ }
+
+ return 0;
+}
+
+int sign_data_block(u8 *source, unsigned length, u8 *signature)
+{
+ return encrypt_and_sign(zero_key, SECURITY_SIGN, source,
+ length, signature);
+}
projects / u-boot.git / commitdiff