Implement a compatible AES-128-CBC decryption function as a counterpart of the encryption function pulled from tegra20-common/crypto.c .

Signed-off-by: Marek Vasut marex@denx.de --- include/aes.h | 10 ++++++++++ lib/aes.c | 28 ++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+)

diff --git a/include/aes.h b/include/aes.h index d9bb387..4897e6f 100644 --- a/include/aes.h +++ b/include/aes.h @@ -63,4 +63,14 @@ void aes_decrypt(u8 *in, u8 *expkey, u8 *out); */ void aes_cbc_encrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks);

+/** + * Decrypt multiple blocks of data with AES CBC. + * + * @key_exp Expanded key to use + * @src Source data to decrypt + * @dst Destination buffer + * @num_aes_blocks Number of AES blocks to decrypt + */ +void aes_cbc_decrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks); + #endif /* _AES_REF_H_ */ diff --git a/lib/aes.c b/lib/aes.c index a6648f9..9dadb22 100644 --- a/lib/aes.c +++ b/lib/aes.c @@ -632,3 +632,31 @@ void aes_cbc_encrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks) dst += AES_KEY_LENGTH; } } + +void aes_cbc_decrypt_blocks(u8 *key_exp, u8 *src, u8 *dst, u32 num_aes_blocks) +{ + u8 tmp_data[AES_KEY_LENGTH], tmp_block[AES_KEY_LENGTH]; + /* Convenient array of 0's for IV */ + u8 cbc_chain_data[AES_KEY_LENGTH] = { 0 }; + u32 i; + + 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); + + memcpy(tmp_block, src, AES_KEY_LENGTH); + + /* Decrypt the AES block */ + aes_decrypt(src, key_exp, tmp_data); + debug_print_vector("AES Xor", AES_KEY_LENGTH, tmp_data); + + /* Apply the chain data */ + apply_cbc_chain_data(cbc_chain_data, tmp_data, dst); + debug_print_vector("AES Dst", AES_KEY_LENGTH, dst); + + /* Update pointers for next loop. */ + memcpy(cbc_chain_data, tmp_block, AES_KEY_LENGTH); + src += AES_KEY_LENGTH; + dst += AES_KEY_LENGTH; + } +}

Add simple 'aes' command, which allows using the AES-128-CBC encryption and decryption functions from U-Boot command line.

Signed-off-by: Marek Vasut marex@denx.de --- README | 1 + common/Makefile | 1 + common/cmd_aes.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 91 insertions(+) create mode 100644 common/cmd_aes.c

diff --git a/README b/README index 216f0c7..fd717bf 100644 --- a/README +++ b/README @@ -910,6 +910,7 @@ The following options need to be configured: The default command configuration includes all commands except those marked below with a "*".

+ CONFIG_CMD_AES AES 128 CBC encrypt/decrypt CONFIG_CMD_ASKENV * ask for env variable CONFIG_CMD_BDI bdinfo CONFIG_CMD_BEDBUG * Include BedBug Debugger diff --git a/common/Makefile b/common/Makefile index 04e9cdd..622f7bb 100644 --- a/common/Makefile +++ b/common/Makefile @@ -48,6 +48,7 @@ obj-$(CONFIG_ENV_IS_IN_UBI) += env_ubi.o obj-$(CONFIG_ENV_IS_NOWHERE) += env_nowhere.o

# command +obj-$(CONFIG_CMD_AES) += cmd_aes.o obj-$(CONFIG_CMD_AMBAPP) += cmd_ambapp.o obj-$(CONFIG_SOURCE) += cmd_source.o obj-$(CONFIG_CMD_SOURCE) += cmd_source.o diff --git a/common/cmd_aes.c b/common/cmd_aes.c new file mode 100644 index 0000000..76da3ef --- /dev/null +++ b/common/cmd_aes.c @@ -0,0 +1,89 @@ +/* + * Copyright (C) 2014 Marek Vasut marex@denx.de + * + * Command for en/de-crypting block of memory with AES-128-CBC cipher. + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#include <common.h> +#include <command.h> +#include <environment.h> +#include <aes.h> +#include <malloc.h> +#include <asm/byteorder.h> +#include <linux/compiler.h> + +DECLARE_GLOBAL_DATA_PTR; + +/** + * do_aes() - Handle the "aes" command-line command + * @cmdtp: Command data struct pointer + * @flag: Command flag + * @argc: Command-line argument count + * @argv: Array of command-line arguments + * + * Returns zero on success, CMD_RET_USAGE in case of misuse and negative + * on error. + */ +static int do_aes(cmd_tbl_t *cmdtp, int flag, int argc, char *const argv[]) +{ + uint32_t key_addr, src_addr, dst_addr, len; + uint8_t *key_ptr, *src_ptr, *dst_ptr; + uint8_t key_exp[AES_EXPAND_KEY_LENGTH]; + uint32_t aes_blocks; + int enc; + + if (argc != 6) + return CMD_RET_USAGE; + + if (!strncmp(argv[1], "enc", 3)) + enc = 1; + else if (!strncmp(argv[1], "dec", 3)) + enc = 0; + else + return CMD_RET_USAGE; + + key_addr = simple_strtoul(argv[2], NULL, 16); + src_addr = simple_strtoul(argv[3], NULL, 16); + dst_addr = simple_strtoul(argv[4], NULL, 16); + len = simple_strtoul(argv[5], NULL, 16); + + key_ptr = (uint8_t *)key_addr; + src_ptr = (uint8_t *)src_addr; + dst_ptr = (uint8_t *)dst_addr; + + /* First we expand the key. */ + aes_expand_key(key_ptr, key_exp); + + /* Calculate the number of AES blocks to encrypt. */ + aes_blocks = DIV_ROUND_UP(len, AES_KEY_LENGTH); + + if (enc) + aes_cbc_encrypt_blocks(key_exp, src_ptr, dst_ptr, aes_blocks); + else + aes_cbc_decrypt_blocks(key_exp, src_ptr, dst_ptr, aes_blocks); + + return 0; +} + +/***************************************************/ +#ifdef CONFIG_SYS_LONGHELP +static char aes_help_text[] = + "enc key src dst len - Encrypt block of data $len bytes long\n" + " at address $src using a key at address\n" + " $key and store the result at address\n" + " $dst. The $len size must be multiple of\n" + " 16 bytes and $key must be 16 bytes long.\n" + "aes dec key src dst len - Decrypt block of data $len bytes long\n" + " at address $src using a key at address\n" + " $key and store the result at address\n" + " $dst. The $len size must be multiple of\n" + " 16 bytes and $key must be 16 bytes long."; +#endif + +U_BOOT_CMD( + aes, 6, 1, do_aes, + "AES 128 CBC encryption", + aes_help_text +);