小巧的AES加密c语言实现

### Tiny AES128 in C This is a small and portable implementation of the AES128 ECB and CBC encryption algorithms written in C. The API is very simple and looks like this (I am using C99 `<stdint.h>`-style annotated types): ```C void AES128_ECB_encrypt(uint8_t* input, const uint8_t* key, uint8_t* output); void AES128_ECB_decrypt(uint8_t* input, const uint8_t* key, uint8_t* output); void AES128_CBC_encrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv); void AES128_CBC_decrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv); ``` You can choose to use one or both of the modes-of-operation, by defining the symbols CBC and ECB. See the header file for clarification. The module uses around 200 bytes of RAM and 2.5K ROM when compiled for ARM (~2K for Thumb but YMMV). It is the smallest implementation in C I've seen yet, but do contact me if you know of something smaller (or have improvements to the code here). I've successfully used the code on 64bit x86, 32bit ARM and 8 bit AVR platforms. GCC size output when ECB mode is compiled for ARM: $ arm-none-eabi-gcc -Os -c aes.c -DCBC=0 $ size aes.o text data bss dec hex filename 2323 0 184 2507 9cb aes.o .. and when compiling for the THUMB instruction set, we end up around 2K in code size. $ arm-none-eabi-gcc -mthumb -Os -c aes.c -DCBC=0 $ size aes.o text data bss dec hex filename 1775 0 184 1959 7a7 aes.o I am using Mentor Graphics free ARM toolchain: $ arm-none-eabi-gcc --version arm-none-eabi-gcc (GNU Tools for ARM Embedded Processors) 4.8.4 20140526 (release) [ARM/embedded-4_8-branch revision 211358] Copyright (C) 2013 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. This implementation is verified against the data in: [National Institute of Standards and Technology Special Publication 800-38A 2001 ED](http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf) Appendix F: Example Vectors for Modes of Operation of the AES. All material in this repository is in the public domain.