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https://github.com/kokke/tiny-AES-c
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60 lines
1.9 KiB
Markdown
60 lines
1.9 KiB
Markdown
### Tiny AES128 in C
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This is a small and portable implementation of the AES128 ECB encryption algorithm written in C.
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The API is very simple and looks like this (I am using C99 `<stdint.h>`-style annotated types):
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```C
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void AES128_ECB_encrypt(uint8_t* input, const uint8_t* key, uint8_t* output);
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void AES128_ECB_decrypt(uint8_t* input, const uint8_t* key, uint8_t* output);
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```
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The module uses around 200 bytes of RAM and 2.5K ROM when compiled for ARM (~2K for Thumb but YMMV).
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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).
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I've successfully used the code on 64bit x86, 32bit ARM and 8 bit AVR platforms.
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GCC size output when compiled for ARM:
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$ arm-none-eabi-gcc -Os -c aes.c
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$ size aes.o
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text data bss dec hex filename
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2323 0 184 2507 9cb aes.o
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.. and when compiling for the THUMB instruction set, we end up around 2K in code size.
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$ arm-none-eabi-gcc -mthumb -Os -c aes.c
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$ size aes.o
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text data bss dec hex filename
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1775 0 184 1959 7a7 aes.o
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I am using Mentor Graphics free ARM toolchain:
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$ arm-none-eabi-gcc --version
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arm-none-eabi-gcc (GNU Tools for ARM Embedded Processors) 4.8.4 20140526 (release) [ARM/embedded-4_8-branch revision 211358]
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Copyright (C) 2013 Free Software Foundation, Inc.
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This is free software; see the source for copying conditions. There is NO
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warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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This implementation is verified against the data in:
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[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.
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All material in this repository is in the public domain.
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