41 lines
1.3 KiB
C
41 lines
1.3 KiB
C
#pragma once
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#include <stdint.h>
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#include <stddef.h>
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// #define the macros below to 1/0 to enable/disable the mode of operation.
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//
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// CBC enables AES encryption in CBC-mode of operation.
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// CTR enables encryption in counter-mode.
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// ECB enables the basic ECB 16-byte block algorithm. All can be enabled simultaneously.
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// The #ifndef-guard allows it to be configured before #include'ing or at compile time.
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#ifndef CBC
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#define CBC 1
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#endif
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#define AES_BLOCKLEN 16 // Block length in bytes - AES is 128b block only
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#define AES_KEYLEN 16 // Key length in bytes
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#define AES_keyExpSize 176
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struct AES_ctx
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{
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uint8_t RoundKey[AES_keyExpSize];
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uint8_t Iv[AES_BLOCKLEN];
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};
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void AES_init_ctx(struct AES_ctx* ctx, const uint8_t* key);
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void AES_init_ctx_iv(struct AES_ctx* ctx, const uint8_t* key, const uint8_t* iv);
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void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv);
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// buffer size MUST be mutile of AES_BLOCKLEN;
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// Suggest https://en.wikipedia.org/wiki/Padding_(cryptography)#PKCS7 for padding scheme
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// NOTES: you need to set IV in ctx via AES_init_ctx_iv() or AES_ctx_set_iv()
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// no IV should ever be reused with the same key
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void AES_CBC_encrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, size_t length);
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void AES_CBC_decrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, size_t length);
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