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tiny-AES-c
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Merge pull request #126 from torfinnberset/master 

Const-qualify all read-only pointers
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kokke 2019-02-22 09:23:16 +01:00 committed by GitHub
parent e72b6eff08 2fe22ab845
commit 4b4b04b8fa
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GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 17 additions and 17 deletions
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12
README.md
View File

@ -15,8 +15,8 @@ void AES_init_ctx_iv(struct AES_ctx* ctx, const uint8_t* key, const uint8_t* iv)
void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv);
/* Then start encrypting and decrypting with the functions below: */
void AES_ECB_encrypt(struct AES_ctx* ctx, uint8_t* buf);
void AES_ECB_decrypt(struct AES_ctx* ctx, uint8_t* buf);
void AES_ECB_encrypt(const struct AES_ctx* ctx, uint8_t* buf);
void AES_ECB_decrypt(const struct AES_ctx* ctx, uint8_t* buf);
void AES_CBC_encrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length);
void AES_CBC_decrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length);
@ -47,21 +47,21 @@ GCC size output when only CTR mode is compiled for ARM:
$ arm-none-eabi-gcc -Os -DCBC=0 -DECB=0 -DCTR=1 -c aes.c
$ size aes.o
text data bss dec hex filename
1203 0 0 1203 4b3 aes.o
1343 0 0 1343 53f aes.o
.. and when compiling for the THUMB instruction set, we end up just below 1K in code size.
$ arm-none-eabi-gcc -Os -mthumb -DCBC=0 -DECB=0 -DCTR=1 -c aes.c
$ size aes.o
text data bss dec hex filename
955 0 0 955 3bb aes.o
979 0 0 979 3d3 aes.o
I am using the Free Software Foundation, ARM GCC compiler:
$ arm-none-eabi-gcc --version
arm-none-eabi-gcc (4.8.4-1+11-1) 4.8.4 20141219 (release)
Copyright (C) 2013 Free Software Foundation, Inc.
arm-none-eabi-gcc (GNU Tools for Arm Embedded Processors 8-2018-q4-major) 8.2.1 20181213 (release)
Copyright (C) 2018 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.

18
aes.c
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@ -240,7 +240,7 @@ void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv)
// This function adds the round key to state.
// The round key is added to the state by an XOR function.
static void AddRoundKey(uint8_t round,state_t* state,uint8_t* RoundKey)
static void AddRoundKey(uint8_t round, state_t* state, const uint8_t* RoundKey)
{
uint8_t i,j;
for (i = 0; i < 4; ++i)
@ -408,7 +408,7 @@ static void InvShiftRows(state_t* state)
#endif // #if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
// Cipher is the main function that encrypts the PlainText.
static void Cipher(state_t* state, uint8_t* RoundKey)
static void Cipher(state_t* state, const uint8_t* RoundKey)
{
uint8_t round = 0;
@ -434,7 +434,7 @@ static void Cipher(state_t* state, uint8_t* RoundKey)
}
#if (defined(CBC) && CBC == 1) || (defined(ECB) && ECB == 1)
static void InvCipher(state_t* state,uint8_t* RoundKey)
static void InvCipher(state_t* state, const uint8_t* RoundKey)
{
uint8_t round = 0;
@ -466,13 +466,13 @@ static void InvCipher(state_t* state,uint8_t* RoundKey)
#if defined(ECB) && (ECB == 1)
void AES_ECB_encrypt(struct AES_ctx *ctx, uint8_t* buf)
void AES_ECB_encrypt(const struct AES_ctx *ctx, uint8_t* buf)
{
// The next function call encrypts the PlainText with the Key using AES algorithm.
Cipher((state_t*)buf, ctx->RoundKey);
}
void AES_ECB_decrypt(struct AES_ctx* ctx, uint8_t* buf)
void AES_ECB_decrypt(const struct AES_ctx* ctx, uint8_t* buf)
{
// The next function call decrypts the PlainText with the Key using AES algorithm.
InvCipher((state_t*)buf, ctx->RoundKey);
@ -488,7 +488,7 @@ void AES_ECB_decrypt(struct AES_ctx* ctx, uint8_t* buf)
#if defined(CBC) && (CBC == 1)
static void XorWithIv(uint8_t* buf, uint8_t* Iv)
static void XorWithIv(uint8_t* buf, const uint8_t* Iv)
{
uint8_t i;
for (i = 0; i < AES_BLOCKLEN; ++i) // The block in AES is always 128bit no matter the key size
@ -497,7 +497,7 @@ static void XorWithIv(uint8_t* buf, uint8_t* Iv)
}
}
void AES_CBC_encrypt_buffer(struct AES_ctx *ctx,uint8_t* buf, uint32_t length)
void AES_CBC_encrypt_buffer(struct AES_ctx *ctx, uint8_t* buf, uint32_t length)
{
uintptr_t i;
uint8_t *Iv = ctx->Iv;
@ -552,9 +552,9 @@ void AES_CTR_xcrypt_buffer(struct AES_ctx* ctx, uint8_t* buf, uint32_t length)
/* Increment Iv and handle overflow */
for (bi = (AES_BLOCKLEN - 1); bi >= 0; --bi)
{
/* inc will owerflow */
/* inc will overflow */
if (ctx->Iv[bi] == 255)
{
{
ctx->Iv[bi] = 0;
continue;
}

4
aes.h
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@ -58,8 +58,8 @@ void AES_ctx_set_iv(struct AES_ctx* ctx, const uint8_t* iv);
// buffer size is exactly AES_BLOCKLEN bytes;
// you need only AES_init_ctx as IV is not used in ECB
// NB: ECB is considered insecure for most uses
void AES_ECB_encrypt(struct AES_ctx* ctx, uint8_t* buf);
void AES_ECB_decrypt(struct AES_ctx* ctx, uint8_t* buf);
void AES_ECB_encrypt(const struct AES_ctx* ctx, uint8_t* buf);
void AES_ECB_decrypt(const struct AES_ctx* ctx, uint8_t* buf);
#endif // #if defined(ECB) && (ECB == !)