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Add functions for AES CBC mode encryption and decryption.

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This commit is contained in:
Stephen Heumann 2017-07-01 23:27:08 -05:00
parent 0386f928ff
commit 60a7aec49c
4 changed files with 326 additions and 1 deletions
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17
aes.asm
View File

@ -377,6 +377,10 @@ finish_aes128 anop
* The encrypted input and unencrypted output are in state1.
* Callable from C, with context structure pointer on stack.
aes_decrypt start
CFunction AES_DECRYPT
end
aes128_decrypt start
CFunction AES128_DECRYPT
end
@ -391,9 +395,18 @@ aes256_decrypt start
* Call with DP = AES context structure (with key expanded),
* DP = bank containing AES tables.
AES256_DECRYPT start
AES_DECRYPT start
using tables
ShortRegs
lda keysize
bne not128
jmp aes128_decrypt_internal
not128 bmi aes256_decrypt_internal
jmp aes192_decrypt_internal
AES256_DECRYPT entry
ShortRegs
aes256_decrypt_internal anop
InvFinalRound 14
InvNormalRound 13
InvNormalRound 12
@ -401,6 +414,7 @@ AES256_DECRYPT start
AES192_DECRYPT entry
ShortRegs
aes192_decrypt_internal anop
InvFinalRound 12
cont1 anop
InvNormalRound 11
@ -409,6 +423,7 @@ cont1 anop
AES128_DECRYPT entry
ShortRegs
aes128_decrypt_internal anop
InvFinalRound 10
cont2 anop
InvNormalRound 9

25
aes.h
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@ -45,8 +45,33 @@ void aes_encrypt(struct aes_context *context);
/*
* AES decryption functions
* aes_decrypt does AES-128, AES-192, or AES-256 decryption, based on the key.
* The others use a specific key size; a corresponding key must have been used.
* The encrypted input and unencrypted output are in context->data.
*/
void aes_decrypt(struct aes_context *context);
void aes128_decrypt(struct aes_context *context);
void aes192_decrypt(struct aes_context *context);
void aes256_decrypt(struct aes_context *context);
/*
* Encrypt data using AES-128, AES-192, or AES-256 in CBC mode.
* The key must have been specified via aes{128,192,256}_expandkey().
* The initialization vector (IV) must be in context->data.
* nblocks gives the number of 16-byte blocks to be processed.
*/
void aes_cbc_encrypt(struct aes_context *context,
const unsigned char *in,
unsigned char *out,
unsigned long nblocks);
/*
* Decrypt data using AES-128, AES-192, or AES-256 in CBC mode.
* The key must have been specified via aes{128,192,256}_expandkey().
* nblocks gives the number of 16-byte blocks to be processed.
*/
void aes_cbc_decrypt(struct aes_context *context,
const unsigned char *in,
unsigned char *out,
unsigned long nblocks,
const unsigned char *iv);

196
aescbc.c Normal file
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@ -0,0 +1,196 @@
#pragma noroot
#pragma lint -1
#pragma optimize -1
#include <string.h>
#include "aes.h"
extern void AES_ENCRYPT(void);
extern void AES_DECRYPT(void);
/*
* Encrypt data using AES-128, AES-192, or AES-256 in CBC mode.
* The key must have been specified via aes{128,192,256}_expandkey().
* The initialization vector (IV) must be in context->data.
* nblocks gives the number of 16-byte blocks to be processed.
*/
void aes_cbc_encrypt(struct aes_context *context,
const unsigned char *in,
unsigned char *out,
unsigned long nblocks)
{
while (nblocks-- > 0) {
asm {
ldy #0
lda [in],y
eor [context],y
sta [context],y
iny
iny
lda [in],y
eor [context],y
sta [context],y
iny
iny
lda [in],y
eor [context],y
sta [context],y
iny
iny
lda [in],y
eor [context],y
sta [context],y
iny
iny
lda [in],y
eor [context],y
sta [context],y
iny
iny
lda [in],y
eor [context],y
sta [context],y
iny
iny
lda [in],y
eor [context],y
sta [context],y
iny
iny
lda [in],y
eor [context],y
sta [context],y
phd
lda context
tcd
jsl AES_ENCRYPT
pld
}
memcpy(out, context->data, 16);
in += 16;
out += 16;
}
}
/*
* Decrypt data using AES-128, AES-192, or AES-256 in CBC mode.
* The key must have been specified via aes{128,192,256}_expandkey().
* nblocks gives the number of 16-byte blocks to be processed.
*/
void aes_cbc_decrypt(struct aes_context *context,
const unsigned char *in,
unsigned char *out,
unsigned long nblocks,
const unsigned char *iv)
{
if (nblocks-- == 0)
return;
memcpy(context->data, in, 16);
asm {
phd
lda context
tcd
jsl AES_DECRYPT
pld
ldy #0
lda [context],y
eor [iv],y
sta [out],y
iny
iny
lda [context],y
eor [iv],y
sta [out],y
iny
iny
lda [context],y
eor [iv],y
sta [out],y
iny
iny
lda [context],y
eor [iv],y
sta [out],y
iny
iny
lda [context],y
eor [iv],y
sta [out],y
iny
iny
lda [context],y
eor [iv],y
sta [out],y
iny
iny
lda [context],y
eor [iv],y
sta [out],y
iny
iny
lda [context],y
eor [iv],y
sta [out],y
}
//in += 16;
out += 16;
while (nblocks-- > 0) {
memcpy(context->data, in+16, 16);
asm {
phd
lda context
tcd
jsl AES_DECRYPT
pld
ldy #0
lda [context],y
eor [in],y
sta [out],y
iny
iny
lda [context],y
eor [in],y
sta [out],y
iny
iny
lda [context],y
eor [in],y
sta [out],y
iny
iny
lda [context],y
eor [in],y
sta [out],y
iny
iny
lda [context],y
eor [in],y
sta [out],y
iny
iny
lda [context],y
eor [in],y
sta [out],y
iny
iny
lda [context],y
eor [in],y
sta [out],y
iny
iny
lda [context],y
eor [in],y
sta [out],y
}
in += 16;
out += 16;
}
}

89
aescbctest.c Normal file
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@ -0,0 +1,89 @@
#include <stdio.h>
#include <string.h>
#include "aes.h"
unsigned char iv[16] = {
0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,
0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f
};
unsigned char key128[16] = {
0x2b,0x7e,0x15,0x16,0x28,0xae,0xd2,0xa6,
0xab,0xf7,0x15,0x88,0x09,0xcf,0x4f,0x3c
};
unsigned char key192[24] = {
0x8e,0x73,0xb0,0xf7,0xda,0x0e,0x64,0x52,
0xc8,0x10,0xf3,0x2b,0x80,0x90,0x79,0xe5,
0x62,0xf8,0xea,0xd2,0x52,0x2c,0x6b,0x7b
};
unsigned char key256[32] = {
0x60,0x3d,0xeb,0x10,0x15,0xca,0x71,0xbe,
0x2b,0x73,0xae,0xf0,0x85,0x7d,0x77,0x81,
0x1f,0x35,0x2c,0x07,0x3b,0x61,0x08,0xd7,
0x2d,0x98,0x10,0xa3,0x09,0x14,0xdf,0xf4
};
unsigned char plaintext[64] = {
0x6b,0xc1,0xbe,0xe2,0x2e,0x40,0x9f,0x96,
0xe9,0x3d,0x7e,0x11,0x73,0x93,0x17,0x2a,
0xae,0x2d,0x8a,0x57,0x1e,0x03,0xac,0x9c,
0x9e,0xb7,0x6f,0xac,0x45,0xaf,0x8e,0x51,
0x30,0xc8,0x1c,0x46,0xa3,0x5c,0xe4,0x11,
0xe5,0xfb,0xc1,0x19,0x1a,0x0a,0x52,0xef,
0xf6,0x9f,0x24,0x45,0xdf,0x4f,0x9b,0x17,
0xad,0x2b,0x41,0x7b,0xe6,0x6c,0x37,0x10
};
unsigned char output[64];
unsigned char output2[64];
static void printhex(char *str, unsigned char *buf, unsigned int count) {
unsigned int i;
if (str)
printf("%s\n", str);
for (i = 0; i < count; i++) {
printf("%02x", buf[i]);
if (i && (i & 0x0F) == 0x0F)
printf("\n");
}
}
int main(void) {
struct aes_context context;
memcpy(context.key, key128, 16);
aes128_expandkey(&context);
memcpy(context.data, iv, 16);
aes_cbc_encrypt(&context, plaintext, output, 4);
printhex("AES-128 ciphertext:", output, 64);
aes_cbc_decrypt(&context, output, output2, 4, iv);
printhex("Decrypted plaintext:", output2, 64);
memcpy(context.key, key192, 24);
aes192_expandkey(&context);
memcpy(context.data, iv, 16);
aes_cbc_encrypt(&context, plaintext, output, 4);
printhex("AES-192 ciphertext:", output, 64);
aes_cbc_decrypt(&context, output, output2, 4, iv);
printhex("Decrypted plaintext:", output2, 64);
memcpy(context.key, key256, 32);
aes256_expandkey(&context);
memcpy(context.data, iv, 16);
aes_cbc_encrypt(&context, plaintext, output, 4);
printhex("AES-256 ciphertext:", output, 64);
aes_cbc_decrypt(&context, output, output2, 4, iv);
printhex("Decrypted plaintext:", output2, 64);
}