Add implementation and test for AES CTR mode.

This commit is contained in:
Stephen Heumann 2017-07-02 18:25:43 -05:00
parent 924789510b
commit cfadee23bb
3 changed files with 250 additions and 0 deletions

15
aes.h
View File

@ -75,3 +75,18 @@ void aes_cbc_decrypt(struct aes_context *context,
unsigned char *out, unsigned char *out,
unsigned long nblocks, unsigned long nblocks,
const unsigned char *iv); const unsigned char *iv);
/*
* Process data using AES-128, AES-192, or AES-256 in CTR mode.
* This either encrypts or decrypts data, depending on whether
* in contains plaintext or ciphertext.
* The key must have been specified via aes{128,192,256}_expandkey().
* nblocks gives the number of 16-byte blocks to be processed.
* counter will be interpreted as a 128-bit big-endian integer,
* and incremented for each block processed.
*/
void aes_ctr_process(struct aes_context *context,
const unsigned char *in,
unsigned char *out,
unsigned long nblocks,
const unsigned char *counter);

126
aesctrtest.c Normal file
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@ -0,0 +1,126 @@
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <Memory.h>
#include <MiscTool.h>
#include <orca.h>
#include "aes.h"
unsigned char initial_counter[16] = {
0xf0,0xf1,0xf2,0xf3,0xf4,0xf5,0xf6,0xf7,
0xf8,0xf9,0xfa,0xfb,0xfc,0xfd,0xfe,0xff
};
unsigned char counter[16];
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];
#define BUFSIZE 64000
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_hndl;
struct aes_context *context;
unsigned char *inbuf, *outbuf;
unsigned long tick_count;
long double bytes_per_sec;
context_hndl = (struct aes_context **)NewHandle(sizeof(struct aes_context),
userid(), attrFixed|attrPage|attrBank|attrNoCross, 0x000000);
if (toolerror())
return 0;
context = *context_hndl;
memcpy(context->key, key128, 16);
aes128_expandkey(context);
memcpy(counter, initial_counter, 16);
aes_ctr_process(context, plaintext, output, 4, counter);
printhex("AES-128 ciphertext:", output, 64);
memcpy(counter, initial_counter, 16);
aes_ctr_process(context, output, output2, 4, counter);
printhex("Decrypted plaintext:", output2, 64);
memcpy(context->key, key192, 24);
aes192_expandkey(context);
memcpy(counter, initial_counter, 16);
aes_ctr_process(context, plaintext, output, 4, counter);
printhex("AES-192 ciphertext:", output, 64);
memcpy(counter, initial_counter, 16);
aes_ctr_process(context, output, output2, 4, counter);
printhex("Decrypted plaintext:", output2, 64);
memcpy(context->key, key256, 32);
aes256_expandkey(context);
memcpy(counter, initial_counter, 16);
aes_ctr_process(context, plaintext, output, 4, counter);
printhex("AES-256 ciphertext:", output, 64);
memcpy(counter, initial_counter, 16);
aes_ctr_process(context, output, output2, 4, counter);
printhex("Decrypted plaintext:", output2, 64);
/* Timing tests */
inbuf = calloc(BUFSIZE, 1);
outbuf = malloc(BUFSIZE);
if (inbuf == NULL || outbuf == NULL)
return -1;
memcpy(context->key, key128, 16);
aes128_expandkey(context);
memcpy(counter, initial_counter, 16);
tick_count = GetTick();
aes_ctr_process(context, inbuf, outbuf, BUFSIZE / 16, counter);
tick_count = GetTick() - tick_count;
bytes_per_sec = (long double)BUFSIZE * 60 / tick_count;
printf("AES-128 CTR encryption/decryption: %lf bytes/sec\n", bytes_per_sec);
}

View File

@ -281,3 +281,112 @@ void aes_cbc_decrypt(struct aes_context *context,
out += 16; out += 16;
} }
} }
/*
* Process data using AES-128, AES-192, or AES-256 in CTR mode.
* This either encrypts or decrypts data, depending on whether
* in contains plaintext or ciphertext.
* The key must have been specified via aes{128,192,256}_expandkey().
* nblocks gives the number of 16-byte blocks to be processed.
* counter will be interpreted as a 128-bit big-endian integer,
* and incremented for each block processed.
*/
void aes_ctr_process(struct aes_context *context,
const unsigned char *in,
unsigned char *out,
unsigned long nblocks,
const unsigned char *counter)
{
while (nblocks-- > 0) {
asm {
lda [counter]
sta [context]
ldy #2
lda [counter],y
sta [context],y
iny
iny
lda [counter],y
sta [context],y
iny
iny
lda [counter],y
sta [context],y
iny
iny
lda [counter],y
sta [context],y
iny
iny
lda [counter],y
sta [context],y
iny
iny
lda [counter],y
sta [context],y
iny
iny
lda [counter],y
sta [context],y
phd
lda context
tcd
jsl AES_ENCRYPT
pld
lda [context]
eor [in]
sta [out]
ldy #2
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
ldy #14
incloop: lda [counter],y
xba
inc a
xba
sta [counter],y
bne incdone
dey
dey
bpl incloop
incdone:
}
in += 16;
out += 16;
}
}