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#include "k5-int.h"
#include "enc_provider.h"
#include "aes.h"
static void
aes_block_size(size_t *blocksize)
{
*blocksize = 16;
}
static void
aes128_keysize(size_t *keybytes, size_t *keylength)
{
*keybytes = *keylength = 16;
}
static void
aes256_keysize(size_t *keybytes, size_t *keylength)
{
*keybytes = *keylength = 32;
}
#if 0
aes_rval aes_blk_len(unsigned int blen, aes_ctx cx[1]);
aes_rval aes_enc_key(const unsigned char in_key[], unsigned int klen, aes_ctx cx[1]);
aes_rval aes_enc_blk(const unsigned char in_blk[], unsigned char out_blk[], const aes_ctx cx[1]);
aes_rval aes_dec_key(const unsigned char in_key[], unsigned int klen, aes_ctx cx[1]);
aes_rval aes_dec_blk(const unsigned char in_blk[], unsigned char out_blk[], const aes_ctx cx[1]);
#endif
#define CHECK_SIZES 0
static void printd (const char *descr, krb5_data *d) {
int i, j;
const int r = 16;
printf("%s:", descr);
for (i = 0; i < d->length; i += r) {
printf("\n %04x: ", i);
for (j = i; j < i + r && j < d->length; j++)
printf(" %02x", 0xff & d->data[j]);
#ifdef SHOW_TEXT
for (; j < i + r; j++)
printf(" ");
printf(" ");
for (j = i; j < i + r && j < d->length; j++) {
int c = 0xff & d->data[j];
printf("%c", isprint(c) ? c : '.');
}
#endif
}
printf("\n");
}
#define enc(OUT, IN, CTX) (aes_enc_blk((IN),(OUT),(CTX)) == aes_good ? (void) 0 : abort())
#define dec(OUT, IN, CTX) (aes_dec_blk((IN),(OUT),(CTX)) == aes_good ? (void) 0 : abort())
static void xorblock(char *out, const char *in)
{
int z;
for (z = 0; z < BLOCK_SIZE; z++)
out[z] ^= in[z];
}
krb5_error_code
krb5int_aes_encrypt(const krb5_keyblock *key, const krb5_data *ivec,
const krb5_data *input, krb5_data *output)
{
aes_ctx ctx;
unsigned char tmp[BLOCK_SIZE], tmp2[BLOCK_SIZE], tmp3[BLOCK_SIZE];
int nblocks = 0, blockno;
/* CHECK_SIZES; */
if (aes_enc_key(key->contents, key->length, &ctx) != aes_good)
abort();
if (ivec)
memcpy(tmp, ivec->data, BLOCK_SIZE);
else
memset(tmp, 0, BLOCK_SIZE);
nblocks = (input->length + BLOCK_SIZE - 1) / BLOCK_SIZE;
if (nblocks == 1) {
/* XXX Used for DK function. */
enc(output->data, input->data, &ctx);
} else {
int nleft;
for (blockno = 0; blockno < nblocks - 2; blockno++) {
xorblock(tmp, input->data + blockno * BLOCK_SIZE);
enc(tmp2, tmp, &ctx);
memcpy(output->data + blockno * BLOCK_SIZE, tmp2, BLOCK_SIZE);
/* Set up for next block. */
memcpy(tmp, tmp2, BLOCK_SIZE);
}
/* Do final CTS step for last two blocks (the second of which
may or may not be incomplete). */
xorblock(tmp, input->data + (nblocks - 2) * BLOCK_SIZE);
enc(tmp2, tmp, &ctx);
nleft = input->length - (nblocks - 1) * BLOCK_SIZE;
memcpy(output->data + (nblocks - 1) * BLOCK_SIZE, tmp2, nleft);
memcpy(tmp, tmp2, BLOCK_SIZE);
memset(tmp3, 0, sizeof(tmp3));
memcpy(tmp3, input->data + (nblocks - 1) * BLOCK_SIZE, nleft);
xorblock(tmp, tmp3);
enc(tmp2, tmp, &ctx);
memcpy(output->data + (nblocks - 2) * BLOCK_SIZE, tmp2, BLOCK_SIZE);
}
return 0;
}
krb5_error_code
krb5int_aes_decrypt(const krb5_keyblock *key, const krb5_data *ivec,
const krb5_data *input, krb5_data *output)
{
aes_ctx ctx;
unsigned char tmp[BLOCK_SIZE], tmp2[BLOCK_SIZE], tmp3[BLOCK_SIZE];
int nblocks = 0, blockno;
CHECK_SIZES;
if (aes_dec_key(key->contents, key->length, &ctx) != aes_good)
abort();
if (ivec)
memcpy(tmp, ivec->data, BLOCK_SIZE);
else
memset(tmp, 0, BLOCK_SIZE);
nblocks = (input->length + BLOCK_SIZE - 1) / BLOCK_SIZE;
if (nblocks == 1) {
if (input->length < BLOCK_SIZE)
abort();
dec(output->data, input->data, &ctx);
} else {
int nleft;
for (blockno = 0; blockno < nblocks - 2; blockno++) {
dec(tmp2, input->data + blockno * BLOCK_SIZE, &ctx);
xorblock(tmp2, tmp);
memcpy(output->data + blockno * BLOCK_SIZE, tmp2, BLOCK_SIZE);
memcpy(tmp, input->data + blockno * BLOCK_SIZE, BLOCK_SIZE);
}
/* Do last two blocks, the second of which (next-to-last block
of plaintext) may be incomplete. */
dec(tmp2, input->data + (nblocks - 2) * BLOCK_SIZE, &ctx);
/* Set tmp3 to last ciphertext block, padded. */
memset(tmp3, 0, sizeof(tmp3));
memcpy(tmp3, input->data + (nblocks - 1) * BLOCK_SIZE,
input->length - (nblocks - 1) * BLOCK_SIZE);
/* Set tmp2 to last (possibly partial) plaintext block, and
save it. */
xorblock(tmp2, tmp3);
memcpy(output->data + (nblocks - 1) * BLOCK_SIZE, tmp2,
input->length - (nblocks - 1) * BLOCK_SIZE);
/* Maybe keep the trailing part, and copy in the last
ciphertext block. */
memcpy(tmp2, tmp3, input->length - (nblocks - 1) * BLOCK_SIZE);
/* Decrypt, to get next to last plaintext block xor previous
ciphertext. */
dec(tmp3, tmp2, &ctx);
xorblock(tmp3, tmp);
memcpy(output->data + (nblocks - 2) * BLOCK_SIZE, tmp3, BLOCK_SIZE);
}
return 0;
}
static krb5_error_code
k5_aes_make_key(const krb5_data *randombits, krb5_keyblock *key)
{
if (key->length != 16 && key->length != 32)
return(KRB5_BAD_KEYSIZE);
if (randombits->length != key->length)
return(KRB5_CRYPTO_INTERNAL);
key->magic = KV5M_KEYBLOCK;
memcpy(key->contents, randombits->data, randombits->length);
return(0);
}
static krb5_error_code
krb5int_aes_init_state (const krb5_keyblock *key, krb5_keyusage usage,
krb5_data *state)
{
state->length = 16;
state->data = (void *) malloc(16);
if (state->data == NULL)
return ENOMEM;
memset(state->data, 0, state->length);
return 0;
}
const struct krb5_enc_provider krb5int_enc_aes128 = {
aes_block_size,
aes128_keysize,
krb5int_aes_encrypt,
krb5int_aes_decrypt,
k5_aes_make_key,
krb5int_aes_init_state,
krb5int_default_free_state
};
const struct krb5_enc_provider krb5int_enc_aes256 = {
aes_block_size,
aes256_keysize,
krb5int_aes_encrypt,
krb5int_aes_decrypt,
k5_aes_make_key,
krb5int_aes_init_state,
krb5int_default_free_state
};
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