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Add incremental CCM authentication processing

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CCM is only meant for packet mode where the length of the input is known in
advance. Since it is a packet mode function, CCM only had one function that
performs the protocol.

However, incremental authentication is usefull in some usecases. It also
ensure some kind of coherencies when processing with a given authentication
mode or another. To achieve this aim, this commit adds the following functions:
    ccm_init()
    ccm_add_aad()
    cm_add_nonce()
    ccm_process()
    ccm_done()
    ccm_reset()
as well as the data structure
    ccm_state

Change-Id: I5225a42bb098708c4af07518b561bb00f85bc243
This commit is contained in:
Pascal Brand 2014-10-17 08:50:01 +02:00
parent ed28703804
commit 992506cb49
8 changed files with 462 additions and 0 deletions
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2
makefile
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@ -121,6 +121,8 @@ src/ciphers/camellia.o src/ciphers/cast5.o src/ciphers/des.o src/ciphers/kasumi.
src/ciphers/kseed.o src/ciphers/multi2.o src/ciphers/noekeon.o src/ciphers/rc2.o src/ciphers/rc5.o \
src/ciphers/rc6.o src/ciphers/safer/safer.o src/ciphers/safer/saferp.o src/ciphers/skipjack.o \
src/ciphers/twofish/twofish.o src/ciphers/xtea.o src/encauth/ccm/ccm_memory.o \
src/encauth/ccm/ccm_done.o src/encauth/ccm/ccm_process.o src/encauth/ccm/ccm_reset.o \
src/encauth/ccm/ccm_add_aad.o src/encauth/ccm/ccm_init.o src/encauth/ccm/ccm_add_nonce.o \
src/encauth/ccm/ccm_memory_ex.o src/encauth/ccm/ccm_test.o src/encauth/eax/eax_addheader.o \
src/encauth/eax/eax_decrypt.o src/encauth/eax/eax_decrypt_verify_memory.o src/encauth/eax/eax_done.o \
src/encauth/eax/eax_encrypt_authenticate_memory.o src/encauth/eax/eax_encrypt.o \

58
src/encauth/ccm/ccm_add_aad.c Normal file
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@ -0,0 +1,58 @@
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
*/
#include "tomcrypt.h"
#ifdef LTC_CCM_MODE
/**
Add AAD to the CCM state
@param ccm The CCM state
@param adata The additional authentication data to add to the CCM state
@param adatalen The length of the AAD data.
@return CRYPT_OK on success
*/
int ccm_add_aad(ccm_state *ccm,
const unsigned char *adata, unsigned long adatalen)
{
unsigned long y;
int err;
if (ccm->aadlen < ccm->current_aadlen + adatalen) {
return CRYPT_INVALID_ARG;
}
ccm->current_aadlen += adatalen;
/* now add the data */
for (y = 0; y < adatalen; y++) {
if (ccm->x == 16) {
/* full block so let's encrypt it */
if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) {
return CRYPT_ERROR;
}
ccm->x = 0;
}
ccm->PAD[ccm->x++] ^= adata[y];
}
/* remainder? */
if (ccm->aadlen == ccm->current_aadlen) {
if (ccm->x != 0) {
if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) {
return CRYPT_ERROR;
}
}
ccm->x = 0;
}
return CRYPT_OK;
}
#endif

108
src/encauth/ccm/ccm_add_nonce.c Normal file
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@ -0,0 +1,108 @@
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
*/
#include "tomcrypt.h"
#ifdef LTC_CCM_MODE
/**
Add nonce data to the CCM state
@param ccm The CCM state
@param nonce The nonce data to add
@param noncelen The length of the nonce
@return CRYPT_OK on success
*/
int ccm_add_nonce(ccm_state *ccm,
const unsigned char *nonce, unsigned long noncelen)
{
unsigned long x, y, len;
int err;
/* increase L to match the nonce len */
ccm->noncelen = (noncelen > 13) ? 13 : noncelen;
if ((15 - ccm->noncelen) > ccm->L) {
ccm->L = 15 - ccm->noncelen;
}
/* decrease noncelen to match L */
if ((ccm->noncelen + ccm->L) > 15) {
ccm->noncelen = 15 - ccm->L;
}
/* form B_0 == flags | Nonce N | l(m) */
x = 0;
ccm->PAD[x++] = (unsigned char)(((ccm->aadlen > 0) ? (1<<6) : 0) |
(((ccm->taglen - 2)>>1)<<3) |
(ccm->L-1));
/* nonce */
for (y = 0; y < (16 - (ccm->L + 1)); y++) {
ccm->PAD[x++] = nonce[y];
}
/* store len */
len = ccm->ptlen;
/* shift len so the upper bytes of len are the contents of the length */
for (y = ccm->L; y < 4; y++) {
len <<= 8;
}
/* store l(m) (only store 32-bits) */
for (y = 0; ccm->L > 4 && (ccm->L-y)>4; y++) {
ccm->PAD[x++] = 0;
}
for (; y < ccm->L; y++) {
ccm->PAD[x++] = (unsigned char)((len >> 24) & 255);
len <<= 8;
}
/* encrypt PAD */
if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) {
return err;
}
/* handle header */
ccm->x = 0;
if (ccm->aadlen > 0) {
/* store length */
if (ccm->aadlen < ((1UL<<16) - (1UL<<8))) {
ccm->PAD[ccm->x++] ^= (ccm->aadlen>>8) & 255;
ccm->PAD[ccm->x++] ^= ccm->aadlen & 255;
} else {
ccm->PAD[ccm->x++] ^= 0xFF;
ccm->PAD[ccm->x++] ^= 0xFE;
ccm->PAD[ccm->x++] ^= (ccm->aadlen>>24) & 255;
ccm->PAD[ccm->x++] ^= (ccm->aadlen>>16) & 255;
ccm->PAD[ccm->x++] ^= (ccm->aadlen>>8) & 255;
ccm->PAD[ccm->x++] ^= ccm->aadlen & 255;
}
}
/* setup the ctr counter */
x = 0;
/* flags */
ccm->ctr[x++] = (unsigned char)ccm->L-1;
/* nonce */
for (y = 0; y < (16 - (ccm->L+1)); ++y) {
ccm->ctr[x++] = nonce[y];
}
/* offset */
while (x < 16) {
ccm->ctr[x++] = 0;
}
ccm->CTRlen = 16;
return CRYPT_OK;
}
#endif

61
src/encauth/ccm/ccm_done.c Normal file
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@ -0,0 +1,61 @@
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
*/
#include "tomcrypt.h"
#ifdef LTC_CCM_MODE
/**
Terminate a CCM stream
@param ccm The CCM state
@param tag [out] The destination for the MAC tag
@param taglen [in/out] The length of the MAC tag
@return CRYPT_OK on success
*/
int ccm_done(ccm_state *ccm,
unsigned char *tag, unsigned long *taglen)
{
unsigned long x, y;
int err;
/* Check all data have been processed */
if (ccm->ptlen != ccm->current_ptlen) {
return CRYPT_ERROR;
}
LTC_ARGCHK(tag != NULL);
LTC_ARGCHK(taglen != NULL);
if (ccm->x != 0) {
if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) {
return err;
}
}
/* setup CTR for the TAG (zero the count) */
for (y = 15; y > 15 - ccm->L; y--) {
ccm->ctr[y] = 0x00;
}
if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->ctr, ccm->CTRPAD, &ccm->K)) != CRYPT_OK) {
return err;
}
cipher_descriptor[ccm->cipher].done(&ccm->K);
/* store the TAG */
for (x = 0; x < 16 && x < *taglen; x++) {
tag[x] = ccm->PAD[x] ^ ccm->CTRPAD[x];
}
*taglen = x;
return CRYPT_OK;
}
#endif

78
src/encauth/ccm/ccm_init.c Normal file
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@ -0,0 +1,78 @@
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
*/
#include "tomcrypt.h"
#ifdef LTC_CCM_MODE
/**
Initialize a CCM state
@param ccm The CCM state to initialize
@param cipher The index of the cipher to use
@param key The secret key
@param keylen The length of the secret key
@param ptlen The length of the plain/cipher text that will be processed
@param taglen The max length of the MAC tag
@param aadlen The length of the AAD
@return CRYPT_OK on success
*/
int ccm_init(ccm_state *ccm, int cipher,
const unsigned char *key, int keylen, int ptlen, int taglen, int aadlen)
{
int err;
LTC_ARGCHK(key != NULL);
LTC_ARGCHK(taglen != 0);
memset(ccm, 0, sizeof(ccm_state));
/* check cipher input */
if ((err = cipher_is_valid(cipher)) != CRYPT_OK) {
return err;
}
if (cipher_descriptor[cipher].block_length != 16) {
return CRYPT_INVALID_CIPHER;
}
/* make sure the taglen is even and <= 16 */
ccm->taglen = taglen;
ccm->taglen &= ~1;
if (ccm->taglen > 16) {
ccm->taglen = 16;
}
/* can't use < 4 */
if (ccm->taglen < 4) {
return CRYPT_INVALID_ARG;
}
/* schedule key */
if ((err = cipher_descriptor[cipher].setup(key, keylen, 0, &ccm->K)) != CRYPT_OK) {
return err;
}
ccm->cipher = cipher;
/* let's get the L value */
ccm->ptlen = ptlen;
ccm->L = 0;
while (ptlen) {
++ccm->L;
ptlen >>= 8;
}
if (ccm->L <= 1) {
ccm->L = 2;
}
ccm->aadlen = aadlen;
return CRYPT_OK;
}
#endif

84
src/encauth/ccm/ccm_process.c Normal file
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@ -0,0 +1,84 @@
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
*/
#include "tomcrypt.h"
#ifdef LTC_CCM_MODE
/**
Process plaintext/ciphertext through CCM
@param ccm The CCM state
@param pt The plaintext
@param ptlen The plaintext length (ciphertext length is the same)
@param ct The ciphertext
@param direction Encrypt or Decrypt mode (CCM_ENCRYPT or CCM_DECRYPT)
@return CRYPT_OK on success
*/
int ccm_process(ccm_state *ccm,
unsigned char *pt, unsigned long ptlen,
unsigned char *ct,
int direction)
{
unsigned char y, z, b;
int err;
/* Check aad has been correctly added */
if (ccm->aadlen != ccm->current_aadlen) {
return CRYPT_ERROR;
}
/* Check we do not process too much data */
if (ccm->ptlen < ccm->current_ptlen + ptlen) {
return CRYPT_ERROR;
}
ccm->current_ptlen += ptlen;
/* now handle the PT */
if (ptlen > 0) {
LTC_ARGCHK(pt != NULL);
LTC_ARGCHK(ct != NULL);
y = 0;
for (; y < ptlen; y++) {
/* increment the ctr? */
if (ccm->CTRlen == 16) {
for (z = 15; z > 15-ccm->L; z--) {
ccm->ctr[z] = (ccm->ctr[z] + 1) & 255;
if (ccm->ctr[z]) break;
}
if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->ctr, ccm->CTRPAD, &ccm->K)) != CRYPT_OK) {
return err;
}
ccm->CTRlen = 0;
}
/* if we encrypt we add the bytes to the MAC first */
if (direction == CCM_ENCRYPT) {
b = pt[y];
ct[y] = b ^ ccm->CTRPAD[ccm->CTRlen++];
} else {
b = ct[y] ^ ccm->CTRPAD[ccm->CTRlen++];
pt[y] = b;
}
if (ccm->x == 16) {
if ((err = cipher_descriptor[ccm->cipher].ecb_encrypt(ccm->PAD, ccm->PAD, &ccm->K)) != CRYPT_OK) {
return err;
}
ccm->x = 0;
}
ccm->PAD[ccm->x++] ^= b;
}
}
return CRYPT_OK;
}
#endif

33
src/encauth/ccm/ccm_reset.c Normal file
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@ -0,0 +1,33 @@
/* LibTomCrypt, modular cryptographic library -- Tom St Denis
*
* LibTomCrypt is a library that provides various cryptographic
* algorithms in a highly modular and flexible manner.
*
* The library is free for all purposes without any express
* guarantee it works.
*
* Tom St Denis, tomstdenis@gmail.com, http://libtom.org
*/
#include "tomcrypt.h"
#ifdef LTC_CCM_MODE
/**
Reset a CCM state to as if you just called ccm_init(). This saves the initialization time.
@param ccm The CCM state to reset
@return CRYPT_OK on success
*/
int ccm_reset(ccm_state *ccm)
{
LTC_ARGCHK(ccm != NULL);
zeromem(ccm->PAD, sizeof(ccm->PAD));
zeromem(ccm->ctr, sizeof(ccm->ctr));
zeromem(ccm->CTRPAD, sizeof(ccm->CTRPAD));
ccm->CTRlen = 0;
ccm->current_ptlen = 0;
ccm->current_aadlen = 0;
return CRYPT_OK;
}
#endif

38
src/headers/tomcrypt_mac.h
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@ -259,6 +259,44 @@ void ocb3_int_xor_blocks(unsigned char *out, const unsigned char *block_a, const
#define CCM_ENCRYPT 0
#define CCM_DECRYPT 1
typedef struct {
symmetric_key K;
int cipher, /* which cipher */
taglen, /* length of the tag */
x; /* index in PAD */
unsigned long L, /* L value */
ptlen, /* length that will be enc / dec */
current_ptlen, /* current processed length */
aadlen, /* length of the aad */
current_aadlen, /* length of the currently provided add */
noncelen; /* length of the nonce */
unsigned char PAD[16],
ctr[16],
CTRPAD[16],
CTRlen;
} ccm_state;
int ccm_init(ccm_state *ccm, int cipher,
const unsigned char *key, int keylen, int ptlen, int taglen, int aad_len);
int ccm_reset(ccm_state *ccm);
int ccm_add_nonce(ccm_state *ccm,
const unsigned char *nonce, unsigned long noncelen);
int ccm_add_aad(ccm_state *ccm,
const unsigned char *adata, unsigned long adatalen);
int ccm_process(ccm_state *ccm,
unsigned char *pt, unsigned long ptlen,
unsigned char *ct,
int direction);
int ccm_done(ccm_state *ccm,
unsigned char *tag, unsigned long *taglen);
int ccm_memory(int cipher,
const unsigned char *key, unsigned long keylen,
symmetric_key *uskey,