/* $NetBSD: aes_ccm.c,v 1.6 2021/10/17 14:45:45 jmcneill Exp $ */
/*-
* Copyright (c) 2020 The NetBSD Foundation, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* AES-CCM, as defined in:
*
* D. Whiting, R. Housley, and N. Ferguson, `Counter with CBC-MAC
* (CCM)', IETF RFC 3610, September 2003.
* https://tools.ietf.org/html/rfc3610
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(1, "$NetBSD: aes_ccm.c,v 1.6 2021/10/17 14:45:45 jmcneill Exp $");
#include <sys/types.h>
#include <sys/param.h>
#include <sys/systm.h>
#include <lib/libkern/libkern.h>
#include <crypto/aes/aes.h>
#include <crypto/aes/aes_ccm.h>
#include <crypto/aes/aes_impl.h>
static inline void
xor(uint8_t *x, const uint8_t *a, const uint8_t *b, size_t n)
{
while (n --> 0)
*x++ = *a++ ^ *b++;
}
/* RFC 3610, §2.2 Authentication */
#define CCM_AFLAGS_ADATA __BIT(6)
#define CCM_AFLAGS_M __BITS(5,3)
#define CCM_AFLAGS_L __BITS(2,0)
/* RFC 3610, §2.3 Encryption */
#define CCM_EFLAGS_L __BITS(2,0)
static void
aes_ccm_inc(struct aes_ccm *C)
{
uint8_t *ctr = C->authctr + 16;
KASSERT(C->L == 2);
if (++ctr[15] == 0 && ++ctr[14] == 0)
panic("AES-CCM overflow");
}
static void
aes_ccm_zero_ctr(struct aes_ccm *C)
{
uint8_t *ctr = C->authctr + 16;
KASSERT(C->L == 2);
ctr[14] = ctr[15] = 0;
}
void
aes_ccm_init(struct aes_ccm *C, unsigned nr, const struct aesenc *enc,
unsigned L, unsigned M,
const uint8_t *nonce, unsigned noncelen, const void *ad, size_t adlen,
size_t mlen)
{
const uint8_t *adp = ad;
uint8_t *auth = C->authctr;
uint8_t *ctr = C->authctr + 16;
unsigned i;
KASSERT(L == 2);
KASSERT(M % 2 == 0);
KASSERT(M >= 4);
KASSERT(M <= 16);
KASSERT(noncelen == 15 - L);
C->enc = enc;
C->nr = nr;
C->L = L;
C->M = M;
C->mlen = C->mleft = mlen;
/* Encode B0, the initial authenticated data block. */
auth[0] = __SHIFTIN(adlen == 0 ? 0 : 1, CCM_AFLAGS_ADATA);
auth[0] |= __SHIFTIN((M - 2)/2, CCM_AFLAGS_M);
auth[0] |= __SHIFTIN(L - 1, CCM_AFLAGS_L);
memcpy(auth + 1, nonce, noncelen);
for (i = 0; i < L; i++, mlen >>= 8) {
KASSERT(i < 16 - 1 - noncelen);
auth[16 - i - 1] = mlen & 0xff;
}
aes_enc(enc, auth, auth, C->nr);
/* Process additional authenticated data, if any. */
if (adlen) {
/* Encode the length according to the table on p. 4. */
if (adlen < 0xff00) {
auth[0] ^= adlen >> 8;
auth[1] ^= adlen;
i = 2;
} else if (adlen < 0xffffffff) {
auth[0] ^= 0xff;
auth[1] ^= 0xfe;
auth[2] ^= adlen >> 24;
auth[3] ^= adlen >> 16;
auth[4] ^= adlen >> 8;
auth[5] ^= adlen;
i = 6;
#if SIZE_MAX > 0xffffffffU
} else {
CTASSERT(SIZE_MAX <= 0xffffffffffffffff);
auth[0] ^= 0xff;
auth[1] ^= 0xff;
auth[2] ^= adlen >> 56;
auth[3] ^= adlen >> 48;
auth[4] ^= adlen >> 40;
auth[5] ^= adlen >> 32;
auth[6] ^= adlen >> 24;
auth[7] ^= adlen >> 16;
auth[8] ^= adlen >> 8;
auth[9] ^= adlen;
i = 10;
#endif
}
/* Fill out the partial block if we can, and encrypt. */
xor(auth + i, auth + i, adp, MIN(adlen, 16 - i));
adp += MIN(adlen, 16 - i);
adlen -= MIN(adlen, 16 - i);
aes_enc(enc, auth, auth, C->nr);
/* If there was anything more, process 16 bytes at a time. */
if (adlen - (adlen % 16)) {
aes_cbcmac_update1(enc, adp, adlen - (adlen % 16),
auth, C->nr);
adlen %= 16;
}
/*
* If there's anything at the end, enter it in (padded
* with zeros, which is a no-op) and process it.
*/
if (adlen) {
xor(auth, auth, adp, adlen);
aes_enc(enc, auth, auth, C->nr);
}
}
/* Set up the AES input for AES-CTR encryption. */
ctr[0] = __SHIFTIN(L - 1, CCM_EFLAGS_L);
memcpy(ctr + 1, nonce, noncelen);
memset(ctr + 1 + noncelen, 0, 16 - 1 - noncelen);
/* Start on a block boundary. */
C->i = 0;
}
void
aes_ccm_enc(struct aes_ccm *C, const void *in, void *out, size_t nbytes)
{
uint8_t *auth = C->authctr;
uint8_t *ctr = C->authctr + 16;
const uint8_t *p = in;
uint8_t *q = out;
KASSERTMSG(C->i != ~0u,
"%s not allowed after message complete", __func__);
KASSERTMSG(nbytes <= C->mleft,
"message too long: promised %zu bytes, processing >=%zu",
C->mlen, C->mlen - C->mleft + nbytes);
C->mleft -= nbytes;
/* Finish a partial block if it was already started. */
if (C->i) {
unsigned m = MIN(16 - C->i, nbytes);
xor(auth + C->i, auth + C->i, p, m);
xor(q, C->out + C->i, p, m);
C->i += m;
p += m;
q += m;
nbytes -= m;
if (C->i == 16) {
/* Finished a block; authenticate it. */
aes_enc(C->enc, auth, auth, C->nr);
C->i = 0;
} else {
/* Didn't finish block, must be done with input. */
KASSERT(nbytes == 0);
return;
}
}
/* Process 16 bytes at a time. */
if (nbytes - (nbytes % 16)) {
aes_ccm_enc1(C->enc, p, q, nbytes - (nbytes % 16), auth,
C->nr);
p += nbytes - (nbytes % 16);
q += nbytes - (nbytes % 16);
nbytes %= 16;
}
/* Incorporate any <16-byte unit as a partial block. */
if (nbytes) {
/* authenticate */
xor(auth, auth, p, nbytes);
/* encrypt */
aes_ccm_inc(C);
aes_enc(C->enc, ctr, C->out, C->nr);
xor(q, C->out, p, nbytes);
C->i = nbytes;
}
}
void
aes_ccm_dec(struct aes_ccm *C, const void *in, void *out, size_t nbytes)
{
uint8_t *auth = C->authctr;
uint8_t *ctr = C->authctr + 16;
const uint8_t *p = in;
uint8_t *q = out;
KASSERTMSG(C->i != ~0u,
"%s not allowed after message complete", __func__);
KASSERTMSG(nbytes <= C->mleft,
"message too long: promised %zu bytes, processing >=%zu",
C->mlen, C->mlen - C->mleft + nbytes);
C->mleft -= nbytes;
/* Finish a partial block if it was already started. */
if (C->i) {
unsigned m = MIN(16 - C->i, nbytes);
xor(q, C->out + C->i, p, m);
xor(auth + C->i, auth + C->i, q, m);
C->i += m;
p += m;
q += m;
nbytes -= m;
if (C->i == 16) {
/* Finished a block; authenticate it. */
aes_enc(C->enc, auth, auth, C->nr);
C->i = 0;
} else {
/* Didn't finish block, must be done with input. */
KASSERT(nbytes == 0);
return;
}
}
/* Process 16 bytes at a time. */
if (nbytes - (nbytes % 16)) {
aes_ccm_dec1(C->enc, p, q, nbytes - (nbytes % 16), auth,
C->nr);
p += nbytes - (nbytes % 16);
q += nbytes - (nbytes % 16);
nbytes %= 16;
}
/* Incorporate any <16-byte unit as a partial block. */
if (nbytes) {
/* decrypt */
aes_ccm_inc(C);
aes_enc(C->enc, ctr, C->out, C->nr);
xor(q, C->out, p, nbytes);
/* authenticate */
xor(auth, auth, q, nbytes);
C->i = nbytes;
}
}
void
#if defined(__m68k__) && __GNUC_PREREQ__(8, 0)
__attribute__((__optimize__("O0")))
#endif
aes_ccm_tag(struct aes_ccm *C, void *out)
{
uint8_t *auth = C->authctr;
const uint8_t *ctr = C->authctr + 16;
KASSERTMSG(C->mleft == 0,
"message too short: promised %zu bytes, processed %zu",
C->mlen, C->mlen - C->mleft);
/* Zero-pad and munch up a partial block, if any. */
if (C->i)
aes_enc(C->enc, auth, auth, C->nr);
/* Zero the counter and generate a pad for the tag. */
aes_ccm_zero_ctr(C);
aes_enc(C->enc, ctr, C->out, C->nr);
/* Copy out as many bytes as requested. */
xor(out, C->out, auth, C->M);
C->i = ~0u; /* paranoia: prevent future misuse */
}
int
aes_ccm_verify(struct aes_ccm *C, const void *tag)
{
uint8_t expected[16];
int result;
aes_ccm_tag(C, expected);
result = consttime_memequal(tag, expected, C->M);
explicit_memset(expected, 0, sizeof expected);
return result;
}
/* RFC 3610, §8 */
static const uint8_t keyC[16] = {
0xc0,0xc1,0xc2,0xc3, 0xc4,0xc5,0xc6,0xc7,
0xc8,0xc9,0xca,0xcb, 0xcc,0xcd,0xce,0xcf,
};
static const uint8_t keyD[16] = {
0xd7,0x82,0x8d,0x13, 0xb2,0xb0,0xbd,0xc3,
0x25,0xa7,0x62,0x36, 0xdf,0x93,0xcc,0x6b,
};
static const uint8_t ptxt_seq[] = {
0x00,0x01,0x02,0x03, 0x04,0x05,0x06,0x07,
0x08,0x09,0x0a,0x0b, 0x0c,0x0d,0x0e,0x0f,
0x10,0x11,0x12,0x13, 0x14,0x15,0x16,0x17,
0x18,0x19,0x1a,0x1b, 0x1c,0x1d,0x1e,0x1f,
0x20,
};
static const uint8_t ptxt_rand[] = {
0x6e,0x37,0xa6,0xef, 0x54,0x6d,0x95,0x5d,
0x34,0xab,0x60,0x59, 0xab,0xf2,0x1c,0x0b,
0x02,0xfe,0xb8,0x8f, 0x85,0x6d,0xf4,0xa3,
0x73,0x81,0xbc,0xe3, 0xcc,0x12,0x85,0x17,
0xd4,
};
static const struct {
const uint8_t *key;
size_t noncelen;
const uint8_t nonce[13];
size_t adlen;
const uint8_t *ad;
size_t mlen;
const uint8_t *ptxt;
unsigned M;
const uint8_t tag[16];
const uint8_t *ctxt;
} T[] = {
[0] = { /* Packet Vector #1, p. 11 */
.key = keyC,
.nonce = {
0x00,0x00,0x00,0x03, 0x02,0x01,0x00,0xa0,
0xa1,0xa2,0xa3,0xa4, 0xa5,
},
.adlen = 8,
.ad = ptxt_seq,
.mlen = 23,
.ptxt = ptxt_seq + 8,
.M = 8,
.tag = {0x17,0xe8,0xd1,0x2c,0xfd, 0xf9,0x26,0xe0},
.ctxt = (const uint8_t[23]) {
0x58,0x8c,0x97,0x9a, 0x61,0xc6,0x63,0xd2,
0xf0,0x66,0xd0,0xc2, 0xc0,0xf9,0x89,0x80,
0x6d,0x5f,0x6b,0x61, 0xda,0xc3,0x84,
},
},
[1] = { /* Packet Vector #2, p. 11 */
.key = keyC,
.nonce = {
0x00,0x00,0x00,0x04, 0x03,0x02,0x01,0xa0,
0xa1,0xa2,0xa3,0xa4, 0xa5,
},
.adlen = 8,
.ad = ptxt_seq,
.mlen = 24,
.ptxt = ptxt_seq + 8,
.M = 8,
.tag = {0xa0,0x91,0xd5,0x6e, 0x10,0x40,0x09,0x16},
.ctxt = (const uint8_t[24]) {
0x72,0xc9,0x1a,0x36, 0xe1,0x35,0xf8,0xcf,
0x29,0x1c,0xa8,0x94, 0x08,0x5c,0x87,0xe3,
0xcc,0x15,0xc4,0x39, 0xc9,0xe4,0x3a,0x3b,
},
},
[2] = { /* Packet Vector #3, p. 12 */
.key = keyC,
.nonce = {
0x00,0x00,0x00,0x05, 0x04,0x03,0x02,0xa0,
0xa1,0xa2,0xa3,0xa4, 0xa5,
},
.adlen = 8,
.ad = ptxt_seq,
.mlen = 25,
.ptxt = ptxt_seq + 8,
.M = 8,
.tag = {0x4a,0xda,0xa7,0x6f, 0xbd,0x9f,0xb0,0xc5},
.ctxt = (const uint8_t[25]) {
0x51,0xb1,0xe5,0xf4, 0x4a,0x19,0x7d,0x1d,
0xa4,0x6b,0x0f,0x8e, 0x2d,0x28,0x2a,0xe8,
0x71,0xe8,0x38,0xbb, 0x64,0xda,0x85,0x96,
0x57,
},
},
[3] = { /* Packet Vector #4, p. 13 */
.key = keyC,
.nonce = {
0x00,0x00,0x00,0x06, 0x05,0x04,0x03,0xa0,
0xa1,0xa2,0xa3,0xa4, 0xa5,
},
.adlen = 12,
.ad = ptxt_seq,
.mlen = 19,
.ptxt = ptxt_seq + 12,
.M = 8,
.tag = {0x96,0xc8,0x61,0xb9, 0xc9,0xe6,0x1e,0xf1},
.ctxt = (const uint8_t[19]) {
0xa2,0x8c,0x68,0x65, 0x93,0x9a,0x9a,0x79,
0xfa,0xaa,0x5c,0x4c, 0x2a,0x9d,0x4a,0x91,
0xcd,0xac,0x8c,
},
},
[4] = { /* Packet Vector #5, p. 13 */
.key = keyC,
.nonce = {
0x00,0x00,0x00,0x07, 0x06,0x05,0x04,0xa0,
0xa1,0xa2,0xa3,0xa4, 0xa5,
},
.adlen = 12,
.ad = ptxt_seq,
.mlen = 20,
.ptxt = ptxt_seq + 12,
.M = 8,
.tag = {0x51,0xe8,0x3f,0x07, 0x7d,0x9c,0x2d,0x93},
.ctxt = (const uint8_t[20]) {
0xdc,0xf1,0xfb,0x7b, 0x5d,0x9e,0x23,0xfb,
0x9d,0x4e,0x13,0x12, 0x53,0x65,0x8a,0xd8,
0x6e,0xbd,0xca,0x3e,
},
},
[5] = { /* Packet Vector #6, p. 13 */
.key = keyC,
.nonce = {
0x00,0x00,0x00,0x08, 0x07,0x06,0x05,0xa0,
0xa1,0xa2,0xa3,0xa4, 0xa5,
},
.adlen = 12,
.ad = ptxt_seq,
.mlen = 21,
.ptxt = ptxt_seq + 12,
.M = 8,
.tag = {0x40,0x5a,0x04,0x43, 0xac,0x91,0xcb,0x94},
.ctxt = (const uint8_t[21]) {
0x6f,0xc1,0xb0,0x11, 0xf0,0x06,0x56,0x8b,
0x51,0x71,0xa4,0x2d, 0x95,0x3d,0x46,0x9b,
0x25,0x70,0xa4,0xbd, 0x87,
},
},
[6] = { /* Packet Vector #24 */
.key = keyD,
.nonce = {
0x00,0x8d,0x49,0x3b, 0x30,0xae,0x8b,0x3c,
0x96,0x96,0x76,0x6c, 0xfa,
},
.adlen = 12,
.ad = ptxt_rand,
.mlen = 21,
.ptxt = ptxt_rand + 12,
.M = 10,
.tag = {0x6d,0xce,0x9e,0x82, 0xef,0xa1,0x6d,0xa6, 0x20,0x59},
.ctxt = (const uint8_t[21]) {
0xf3,0x29,0x05,0xb8, 0x8a,0x64,0x1b,0x04,
0xb9,0xc9,0xff,0xb5, 0x8c,0xc3,0x90,0x90,
0x0f,0x3d,0xa1,0x2a, 0xb1,
},
},
};
int
aes_ccm_selftest(void)
{
const unsigned L = 2;
const unsigned noncelen = 13;
struct aesenc enc, *AE = &enc;
struct aes_ccm ccm, *C = &ccm;
uint8_t buf[33 + 2], *bufp = buf + 1;
uint8_t tag[16 + 2], *tagp = tag + 1;
unsigned i;
int result = 0;
bufp[-1] = bufp[33] = 0x1a;
tagp[-1] = tagp[16] = 0x53;
for (i = 0; i < __arraycount(T); i++) {
const unsigned nr = aes_setenckey128(AE, T[i].key);
/* encrypt and authenticate */
aes_ccm_init(C, nr, AE, L, T[i].M, T[i].nonce, noncelen,
T[i].ad, T[i].adlen, T[i].mlen);
aes_ccm_enc(C, T[i].ptxt, bufp, 1);
aes_ccm_enc(C, T[i].ptxt + 1, bufp + 1, 2);
aes_ccm_enc(C, T[i].ptxt + 3, bufp + 3, T[i].mlen - 4);
aes_ccm_enc(C, T[i].ptxt + T[i].mlen - 1,
bufp + T[i].mlen - 1, 1);
aes_ccm_tag(C, tagp);
if (memcmp(bufp, T[i].ctxt, T[i].mlen)) {
char name[32];
snprintf(name, sizeof name, "%s: ctxt %u", __func__,
i);
hexdump(printf, name, bufp, T[i].mlen);
result = -1;
}
if (memcmp(tagp, T[i].tag, T[i].M)) {
char name[32];
snprintf(name, sizeof name, "%s: tag %u", __func__, i);
hexdump(printf, name, tagp, T[i].M);
result = -1;
}
/* decrypt and verify */
aes_ccm_init(C, nr, AE, L, T[i].M, T[i].nonce, noncelen,
T[i].ad, T[i].adlen, T[i].mlen);
aes_ccm_dec(C, T[i].ctxt, bufp, 1);
aes_ccm_dec(C, T[i].ctxt + 1, bufp + 1, 2);
aes_ccm_dec(C, T[i].ctxt + 3, bufp + 3, T[i].mlen - 4);
aes_ccm_dec(C, T[i].ctxt + T[i].mlen - 1,
bufp + T[i].mlen - 1, 1);
if (!aes_ccm_verify(C, T[i].tag)) {
printf("%s: verify %u failed\n", __func__, i);
result = -1;
}
if (memcmp(bufp, T[i].ptxt, T[i].mlen)) {
char name[32];
snprintf(name, sizeof name, "%s: ptxt %u", __func__,
i);
hexdump(printf, name, bufp, T[i].mlen);
result = -1;
}
/* decrypt and verify with a bit flipped */
memcpy(tagp, T[i].tag, T[i].M);
tagp[0] ^= 0x80;
aes_ccm_init(C, nr, AE, L, T[i].M, T[i].nonce, noncelen,
T[i].ad, T[i].adlen, T[i].mlen);
aes_ccm_dec(C, T[i].ctxt, bufp, 1);
aes_ccm_dec(C, T[i].ctxt + 1, bufp + 1, 2);
aes_ccm_dec(C, T[i].ctxt + 3, bufp + 3, T[i].mlen - 4);
aes_ccm_dec(C, T[i].ctxt + T[i].mlen - 1,
bufp + T[i].mlen - 1, 1);
if (aes_ccm_verify(C, tagp)) {
printf("%s: forgery %u succeeded\n", __func__, i);
result = -1;
}
}
if (bufp[-1] != 0x1a || bufp[33] != 0x1a) {
printf("%s: buffer overrun\n", __func__);
result = -1;
}
if (tagp[-1] != 0x53 || tagp[16] != 0x53) {
printf("%s: tag overrun\n", __func__);
result = -1;
}
return result;
}
/* XXX provisional hack */
#include <sys/module.h>
MODULE(MODULE_CLASS_MISC, aes_ccm, "aes");
static int
aes_ccm_modcmd(modcmd_t cmd, void *opaque)
{
switch (cmd) {
case MODULE_CMD_INIT:
if (aes_ccm_selftest())
return EIO;
aprint_debug("aes_ccm: self-test passed\n");
return 0;
case MODULE_CMD_FINI:
return 0;
default:
return ENOTTY;
}
}