/* $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 __KERNEL_RCSID(1, "$NetBSD: aes_ccm.c,v 1.6 2021/10/17 14:45:45 jmcneill Exp $"); #include #include #include #include #include #include #include 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 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; } }