/* * Armv8-A Cryptographic Extension support functions for Aarch64 * * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #if defined(__aarch64__) && !defined(__ARM_FEATURE_CRYPTO) && \ defined(__clang__) && __clang_major__ >= 4 /* TODO: Re-consider above after https://reviews.llvm.org/D131064 merged. * * The intrinsic declaration are guarded by predefined ACLE macros in clang: * these are normally only enabled by the -march option on the command line. * By defining the macros ourselves we gain access to those declarations without * requiring -march on the command line. * * `arm_neon.h` could be included by any header file, so we put these defines * at the top of this file, before any includes. */ #define __ARM_FEATURE_CRYPTO 1 /* See: https://arm-software.github.io/acle/main/acle.html#cryptographic-extensions * * `__ARM_FEATURE_CRYPTO` is deprecated, but we need to continue to specify it * for older compilers. */ #define __ARM_FEATURE_AES 1 #define MBEDTLS_ENABLE_ARM_CRYPTO_EXTENSIONS_COMPILER_FLAG #endif #include #include "common.h" #if defined(MBEDTLS_AESCE_C) #include "aesce.h" #if defined(MBEDTLS_HAVE_ARM64) #if !defined(__ARM_FEATURE_AES) || defined(MBEDTLS_ENABLE_ARM_CRYPTO_EXTENSIONS_COMPILER_FLAG) # if defined(__clang__) # if __clang_major__ < 4 # error "A more recent Clang is required for MBEDTLS_AESCE_C" # endif # pragma clang attribute push (__attribute__((target("crypto"))), apply_to=function) # define MBEDTLS_POP_TARGET_PRAGMA # elif defined(__GNUC__) # if __GNUC__ < 6 # error "A more recent GCC is required for MBEDTLS_AESCE_C" # endif # pragma GCC push_options # pragma GCC target ("arch=armv8-a+crypto") # define MBEDTLS_POP_TARGET_PRAGMA # else # error "Only GCC and Clang supported for MBEDTLS_AESCE_C" # endif #endif /* !__ARM_FEATURE_AES || MBEDTLS_ENABLE_ARM_CRYPTO_EXTENSIONS_COMPILER_FLAG */ #include #if defined(__linux__) #include #include #endif /* * AES instruction support detection routine */ int mbedtls_aesce_has_support(void) { #if defined(__linux__) unsigned long auxval = getauxval(AT_HWCAP); return (auxval & (HWCAP_ASIMD | HWCAP_AES)) == (HWCAP_ASIMD | HWCAP_AES); #else /* Assume AES instructions are supported. */ return 1; #endif } static uint8x16_t aesce_encrypt_block(uint8x16_t block, unsigned char *keys, int rounds) { for (int i = 0; i < rounds - 1; i++) { /* AES AddRoundKey, SubBytes, ShiftRows (in this order). * AddRoundKey adds the round key for the previous round. */ block = vaeseq_u8(block, vld1q_u8(keys + i * 16)); /* AES mix columns */ block = vaesmcq_u8(block); } /* AES AddRoundKey for the previous round. * SubBytes, ShiftRows for the final round. */ block = vaeseq_u8(block, vld1q_u8(keys + (rounds -1) * 16)); /* Final round: no MixColumns */ /* Final AddRoundKey */ block = veorq_u8(block, vld1q_u8(keys + rounds * 16)); return block; } static uint8x16_t aesce_decrypt_block(uint8x16_t block, unsigned char *keys, int rounds) { for (int i = 0; i < rounds - 1; i++) { /* AES AddRoundKey, SubBytes, ShiftRows */ block = vaesdq_u8(block, vld1q_u8(keys + i * 16)); /* AES inverse MixColumns for the next round. * * This means that we switch the order of the inverse AddRoundKey and * inverse MixColumns operations. We have to do this as AddRoundKey is * done in an atomic instruction together with the inverses of SubBytes * and ShiftRows. * * It works because MixColumns is a linear operation over GF(2^8) and * AddRoundKey is an exclusive or, which is equivalent to addition over * GF(2^8). (The inverse of MixColumns needs to be applied to the * affected round keys separately which has been done when the * decryption round keys were calculated.) */ block = vaesimcq_u8(block); } /* The inverses of AES AddRoundKey, SubBytes, ShiftRows finishing up the * last full round. */ block = vaesdq_u8(block, vld1q_u8(keys + (rounds - 1) * 16)); /* Inverse AddRoundKey for inverting the initial round key addition. */ block = veorq_u8(block, vld1q_u8(keys + rounds * 16)); return block; } /* * AES-ECB block en(de)cryption */ int mbedtls_aesce_crypt_ecb(mbedtls_aes_context *ctx, int mode, const unsigned char input[16], unsigned char output[16]) { uint8x16_t block = vld1q_u8(&input[0]); unsigned char *keys = (unsigned char *) (ctx->buf + ctx->rk_offset); if (mode == MBEDTLS_AES_ENCRYPT) { block = aesce_encrypt_block(block, keys, ctx->nr); } else { block = aesce_decrypt_block(block, keys, ctx->nr); } vst1q_u8(&output[0], block); return 0; } /* * Compute decryption round keys from encryption round keys */ void mbedtls_aesce_inverse_key(unsigned char *invkey, const unsigned char *fwdkey, int nr) { int i, j; j = nr; vst1q_u8(invkey, vld1q_u8(fwdkey + j * 16)); for (i = 1, j--; j > 0; i++, j--) { vst1q_u8(invkey + i * 16, vaesimcq_u8(vld1q_u8(fwdkey + j * 16))); } vst1q_u8(invkey + i * 16, vld1q_u8(fwdkey + j * 16)); } static inline uint32_t aes_rot_word(uint32_t word) { return (word << (32 - 8)) | (word >> 8); } static inline uint32_t aes_sub_word(uint32_t in) { uint8x16_t v = vreinterpretq_u8_u32(vdupq_n_u32(in)); uint8x16_t zero = vdupq_n_u8(0); /* vaeseq_u8 does both SubBytes and ShiftRows. Taking the first row yields * the correct result as ShiftRows doesn't change the first row. */ v = vaeseq_u8(zero, v); return vgetq_lane_u32(vreinterpretq_u32_u8(v), 0); } /* * Key expansion function */ static void aesce_setkey_enc(unsigned char *rk, const unsigned char *key, const size_t key_bit_length) { static uint8_t const rcon[] = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36 }; /* See https://nvlpubs.nist.gov/nistpubs/FIPS/NIST.FIPS.197.pdf * - Section 5, Nr = Nk + 6 * - Section 5.2, the length of round keys is Nb*(Nr+1) */ const uint32_t key_len_in_words = key_bit_length / 32; /* Nk */ const size_t round_key_len_in_words = 4; /* Nb */ const size_t rounds_needed = key_len_in_words + 6; /* Nr */ const size_t round_keys_len_in_words = round_key_len_in_words * (rounds_needed + 1); /* Nb*(Nr+1) */ const uint32_t *rko_end = (uint32_t *) rk + round_keys_len_in_words; memcpy(rk, key, key_len_in_words * 4); for (uint32_t *rki = (uint32_t *) rk; rki + key_len_in_words < rko_end; rki += key_len_in_words) { size_t iteration = (rki - (uint32_t *) rk) / key_len_in_words; uint32_t *rko; rko = rki + key_len_in_words; rko[0] = aes_rot_word(aes_sub_word(rki[key_len_in_words - 1])); rko[0] ^= rcon[iteration] ^ rki[0]; rko[1] = rko[0] ^ rki[1]; rko[2] = rko[1] ^ rki[2]; rko[3] = rko[2] ^ rki[3]; if (rko + key_len_in_words > rko_end) { /* Do not write overflow words.*/ continue; } switch (key_bit_length) { case 128: break; case 192: rko[4] = rko[3] ^ rki[4]; rko[5] = rko[4] ^ rki[5]; break; case 256: rko[4] = aes_sub_word(rko[3]) ^ rki[4]; rko[5] = rko[4] ^ rki[5]; rko[6] = rko[5] ^ rki[6]; rko[7] = rko[6] ^ rki[7]; break; } } } /* * Key expansion, wrapper */ int mbedtls_aesce_setkey_enc(unsigned char *rk, const unsigned char *key, size_t bits) { switch (bits) { case 128: case 192: case 256: aesce_setkey_enc(rk, key, bits); break; default: return MBEDTLS_ERR_AES_INVALID_KEY_LENGTH; } return 0; } #if defined(MBEDTLS_GCM_C) #if !defined(__clang__) && defined(__GNUC__) && __GNUC__ == 5 /* Some intrinsics are not available for GCC 5.X. */ #define vreinterpretq_p64_u8(a) ((poly64x2_t) a) #define vreinterpretq_u8_p128(a) ((uint8x16_t) a) static inline poly64_t vget_low_p64(poly64x2_t __a) { uint64x2_t tmp = (uint64x2_t) (__a); uint64x1_t lo = vcreate_u64(vgetq_lane_u64(tmp, 0)); return (poly64_t) (lo); } #endif /* !__clang__ && __GNUC__ && __GNUC__ == 5*/ /* vmull_p64/vmull_high_p64 wrappers. * * Older compilers miss some intrinsic functions for `poly*_t`. We use * uint8x16_t and uint8x16x3_t as input/output parameters. */ static inline uint8x16_t pmull_low(uint8x16_t a, uint8x16_t b) { return vreinterpretq_u8_p128( vmull_p64( (poly64_t) vget_low_p64(vreinterpretq_p64_u8(a)), (poly64_t) vget_low_p64(vreinterpretq_p64_u8(b)))); } static inline uint8x16_t pmull_high(uint8x16_t a, uint8x16_t b) { return vreinterpretq_u8_p128( vmull_high_p64(vreinterpretq_p64_u8(a), vreinterpretq_p64_u8(b))); } /* GHASH does 128b polynomial multiplication on block in GF(2^128) defined by * `x^128 + x^7 + x^2 + x + 1`. * * Arm64 only has 64b->128b polynomial multipliers, we need to do 4 64b * multiplies to generate a 128b. * * `poly_mult_128` executes polynomial multiplication and outputs 256b that * represented by 3 128b due to code size optimization. * * Output layout: * | | | | * |------------|-------------|-------------| * | ret.val[0] | h3:h2:00:00 | high 128b | * | ret.val[1] | :m2:m1:00 | middle 128b | * | ret.val[2] | : :l1:l0 | low 128b | */ static inline uint8x16x3_t poly_mult_128(uint8x16_t a, uint8x16_t b) { uint8x16x3_t ret; uint8x16_t h, m, l; /* retval high/middle/low */ uint8x16_t c, d, e; h = pmull_high(a, b); /* h3:h2:00:00 = a1*b1 */ l = pmull_low(a, b); /* : :l1:l0 = a0*b0 */ c = vextq_u8(b, b, 8); /* :c1:c0 = b0:b1 */ d = pmull_high(a, c); /* :d2:d1:00 = a1*b0 */ e = pmull_low(a, c); /* :e2:e1:00 = a0*b1 */ m = veorq_u8(d, e); /* :m2:m1:00 = d + e */ ret.val[0] = h; ret.val[1] = m; ret.val[2] = l; return ret; } /* * Modulo reduction. * * See: https://www.researchgate.net/publication/285612706_Implementing_GCM_on_ARMv8 * * Section 4.3 * * Modular reduction is slightly more complex. Write the GCM modulus as f(z) = * z^128 +r(z), where r(z) = z^7+z^2+z+ 1. The well known approach is to * consider that z^128 ≡r(z) (mod z^128 +r(z)), allowing us to write the 256-bit * operand to be reduced as a(z) = h(z)z^128 +l(z)≡h(z)r(z) + l(z). That is, we * simply multiply the higher part of the operand by r(z) and add it to l(z). If * the result is still larger than 128 bits, we reduce again. */ static inline uint8x16_t poly_mult_reduce(uint8x16x3_t input) { uint8x16_t const ZERO = vdupq_n_u8(0); /* use 'asm' as an optimisation barrier to prevent loading MODULO from memory */ uint64x2_t r = vreinterpretq_u64_u8(vdupq_n_u8(0x87)); asm ("" : "+w" (r)); uint8x16_t const MODULO = vreinterpretq_u8_u64(vshrq_n_u64(r, 64 - 8)); uint8x16_t h, m, l; /* input high/middle/low 128b */ uint8x16_t c, d, e, f, g, n, o; h = input.val[0]; /* h3:h2:00:00 */ m = input.val[1]; /* :m2:m1:00 */ l = input.val[2]; /* : :l1:l0 */ c = pmull_high(h, MODULO); /* :c2:c1:00 = reduction of h3 */ d = pmull_low(h, MODULO); /* : :d1:d0 = reduction of h2 */ e = veorq_u8(c, m); /* :e2:e1:00 = m2:m1:00 + c2:c1:00 */ f = pmull_high(e, MODULO); /* : :f1:f0 = reduction of e2 */ g = vextq_u8(ZERO, e, 8); /* : :g1:00 = e1:00 */ n = veorq_u8(d, l); /* : :n1:n0 = d1:d0 + l1:l0 */ o = veorq_u8(n, f); /* o1:o0 = f1:f0 + n1:n0 */ return veorq_u8(o, g); /* = o1:o0 + g1:00 */ } /* * GCM multiplication: c = a times b in GF(2^128) */ void mbedtls_aesce_gcm_mult(unsigned char c[16], const unsigned char a[16], const unsigned char b[16]) { uint8x16_t va, vb, vc; va = vrbitq_u8(vld1q_u8(&a[0])); vb = vrbitq_u8(vld1q_u8(&b[0])); vc = vrbitq_u8(poly_mult_reduce(poly_mult_128(va, vb))); vst1q_u8(&c[0], vc); } #endif /* MBEDTLS_GCM_C */ #if defined(MBEDTLS_POP_TARGET_PRAGMA) #if defined(__clang__) #pragma clang attribute pop #elif defined(__GNUC__) #pragma GCC pop_options #endif #undef MBEDTLS_POP_TARGET_PRAGMA #endif #endif /* MBEDTLS_HAVE_ARM64 */ #endif /* MBEDTLS_AESCE_C */