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Diffstat (limited to 'lib/crypto/gf128mul.c')
| -rw-r--r-- | lib/crypto/gf128mul.c | 436 |
1 files changed, 436 insertions, 0 deletions
diff --git a/lib/crypto/gf128mul.c b/lib/crypto/gf128mul.c new file mode 100644 index 0000000000..8f8c45e0cd --- /dev/null +++ b/lib/crypto/gf128mul.c @@ -0,0 +1,436 @@ +/* gf128mul.c - GF(2^128) multiplication functions + * + * Copyright (c) 2003, Dr Brian Gladman, Worcester, UK. + * Copyright (c) 2006, Rik Snel <rsnel@cube.dyndns.org> + * + * Based on Dr Brian Gladman's (GPL'd) work published at + * http://gladman.plushost.co.uk/oldsite/cryptography_technology/index.php + * See the original copyright notice below. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the Free + * Software Foundation; either version 2 of the License, or (at your option) + * any later version. + */ + +/* + --------------------------------------------------------------------------- + Copyright (c) 2003, Dr Brian Gladman, Worcester, UK. All rights reserved. + + LICENSE TERMS + + The free distribution and use of this software in both source and binary + form is allowed (with or without changes) provided that: + + 1. distributions of this source code include the above copyright + notice, this list of conditions and the following disclaimer; + + 2. distributions in binary form include the above copyright + notice, this list of conditions and the following disclaimer + in the documentation and/or other associated materials; + + 3. the copyright holder's name is not used to endorse products + built using this software without specific written permission. + + ALTERNATIVELY, provided that this notice is retained in full, this product + may be distributed under the terms of the GNU General Public License (GPL), + in which case the provisions of the GPL apply INSTEAD OF those given above. + + DISCLAIMER + + This software is provided 'as is' with no explicit or implied warranties + in respect of its properties, including, but not limited to, correctness + and/or fitness for purpose. + --------------------------------------------------------------------------- + Issue 31/01/2006 + + This file provides fast multiplication in GF(2^128) as required by several + cryptographic authentication modes +*/ + +#include <crypto/gf128mul.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/slab.h> + +#define gf128mul_dat(q) { \ + q(0x00), q(0x01), q(0x02), q(0x03), q(0x04), q(0x05), q(0x06), q(0x07),\ + q(0x08), q(0x09), q(0x0a), q(0x0b), q(0x0c), q(0x0d), q(0x0e), q(0x0f),\ + q(0x10), q(0x11), q(0x12), q(0x13), q(0x14), q(0x15), q(0x16), q(0x17),\ + q(0x18), q(0x19), q(0x1a), q(0x1b), q(0x1c), q(0x1d), q(0x1e), q(0x1f),\ + q(0x20), q(0x21), q(0x22), q(0x23), q(0x24), q(0x25), q(0x26), q(0x27),\ + q(0x28), q(0x29), q(0x2a), q(0x2b), q(0x2c), q(0x2d), q(0x2e), q(0x2f),\ + q(0x30), q(0x31), q(0x32), q(0x33), q(0x34), q(0x35), q(0x36), q(0x37),\ + q(0x38), q(0x39), q(0x3a), q(0x3b), q(0x3c), q(0x3d), q(0x3e), q(0x3f),\ + q(0x40), q(0x41), q(0x42), q(0x43), q(0x44), q(0x45), q(0x46), q(0x47),\ + q(0x48), q(0x49), q(0x4a), q(0x4b), q(0x4c), q(0x4d), q(0x4e), q(0x4f),\ + q(0x50), q(0x51), q(0x52), q(0x53), q(0x54), q(0x55), q(0x56), q(0x57),\ + q(0x58), q(0x59), q(0x5a), q(0x5b), q(0x5c), q(0x5d), q(0x5e), q(0x5f),\ + q(0x60), q(0x61), q(0x62), q(0x63), q(0x64), q(0x65), q(0x66), q(0x67),\ + q(0x68), q(0x69), q(0x6a), q(0x6b), q(0x6c), q(0x6d), q(0x6e), q(0x6f),\ + q(0x70), q(0x71), q(0x72), q(0x73), q(0x74), q(0x75), q(0x76), q(0x77),\ + q(0x78), q(0x79), q(0x7a), q(0x7b), q(0x7c), q(0x7d), q(0x7e), q(0x7f),\ + q(0x80), q(0x81), q(0x82), q(0x83), q(0x84), q(0x85), q(0x86), q(0x87),\ + q(0x88), q(0x89), q(0x8a), q(0x8b), q(0x8c), q(0x8d), q(0x8e), q(0x8f),\ + q(0x90), q(0x91), q(0x92), q(0x93), q(0x94), q(0x95), q(0x96), q(0x97),\ + q(0x98), q(0x99), q(0x9a), q(0x9b), q(0x9c), q(0x9d), q(0x9e), q(0x9f),\ + q(0xa0), q(0xa1), q(0xa2), q(0xa3), q(0xa4), q(0xa5), q(0xa6), q(0xa7),\ + q(0xa8), q(0xa9), q(0xaa), q(0xab), q(0xac), q(0xad), q(0xae), q(0xaf),\ + q(0xb0), q(0xb1), q(0xb2), q(0xb3), q(0xb4), q(0xb5), q(0xb6), q(0xb7),\ + q(0xb8), q(0xb9), q(0xba), q(0xbb), q(0xbc), q(0xbd), q(0xbe), q(0xbf),\ + q(0xc0), q(0xc1), q(0xc2), q(0xc3), q(0xc4), q(0xc5), q(0xc6), q(0xc7),\ + q(0xc8), q(0xc9), q(0xca), q(0xcb), q(0xcc), q(0xcd), q(0xce), q(0xcf),\ + q(0xd0), q(0xd1), q(0xd2), q(0xd3), q(0xd4), q(0xd5), q(0xd6), q(0xd7),\ + q(0xd8), q(0xd9), q(0xda), q(0xdb), q(0xdc), q(0xdd), q(0xde), q(0xdf),\ + q(0xe0), q(0xe1), q(0xe2), q(0xe3), q(0xe4), q(0xe5), q(0xe6), q(0xe7),\ + q(0xe8), q(0xe9), q(0xea), q(0xeb), q(0xec), q(0xed), q(0xee), q(0xef),\ + q(0xf0), q(0xf1), q(0xf2), q(0xf3), q(0xf4), q(0xf5), q(0xf6), q(0xf7),\ + q(0xf8), q(0xf9), q(0xfa), q(0xfb), q(0xfc), q(0xfd), q(0xfe), q(0xff) \ +} + +/* + * Given a value i in 0..255 as the byte overflow when a field element + * in GF(2^128) is multiplied by x^8, the following macro returns the + * 16-bit value that must be XOR-ed into the low-degree end of the + * product to reduce it modulo the polynomial x^128 + x^7 + x^2 + x + 1. + * + * There are two versions of the macro, and hence two tables: one for + * the "be" convention where the highest-order bit is the coefficient of + * the highest-degree polynomial term, and one for the "le" convention + * where the highest-order bit is the coefficient of the lowest-degree + * polynomial term. In both cases the values are stored in CPU byte + * endianness such that the coefficients are ordered consistently across + * bytes, i.e. in the "be" table bits 15..0 of the stored value + * correspond to the coefficients of x^15..x^0, and in the "le" table + * bits 15..0 correspond to the coefficients of x^0..x^15. + * + * Therefore, provided that the appropriate byte endianness conversions + * are done by the multiplication functions (and these must be in place + * anyway to support both little endian and big endian CPUs), the "be" + * table can be used for multiplications of both "bbe" and "ble" + * elements, and the "le" table can be used for multiplications of both + * "lle" and "lbe" elements. + */ + +#define xda_be(i) ( \ + (i & 0x80 ? 0x4380 : 0) ^ (i & 0x40 ? 0x21c0 : 0) ^ \ + (i & 0x20 ? 0x10e0 : 0) ^ (i & 0x10 ? 0x0870 : 0) ^ \ + (i & 0x08 ? 0x0438 : 0) ^ (i & 0x04 ? 0x021c : 0) ^ \ + (i & 0x02 ? 0x010e : 0) ^ (i & 0x01 ? 0x0087 : 0) \ +) + +#define xda_le(i) ( \ + (i & 0x80 ? 0xe100 : 0) ^ (i & 0x40 ? 0x7080 : 0) ^ \ + (i & 0x20 ? 0x3840 : 0) ^ (i & 0x10 ? 0x1c20 : 0) ^ \ + (i & 0x08 ? 0x0e10 : 0) ^ (i & 0x04 ? 0x0708 : 0) ^ \ + (i & 0x02 ? 0x0384 : 0) ^ (i & 0x01 ? 0x01c2 : 0) \ +) + +static const u16 gf128mul_table_le[256] = gf128mul_dat(xda_le); +static const u16 gf128mul_table_be[256] = gf128mul_dat(xda_be); + +/* + * The following functions multiply a field element by x^8 in + * the polynomial field representation. They use 64-bit word operations + * to gain speed but compensate for machine endianness and hence work + * correctly on both styles of machine. + */ + +static void gf128mul_x8_lle(be128 *x) +{ + u64 a = be64_to_cpu(x->a); + u64 b = be64_to_cpu(x->b); + u64 _tt = gf128mul_table_le[b & 0xff]; + + x->b = cpu_to_be64((b >> 8) | (a << 56)); + x->a = cpu_to_be64((a >> 8) ^ (_tt << 48)); +} + +/* time invariant version of gf128mul_x8_lle */ +static void gf128mul_x8_lle_ti(be128 *x) +{ + u64 a = be64_to_cpu(x->a); + u64 b = be64_to_cpu(x->b); + u64 _tt = xda_le(b & 0xff); /* avoid table lookup */ + + x->b = cpu_to_be64((b >> 8) | (a << 56)); + x->a = cpu_to_be64((a >> 8) ^ (_tt << 48)); +} + +static void gf128mul_x8_bbe(be128 *x) +{ + u64 a = be64_to_cpu(x->a); + u64 b = be64_to_cpu(x->b); + u64 _tt = gf128mul_table_be[a >> 56]; + + x->a = cpu_to_be64((a << 8) | (b >> 56)); + x->b = cpu_to_be64((b << 8) ^ _tt); +} + +void gf128mul_x8_ble(le128 *r, const le128 *x) +{ + u64 a = le64_to_cpu(x->a); + u64 b = le64_to_cpu(x->b); + u64 _tt = gf128mul_table_be[a >> 56]; + + r->a = cpu_to_le64((a << 8) | (b >> 56)); + r->b = cpu_to_le64((b << 8) ^ _tt); +} +EXPORT_SYMBOL(gf128mul_x8_ble); + +void gf128mul_lle(be128 *r, const be128 *b) +{ + /* + * The p array should be aligned to twice the size of its element type, + * so that every even/odd pair is guaranteed to share a cacheline + * (assuming a cacheline size of 32 bytes or more, which is by far the + * most common). This ensures that each be128_xor() call in the loop + * takes the same amount of time regardless of the value of 'ch', which + * is derived from function parameter 'b', which is commonly used as a + * key, e.g., for GHASH. The odd array elements are all set to zero, + * making each be128_xor() a NOP if its associated bit in 'ch' is not + * set, and this is equivalent to calling be128_xor() conditionally. + * This approach aims to avoid leaking information about such keys + * through execution time variances. + * + * Unfortunately, __aligned(16) or higher does not work on x86 for + * variables on the stack so we need to perform the alignment by hand. + */ + be128 array[16 + 3] = {}; + be128 *p = PTR_ALIGN(&array[0], 2 * sizeof(be128)); + int i; + + p[0] = *r; + for (i = 0; i < 7; ++i) + gf128mul_x_lle(&p[2 * i + 2], &p[2 * i]); + + memset(r, 0, sizeof(*r)); + for (i = 0;;) { + u8 ch = ((u8 *)b)[15 - i]; + + be128_xor(r, r, &p[ 0 + !(ch & 0x80)]); + be128_xor(r, r, &p[ 2 + !(ch & 0x40)]); + be128_xor(r, r, &p[ 4 + !(ch & 0x20)]); + be128_xor(r, r, &p[ 6 + !(ch & 0x10)]); + be128_xor(r, r, &p[ 8 + !(ch & 0x08)]); + be128_xor(r, r, &p[10 + !(ch & 0x04)]); + be128_xor(r, r, &p[12 + !(ch & 0x02)]); + be128_xor(r, r, &p[14 + !(ch & 0x01)]); + + if (++i >= 16) + break; + + gf128mul_x8_lle_ti(r); /* use the time invariant version */ + } +} +EXPORT_SYMBOL(gf128mul_lle); + +void gf128mul_bbe(be128 *r, const be128 *b) +{ + be128 p[8]; + int i; + + p[0] = *r; + for (i = 0; i < 7; ++i) + gf128mul_x_bbe(&p[i + 1], &p[i]); + + memset(r, 0, sizeof(*r)); + for (i = 0;;) { + u8 ch = ((u8 *)b)[i]; + + if (ch & 0x80) + be128_xor(r, r, &p[7]); + if (ch & 0x40) + be128_xor(r, r, &p[6]); + if (ch & 0x20) + be128_xor(r, r, &p[5]); + if (ch & 0x10) + be128_xor(r, r, &p[4]); + if (ch & 0x08) + be128_xor(r, r, &p[3]); + if (ch & 0x04) + be128_xor(r, r, &p[2]); + if (ch & 0x02) + be128_xor(r, r, &p[1]); + if (ch & 0x01) + be128_xor(r, r, &p[0]); + + if (++i >= 16) + break; + + gf128mul_x8_bbe(r); + } +} +EXPORT_SYMBOL(gf128mul_bbe); + +/* This version uses 64k bytes of table space. + A 16 byte buffer has to be multiplied by a 16 byte key + value in GF(2^128). If we consider a GF(2^128) value in + the buffer's lowest byte, we can construct a table of + the 256 16 byte values that result from the 256 values + of this byte. This requires 4096 bytes. But we also + need tables for each of the 16 higher bytes in the + buffer as well, which makes 64 kbytes in total. +*/ +/* additional explanation + * t[0][BYTE] contains g*BYTE + * t[1][BYTE] contains g*x^8*BYTE + * .. + * t[15][BYTE] contains g*x^120*BYTE */ +struct gf128mul_64k *gf128mul_init_64k_bbe(const be128 *g) +{ + struct gf128mul_64k *t; + int i, j, k; + + t = kzalloc(sizeof(*t), GFP_KERNEL); + if (!t) + goto out; + + for (i = 0; i < 16; i++) { + t->t[i] = kzalloc(sizeof(*t->t[i]), GFP_KERNEL); + if (!t->t[i]) { + gf128mul_free_64k(t); + t = NULL; + goto out; + } + } + + t->t[0]->t[1] = *g; + for (j = 1; j <= 64; j <<= 1) + gf128mul_x_bbe(&t->t[0]->t[j + j], &t->t[0]->t[j]); + + for (i = 0;;) { + for (j = 2; j < 256; j += j) + for (k = 1; k < j; ++k) + be128_xor(&t->t[i]->t[j + k], + &t->t[i]->t[j], &t->t[i]->t[k]); + + if (++i >= 16) + break; + + for (j = 128; j > 0; j >>= 1) { + t->t[i]->t[j] = t->t[i - 1]->t[j]; + gf128mul_x8_bbe(&t->t[i]->t[j]); + } + } + +out: + return t; +} +EXPORT_SYMBOL(gf128mul_init_64k_bbe); + +void gf128mul_free_64k(struct gf128mul_64k *t) +{ + int i; + + for (i = 0; i < 16; i++) + kfree_sensitive(t->t[i]); + kfree_sensitive(t); +} +EXPORT_SYMBOL(gf128mul_free_64k); + +void gf128mul_64k_bbe(be128 *a, const struct gf128mul_64k *t) +{ + u8 *ap = (u8 *)a; + be128 r[1]; + int i; + + *r = t->t[0]->t[ap[15]]; + for (i = 1; i < 16; ++i) + be128_xor(r, r, &t->t[i]->t[ap[15 - i]]); + *a = *r; +} +EXPORT_SYMBOL(gf128mul_64k_bbe); + +/* This version uses 4k bytes of table space. + A 16 byte buffer has to be multiplied by a 16 byte key + value in GF(2^128). If we consider a GF(2^128) value in a + single byte, we can construct a table of the 256 16 byte + values that result from the 256 values of this byte. + This requires 4096 bytes. If we take the highest byte in + the buffer and use this table to get the result, we then + have to multiply by x^120 to get the final value. For the + next highest byte the result has to be multiplied by x^112 + and so on. But we can do this by accumulating the result + in an accumulator starting with the result for the top + byte. We repeatedly multiply the accumulator value by + x^8 and then add in (i.e. xor) the 16 bytes of the next + lower byte in the buffer, stopping when we reach the + lowest byte. This requires a 4096 byte table. +*/ +struct gf128mul_4k *gf128mul_init_4k_lle(const be128 *g) +{ + struct gf128mul_4k *t; + int j, k; + + t = kzalloc(sizeof(*t), GFP_KERNEL); + if (!t) + goto out; + + t->t[128] = *g; + for (j = 64; j > 0; j >>= 1) + gf128mul_x_lle(&t->t[j], &t->t[j+j]); + + for (j = 2; j < 256; j += j) + for (k = 1; k < j; ++k) + be128_xor(&t->t[j + k], &t->t[j], &t->t[k]); + +out: + return t; +} +EXPORT_SYMBOL(gf128mul_init_4k_lle); + +struct gf128mul_4k *gf128mul_init_4k_bbe(const be128 *g) +{ + struct gf128mul_4k *t; + int j, k; + + t = kzalloc(sizeof(*t), GFP_KERNEL); + if (!t) + goto out; + + t->t[1] = *g; + for (j = 1; j <= 64; j <<= 1) + gf128mul_x_bbe(&t->t[j + j], &t->t[j]); + + for (j = 2; j < 256; j += j) + for (k = 1; k < j; ++k) + be128_xor(&t->t[j + k], &t->t[j], &t->t[k]); + +out: + return t; +} +EXPORT_SYMBOL(gf128mul_init_4k_bbe); + +void gf128mul_4k_lle(be128 *a, const struct gf128mul_4k *t) +{ + u8 *ap = (u8 *)a; + be128 r[1]; + int i = 15; + + *r = t->t[ap[15]]; + while (i--) { + gf128mul_x8_lle(r); + be128_xor(r, r, &t->t[ap[i]]); + } + *a = *r; +} +EXPORT_SYMBOL(gf128mul_4k_lle); + +void gf128mul_4k_bbe(be128 *a, const struct gf128mul_4k *t) +{ + u8 *ap = (u8 *)a; + be128 r[1]; + int i = 0; + + *r = t->t[ap[0]]; + while (++i < 16) { + gf128mul_x8_bbe(r); + be128_xor(r, r, &t->t[ap[i]]); + } + *a = *r; +} +EXPORT_SYMBOL(gf128mul_4k_bbe); + +MODULE_LICENSE("GPL"); +MODULE_DESCRIPTION("Functions for multiplying elements of GF(2^128)"); |