diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-11 14:27:06 -0800 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-12-11 14:27:06 -0800 |
commit | 70e71ca0af244f48a5dcf56dc435243792e3a495 (patch) | |
tree | f7d9c4c4d9a857a00043e9bf6aa2d6f533a34778 /net/bluetooth/ecc.c | |
parent | bae41e45b7400496b9bf0c70c6004419d9987819 (diff) | |
parent | 00c83b01d58068dfeb2e1351cca6fccf2a83fa8f (diff) |
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next
Pull networking updates from David Miller:
1) New offloading infrastructure and example 'rocker' driver for
offloading of switching and routing to hardware.
This work was done by a large group of dedicated individuals, not
limited to: Scott Feldman, Jiri Pirko, Thomas Graf, John Fastabend,
Jamal Hadi Salim, Andy Gospodarek, Florian Fainelli, Roopa Prabhu
2) Start making the networking operate on IOV iterators instead of
modifying iov objects in-situ during transfers. Thanks to Al Viro
and Herbert Xu.
3) A set of new netlink interfaces for the TIPC stack, from Richard
Alpe.
4) Remove unnecessary looping during ipv6 routing lookups, from Martin
KaFai Lau.
5) Add PAUSE frame generation support to gianfar driver, from Matei
Pavaluca.
6) Allow for larger reordering levels in TCP, which are easily
achievable in the real world right now, from Eric Dumazet.
7) Add a variable of napi_schedule that doesn't need to disable cpu
interrupts, from Eric Dumazet.
8) Use a doubly linked list to optimize neigh_parms_release(), from
Nicolas Dichtel.
9) Various enhancements to the kernel BPF verifier, and allow eBPF
programs to actually be attached to sockets. From Alexei
Starovoitov.
10) Support TSO/LSO in sunvnet driver, from David L Stevens.
11) Allow controlling ECN usage via routing metrics, from Florian
Westphal.
12) Remote checksum offload, from Tom Herbert.
13) Add split-header receive, BQL, and xmit_more support to amd-xgbe
driver, from Thomas Lendacky.
14) Add MPLS support to openvswitch, from Simon Horman.
15) Support wildcard tunnel endpoints in ipv6 tunnels, from Steffen
Klassert.
16) Do gro flushes on a per-device basis using a timer, from Eric
Dumazet. This tries to resolve the conflicting goals between the
desired handling of bulk vs. RPC-like traffic.
17) Allow userspace to ask for the CPU upon what a packet was
received/steered, via SO_INCOMING_CPU. From Eric Dumazet.
18) Limit GSO packets to half the current congestion window, from Eric
Dumazet.
19) Add a generic helper so that all drivers set their RSS keys in a
consistent way, from Eric Dumazet.
20) Add xmit_more support to enic driver, from Govindarajulu
Varadarajan.
21) Add VLAN packet scheduler action, from Jiri Pirko.
22) Support configurable RSS hash functions via ethtool, from Eyal
Perry.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1820 commits)
Fix race condition between vxlan_sock_add and vxlan_sock_release
net/macb: fix compilation warning for print_hex_dump() called with skb->mac_header
net/mlx4: Add support for A0 steering
net/mlx4: Refactor QUERY_PORT
net/mlx4_core: Add explicit error message when rule doesn't meet configuration
net/mlx4: Add A0 hybrid steering
net/mlx4: Add mlx4_bitmap zone allocator
net/mlx4: Add a check if there are too many reserved QPs
net/mlx4: Change QP allocation scheme
net/mlx4_core: Use tasklet for user-space CQ completion events
net/mlx4_core: Mask out host side virtualization features for guests
net/mlx4_en: Set csum level for encapsulated packets
be2net: Export tunnel offloads only when a VxLAN tunnel is created
gianfar: Fix dma check map error when DMA_API_DEBUG is enabled
cxgb4/csiostor: Don't use MASTER_MUST for fw_hello call
net: fec: only enable mdio interrupt before phy device link up
net: fec: clear all interrupt events to support i.MX6SX
net: fec: reset fep link status in suspend function
net: sock: fix access via invalid file descriptor
net: introduce helper macro for_each_cmsghdr
...
Diffstat (limited to 'net/bluetooth/ecc.c')
-rw-r--r-- | net/bluetooth/ecc.c | 816 |
1 files changed, 816 insertions, 0 deletions
diff --git a/net/bluetooth/ecc.c b/net/bluetooth/ecc.c new file mode 100644 index 000000000000..e1709f8467ac --- /dev/null +++ b/net/bluetooth/ecc.c @@ -0,0 +1,816 @@ +/* + * Copyright (c) 2013, Kenneth MacKay + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * 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 COPYRIGHT HOLDERS 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 COPYRIGHT + * HOLDER 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. + */ + +#include <linux/random.h> + +#include "ecc.h" + +/* 256-bit curve */ +#define ECC_BYTES 32 + +#define MAX_TRIES 16 + +/* Number of u64's needed */ +#define NUM_ECC_DIGITS (ECC_BYTES / 8) + +struct ecc_point { + u64 x[NUM_ECC_DIGITS]; + u64 y[NUM_ECC_DIGITS]; +}; + +typedef struct { + u64 m_low; + u64 m_high; +} uint128_t; + +#define CURVE_P_32 { 0xFFFFFFFFFFFFFFFFull, 0x00000000FFFFFFFFull, \ + 0x0000000000000000ull, 0xFFFFFFFF00000001ull } + +#define CURVE_G_32 { \ + { 0xF4A13945D898C296ull, 0x77037D812DEB33A0ull, \ + 0xF8BCE6E563A440F2ull, 0x6B17D1F2E12C4247ull }, \ + { 0xCBB6406837BF51F5ull, 0x2BCE33576B315ECEull, \ + 0x8EE7EB4A7C0F9E16ull, 0x4FE342E2FE1A7F9Bull } \ +} + +#define CURVE_N_32 { 0xF3B9CAC2FC632551ull, 0xBCE6FAADA7179E84ull, \ + 0xFFFFFFFFFFFFFFFFull, 0xFFFFFFFF00000000ull } + +static u64 curve_p[NUM_ECC_DIGITS] = CURVE_P_32; +static struct ecc_point curve_g = CURVE_G_32; +static u64 curve_n[NUM_ECC_DIGITS] = CURVE_N_32; + +static void vli_clear(u64 *vli) +{ + int i; + + for (i = 0; i < NUM_ECC_DIGITS; i++) + vli[i] = 0; +} + +/* Returns true if vli == 0, false otherwise. */ +static bool vli_is_zero(const u64 *vli) +{ + int i; + + for (i = 0; i < NUM_ECC_DIGITS; i++) { + if (vli[i]) + return false; + } + + return true; +} + +/* Returns nonzero if bit bit of vli is set. */ +static u64 vli_test_bit(const u64 *vli, unsigned int bit) +{ + return (vli[bit / 64] & ((u64) 1 << (bit % 64))); +} + +/* Counts the number of 64-bit "digits" in vli. */ +static unsigned int vli_num_digits(const u64 *vli) +{ + int i; + + /* Search from the end until we find a non-zero digit. + * We do it in reverse because we expect that most digits will + * be nonzero. + */ + for (i = NUM_ECC_DIGITS - 1; i >= 0 && vli[i] == 0; i--); + + return (i + 1); +} + +/* Counts the number of bits required for vli. */ +static unsigned int vli_num_bits(const u64 *vli) +{ + unsigned int i, num_digits; + u64 digit; + + num_digits = vli_num_digits(vli); + if (num_digits == 0) + return 0; + + digit = vli[num_digits - 1]; + for (i = 0; digit; i++) + digit >>= 1; + + return ((num_digits - 1) * 64 + i); +} + +/* Sets dest = src. */ +static void vli_set(u64 *dest, const u64 *src) +{ + int i; + + for (i = 0; i < NUM_ECC_DIGITS; i++) + dest[i] = src[i]; +} + +/* Returns sign of left - right. */ +static int vli_cmp(const u64 *left, const u64 *right) +{ + int i; + + for (i = NUM_ECC_DIGITS - 1; i >= 0; i--) { + if (left[i] > right[i]) + return 1; + else if (left[i] < right[i]) + return -1; + } + + return 0; +} + +/* Computes result = in << c, returning carry. Can modify in place + * (if result == in). 0 < shift < 64. + */ +static u64 vli_lshift(u64 *result, const u64 *in, + unsigned int shift) +{ + u64 carry = 0; + int i; + + for (i = 0; i < NUM_ECC_DIGITS; i++) { + u64 temp = in[i]; + + result[i] = (temp << shift) | carry; + carry = temp >> (64 - shift); + } + + return carry; +} + +/* Computes vli = vli >> 1. */ +static void vli_rshift1(u64 *vli) +{ + u64 *end = vli; + u64 carry = 0; + + vli += NUM_ECC_DIGITS; + + while (vli-- > end) { + u64 temp = *vli; + *vli = (temp >> 1) | carry; + carry = temp << 63; + } +} + +/* Computes result = left + right, returning carry. Can modify in place. */ +static u64 vli_add(u64 *result, const u64 *left, + const u64 *right) +{ + u64 carry = 0; + int i; + + for (i = 0; i < NUM_ECC_DIGITS; i++) { + u64 sum; + + sum = left[i] + right[i] + carry; + if (sum != left[i]) + carry = (sum < left[i]); + + result[i] = sum; + } + + return carry; +} + +/* Computes result = left - right, returning borrow. Can modify in place. */ +static u64 vli_sub(u64 *result, const u64 *left, const u64 *right) +{ + u64 borrow = 0; + int i; + + for (i = 0; i < NUM_ECC_DIGITS; i++) { + u64 diff; + + diff = left[i] - right[i] - borrow; + if (diff != left[i]) + borrow = (diff > left[i]); + + result[i] = diff; + } + + return borrow; +} + +static uint128_t mul_64_64(u64 left, u64 right) +{ + u64 a0 = left & 0xffffffffull; + u64 a1 = left >> 32; + u64 b0 = right & 0xffffffffull; + u64 b1 = right >> 32; + u64 m0 = a0 * b0; + u64 m1 = a0 * b1; + u64 m2 = a1 * b0; + u64 m3 = a1 * b1; + uint128_t result; + + m2 += (m0 >> 32); + m2 += m1; + + /* Overflow */ + if (m2 < m1) + m3 += 0x100000000ull; + + result.m_low = (m0 & 0xffffffffull) | (m2 << 32); + result.m_high = m3 + (m2 >> 32); + + return result; +} + +static uint128_t add_128_128(uint128_t a, uint128_t b) +{ + uint128_t result; + + result.m_low = a.m_low + b.m_low; + result.m_high = a.m_high + b.m_high + (result.m_low < a.m_low); + + return result; +} + +static void vli_mult(u64 *result, const u64 *left, const u64 *right) +{ + uint128_t r01 = { 0, 0 }; + u64 r2 = 0; + unsigned int i, k; + + /* Compute each digit of result in sequence, maintaining the + * carries. + */ + for (k = 0; k < NUM_ECC_DIGITS * 2 - 1; k++) { + unsigned int min; + + if (k < NUM_ECC_DIGITS) + min = 0; + else + min = (k + 1) - NUM_ECC_DIGITS; + + for (i = min; i <= k && i < NUM_ECC_DIGITS; i++) { + uint128_t product; + + product = mul_64_64(left[i], right[k - i]); + + r01 = add_128_128(r01, product); + r2 += (r01.m_high < product.m_high); + } + + result[k] = r01.m_low; + r01.m_low = r01.m_high; + r01.m_high = r2; + r2 = 0; + } + + result[NUM_ECC_DIGITS * 2 - 1] = r01.m_low; +} + +static void vli_square(u64 *result, const u64 *left) +{ + uint128_t r01 = { 0, 0 }; + u64 r2 = 0; + int i, k; + + for (k = 0; k < NUM_ECC_DIGITS * 2 - 1; k++) { + unsigned int min; + + if (k < NUM_ECC_DIGITS) + min = 0; + else + min = (k + 1) - NUM_ECC_DIGITS; + + for (i = min; i <= k && i <= k - i; i++) { + uint128_t product; + + product = mul_64_64(left[i], left[k - i]); + + if (i < k - i) { + r2 += product.m_high >> 63; + product.m_high = (product.m_high << 1) | + (product.m_low >> 63); + product.m_low <<= 1; + } + + r01 = add_128_128(r01, product); + r2 += (r01.m_high < product.m_high); + } + + result[k] = r01.m_low; + r01.m_low = r01.m_high; + r01.m_high = r2; + r2 = 0; + } + + result[NUM_ECC_DIGITS * 2 - 1] = r01.m_low; +} + +/* Computes result = (left + right) % mod. + * Assumes that left < mod and right < mod, result != mod. + */ +static void vli_mod_add(u64 *result, const u64 *left, const u64 *right, + const u64 *mod) +{ + u64 carry; + + carry = vli_add(result, left, right); + + /* result > mod (result = mod + remainder), so subtract mod to + * get remainder. + */ + if (carry || vli_cmp(result, mod) >= 0) + vli_sub(result, result, mod); +} + +/* Computes result = (left - right) % mod. + * Assumes that left < mod and right < mod, result != mod. + */ +static void vli_mod_sub(u64 *result, const u64 *left, const u64 *right, + const u64 *mod) +{ + u64 borrow = vli_sub(result, left, right); + + /* In this case, p_result == -diff == (max int) - diff. + * Since -x % d == d - x, we can get the correct result from + * result + mod (with overflow). + */ + if (borrow) + vli_add(result, result, mod); +} + +/* Computes result = product % curve_p + from http://www.nsa.gov/ia/_files/nist-routines.pdf */ +static void vli_mmod_fast(u64 *result, const u64 *product) +{ + u64 tmp[NUM_ECC_DIGITS]; + int carry; + + /* t */ + vli_set(result, product); + + /* s1 */ + tmp[0] = 0; + tmp[1] = product[5] & 0xffffffff00000000ull; + tmp[2] = product[6]; + tmp[3] = product[7]; + carry = vli_lshift(tmp, tmp, 1); + carry += vli_add(result, result, tmp); + + /* s2 */ + tmp[1] = product[6] << 32; + tmp[2] = (product[6] >> 32) | (product[7] << 32); + tmp[3] = product[7] >> 32; + carry += vli_lshift(tmp, tmp, 1); + carry += vli_add(result, result, tmp); + + /* s3 */ + tmp[0] = product[4]; + tmp[1] = product[5] & 0xffffffff; + tmp[2] = 0; + tmp[3] = product[7]; + carry += vli_add(result, result, tmp); + + /* s4 */ + tmp[0] = (product[4] >> 32) | (product[5] << 32); + tmp[1] = (product[5] >> 32) | (product[6] & 0xffffffff00000000ull); + tmp[2] = product[7]; + tmp[3] = (product[6] >> 32) | (product[4] << 32); + carry += vli_add(result, result, tmp); + + /* d1 */ + tmp[0] = (product[5] >> 32) | (product[6] << 32); + tmp[1] = (product[6] >> 32); + tmp[2] = 0; + tmp[3] = (product[4] & 0xffffffff) | (product[5] << 32); + carry -= vli_sub(result, result, tmp); + + /* d2 */ + tmp[0] = product[6]; + tmp[1] = product[7]; + tmp[2] = 0; + tmp[3] = (product[4] >> 32) | (product[5] & 0xffffffff00000000ull); + carry -= vli_sub(result, result, tmp); + + /* d3 */ + tmp[0] = (product[6] >> 32) | (product[7] << 32); + tmp[1] = (product[7] >> 32) | (product[4] << 32); + tmp[2] = (product[4] >> 32) | (product[5] << 32); + tmp[3] = (product[6] << 32); + carry -= vli_sub(result, result, tmp); + + /* d4 */ + tmp[0] = product[7]; + tmp[1] = product[4] & 0xffffffff00000000ull; + tmp[2] = product[5]; + tmp[3] = product[6] & 0xffffffff00000000ull; + carry -= vli_sub(result, result, tmp); + + if (carry < 0) { + do { + carry += vli_add(result, result, curve_p); + } while (carry < 0); + } else { + while (carry || vli_cmp(curve_p, result) != 1) + carry -= vli_sub(result, result, curve_p); + } +} + +/* Computes result = (left * right) % curve_p. */ +static void vli_mod_mult_fast(u64 *result, const u64 *left, const u64 *right) +{ + u64 product[2 * NUM_ECC_DIGITS]; + + vli_mult(product, left, right); + vli_mmod_fast(result, product); +} + +/* Computes result = left^2 % curve_p. */ +static void vli_mod_square_fast(u64 *result, const u64 *left) +{ + u64 product[2 * NUM_ECC_DIGITS]; + + vli_square(product, left); + vli_mmod_fast(result, product); +} + +#define EVEN(vli) (!(vli[0] & 1)) +/* Computes result = (1 / p_input) % mod. All VLIs are the same size. + * See "From Euclid's GCD to Montgomery Multiplication to the Great Divide" + * https://labs.oracle.com/techrep/2001/smli_tr-2001-95.pdf + */ +static void vli_mod_inv(u64 *result, const u64 *input, const u64 *mod) +{ + u64 a[NUM_ECC_DIGITS], b[NUM_ECC_DIGITS]; + u64 u[NUM_ECC_DIGITS], v[NUM_ECC_DIGITS]; + u64 carry; + int cmp_result; + + if (vli_is_zero(input)) { + vli_clear(result); + return; + } + + vli_set(a, input); + vli_set(b, mod); + vli_clear(u); + u[0] = 1; + vli_clear(v); + + while ((cmp_result = vli_cmp(a, b)) != 0) { + carry = 0; + + if (EVEN(a)) { + vli_rshift1(a); + + if (!EVEN(u)) + carry = vli_add(u, u, mod); + + vli_rshift1(u); + if (carry) + u[NUM_ECC_DIGITS - 1] |= 0x8000000000000000ull; + } else if (EVEN(b)) { + vli_rshift1(b); + + if (!EVEN(v)) + carry = vli_add(v, v, mod); + + vli_rshift1(v); + if (carry) + v[NUM_ECC_DIGITS - 1] |= 0x8000000000000000ull; + } else if (cmp_result > 0) { + vli_sub(a, a, b); + vli_rshift1(a); + + if (vli_cmp(u, v) < 0) + vli_add(u, u, mod); + + vli_sub(u, u, v); + if (!EVEN(u)) + carry = vli_add(u, u, mod); + + vli_rshift1(u); + if (carry) + u[NUM_ECC_DIGITS - 1] |= 0x8000000000000000ull; + } else { + vli_sub(b, b, a); + vli_rshift1(b); + + if (vli_cmp(v, u) < 0) + vli_add(v, v, mod); + + vli_sub(v, v, u); + if (!EVEN(v)) + carry = vli_add(v, v, mod); + + vli_rshift1(v); + if (carry) + v[NUM_ECC_DIGITS - 1] |= 0x8000000000000000ull; + } + } + + vli_set(result, u); +} + +/* ------ Point operations ------ */ + +/* Returns true if p_point is the point at infinity, false otherwise. */ +static bool ecc_point_is_zero(const struct ecc_point *point) +{ + return (vli_is_zero(point->x) && vli_is_zero(point->y)); +} + +/* Point multiplication algorithm using Montgomery's ladder with co-Z + * coordinates. From http://eprint.iacr.org/2011/338.pdf + */ + +/* Double in place */ +static void ecc_point_double_jacobian(u64 *x1, u64 *y1, u64 *z1) +{ + /* t1 = x, t2 = y, t3 = z */ + u64 t4[NUM_ECC_DIGITS]; + u64 t5[NUM_ECC_DIGITS]; + + if (vli_is_zero(z1)) + return; + + vli_mod_square_fast(t4, y1); /* t4 = y1^2 */ + vli_mod_mult_fast(t5, x1, t4); /* t5 = x1*y1^2 = A */ + vli_mod_square_fast(t4, t4); /* t4 = y1^4 */ + vli_mod_mult_fast(y1, y1, z1); /* t2 = y1*z1 = z3 */ + vli_mod_square_fast(z1, z1); /* t3 = z1^2 */ + + vli_mod_add(x1, x1, z1, curve_p); /* t1 = x1 + z1^2 */ + vli_mod_add(z1, z1, z1, curve_p); /* t3 = 2*z1^2 */ + vli_mod_sub(z1, x1, z1, curve_p); /* t3 = x1 - z1^2 */ + vli_mod_mult_fast(x1, x1, z1); /* t1 = x1^2 - z1^4 */ + + vli_mod_add(z1, x1, x1, curve_p); /* t3 = 2*(x1^2 - z1^4) */ + vli_mod_add(x1, x1, z1, curve_p); /* t1 = 3*(x1^2 - z1^4) */ + if (vli_test_bit(x1, 0)) { + u64 carry = vli_add(x1, x1, curve_p); + vli_rshift1(x1); + x1[NUM_ECC_DIGITS - 1] |= carry << 63; + } else { + vli_rshift1(x1); + } + /* t1 = 3/2*(x1^2 - z1^4) = B */ + + vli_mod_square_fast(z1, x1); /* t3 = B^2 */ + vli_mod_sub(z1, z1, t5, curve_p); /* t3 = B^2 - A */ + vli_mod_sub(z1, z1, t5, curve_p); /* t3 = B^2 - 2A = x3 */ + vli_mod_sub(t5, t5, z1, curve_p); /* t5 = A - x3 */ + vli_mod_mult_fast(x1, x1, t5); /* t1 = B * (A - x3) */ + vli_mod_sub(t4, x1, t4, curve_p); /* t4 = B * (A - x3) - y1^4 = y3 */ + + vli_set(x1, z1); + vli_set(z1, y1); + vli_set(y1, t4); +} + +/* Modify (x1, y1) => (x1 * z^2, y1 * z^3) */ +static void apply_z(u64 *x1, u64 *y1, u64 *z) +{ + u64 t1[NUM_ECC_DIGITS]; + + vli_mod_square_fast(t1, z); /* z^2 */ + vli_mod_mult_fast(x1, x1, t1); /* x1 * z^2 */ + vli_mod_mult_fast(t1, t1, z); /* z^3 */ + vli_mod_mult_fast(y1, y1, t1); /* y1 * z^3 */ +} + +/* P = (x1, y1) => 2P, (x2, y2) => P' */ +static void xycz_initial_double(u64 *x1, u64 *y1, u64 *x2, u64 *y2, + u64 *p_initial_z) +{ + u64 z[NUM_ECC_DIGITS]; + + vli_set(x2, x1); + vli_set(y2, y1); + + vli_clear(z); + z[0] = 1; + + if (p_initial_z) + vli_set(z, p_initial_z); + + apply_z(x1, y1, z); + + ecc_point_double_jacobian(x1, y1, z); + + apply_z(x2, y2, z); +} + +/* Input P = (x1, y1, Z), Q = (x2, y2, Z) + * Output P' = (x1', y1', Z3), P + Q = (x3, y3, Z3) + * or P => P', Q => P + Q + */ +static void xycz_add(u64 *x1, u64 *y1, u64 *x2, u64 *y2) +{ + /* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */ + u64 t5[NUM_ECC_DIGITS]; + + vli_mod_sub(t5, x2, x1, curve_p); /* t5 = x2 - x1 */ + vli_mod_square_fast(t5, t5); /* t5 = (x2 - x1)^2 = A */ + vli_mod_mult_fast(x1, x1, t5); /* t1 = x1*A = B */ + vli_mod_mult_fast(x2, x2, t5); /* t3 = x2*A = C */ + vli_mod_sub(y2, y2, y1, curve_p); /* t4 = y2 - y1 */ + vli_mod_square_fast(t5, y2); /* t5 = (y2 - y1)^2 = D */ + + vli_mod_sub(t5, t5, x1, curve_p); /* t5 = D - B */ + vli_mod_sub(t5, t5, x2, curve_p); /* t5 = D - B - C = x3 */ + vli_mod_sub(x2, x2, x1, curve_p); /* t3 = C - B */ + vli_mod_mult_fast(y1, y1, x2); /* t2 = y1*(C - B) */ + vli_mod_sub(x2, x1, t5, curve_p); /* t3 = B - x3 */ + vli_mod_mult_fast(y2, y2, x2); /* t4 = (y2 - y1)*(B - x3) */ + vli_mod_sub(y2, y2, y1, curve_p); /* t4 = y3 */ + + vli_set(x2, t5); +} + +/* Input P = (x1, y1, Z), Q = (x2, y2, Z) + * Output P + Q = (x3, y3, Z3), P - Q = (x3', y3', Z3) + * or P => P - Q, Q => P + Q + */ +static void xycz_add_c(u64 *x1, u64 *y1, u64 *x2, u64 *y2) +{ + /* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */ + u64 t5[NUM_ECC_DIGITS]; + u64 t6[NUM_ECC_DIGITS]; + u64 t7[NUM_ECC_DIGITS]; + + vli_mod_sub(t5, x2, x1, curve_p); /* t5 = x2 - x1 */ + vli_mod_square_fast(t5, t5); /* t5 = (x2 - x1)^2 = A */ + vli_mod_mult_fast(x1, x1, t5); /* t1 = x1*A = B */ + vli_mod_mult_fast(x2, x2, t5); /* t3 = x2*A = C */ + vli_mod_add(t5, y2, y1, curve_p); /* t4 = y2 + y1 */ + vli_mod_sub(y2, y2, y1, curve_p); /* t4 = y2 - y1 */ + + vli_mod_sub(t6, x2, x1, curve_p); /* t6 = C - B */ + vli_mod_mult_fast(y1, y1, t6); /* t2 = y1 * (C - B) */ + vli_mod_add(t6, x1, x2, curve_p); /* t6 = B + C */ + vli_mod_square_fast(x2, y2); /* t3 = (y2 - y1)^2 */ + vli_mod_sub(x2, x2, t6, curve_p); /* t3 = x3 */ + + vli_mod_sub(t7, x1, x2, curve_p); /* t7 = B - x3 */ + vli_mod_mult_fast(y2, y2, t7); /* t4 = (y2 - y1)*(B - x3) */ + vli_mod_sub(y2, y2, y1, curve_p); /* t4 = y3 */ + + vli_mod_square_fast(t7, t5); /* t7 = (y2 + y1)^2 = F */ + vli_mod_sub(t7, t7, t6, curve_p); /* t7 = x3' */ + vli_mod_sub(t6, t7, x1, curve_p); /* t6 = x3' - B */ + vli_mod_mult_fast(t6, t6, t5); /* t6 = (y2 + y1)*(x3' - B) */ + vli_mod_sub(y1, t6, y1, curve_p); /* t2 = y3' */ + + vli_set(x1, t7); +} + +static void ecc_point_mult(struct ecc_point *result, + const struct ecc_point *point, u64 *scalar, + u64 *initial_z, int num_bits) +{ + /* R0 and R1 */ + u64 rx[2][NUM_ECC_DIGITS]; + u64 ry[2][NUM_ECC_DIGITS]; + u64 z[NUM_ECC_DIGITS]; + int i, nb; + + vli_set(rx[1], point->x); + vli_set(ry[1], point->y); + + xycz_initial_double(rx[1], ry[1], rx[0], ry[0], initial_z); + + for (i = num_bits - 2; i > 0; i--) { + nb = !vli_test_bit(scalar, i); + xycz_add_c(rx[1 - nb], ry[1 - nb], rx[nb], ry[nb]); + xycz_add(rx[nb], ry[nb], rx[1 - nb], ry[1 - nb]); + } + + nb = !vli_test_bit(scalar, 0); + xycz_add_c(rx[1 - nb], ry[1 - nb], rx[nb], ry[nb]); + + /* Find final 1/Z value. */ + vli_mod_sub(z, rx[1], rx[0], curve_p); /* X1 - X0 */ + vli_mod_mult_fast(z, z, ry[1 - nb]); /* Yb * (X1 - X0) */ + vli_mod_mult_fast(z, z, point->x); /* xP * Yb * (X1 - X0) */ + vli_mod_inv(z, z, curve_p); /* 1 / (xP * Yb * (X1 - X0)) */ + vli_mod_mult_fast(z, z, point->y); /* yP / (xP * Yb * (X1 - X0)) */ + vli_mod_mult_fast(z, z, rx[1 - nb]); /* Xb * yP / (xP * Yb * (X1 - X0)) */ + /* End 1/Z calculation */ + + xycz_add(rx[nb], ry[nb], rx[1 - nb], ry[1 - nb]); + + apply_z(rx[0], ry[0], z); + + vli_set(result->x, rx[0]); + vli_set(result->y, ry[0]); +} + +static void ecc_bytes2native(const u8 bytes[ECC_BYTES], + u64 native[NUM_ECC_DIGITS]) +{ + int i; + + for (i = 0; i < NUM_ECC_DIGITS; i++) { + const u8 *digit = bytes + 8 * (NUM_ECC_DIGITS - 1 - i); + + native[NUM_ECC_DIGITS - 1 - i] = + ((u64) digit[0] << 0) | + ((u64) digit[1] << 8) | + ((u64) digit[2] << 16) | + ((u64) digit[3] << 24) | + ((u64) digit[4] << 32) | + ((u64) digit[5] << 40) | + ((u64) digit[6] << 48) | + ((u64) digit[7] << 56); + } +} + +static void ecc_native2bytes(const u64 native[NUM_ECC_DIGITS], + u8 bytes[ECC_BYTES]) +{ + int i; + + for (i = 0; i < NUM_ECC_DIGITS; i++) { + u8 *digit = bytes + 8 * (NUM_ECC_DIGITS - 1 - i); + + digit[0] = native[NUM_ECC_DIGITS - 1 - i] >> 0; + digit[1] = native[NUM_ECC_DIGITS - 1 - i] >> 8; + digit[2] = native[NUM_ECC_DIGITS - 1 - i] >> 16; + digit[3] = native[NUM_ECC_DIGITS - 1 - i] >> 24; + digit[4] = native[NUM_ECC_DIGITS - 1 - i] >> 32; + digit[5] = native[NUM_ECC_DIGITS - 1 - i] >> 40; + digit[6] = native[NUM_ECC_DIGITS - 1 - i] >> 48; + digit[7] = native[NUM_ECC_DIGITS - 1 - i] >> 56; + } +} + +bool ecc_make_key(u8 public_key[64], u8 private_key[32]) +{ + struct ecc_point pk; + u64 priv[NUM_ECC_DIGITS]; + unsigned int tries = 0; + + do { + if (tries++ >= MAX_TRIES) + return false; + + get_random_bytes(priv, ECC_BYTES); + + if (vli_is_zero(priv)) + continue; + + /* Make sure the private key is in the range [1, n-1]. */ + if (vli_cmp(curve_n, priv) != 1) + continue; + + ecc_point_mult(&pk, &curve_g, priv, NULL, vli_num_bits(priv)); + } while (ecc_point_is_zero(&pk)); + + ecc_native2bytes(priv, private_key); + ecc_native2bytes(pk.x, public_key); + ecc_native2bytes(pk.y, &public_key[32]); + + return true; +} + +bool ecdh_shared_secret(const u8 public_key[64], const u8 private_key[32], + u8 secret[32]) +{ + u64 priv[NUM_ECC_DIGITS]; + u64 rand[NUM_ECC_DIGITS]; + struct ecc_point product, pk; + + get_random_bytes(rand, ECC_BYTES); + + ecc_bytes2native(public_key, pk.x); + ecc_bytes2native(&public_key[32], pk.y); + ecc_bytes2native(private_key, priv); + + ecc_point_mult(&product, &pk, priv, rand, vli_num_bits(priv)); + + ecc_native2bytes(product.x, secret); + + return !ecc_point_is_zero(&product); +} |