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diff --git a/comm/third_party/libgcrypt/mpi/mpi-inv.c b/comm/third_party/libgcrypt/mpi/mpi-inv.c
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+/* mpi-inv.c - MPI functions
+ * Copyright (C) 1998, 2001, 2002, 2003 Free Software Foundation, Inc.
+ *
+ * This file is part of Libgcrypt.
+ *
+ * Libgcrypt is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * Libgcrypt is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "mpi-internal.h"
+#include "g10lib.h"
+
+/*
+ * This uses a modular inversion algorithm designed by Niels Möller
+ * which was implemented in Nettle. The same algorithm was later also
+ * adapted to GMP in mpn_sec_invert.
+ *
+ * For the description of the algorithm, see Algorithm 5 in Appendix A
+ * of "Fast Software Polynomial Multiplication on ARM Processors using
+ * the NEON Engine" by Danilo Câmara, Conrado P. L. Gouvêa, Julio
+ * López, and Ricardo Dahab:
+ * https://hal.inria.fr/hal-01506572/document
+ *
+ * Note that in the reference above, at the line 2 of Algorithm 5,
+ * initial value of V was described as V:=1 wrongly. It must be V:=0.
+ */
+static mpi_ptr_t
+mpih_invm_odd (mpi_ptr_t ap, mpi_ptr_t np, mpi_size_t nsize)
+{
+ int secure;
+ unsigned int iterations;
+ mpi_ptr_t n1hp;
+ mpi_ptr_t bp;
+ mpi_ptr_t up, vp;
+
+ secure = _gcry_is_secure (ap);
+ up = mpi_alloc_limb_space (nsize, secure);
+ MPN_ZERO (up, nsize);
+ up[0] = 1;
+
+ vp = mpi_alloc_limb_space (nsize, secure);
+ MPN_ZERO (vp, nsize);
+
+ secure = _gcry_is_secure (np);
+ bp = mpi_alloc_limb_space (nsize, secure);
+ MPN_COPY (bp, np, nsize);
+
+ n1hp = mpi_alloc_limb_space (nsize, secure);
+ MPN_COPY (n1hp, np, nsize);
+ _gcry_mpih_rshift (n1hp, n1hp, nsize, 1);
+ _gcry_mpih_add_1 (n1hp, n1hp, nsize, 1);
+
+ iterations = 2 * nsize * BITS_PER_MPI_LIMB;
+
+ while (iterations-- > 0)
+ {
+ mpi_limb_t odd_a, odd_u, underflow, borrow;
+
+ odd_a = ap[0] & 1;
+
+ underflow = mpih_sub_n_cond (ap, ap, bp, nsize, odd_a);
+ mpih_add_n_cond (bp, bp, ap, nsize, underflow);
+ mpih_abs_cond (ap, ap, nsize, underflow);
+ mpih_swap_cond (up, vp, nsize, underflow);
+
+ _gcry_mpih_rshift (ap, ap, nsize, 1);
+
+ borrow = mpih_sub_n_cond (up, up, vp, nsize, odd_a);
+ mpih_add_n_cond (up, up, np, nsize, borrow);
+
+ odd_u = _gcry_mpih_rshift (up, up, nsize, 1) != 0;
+ mpih_add_n_cond (up, up, n1hp, nsize, odd_u);
+ }
+
+ _gcry_mpi_free_limb_space (n1hp, nsize);
+ _gcry_mpi_free_limb_space (up, nsize);
+
+ if (_gcry_mpih_cmp_ui (bp, nsize, 1) == 0)
+ {
+ /* Inverse exists. */
+ _gcry_mpi_free_limb_space (bp, nsize);
+ return vp;
+ }
+ else
+ {
+ _gcry_mpi_free_limb_space (bp, nsize);
+ _gcry_mpi_free_limb_space (vp, nsize);
+ return NULL;
+ }
+}
+
+
+/*
+ * Calculate the multiplicative inverse X of A mod 2^K
+ * A must be positive.
+ *
+ * See section 7 in "A New Algorithm for Inversion mod p^k" by Çetin
+ * Kaya Koç: https://eprint.iacr.org/2017/411.pdf
+ */
+static mpi_ptr_t
+mpih_invm_pow2 (mpi_ptr_t ap, mpi_size_t asize, unsigned int k)
+{
+ int secure = _gcry_is_secure (ap);
+ mpi_size_t i;
+ unsigned int iterations;
+ mpi_ptr_t xp, wp, up, vp;
+ mpi_size_t usize;
+
+ if (!(ap[0] & 1))
+ return NULL;
+
+ iterations = ((k + BITS_PER_MPI_LIMB - 1) / BITS_PER_MPI_LIMB)
+ * BITS_PER_MPI_LIMB;
+ usize = iterations / BITS_PER_MPI_LIMB;
+
+ up = mpi_alloc_limb_space (usize, secure);
+ MPN_ZERO (up, usize);
+ up[0] = 1;
+
+ vp = mpi_alloc_limb_space (usize, secure);
+ for (i = 0; i < (usize < asize ? usize : asize); i++)
+ vp[i] = ap[i];
+ for (; i < usize; i++)
+ vp[i] = 0;
+ if ((k % BITS_PER_MPI_LIMB))
+ for (i = k % BITS_PER_MPI_LIMB; i < BITS_PER_MPI_LIMB; i++)
+ vp[k/BITS_PER_MPI_LIMB] &= ~(((mpi_limb_t)1) << i);
+
+ wp = mpi_alloc_limb_space (usize, secure);
+ MPN_COPY (wp, up, usize);
+
+ xp = mpi_alloc_limb_space (usize, secure);
+ MPN_ZERO (xp, usize);
+
+ /*
+ * It can be considered that overflow at _gcry_mpih_sub_n results
+ * adding 2^(USIZE*BITS_PER_MPI_LIMB), which is no problem in modulo
+ * 2^K computation.
+ */
+ for (i = 0; i < iterations; i++)
+ {
+ int b0 = (up[0] & 1);
+
+ xp[i/BITS_PER_MPI_LIMB] |= ((mpi_limb_t)b0<<(i%BITS_PER_MPI_LIMB));
+ _gcry_mpih_sub_n (wp, up, vp, usize);
+ mpih_set_cond (up, wp, usize, b0);
+ _gcry_mpih_rshift (up, up, usize, 1);
+ }
+
+ if ((k % BITS_PER_MPI_LIMB))
+ for (i = k % BITS_PER_MPI_LIMB; i < BITS_PER_MPI_LIMB; i++)
+ xp[k/BITS_PER_MPI_LIMB] &= ~(((mpi_limb_t)1) << i);
+
+ _gcry_mpi_free_limb_space (up, usize);
+ _gcry_mpi_free_limb_space (vp, usize);
+ _gcry_mpi_free_limb_space (wp, usize);
+
+ return xp;
+}
+
+
+/****************
+ * Calculate the multiplicative inverse X of A mod N
+ * That is: Find the solution x for
+ * 1 = (a*x) mod n
+ */
+static int
+mpi_invm_generic (gcry_mpi_t x, gcry_mpi_t a, gcry_mpi_t n)
+{
+ int is_gcd_one;
+#if 0
+ /* Extended Euclid's algorithm (See TAOCP Vol II, 4.5.2, Alg X) */
+ gcry_mpi_t u, v, u1, u2, u3, v1, v2, v3, q, t1, t2, t3;
+
+ u = mpi_copy(a);
+ v = mpi_copy(n);
+ u1 = mpi_alloc_set_ui(1);
+ u2 = mpi_alloc_set_ui(0);
+ u3 = mpi_copy(u);
+ v1 = mpi_alloc_set_ui(0);
+ v2 = mpi_alloc_set_ui(1);
+ v3 = mpi_copy(v);
+ q = mpi_alloc( mpi_get_nlimbs(u)+1 );
+ t1 = mpi_alloc( mpi_get_nlimbs(u)+1 );
+ t2 = mpi_alloc( mpi_get_nlimbs(u)+1 );
+ t3 = mpi_alloc( mpi_get_nlimbs(u)+1 );
+ while( mpi_cmp_ui( v3, 0 ) ) {
+ mpi_fdiv_q( q, u3, v3 );
+ mpi_mul(t1, v1, q); mpi_mul(t2, v2, q); mpi_mul(t3, v3, q);
+ mpi_sub(t1, u1, t1); mpi_sub(t2, u2, t2); mpi_sub(t3, u3, t3);
+ mpi_set(u1, v1); mpi_set(u2, v2); mpi_set(u3, v3);
+ mpi_set(v1, t1); mpi_set(v2, t2); mpi_set(v3, t3);
+ }
+ /* log_debug("result:\n");
+ log_mpidump("q =", q );
+ log_mpidump("u1=", u1);
+ log_mpidump("u2=", u2);
+ log_mpidump("u3=", u3);
+ log_mpidump("v1=", v1);
+ log_mpidump("v2=", v2); */
+ mpi_set(x, u1);
+
+ is_gcd_one = (mpi_cmp_ui (u3, 1) == 0);
+
+ mpi_free(u1);
+ mpi_free(u2);
+ mpi_free(u3);
+ mpi_free(v1);
+ mpi_free(v2);
+ mpi_free(v3);
+ mpi_free(q);
+ mpi_free(t1);
+ mpi_free(t2);
+ mpi_free(t3);
+ mpi_free(u);
+ mpi_free(v);
+#elif 0
+ /* Extended Euclid's algorithm (See TAOCP Vol II, 4.5.2, Alg X)
+ * modified according to Michael Penk's solution for Exercise 35
+ * (in the first edition)
+ * In the third edition, it's Exercise 39, and it is described in
+ * page 646 of ANSWERS TO EXERCISES chapter.
+ */
+
+ /* FIXME: we can simplify this in most cases (see Knuth) */
+ gcry_mpi_t u, v, u1, u2, u3, v1, v2, v3, t1, t2, t3;
+ unsigned k;
+ int sign;
+
+ u = mpi_copy(a);
+ v = mpi_copy(n);
+ for(k=0; !mpi_test_bit(u,0) && !mpi_test_bit(v,0); k++ ) {
+ mpi_rshift(u, u, 1);
+ mpi_rshift(v, v, 1);
+ }
+
+
+ u1 = mpi_alloc_set_ui(1);
+ u2 = mpi_alloc_set_ui(0);
+ u3 = mpi_copy(u);
+ v1 = mpi_copy(v); /* !-- used as const 1 */
+ v2 = mpi_alloc( mpi_get_nlimbs(u) ); mpi_sub( v2, u1, u );
+ v3 = mpi_copy(v);
+ if( mpi_test_bit(u, 0) ) { /* u is odd */
+ t1 = mpi_alloc_set_ui(0);
+ t2 = mpi_alloc_set_ui(1); t2->sign = 1;
+ t3 = mpi_copy(v); t3->sign = !t3->sign;
+ goto Y4;
+ }
+ else {
+ t1 = mpi_alloc_set_ui(1);
+ t2 = mpi_alloc_set_ui(0);
+ t3 = mpi_copy(u);
+ }
+ do {
+ do {
+ if( mpi_test_bit(t1, 0) || mpi_test_bit(t2, 0) ) { /* one is odd */
+ mpi_add(t1, t1, v);
+ mpi_sub(t2, t2, u);
+ }
+ mpi_rshift(t1, t1, 1);
+ mpi_rshift(t2, t2, 1);
+ mpi_rshift(t3, t3, 1);
+ Y4:
+ ;
+ } while( !mpi_test_bit( t3, 0 ) ); /* while t3 is even */
+
+ if( !t3->sign ) {
+ mpi_set(u1, t1);
+ mpi_set(u2, t2);
+ mpi_set(u3, t3);
+ }
+ else {
+ mpi_sub(v1, v, t1);
+ sign = u->sign; u->sign = !u->sign;
+ mpi_sub(v2, u, t2);
+ u->sign = sign;
+ sign = t3->sign; t3->sign = !t3->sign;
+ mpi_set(v3, t3);
+ t3->sign = sign;
+ }
+ mpi_sub(t1, u1, v1);
+ mpi_sub(t2, u2, v2);
+ mpi_sub(t3, u3, v3);
+ if( t1->sign ) {
+ mpi_add(t1, t1, v);
+ mpi_sub(t2, t2, u);
+ }
+ } while( mpi_cmp_ui( t3, 0 ) ); /* while t3 != 0 */
+ /* mpi_lshift( u3, u3, k ); */
+ is_gcd_one = (k == 0 && mpi_cmp_ui (u3, 1) == 0);
+ mpi_set(x, u1);
+
+ mpi_free(u1);
+ mpi_free(u2);
+ mpi_free(u3);
+ mpi_free(v1);
+ mpi_free(v2);
+ mpi_free(v3);
+ mpi_free(t1);
+ mpi_free(t2);
+ mpi_free(t3);
+#else
+ /* Extended Euclid's algorithm (See TAOCP Vol II, 4.5.2, Alg X)
+ * modified according to Michael Penk's solution for Exercise 35
+ * with further enhancement */
+ /* The reference in the comment above is for the first edition.
+ * In the third edition, it's Exercise 39, and it is described in
+ * page 646 of ANSWERS TO EXERCISES chapter.
+ */
+ gcry_mpi_t u, v, u1, u2=NULL, u3, v1, v2=NULL, v3, t1, t2=NULL, t3;
+ unsigned k;
+ int sign;
+ int odd ;
+
+ u = mpi_copy(a);
+ v = mpi_copy(n);
+
+ for(k=0; !mpi_test_bit(u,0) && !mpi_test_bit(v,0); k++ ) {
+ mpi_rshift(u, u, 1);
+ mpi_rshift(v, v, 1);
+ }
+ odd = mpi_test_bit(v,0);
+
+ u1 = mpi_alloc_set_ui(1);
+ if( !odd )
+ u2 = mpi_alloc_set_ui(0);
+ u3 = mpi_copy(u);
+ v1 = mpi_copy(v);
+ if( !odd ) {
+ v2 = mpi_alloc( mpi_get_nlimbs(u) );
+ mpi_sub( v2, u1, u ); /* U is used as const 1 */
+ }
+ v3 = mpi_copy(v);
+ if( mpi_test_bit(u, 0) ) { /* u is odd */
+ t1 = mpi_alloc_set_ui(0);
+ if( !odd ) {
+ t2 = mpi_alloc_set_ui(1); t2->sign = 1;
+ }
+ t3 = mpi_copy(v); t3->sign = !t3->sign;
+ goto Y4;
+ }
+ else {
+ t1 = mpi_alloc_set_ui(1);
+ if( !odd )
+ t2 = mpi_alloc_set_ui(0);
+ t3 = mpi_copy(u);
+ }
+ do {
+ do {
+ if( !odd ) {
+ if( mpi_test_bit(t1, 0) || mpi_test_bit(t2, 0) ) { /* one is odd */
+ mpi_add(t1, t1, v);
+ mpi_sub(t2, t2, u);
+ }
+ mpi_rshift(t1, t1, 1);
+ mpi_rshift(t2, t2, 1);
+ mpi_rshift(t3, t3, 1);
+ }
+ else {
+ if( mpi_test_bit(t1, 0) )
+ mpi_add(t1, t1, v);
+ mpi_rshift(t1, t1, 1);
+ mpi_rshift(t3, t3, 1);
+ }
+ Y4:
+ ;
+ } while( !mpi_test_bit( t3, 0 ) ); /* while t3 is even */
+
+ if( !t3->sign ) {
+ mpi_set(u1, t1);
+ if( !odd )
+ mpi_set(u2, t2);
+ mpi_set(u3, t3);
+ }
+ else {
+ mpi_sub(v1, v, t1);
+ sign = u->sign; u->sign = !u->sign;
+ if( !odd )
+ mpi_sub(v2, u, t2);
+ u->sign = sign;
+ sign = t3->sign; t3->sign = !t3->sign;
+ mpi_set(v3, t3);
+ t3->sign = sign;
+ }
+ mpi_sub(t1, u1, v1);
+ if( !odd )
+ mpi_sub(t2, u2, v2);
+ mpi_sub(t3, u3, v3);
+ if( t1->sign ) {
+ mpi_add(t1, t1, v);
+ if( !odd )
+ mpi_sub(t2, t2, u);
+ }
+ } while( mpi_cmp_ui( t3, 0 ) ); /* while t3 != 0 */
+ /* mpi_lshift( u3, u3, k ); */
+ is_gcd_one = (k == 0 && mpi_cmp_ui (u3, 1) == 0);
+ mpi_set(x, u1);
+
+ mpi_free(u1);
+ mpi_free(v1);
+ mpi_free(t1);
+ if( !odd ) {
+ mpi_free(u2);
+ mpi_free(v2);
+ mpi_free(t2);
+ }
+ mpi_free(u3);
+ mpi_free(v3);
+ mpi_free(t3);
+
+ mpi_free(u);
+ mpi_free(v);
+#endif
+ return is_gcd_one;
+}
+
+
+/*
+ * Set X to the multiplicative inverse of A mod M. Return true if the
+ * inverse exists.
+ */
+int
+_gcry_mpi_invm (gcry_mpi_t x, gcry_mpi_t a, gcry_mpi_t n)
+{
+ mpi_ptr_t ap, xp;
+
+ if (!mpi_cmp_ui (a, 0))
+ return 0; /* Inverse does not exists. */
+ if (!mpi_cmp_ui (n, 1))
+ return 0; /* Inverse does not exists. */
+
+ if (mpi_test_bit (n, 0))
+ {
+ if (a->nlimbs <= n->nlimbs)
+ {
+ ap = mpi_alloc_limb_space (n->nlimbs, _gcry_is_secure (a->d));
+ MPN_ZERO (ap, n->nlimbs);
+ MPN_COPY (ap, a->d, a->nlimbs);
+ }
+ else
+ ap = _gcry_mpih_mod (a->d, a->nlimbs, n->d, n->nlimbs);
+
+ xp = mpih_invm_odd (ap, n->d, n->nlimbs);
+ _gcry_mpi_free_limb_space (ap, n->nlimbs);
+
+ if (xp)
+ {
+ _gcry_mpi_assign_limb_space (x, xp, n->nlimbs);
+ x->nlimbs = n->nlimbs;
+ return 1;
+ }
+ else
+ return 0; /* Inverse does not exists. */
+ }
+ else if (!a->sign && !n->sign)
+ {
+ unsigned int k = mpi_trailing_zeros (n);
+ mpi_size_t x1size = ((k + BITS_PER_MPI_LIMB - 1) / BITS_PER_MPI_LIMB);
+ mpi_size_t hsize;
+ gcry_mpi_t q;
+ mpi_ptr_t x1p, x2p, q_invp, hp, diffp;
+ mpi_size_t i;
+
+ if (k == _gcry_mpi_get_nbits (n) - 1)
+ {
+ x1p = mpih_invm_pow2 (a->d, a->nlimbs, k);
+
+ if (x1p)
+ {
+ _gcry_mpi_assign_limb_space (x, x1p, x1size);
+ x->nlimbs = x1size;
+ return 1;
+ }
+ else
+ return 0; /* Inverse does not exists. */
+ }
+
+ /* N can be expressed as P * Q, where P = 2^K. P and Q are coprime. */
+ /*
+ * Compute X1 = invm (A, P) and X2 = invm (A, Q), and combine
+ * them by Garner's formula, to get X = invm (A, P*Q).
+ * A special case of Chinese Remainder Theorem.
+ */
+
+ /* X1 = invm (A, P) */
+ x1p = mpih_invm_pow2 (a->d, a->nlimbs, k);
+ if (!x1p)
+ return 0; /* Inverse does not exists. */
+
+ /* Q = N / P */
+ q = mpi_new (0);
+ mpi_rshift (q, n, k);
+
+ /* X2 = invm (A%Q, Q) */
+ ap = _gcry_mpih_mod (a->d, a->nlimbs, q->d, q->nlimbs);
+ x2p = mpih_invm_odd (ap, q->d, q->nlimbs);
+ _gcry_mpi_free_limb_space (ap, q->nlimbs);
+ if (!x2p)
+ {
+ _gcry_mpi_free_limb_space (x1p, x1size);
+ mpi_free (q);
+ return 0; /* Inverse does not exists. */
+ }
+
+ /* Q_inv = Q^(-1) = invm (Q, P) */
+ q_invp = mpih_invm_pow2 (q->d, q->nlimbs, k);
+
+ /* H = (X1 - X2) * Q_inv % P */
+ diffp = mpi_alloc_limb_space (x1size, _gcry_is_secure (a->d));
+ if (x1size >= q->nlimbs)
+ _gcry_mpih_sub (diffp, x1p, x1size, x2p, q->nlimbs);
+ else
+ _gcry_mpih_sub_n (diffp, x1p, x2p, x1size);
+ _gcry_mpi_free_limb_space (x1p, x1size);
+ if ((k % BITS_PER_MPI_LIMB))
+ for (i = k % BITS_PER_MPI_LIMB; i < BITS_PER_MPI_LIMB; i++)
+ diffp[k/BITS_PER_MPI_LIMB] &= ~(((mpi_limb_t)1) << i);
+
+ hsize = x1size * 2;
+ hp = mpi_alloc_limb_space (hsize, _gcry_is_secure (a->d));
+ _gcry_mpih_mul_n (hp, diffp, q_invp, x1size);
+ _gcry_mpi_free_limb_space (diffp, x1size);
+ _gcry_mpi_free_limb_space (q_invp, x1size);
+
+ for (i = x1size; i < hsize; i++)
+ hp[i] = 0;
+ if ((k % BITS_PER_MPI_LIMB))
+ for (i = k % BITS_PER_MPI_LIMB; i < BITS_PER_MPI_LIMB; i++)
+ hp[k/BITS_PER_MPI_LIMB] &= ~(((mpi_limb_t)1) << i);
+
+ xp = mpi_alloc_limb_space (x1size + q->nlimbs, _gcry_is_secure (a->d));
+ if (x1size >= q->nlimbs)
+ _gcry_mpih_mul (xp, hp, x1size, q->d, q->nlimbs);
+ else
+ _gcry_mpih_mul (xp, q->d, q->nlimbs, hp, x1size);
+
+ _gcry_mpi_free_limb_space (hp, hsize);
+
+ _gcry_mpih_add (xp, xp, x1size + q->nlimbs, x2p, q->nlimbs);
+ _gcry_mpi_free_limb_space (x2p, q->nlimbs);
+
+ _gcry_mpi_assign_limb_space (x, xp, x1size + q->nlimbs);
+ x->nlimbs = x1size + q->nlimbs;
+
+ mpi_free (q);
+
+ return 1;
+ }
+ else
+ return mpi_invm_generic (x, a, n);
+}
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