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authorLinus Torvalds <torvalds@linux-foundation.org>2020-10-13 08:50:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-10-13 08:50:16 -0700
commit39a5101f989e8d2be557136704d53990f9b402c8 (patch)
treeb9c16c6f32508939111fb6d0159d7450713a5f33 /lib/mpi/mpi-inv.c
parent865c50e1d279671728c2936cb7680eb89355eeea (diff)
parent3093e7c16e12d729c325adb3c53dde7308cefbd8 (diff)
downloadlinux-39a5101f989e8d2be557136704d53990f9b402c8.tar.bz2
Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
Pull crypto updates from Herbert Xu: "API: - Allow DRBG testing through user-space af_alg - Add tcrypt speed testing support for keyed hashes - Add type-safe init/exit hooks for ahash Algorithms: - Mark arc4 as obsolete and pending for future removal - Mark anubis, khazad, sead and tea as obsolete - Improve boot-time xor benchmark - Add OSCCA SM2 asymmetric cipher algorithm and use it for integrity Drivers: - Fixes and enhancement for XTS in caam - Add support for XIP8001B hwrng in xiphera-trng - Add RNG and hash support in sun8i-ce/sun8i-ss - Allow imx-rngc to be used by kernel entropy pool - Use crypto engine in omap-sham - Add support for Ingenic X1830 with ingenic" * 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (205 commits) X.509: Fix modular build of public_key_sm2 crypto: xor - Remove unused variable count in do_xor_speed X.509: fix error return value on the failed path crypto: bcm - Verify GCM/CCM key length in setkey crypto: qat - drop input parameter from adf_enable_aer() crypto: qat - fix function parameters descriptions crypto: atmel-tdes - use semicolons rather than commas to separate statements crypto: drivers - use semicolons rather than commas to separate statements hwrng: mxc-rnga - use semicolons rather than commas to separate statements hwrng: iproc-rng200 - use semicolons rather than commas to separate statements hwrng: stm32 - use semicolons rather than commas to separate statements crypto: xor - use ktime for template benchmarking crypto: xor - defer load time benchmark to a later time crypto: hisilicon/zip - fix the uninitalized 'curr_qm_qp_num' crypto: hisilicon/zip - fix the return value when device is busy crypto: hisilicon/zip - fix zero length input in GZIP decompress crypto: hisilicon/zip - fix the uncleared debug registers lib/mpi: Fix unused variable warnings crypto: x86/poly1305 - Remove assignments with no effect hwrng: npcm - modify readl to readb ...
Diffstat (limited to 'lib/mpi/mpi-inv.c')
-rw-r--r--lib/mpi/mpi-inv.c143
1 files changed, 143 insertions, 0 deletions
diff --git a/lib/mpi/mpi-inv.c b/lib/mpi/mpi-inv.c
new file mode 100644
index 000000000000..61e37d18f793
--- /dev/null
+++ b/lib/mpi/mpi-inv.c
@@ -0,0 +1,143 @@
+/* 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 "mpi-internal.h"
+
+/****************
+ * Calculate the multiplicative inverse X of A mod N
+ * That is: Find the solution x for
+ * 1 = (a*x) mod n
+ */
+int mpi_invm(MPI x, MPI a, MPI n)
+{
+ /* 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
+ */
+ MPI u, v, u1, u2 = NULL, u3, v1, v2 = NULL, v3, t1, t2 = NULL, t3;
+ unsigned int k;
+ int sign;
+ int odd;
+
+ if (!mpi_cmp_ui(a, 0))
+ return 0; /* Inverse does not exists. */
+ if (!mpi_cmp_ui(n, 1))
+ return 0; /* Inverse does not exists. */
+
+ 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, k ); */
+ 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);
+ return 1;
+}
+EXPORT_SYMBOL_GPL(mpi_invm);