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authorSteffen Jaeckel <s_jaeckel@gmx.de>2019-09-16 15:50:38 +0200
committerSteffen Jaeckel <s_jaeckel@gmx.de>2019-09-16 15:50:38 +0200
commit577b7c01fef2c4dd6ec499398e64aa2adeda7e8f (patch)
tree8d6f745fddd3a9c170f7c98603518f77b515da4f /libtommath/bn_mp_kronecker.c
parent663fc015dbb5b39ac6be6630a003f0530af734fb (diff)
downloaddropbear-577b7c01fef2c4dd6ec499398e64aa2adeda7e8f.tar.gz
update ltm to 1.1.0 and enable FIPS 186.4 compliant key-generation (#79)
* make key-generation compliant to FIPS 186.4 * fix includes in tommath_class.h * update fuzzcorpus instead of error-out * fixup fuzzing make-targets * update Makefile.in * apply necessary patches to ltm sources * clean-up not required ltm files * update to vanilla ltm 1.1.0 this already only contains the required files * remove set/get double
Diffstat (limited to 'libtommath/bn_mp_kronecker.c')
-rw-r--r--libtommath/bn_mp_kronecker.c144
1 files changed, 144 insertions, 0 deletions
diff --git a/libtommath/bn_mp_kronecker.c b/libtommath/bn_mp_kronecker.c
new file mode 100644
index 0000000..4c70b76
--- /dev/null
+++ b/libtommath/bn_mp_kronecker.c
@@ -0,0 +1,144 @@
+#include "tommath_private.h"
+#ifdef BN_MP_KRONECKER_C
+
+/* LibTomMath, multiple-precision integer library -- Tom St Denis
+ *
+ * LibTomMath is a library that provides multiple-precision
+ * integer arithmetic as well as number theoretic functionality.
+ *
+ * The library was designed directly after the MPI library by
+ * Michael Fromberger but has been written from scratch with
+ * additional optimizations in place.
+ *
+ * SPDX-License-Identifier: Unlicense
+ */
+
+/*
+ Kronecker symbol (a|p)
+ Straightforward implementation of algorithm 1.4.10 in
+ Henri Cohen: "A Course in Computational Algebraic Number Theory"
+
+ @book{cohen2013course,
+ title={A course in computational algebraic number theory},
+ author={Cohen, Henri},
+ volume={138},
+ year={2013},
+ publisher={Springer Science \& Business Media}
+ }
+ */
+int mp_kronecker(const mp_int *a, const mp_int *p, int *c)
+{
+ mp_int a1, p1, r;
+
+ int e = MP_OKAY;
+ int v, k;
+
+ static const int table[8] = {0, 1, 0, -1, 0, -1, 0, 1};
+
+ if (mp_iszero(p) != MP_NO) {
+ if ((a->used == 1) && (a->dp[0] == 1u)) {
+ *c = 1;
+ return e;
+ } else {
+ *c = 0;
+ return e;
+ }
+ }
+
+ if ((mp_iseven(a) != MP_NO) && (mp_iseven(p) != MP_NO)) {
+ *c = 0;
+ return e;
+ }
+
+ if ((e = mp_init_copy(&a1, a)) != MP_OKAY) {
+ return e;
+ }
+ if ((e = mp_init_copy(&p1, p)) != MP_OKAY) {
+ goto LBL_KRON_0;
+ }
+
+ v = mp_cnt_lsb(&p1);
+ if ((e = mp_div_2d(&p1, v, &p1, NULL)) != MP_OKAY) {
+ goto LBL_KRON_1;
+ }
+
+ if ((v & 0x1) == 0) {
+ k = 1;
+ } else {
+ k = table[a->dp[0] & 7u];
+ }
+
+ if (p1.sign == MP_NEG) {
+ p1.sign = MP_ZPOS;
+ if (a1.sign == MP_NEG) {
+ k = -k;
+ }
+ }
+
+ if ((e = mp_init(&r)) != MP_OKAY) {
+ goto LBL_KRON_1;
+ }
+
+ for (;;) {
+ if (mp_iszero(&a1) != MP_NO) {
+ if (mp_cmp_d(&p1, 1uL) == MP_EQ) {
+ *c = k;
+ goto LBL_KRON;
+ } else {
+ *c = 0;
+ goto LBL_KRON;
+ }
+ }
+
+ v = mp_cnt_lsb(&a1);
+ if ((e = mp_div_2d(&a1, v, &a1, NULL)) != MP_OKAY) {
+ goto LBL_KRON;
+ }
+
+ if ((v & 0x1) == 1) {
+ k = k * table[p1.dp[0] & 7u];
+ }
+
+ if (a1.sign == MP_NEG) {
+ /*
+ * Compute k = (-1)^((a1)*(p1-1)/4) * k
+ * a1.dp[0] + 1 cannot overflow because the MSB
+ * of the type mp_digit is not set by definition
+ */
+ if (((a1.dp[0] + 1u) & p1.dp[0] & 2u) != 0u) {
+ k = -k;
+ }
+ } else {
+ /* compute k = (-1)^((a1-1)*(p1-1)/4) * k */
+ if ((a1.dp[0] & p1.dp[0] & 2u) != 0u) {
+ k = -k;
+ }
+ }
+
+ if ((e = mp_copy(&a1, &r)) != MP_OKAY) {
+ goto LBL_KRON;
+ }
+ r.sign = MP_ZPOS;
+ if ((e = mp_mod(&p1, &r, &a1)) != MP_OKAY) {
+ goto LBL_KRON;
+ }
+ if ((e = mp_copy(&r, &p1)) != MP_OKAY) {
+ goto LBL_KRON;
+ }
+ }
+
+LBL_KRON:
+ mp_clear(&r);
+LBL_KRON_1:
+ mp_clear(&p1);
+LBL_KRON_0:
+ mp_clear(&a1);
+
+ return e;
+}
+
+#endif
+
+/* ref: HEAD -> master, tag: v1.1.0 */
+/* git commit: 08549ad6bc8b0cede0b357a9c341c5c6473a9c55 */
+/* commit time: 2019-01-28 20:32:32 +0100 */