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Diffstat (limited to 'libtommath/bn_mp_exteuclid.c')
-rw-r--r--libtommath/bn_mp_exteuclid.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/libtommath/bn_mp_exteuclid.c b/libtommath/bn_mp_exteuclid.c
index 545450b..c4ebab4 100644
--- a/libtommath/bn_mp_exteuclid.c
+++ b/libtommath/bn_mp_exteuclid.c
@@ -59,6 +59,13 @@ int mp_exteuclid(mp_int *a, mp_int *b, mp_int *U1, mp_int *U2, mp_int *U3)
if ((err = mp_copy(&t3, &v3)) != MP_OKAY) { goto _ERR; }
}
+ /* make sure U3 >= 0 */
+ if (u3.sign == MP_NEG) {
+ mp_neg(&u1, &u1);
+ mp_neg(&u2, &u2);
+ mp_neg(&u3, &u3);
+ }
+
/* copy result out */
if (U1 != NULL) { mp_exch(U1, &u1); }
if (U2 != NULL) { mp_exch(U2, &u2); }