diff options
Diffstat (limited to 'third_party/heimdal/lib/hcrypto/libtommath/bn_mp_dr_is_modulus.c')
-rw-r--r-- | third_party/heimdal/lib/hcrypto/libtommath/bn_mp_dr_is_modulus.c | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_dr_is_modulus.c b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_dr_is_modulus.c new file mode 100644 index 0000000..83760ea --- /dev/null +++ b/third_party/heimdal/lib/hcrypto/libtommath/bn_mp_dr_is_modulus.c @@ -0,0 +1,27 @@ +#include "tommath_private.h" +#ifdef BN_MP_DR_IS_MODULUS_C +/* LibTomMath, multiple-precision integer library -- Tom St Denis */ +/* SPDX-License-Identifier: Unlicense */ + +/* determines if a number is a valid DR modulus */ +mp_bool mp_dr_is_modulus(const mp_int *a) +{ + int ix; + + /* must be at least two digits */ + if (a->used < 2) { + return MP_NO; + } + + /* must be of the form b**k - a [a <= b] so all + * but the first digit must be equal to -1 (mod b). + */ + for (ix = 1; ix < a->used; ix++) { + if (a->dp[ix] != MP_MASK) { + return MP_NO; + } + } + return MP_YES; +} + +#endif |