Mercurial > dropbear
view libtommath/bn_mp_karatsuba_sqr.c @ 1156:a8f4dade70e5
avoid getpass when not used
some systems (like android's bionic) do not provide getpass. you can
disable ENABLE_CLI_PASSWORD_AUTH & ENABLE_CLI_INTERACT_AUTH to avoid
its use (and rely on pubkey auth), but the link still fails because
the support file calls getpass. do not define this func if both of
those auth methods are not used.
author | Mike Frysinger <vapier@gentoo.org> |
---|---|
date | Wed, 21 Oct 2015 22:39:55 +0800 |
parents | 5ff8218bcee9 |
children | 60fc6476e044 |
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line source
#include <tommath.h> #ifdef BN_MP_KARATSUBA_SQR_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. * * The library is free for all purposes without any express * guarantee it works. * * Tom St Denis, [email protected], http://math.libtomcrypt.com */ /* Karatsuba squaring, computes b = a*a using three * half size squarings * * See comments of karatsuba_mul for details. It * is essentially the same algorithm but merely * tuned to perform recursive squarings. */ int mp_karatsuba_sqr (mp_int * a, mp_int * b) { mp_int x0, x1, t1, t2, x0x0, x1x1; int B, err; err = MP_MEM; /* min # of digits */ B = a->used; /* now divide in two */ B = B >> 1; /* init copy all the temps */ if (mp_init_size (&x0, B) != MP_OKAY) goto ERR; if (mp_init_size (&x1, a->used - B) != MP_OKAY) goto X0; /* init temps */ if (mp_init_size (&t1, a->used * 2) != MP_OKAY) goto X1; if (mp_init_size (&t2, a->used * 2) != MP_OKAY) goto T1; if (mp_init_size (&x0x0, B * 2) != MP_OKAY) goto T2; if (mp_init_size (&x1x1, (a->used - B) * 2) != MP_OKAY) goto X0X0; { register int x; register mp_digit *dst, *src; src = a->dp; /* now shift the digits */ dst = x0.dp; for (x = 0; x < B; x++) { *dst++ = *src++; } dst = x1.dp; for (x = B; x < a->used; x++) { *dst++ = *src++; } } x0.used = B; x1.used = a->used - B; mp_clamp (&x0); /* now calc the products x0*x0 and x1*x1 */ if (mp_sqr (&x0, &x0x0) != MP_OKAY) goto X1X1; /* x0x0 = x0*x0 */ if (mp_sqr (&x1, &x1x1) != MP_OKAY) goto X1X1; /* x1x1 = x1*x1 */ /* now calc (x1+x0)**2 */ if (s_mp_add (&x1, &x0, &t1) != MP_OKAY) goto X1X1; /* t1 = x1 - x0 */ if (mp_sqr (&t1, &t1) != MP_OKAY) goto X1X1; /* t1 = (x1 - x0) * (x1 - x0) */ /* add x0y0 */ if (s_mp_add (&x0x0, &x1x1, &t2) != MP_OKAY) goto X1X1; /* t2 = x0x0 + x1x1 */ if (s_mp_sub (&t1, &t2, &t1) != MP_OKAY) goto X1X1; /* t1 = (x1+x0)**2 - (x0x0 + x1x1) */ /* shift by B */ if (mp_lshd (&t1, B) != MP_OKAY) goto X1X1; /* t1 = (x0x0 + x1x1 - (x1-x0)*(x1-x0))<<B */ if (mp_lshd (&x1x1, B * 2) != MP_OKAY) goto X1X1; /* x1x1 = x1x1 << 2*B */ if (mp_add (&x0x0, &t1, &t1) != MP_OKAY) goto X1X1; /* t1 = x0x0 + t1 */ if (mp_add (&t1, &x1x1, b) != MP_OKAY) goto X1X1; /* t1 = x0x0 + t1 + x1x1 */ err = MP_OKAY; X1X1:mp_clear (&x1x1); X0X0:mp_clear (&x0x0); T2:mp_clear (&t2); T1:mp_clear (&t1); X1:mp_clear (&x1); X0:mp_clear (&x0); ERR: return err; } #endif /* $Source: /cvs/libtom/libtommath/bn_mp_karatsuba_sqr.c,v $ */ /* $Revision: 1.5 $ */ /* $Date: 2006/03/31 14:18:44 $ */