34 lines
851 B
C
34 lines
851 B
C
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/* LibTomPoly, Polynomial Basis Math -- Tom St Denis
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*
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* LibTomPoly is a public domain library that provides
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* polynomial basis arithmetic support. It relies on
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* LibTomMath for large integer support.
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*
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* This library is free for all purposes without any
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* express guarantee that it works.
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*
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* Tom St Denis, tomstdenis@iahu.ca, http://poly.libtomcrypt.org
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*/
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#include <tompoly.h>
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int pb_invmod(pb_poly *a, pb_poly *b, pb_poly *c)
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{
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int err;
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pb_poly tmp;
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if ((err = pb_init(&tmp, &(c->characteristic))) != MP_OKAY) {
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return err;
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}
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if ((err = pb_exteuclid(a, b, c, NULL, &tmp)) != MP_OKAY) { goto _ERR; }
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/* if deg(tmp(x)) > 0 then there is no invmod */
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if (tmp.used > 1) { err = MP_VAL; goto _ERR; }
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err = MP_OKAY;
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_ERR: pb_clear(&tmp);
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return err;
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}
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