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POLY: improve error handling

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hasufell 2014-05-13 00:20:46 +02:00
parent 30e18177e8
commit 782ccf0524
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GPG Key ID: 220CD1C5BDEED020
2 changed files with 10 additions and 5 deletions
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13
src/poly.c
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@ -300,11 +300,11 @@ void pb_xor(pb_poly *a,
* Get the degree of the polynomial. * Get the degree of the polynomial.
* *
* @param poly the polynomial * @param poly the polynomial
* @return the degree * @return the degree, -1 if polynom is empty
*/ */
unsigned int get_degree(pb_poly const * const poly) int get_degree(pb_poly const * const poly)
{ {
unsigned int count = 0; int count = -1;
for (int i = 0; i < poly->alloc; i++) for (int i = 0; i < poly->alloc; i++)
if (mp_iszero(&(poly->terms[i])) == MP_NO) if (mp_iszero(&(poly->terms[i])) == MP_NO)
@ -354,7 +354,7 @@ static void pb_mod2_to_modq(pb_poly * const a,
* @param a polynomial to invert (is allowed to be the same as param Fq) * @param a polynomial to invert (is allowed to be the same as param Fq)
* @param Fq polynomial [out] * @param Fq polynomial [out]
* @param ctx NTRU context * @param ctx NTRU context
* @return true/false for success/failure * @return true if invertible, false if not
*/ */
bool pb_inverse_poly_q(pb_poly * const a, bool pb_inverse_poly_q(pb_poly * const a,
pb_poly *Fq, pb_poly *Fq,
@ -395,6 +395,8 @@ bool pb_inverse_poly_q(pb_poly * const a,
MP_SET(&(f->terms[ctx->N]), 0); MP_SET(&(f->terms[ctx->N]), 0);
MP_SET(&(c->terms[0]), 0); MP_SET(&(c->terms[0]), 0);
k++; k++;
if (get_degree(f) == -1)
return false;
} }
if (get_degree(f) == 0) if (get_degree(f) == 0)
@ -411,6 +413,9 @@ bool pb_inverse_poly_q(pb_poly * const a,
k = k % ctx->N; k = k % ctx->N;
if (mp_cmp_d(&(b->terms[ctx->N]), 0) != MP_EQ)
return false;
/* Fq(x) = x^(N-k) * b(x) */ /* Fq(x) = x^(N-k) * b(x) */
for (int i = ctx->N - 1; i >= 0; i--) { for (int i = ctx->N - 1; i >= 0; i--) {
j = i - k; j = i - k;

2
src/poly.h
View File

@ -202,7 +202,7 @@ void pb_xor(pb_poly *a,
pb_poly *c, pb_poly *c,
const size_t len); const size_t len);
unsigned int get_degree(pb_poly const * const poly); int get_degree(pb_poly const * const poly);
bool pb_inverse_poly_q(pb_poly *a, bool pb_inverse_poly_q(pb_poly *a,
pb_poly *Fq, pb_poly *Fq,