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Strengthen preconditions on polyveck_add() and polyvecl_add() #724

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Strengthen preconditions on polyveck_add() and polyvecl_add() #724

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c72c4cf
Strengthen preconditions on polyveck_add() and polyvecl_add()
rod-chapman Nov 19, 2025
833a812
Remove now-redundant preconditions
rod-chapman Nov 20, 2025
1f95625
Weaken post-condition and invariant of polyvecl_add()
rod-chapman Nov 21, 2025
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30 changes: 16 additions & 14 deletions mldsa/src/polyvec.h
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Original file line number Diff line number Diff line change
Expand Up @@ -81,21 +81,22 @@ __contract__(
* No modular reduction is performed.
*
* Arguments: - mld_polyveck *u: pointer to input-output vector of polynomials
*to be added to
* to be added to
* - const mld_polyveck *v: pointer to second input vector of
* polynomials
* polynomials
**************************************************/
MLD_INTERNAL_API
void mld_polyvecl_add(mld_polyvecl *u, const mld_polyvecl *v)
__contract__(
requires(memory_no_alias(u, sizeof(mld_polyvecl)))
requires(memory_no_alias(v, sizeof(mld_polyvecl)))
requires(forall(k0, 0, MLDSA_L, forall(k1, 0, MLDSA_N, (int64_t) u->vec[k0].coeffs[k1] + v->vec[k0].coeffs[k1] < REDUCE32_DOMAIN_MAX)))
requires(forall(k2, 0, MLDSA_L, forall(k3, 0, MLDSA_N, (int64_t) u->vec[k2].coeffs[k3] + v->vec[k2].coeffs[k3] >= INT32_MIN)))
requires(forall(p0, 0, MLDSA_L, array_abs_bound(u->vec[p0].coeffs, 0 , MLDSA_N, MLD_INTT_BOUND)))
requires(forall(p1, 0, MLDSA_L,
array_bound(v->vec[p1].coeffs, 0, MLDSA_N, -(MLDSA_GAMMA1 - 1), MLDSA_GAMMA1 + 1)))
assigns(object_whole(u))
ensures(forall(k4, 0, MLDSA_L, forall(k5, 0, MLDSA_N, u->vec[k4].coeffs[k5] == old(*u).vec[k4].coeffs[k5] + v->vec[k4].coeffs[k5])))
ensures(forall(k6, 0, MLDSA_L,
array_bound(u->vec[k6].coeffs, 0, MLDSA_N, INT32_MIN, REDUCE32_DOMAIN_MAX)))
ensures(forall(q0, 0, MLDSA_L, forall(q1, 0, MLDSA_N, u->vec[q0].coeffs[q1] == old(*u).vec[q0].coeffs[q1] + v->vec[q0].coeffs[q1])))
ensures(forall(q2, 0, MLDSA_L,
array_bound(u->vec[q2].coeffs, 0, MLDSA_N, INT32_MIN, REDUCE32_DOMAIN_MAX)))
);

#define mld_polyvecl_ntt MLD_NAMESPACE_KL(polyvecl_ntt)
Expand Down Expand Up @@ -279,21 +280,22 @@ __contract__(
* No modular reduction is performed.
*
* Arguments: - mld_polyveck *u: pointer to input-output vector of polynomials
*to be added to
* to be added to
* - const mld_polyveck *v: pointer to second input vector of
* polynomials
* polynomials
**************************************************/
MLD_INTERNAL_API
void mld_polyveck_add(mld_polyveck *u, const mld_polyveck *v)
__contract__(
requires(memory_no_alias(u, sizeof(mld_polyveck)))
requires(memory_no_alias(v, sizeof(mld_polyveck)))
requires(forall(k0, 0, MLDSA_K, forall(k1, 0, MLDSA_N, (int64_t) u->vec[k0].coeffs[k1] + v->vec[k0].coeffs[k1] < REDUCE32_DOMAIN_MAX)))
requires(forall(k2, 0, MLDSA_K, forall(k3, 0, MLDSA_N, (int64_t) u->vec[k2].coeffs[k3] + v->vec[k2].coeffs[k3] >= INT32_MIN)))
requires(forall(p0, 0, MLDSA_K, array_abs_bound(u->vec[p0].coeffs, 0, MLDSA_N, MLD_INTT_BOUND)))
requires(forall(p1, 0, MLDSA_K,
array_bound(v->vec[p1].coeffs, 0, MLDSA_N, -REDUCE32_RANGE_MAX, REDUCE32_RANGE_MAX)))
assigns(object_whole(u))
ensures(forall(k4, 0, MLDSA_K, forall(k5, 0, MLDSA_N, u->vec[k4].coeffs[k5] == old(*u).vec[k4].coeffs[k5] + v->vec[k4].coeffs[k5])))
ensures(forall(k6, 0, MLDSA_L,
array_bound(u->vec[k6].coeffs, 0, MLDSA_N, INT32_MIN, REDUCE32_DOMAIN_MAX)))
ensures(forall(q0, 0, MLDSA_K, forall(q1, 0, MLDSA_N, u->vec[q0].coeffs[q1] == old(*u).vec[q0].coeffs[q1] + v->vec[q0].coeffs[q1])))
ensures(forall(q2, 0, MLDSA_L,
array_bound(u->vec[q2].coeffs, 0, MLDSA_N, INT32_MIN, REDUCE32_DOMAIN_MAX)))
);

#define mld_polyveck_sub MLD_NAMESPACE_KL(polyveck_sub)
Expand Down