Source code
Revision control
Copy as Markdown
Other Tools
/*
* SPDX-FileCopyrightText: 2026 CE Labs
*
* SPDX-License-Identifier: MIT or Apache-2.0
*
* This code was generated with the following revisions:
* Charon: e656e17bff6ca5efac8ab6919b9b74cb9a8dd8ad
* Eurydice: aaa9fa657fb6f09802edb890252040d94cd93982
* Karamel: 8c19d41458ce5cbfea029ebc03334ba96d149039
* F*: 70671ffb81fa30aba09b9d6e2af275dfbccaa8f8
* Libcrux: 10066f256cec8d50d6111a4cf33ab920cfdb96cb
*/
#include "libcrux_ct_ops.h"
#include "libcrux_mlkem_core.h"
#include "combined_core.h"
#include "internal/combined_core.h"
/**
Return 1 if `value` is not zero and 0 otherwise.
*/
KRML_NOINLINE uint8_t libcrux_ml_kem_constant_time_ops_inz(uint8_t value)
{
uint16_t value0 = (uint16_t)(uint32_t)value;
uint8_t result = (uint8_t)((uint32_t)core_num__u16__wrapping_add(~value0, 1U) >> 8U & 0xFFFFU);
return (uint32_t)result & 1U;
}
KRML_NOINLINE uint8_t libcrux_ml_kem_constant_time_ops_is_non_zero(uint8_t value)
{
return libcrux_ml_kem_constant_time_ops_inz(value);
}
/**
Return 1 if the bytes of `lhs` and `rhs` do not exactly
match and 0 otherwise.
*/
KRML_NOINLINE uint8_t
libcrux_ml_kem_constant_time_ops_compare(
Eurydice_borrow_slice_u8 lhs,
Eurydice_borrow_slice_u8 rhs
)
{
uint8_t r = 0U;
for (size_t i = (size_t)0U; i < lhs.meta; i++)
{
size_t i0 = i;
uint8_t nr = (uint32_t)r | ((uint32_t)lhs.ptr[i0] ^ (uint32_t)rhs.ptr[i0]);
r = nr;
}
return libcrux_ml_kem_constant_time_ops_is_non_zero(r);
}
KRML_NOINLINE uint8_t
libcrux_ml_kem_constant_time_ops_compare_ciphertexts_in_constant_time(
Eurydice_borrow_slice_u8 lhs,
Eurydice_borrow_slice_u8 rhs
)
{
return libcrux_ml_kem_constant_time_ops_compare(lhs, rhs);
}
/**
If `selector` is not zero, return the bytes in `rhs`; return the bytes in
`lhs` otherwise.
*/
KRML_NOINLINE Eurydice_arr_ec
libcrux_ml_kem_constant_time_ops_select_ct(
Eurydice_borrow_slice_u8 lhs,
Eurydice_borrow_slice_u8 rhs,
uint8_t selector
)
{
uint8_t
mask = core_num__u8__wrapping_sub(libcrux_ml_kem_constant_time_ops_is_non_zero(selector), 1U);
Eurydice_arr_ec out = { .data = { 0U } };
for (size_t i = (size_t)0U; i < LIBCRUX_ML_KEM_CONSTANTS_SHARED_SECRET_SIZE; i++)
{
size_t i0 = i;
uint8_t
outi =
((uint32_t)lhs.ptr[i0] & (uint32_t)mask) | ((uint32_t)rhs.ptr[i0] & (~(uint32_t)mask & 0xFFU));
out.data[i0] = outi;
}
return out;
}
KRML_NOINLINE Eurydice_arr_ec
libcrux_ml_kem_constant_time_ops_select_shared_secret_in_constant_time(
Eurydice_borrow_slice_u8 lhs,
Eurydice_borrow_slice_u8 rhs,
uint8_t selector
)
{
return libcrux_ml_kem_constant_time_ops_select_ct(lhs, rhs, selector);
}
KRML_NOINLINE Eurydice_arr_ec
libcrux_ml_kem_constant_time_ops_compare_ciphertexts_select_shared_secret_in_constant_time(
Eurydice_borrow_slice_u8 lhs_c,
Eurydice_borrow_slice_u8 rhs_c,
Eurydice_borrow_slice_u8 lhs_s,
Eurydice_borrow_slice_u8 rhs_s
)
{
uint8_t
selector = libcrux_ml_kem_constant_time_ops_compare_ciphertexts_in_constant_time(lhs_c, rhs_c);
return
libcrux_ml_kem_constant_time_ops_select_shared_secret_in_constant_time(lhs_s,
rhs_s,
selector);
}