1/**
2 * \file bignum_helpers.c
3 *
4 * \brief   This file contains the prototypes of helper functions for
5 *          bignum-related testing.
6 */
7
8/*
9 *  Copyright The Mbed TLS Contributors
10 *  SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later
11 */
12
13#define MBEDTLS_ALLOW_PRIVATE_ACCESS
14#include <test/bignum_helpers.h>
15
16#if defined(MBEDTLS_BIGNUM_C)
17
18#include <stdlib.h>
19#include <string.h>
20
21#include <mbedtls/bignum.h>
22#include <bignum_core.h>
23#include <bignum_mod.h>
24#include <bignum_mod_raw.h>
25
26#include <test/helpers.h>
27#include <test/macros.h>
28
29int mbedtls_test_read_mpi_core(mbedtls_mpi_uint **pX, size_t *plimbs,
30                               const char *input)
31{
32    /* Sanity check */
33    if (*pX != NULL) {
34        return MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
35    }
36
37    size_t hex_len = strlen(input);
38    size_t byte_len = (hex_len + 1) / 2;
39    *plimbs = CHARS_TO_LIMBS(byte_len);
40
41    /* A core bignum is not allowed to be empty. Forbid it as test data,
42     * this way static analyzers have a chance of knowing we don't expect
43     * the bignum functions to support empty inputs. */
44    if (*plimbs == 0) {
45        return MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
46    }
47
48    *pX = mbedtls_calloc(*plimbs, sizeof(**pX));
49    if (*pX == NULL) {
50        return MBEDTLS_ERR_MPI_ALLOC_FAILED;
51    }
52
53    unsigned char *byte_start = (unsigned char *) *pX;
54    if (byte_len % sizeof(mbedtls_mpi_uint) != 0) {
55        byte_start += sizeof(mbedtls_mpi_uint) - byte_len % sizeof(mbedtls_mpi_uint);
56    }
57    if ((hex_len & 1) != 0) {
58        /* mbedtls_test_unhexify wants an even number of hex digits */
59        TEST_ASSERT(mbedtls_test_ascii2uc(*input, byte_start) == 0);
60        ++byte_start;
61        ++input;
62        --byte_len;
63    }
64    TEST_ASSERT(mbedtls_test_unhexify(byte_start,
65                                      byte_len,
66                                      input,
67                                      &byte_len) == 0);
68
69    mbedtls_mpi_core_bigendian_to_host(*pX, *plimbs);
70    return 0;
71
72exit:
73    mbedtls_free(*pX);
74    return MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
75}
76
77#if defined(MBEDTLS_ECP_WITH_MPI_UINT)
78int mbedtls_test_read_mpi_modulus(mbedtls_mpi_mod_modulus *N,
79                                  const char *s,
80                                  mbedtls_mpi_mod_rep_selector int_rep)
81{
82    mbedtls_mpi_uint *p = NULL;
83    size_t limbs = 0;
84    if (N->limbs != 0) {
85        return MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
86    }
87    int ret = mbedtls_test_read_mpi_core(&p, &limbs, s);
88    if (ret != 0) {
89        return ret;
90    }
91
92    switch (int_rep) {
93        case MBEDTLS_MPI_MOD_REP_MONTGOMERY:
94            ret = mbedtls_mpi_mod_modulus_setup(N, p, limbs);
95            break;
96        case MBEDTLS_MPI_MOD_REP_OPT_RED:
97            ret = mbedtls_mpi_mod_optred_modulus_setup(N, p, limbs, NULL);
98            break;
99        default:
100            ret = MBEDTLS_ERR_MPI_BAD_INPUT_DATA;
101            break;
102    }
103    if (ret != 0) {
104        mbedtls_free(p);
105    }
106    return ret;
107}
108
109void mbedtls_test_mpi_mod_modulus_free_with_limbs(mbedtls_mpi_mod_modulus *N)
110{
111    mbedtls_free((mbedtls_mpi_uint *) N->p);
112    mbedtls_mpi_mod_modulus_free(N);
113}
114#endif /* MBEDTLS_ECP_WITH_MPI_UINT */
115
116int mbedtls_test_read_mpi(mbedtls_mpi *X, const char *s)
117{
118    int negative = 0;
119    /* Always set the sign bit to -1 if the input has a minus sign, even for 0.
120     * This creates an invalid representation, which mbedtls_mpi_read_string()
121     * avoids but we want to be able to create that in test data. */
122    if (s[0] == '-') {
123        ++s;
124        negative = 1;
125    }
126    /* mbedtls_mpi_read_string() currently retains leading zeros.
127     * It always allocates at least one limb for the value 0. */
128    if (s[0] == 0) {
129        mbedtls_mpi_free(X);
130        return 0;
131    }
132    int ret = mbedtls_mpi_read_string(X, 16, s);
133    if (ret != 0) {
134        return ret;
135    }
136    if (negative) {
137        if (mbedtls_mpi_cmp_int(X, 0) == 0) {
138            mbedtls_test_increment_case_uses_negative_0();
139        }
140        X->s = -1;
141    }
142    return 0;
143}
144
145#endif /* MBEDTLS_BIGNUM_C */
146