43 lines
950 B
C
43 lines
950 B
C
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#include "tommath_private.h"
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#ifdef BN_MP_TO_UBIN_C
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/* LibTomMath, multiple-precision integer library -- Tom St Denis */
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/* SPDX-License-Identifier: Unlicense */
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/* store in unsigned [big endian] format */
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mp_err mp_to_ubin(const mp_int *a, unsigned char *buf, size_t maxlen, size_t *written)
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{
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size_t x, count;
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mp_err err;
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mp_int t;
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size_t size = (size_t)mp_count_bits(a);
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count = (size / 8u) + (((size & 7u) != 0u) ? 1u : 0u);
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if (count > maxlen) {
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return MP_BUF;
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}
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if ((err = mp_init_copy(&t, a)) != MP_OKAY) {
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return err;
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}
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for (x = count; x --> 0u;) {
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#ifndef MP_8BIT
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buf[x] = (unsigned char)(t.dp[0] & 255u);
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#else
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buf[x] = (unsigned char)(t.dp[0] | ((t.dp[1] & 1u) << 7));
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#endif
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if ((err = mp_div_2d(&t, 8, &t, NULL)) != MP_OKAY) {
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goto LBL_ERR;
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}
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}
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if (written != NULL) {
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*written = count;
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}
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LBL_ERR:
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mp_clear(&t);
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return err;
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}
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#endif
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