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- /**
- * Copyright (c) 2018 - 2020, Nordic Semiconductor ASA
- *
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without modification,
- * are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice, this
- * list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form, except as embedded into a Nordic
- * Semiconductor ASA integrated circuit in a product or a software update for
- * such product, must reproduce the above copyright notice, this list of
- * conditions and the following disclaimer in the documentation and/or other
- * materials provided with the distribution.
- *
- * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
- * contributors may be used to endorse or promote products derived from this
- * software without specific prior written permission.
- *
- * 4. This software, with or without modification, must only be used with a
- * Nordic Semiconductor ASA integrated circuit.
- *
- * 5. Any software provided in binary form under this license must not be reverse
- * engineered, decompiled, modified and/or disassembled.
- *
- * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
- * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
- * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
- * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- *
- */
- #include <string.h>
- #include "optiga_backend_utils.h"
- #include "nrf_crypto_error.h"
- /**
- * @brief Decodes two ASN.1 integers to the R and S components of a ECC signature.
- *
- * @param[in] p_asn1 Pointer to buffer containing the ASN.1 encoded R and S values.
- * @param[in] asn1_len Length of the asn1 buffer.
- * @param[out] p_rs Pointer to buffer where to write the R and S values
- * @param[in,out] p_rs_len pointer to variable containing length of the rs buffer,
- * updated to actual length after the call.
- *
- * @returns NRF_SUCCESS on success, otherwise NRF_ERROR_CRYPTO_INTERNAL.
- */
- ret_code_t asn1_to_ecdsa_rs(uint8_t const * p_asn1,
- size_t asn1_len,
- uint8_t * p_rs,
- size_t * p_rs_len)
- {
- uint8_t const * p_cur = p_asn1;
- uint8_t const * p_end = p_asn1 + asn1_len; // Points to first invalid mem-location
- uint8_t r_len;
- uint8_t s_len;
- if (p_asn1 == NULL || p_rs == NULL || p_rs_len == NULL)
- {
- return NRF_ERROR_CRYPTO_INTERNAL;
- }
- if (asn1_len == 0 || *p_rs_len == 0)
- {
- return NRF_ERROR_CRYPTO_INTERNAL;
- }
- if (*p_cur != DER_TAG_INTEGER)
- {
- // Wrong tag type
- return NRF_ERROR_CRYPTO_INTERNAL;
- }
- if ((p_cur + 2) >= p_end)
- {
- // Prevented out-of-bounds read
- return NRF_ERROR_CRYPTO_INTERNAL;
- }
- // Move to length value
- p_cur++;
- r_len = *p_cur;
- if (r_len > DER_INTEGER_MAX_LEN)
- {
- // Unsupported length
- return NRF_ERROR_CRYPTO_INTERNAL;
- }
- // Move to first data value
- p_cur++;
- // Check for stuffing bits
- if (*p_cur == 0x00)
- {
- p_cur++;
- r_len--;
- }
- // Check for out-of-bounds read
- if ((p_cur + r_len) >= p_end)
- {
- // prevented out-of-bounds read
- return NRF_ERROR_CRYPTO_INTERNAL;
- }
- // Check for out-of-bounds write
- if ((p_rs + r_len) > (p_rs + *p_rs_len))
- {
- // prevented out-of-bounds write
- return NRF_ERROR_CRYPTO_INTERNAL;
- }
- // Copy R component to output
- memcpy(p_rs, p_cur, r_len);
- // Move to next tag
- p_cur += r_len;
- if (*p_cur != DER_TAG_INTEGER)
- {
- // Wrong tag type
- return NRF_ERROR_CRYPTO_INTERNAL;
- }
- if ((p_cur + 2) >= p_end)
- {
- // Prevented out-of-bounds read
- return NRF_ERROR_CRYPTO_INTERNAL;
- }
- p_cur++;
- s_len = *p_cur;
- if (s_len > DER_INTEGER_MAX_LEN)
- {
- // Unsupported length
- return NRF_ERROR_CRYPTO_INTERNAL;
- }
- p_cur++;
- if (*p_cur == 0x00)
- {
- p_cur++;
- s_len--;
- }
- // Check for out-of-bounds read
- if ((p_cur + s_len) > p_end)
- {
- // prevented out-of-bounds read
- return NRF_ERROR_CRYPTO_INTERNAL;
- }
- // Check for out-of-bounds write
- if ((p_rs + r_len + s_len) > (p_rs + *p_rs_len))
- {
- // Prevented out-of-bounds write
- return NRF_ERROR_CRYPTO_INTERNAL;
- }
- memcpy(p_rs + r_len, p_cur, s_len);
- *p_rs_len = r_len + s_len;
- return NRF_SUCCESS;
- }
- /**
- * @brief Encodes the ECDSA signature components (r, s) in ASN.1 format.
- *
- * @param[in] p_r Pointer to buffer containing component r of the ECDSA signature.
- * @param[in] r_len Length of the r component of the ECDSA signature.
- * @param[in] p_s Pointer to buffer containing component s of the ECDSA signature.
- * @param[in] s_len Length of the s component of the ECDSA signature.
- * @param[out] p_asn_sig Pointer to buffer to hold the resulting ASN.1-encoded ECDSA signature.
- * @param[out] p_asn_sig_len Pointer to variable holding the length of the buffer for ASN.1-encoded
- * ECDSA signature. This will be updated to the actual size when the
- * function is called.
- *
- * @returns True on success, otherwise false.
- */
- bool ecdsa_rs_to_asn1(uint8_t const * p_r,
- size_t r_len,
- uint8_t const * p_s,
- size_t s_len,
- uint8_t * p_asn_sig,
- size_t * p_asn_sig_len)
- {
- size_t index = 0;
- // NULL checks
- if (p_r == NULL || p_s == NULL || p_asn_sig_len == NULL)
- {
- return false;
- }
- if (r_len == 0 || r_len > DER_INTEGER_MAX_LEN || s_len == 0 || s_len > DER_INTEGER_MAX_LEN)
- {
- return false;
- }
- if (*p_asn_sig_len < (r_len + s_len + DER_OVERHEAD))
- {
- // Not enough space in output buffer
- return false;
- }
- // R component
- // DER TAG INTEGER
- p_asn_sig[index] = DER_TAG_INTEGER;
- index++;
- // Set length
- p_asn_sig[index] = r_len;
- // check if extra byte needed
- if (p_r[0] & 0x80)
- {
- // Update length value
- p_asn_sig[index] += 1;
- index++;
- // Insert zero byte for padding
- p_asn_sig[index] = 0;
- }
- index++;
- memcpy(&p_asn_sig[index], p_r, r_len);
- index += r_len;
- // S component
- // DER TAG INTEGER
- p_asn_sig[index] = DER_TAG_INTEGER;
- index++;
- // Set length
- p_asn_sig[index] = s_len;
- if (p_s[0] & 0x80)
- {
- // Update length value
- p_asn_sig[index] += 1;
- index++;
- // Insert zero byte for padding
- p_asn_sig[index] = 0;
- }
- index++;
- memcpy(&p_asn_sig[index], p_s, s_len);
- index += s_len;
- // Return total length of ASN.1-encoded data structure
- *p_asn_sig_len = index;
- return true;
- }
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