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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 #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; }