Add initial implementation of MCUBoot application for Cypress PSOC6 platform

Signed-off-by: Roman Okhrimenko <roman.okhrimenko@cypress.com>
diff --git a/boot/cypress/MCUBootApp/image_ec256_mbedtls.c b/boot/cypress/MCUBootApp/image_ec256_mbedtls.c
new file mode 100644
index 0000000..4053165
--- /dev/null
+++ b/boot/cypress/MCUBootApp/image_ec256_mbedtls.c
@@ -0,0 +1,166 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+/*******************************************************************************
+* \copyright
+*
+* (c) 2019, Cypress Semiconductor Corporation
+* or a subsidiary of Cypress Semiconductor Corporation. All rights
+* reserved.
+*
+* This software is a port of the open source MCUBoot project.
+*
+* This file was modified to fit PSoC6-based MCUBoot applications.
+*
+* Portions of this software, including source code, documentation and related
+* materials ("Software"), are owned by Cypress Semiconductor
+* Corporation or one of its subsidiaries ("Cypress") and is protected by
+* and subject to worldwide patent protection (United States and foreign),
+* United States copyright laws and international treaty provisions.
+* Therefore, you may use this Software only as provided in the license
+* agreement accompanying the software package from which you
+* obtained this Software ("EULA").
+*
+* If no EULA applies, Cypress hereby grants you a personal, non-
+* exclusive, non-transferable license to copy, modify, and compile the
+* Software source code solely for use in connection with Cypress's
+* integrated circuit products. Any reproduction, modification, translation,
+* compilation, or representation of this Software except as specified
+* above is prohibited without the express written permission of Cypress.
+*
+* Disclaimer: THIS SOFTWARE IS PROVIDED AS-IS, WITH NO
+* WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING,
+* BUT NOT LIMITED TO, NONINFRINGEMENT, IMPLIED
+* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+* PARTICULAR PURPOSE. Cypress reserves the right to make
+* changes to the Software without notice. Cypress does not assume any
+* liability arising out of the application or use of the Software or any
+* product or circuit described in the Software. Cypress does not
+* authorize its products for use in any products where a malfunction or
+* failure of the Cypress product may reasonably be expected to result in
+* significant property damage, injury or death ("High Risk Product"). By
+* including Cypress's product in a High Risk Product, the manufacturer
+* of such system or application assumes all risk of such use and in doing
+* so agrees to indemnify Cypress against all liability.
+*
+********************************************************************************/
+
+#include "mcuboot_config/mcuboot_config.h"
+
+#ifdef MCUBOOT_SIGN_EC256
+
+#include "bootutil/sign_key.h"
+
+#ifdef MCUBOOT_USE_MBED_TLS
+
+#include "mbedtls/oid.h"
+#include "mbedtls/asn1.h"
+#include "mbedtls/ecdsa.h"
+
+#include "bootutil_priv.h"
+
+#include <string.h>
+
+/*
+ * Declaring these like this adds NULL termination.
+ */
+static const uint8_t ec_pubkey_oid[] = MBEDTLS_OID_EC_ALG_UNRESTRICTED;
+static const uint8_t ec_secp256r1_oid[] = MBEDTLS_OID_EC_GRP_SECP256R1;
+
+/*
+ * Parse the public key used for signing.
+ */
+static int
+bootutil_parse_eckey(mbedtls_ecdsa_context *ctx, uint8_t **p, uint8_t *end)
+{
+    size_t len;
+    mbedtls_asn1_buf alg;
+    mbedtls_asn1_buf param;
+
+    if (mbedtls_asn1_get_tag(p, end, &len,
+        MBEDTLS_ASN1_CONSTRUCTED | MBEDTLS_ASN1_SEQUENCE)) {
+        return -1;
+    }
+    end = *p + len;
+
+    if (mbedtls_asn1_get_alg(p, end, &alg, &param)) {
+        return -2;
+    }
+    if (alg.len != sizeof(ec_pubkey_oid) - 1 ||
+      memcmp(alg.p, ec_pubkey_oid, sizeof(ec_pubkey_oid) - 1)) {
+        return -3;
+    }
+    if (param.len != sizeof(ec_secp256r1_oid) - 1||
+      memcmp(param.p, ec_secp256r1_oid, sizeof(ec_secp256r1_oid) - 1)) {
+        return -4;
+    }
+
+    if (mbedtls_ecp_group_load(&ctx->grp, MBEDTLS_ECP_DP_SECP256R1)) {
+        return -5;
+    }
+
+    if (mbedtls_asn1_get_bitstring_null(p, end, &len)) {
+        return -6;
+    }
+    if (*p + len != end) {
+        return -7;
+    }
+
+    if (mbedtls_ecp_point_read_binary(&ctx->grp, &ctx->Q, *p, end - *p)) {
+        return -8;
+    }
+
+    if (mbedtls_ecp_check_pubkey(&ctx->grp, &ctx->Q)) {
+        return -9;
+    }
+    return 0;
+}
+
+int
+bootutil_verify_sig(uint8_t *hash, uint32_t hlen, uint8_t *sig, size_t slen, uint8_t key_id)
+{
+    int rc;
+    uint8_t *cp;
+    uint8_t *end;
+    mbedtls_ecdsa_context ctx;
+
+    mbedtls_ecdsa_init(&ctx);
+
+    cp = (uint8_t *)bootutil_keys[key_id].key;
+    end = cp + *bootutil_keys[key_id].len;
+
+    rc = bootutil_parse_eckey(&ctx, &cp, end);
+    if (rc) {
+        return -1;
+    }
+
+    while (sig[slen - 1] == '\0') {
+        slen--;
+    }
+
+    rc = mbedtls_ecdsa_read_signature(&ctx, hash, hlen, sig, slen);
+
+    mbedtls_ecdsa_free(&ctx);
+
+    return rc;
+}
+
+#endif /* MCUBOOT_USE_MBED_TLS */
+
+#endif /* MCUBOOT_SIGN_EC256 */