[nrf noup] boot: Add shared crypto for ECDSA and SHA

* Add functions for ecdsa_verify_secp256r1 and sha256 to use the shared
crypto API
* Add Kconfig and CMake variables for selecting shared crypto when using
ecdsa
* Add custom section to project for placing the API section in the
correct location in flash
* Add kconfig fragment for using external crypto

Signed-off-by: Sigvart Hovland <sigvart.m@gmail.com>
Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>
Signed-off-by: Emil Obalski <emil.obalski@nordicsemi.no>
Signed-off-by: Andrzej Puzdrowski <andrzej.puzdrowski@nordicsemi.no>
Signed-off-by: Håkon Øye Amundsen <haakon.amundsen@nordicsemi.no>
Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>
Signed-off-by: Trond Einar Snekvik <Trond.Einar.Snekvik@nordicsemi.no>
Signed-off-by: Georgios Vasilakis <georgios.vasilakis@nordicsemi.no>
Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>
Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>
Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>
Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>
(cherry picked from commit 55683e3)
(cherry picked from commit 0faa8b2)
(cherry picked from commit a42e9cc)
(cherry picked from commit 895c76b)
(cherry picked from commit ff53382)
(cherry picked from commit cc42516)

boot/bootutil/include/bootutil/crypto/ecdsa.h

@@ -34,6 +34,7 @@
 
 #if (defined(MCUBOOT_USE_TINYCRYPT) + \
      defined(MCUBOOT_USE_CC310) + \
+     defined(MCUBOOT_USE_NRF_EXTERNAL_CRYPTO) + \
      defined(MCUBOOT_USE_PSA_OR_MBED_TLS)) != 1
     #error "One crypto backend must be defined: either CC310/TINYCRYPT/MBED_TLS/PSA_CRYPTO"
 #endif
@@ -70,12 +71,18 @@
 #include "bootutil/sign_key.h"
 #include "common.h"
 
+#if defined(MCUBOOT_USE_NRF_EXTERNAL_CRYPTO)
+    #include <bl_crypto.h>
+    #define NUM_ECC_BYTES (256 / 8)
+#endif /* MCUBOOT_USE_NRF_EXTERNAL_CRYPTO */
+
 #ifdef __cplusplus
 extern "C" {
 #endif
 
 #if (defined(MCUBOOT_USE_TINYCRYPT) || defined(MCUBOOT_USE_MBED_TLS) || \
-     defined(MCUBOOT_USE_CC310)) && !defined(MCUBOOT_USE_PSA_CRYPTO)
+     defined(MCUBOOT_USE_CC310) || defined(MCUBOOT_USE_NRF_EXTERNAL_CRYPTO)) \
+     && !defined(MCUBOOT_USE_PSA_CRYPTO)
 /*
  * Declaring these like this adds NULL termination.
  */
@@ -127,8 +134,6 @@ static int bootutil_import_key(uint8_t **cp, uint8_t *end)
 }
 #endif /* (MCUBOOT_USE_TINYCRYPT || MCUBOOT_USE_MBED_TLS || MCUBOOT_USE_CC310) && !MCUBOOT_USE_PSA_CRYPTO */
 
-#if defined(MCUBOOT_USE_TINYCRYPT)
-#ifndef MCUBOOT_ECDSA_NEED_ASN1_SIG
 /*
  * cp points to ASN1 string containing an integer.
  * Verify the tag, and that the length is 32 bytes. Helper function.
@@ -178,8 +183,8 @@ static int bootutil_decode_sig(uint8_t signature[NUM_ECC_BYTES * 2], uint8_t *cp
     }
     return 0;
 }
-#endif /* not MCUBOOT_ECDSA_NEED_ASN1_SIG */
 
+#if defined(MCUBOOT_USE_TINYCRYPT)
 typedef uintptr_t bootutil_ecdsa_context;
 static inline void bootutil_ecdsa_init(bootutil_ecdsa_context *ctx)
 {
@@ -248,16 +253,20 @@ static inline int bootutil_ecdsa_verify(bootutil_ecdsa_context *ctx,
 {
     (void)ctx;
     (void)pk_len;
-    (void)sig_len;
     (void)hash_len;
+    uint8_t dsig[2 * NUM_ECC_BYTES];
+
+    if (bootutil_decode_sig(dsig, sig, sig + sig_len)) {
+        return -1;
+    }
 
     /* Only support uncompressed keys. */
     if (pk[0] != 0x04) {
         return -1;
     }
     pk++;
 
-    return cc310_ecdsa_verify_secp256r1(hash, pk, sig, BOOTUTIL_CRYPTO_ECDSA_P256_HASH_SIZE);
+    return cc310_ecdsa_verify_secp256r1(hash, pk, dsig, BOOTUTIL_CRYPTO_ECDSA_P256_HASH_SIZE);
 }
 
 static inline int bootutil_ecdsa_parse_public_key(bootutil_ecdsa_context *ctx,
@@ -613,6 +622,49 @@ static inline int bootutil_ecdsa_parse_public_key(bootutil_ecdsa_context *ctx,
 
 #endif /* MCUBOOT_USE_MBED_TLS */
 
+#if defined(MCUBOOT_USE_NRF_EXTERNAL_CRYPTO)
+typedef uintptr_t bootutil_ecdsa_context;
+static inline void bootutil_ecdsa_init(bootutil_ecdsa_context *ctx)
+{
+    (void)ctx;
+}
+
+static inline void bootutil_ecdsa_drop(bootutil_ecdsa_context *ctx)
+{
+    (void)ctx;
+}
+
+static inline int bootutil_ecdsa_verify(bootutil_ecdsa_context *ctx,
+                                        uint8_t *pk, size_t pk_len,
+                                        uint8_t *hash, size_t hash_len,
+                                        uint8_t *sig, size_t sig_len)
+{
+    (void)ctx;
+    (void)pk_len;
+    (void)hash_len;
+    uint8_t dsig[2 * NUM_ECC_BYTES];
+
+    if (bootutil_decode_sig(dsig, sig, sig + sig_len)) {
+        return -1;
+    }
+
+    /* Only support uncompressed keys. */
+    if (pk[0] != 0x04) {
+        return -1;
+    }
+    pk++;
+
+    return bl_secp256r1_validate(hash, BOOTUTIL_CRYPTO_ECDSA_P256_HASH_SIZE, pk, dsig);
+}
+
+static inline int bootutil_ecdsa_parse_public_key(bootutil_ecdsa_context *ctx,
+                                                  uint8_t **cp,uint8_t *end)
+{
+    (void)ctx;
+    return bootutil_import_key(cp, end);
+}
+#endif /* MCUBOOT_USE_NRF_EXTERNAL_CRYPTO */
+
 #ifdef __cplusplus
 }
 #endif

boot/bootutil/include/bootutil/crypto/sha.h

@@ -30,6 +30,7 @@
 
 #if (defined(MCUBOOT_USE_PSA_OR_MBED_TLS) + \
      defined(MCUBOOT_USE_TINYCRYPT) + \
+     defined(MCUBOOT_USE_NRF_EXTERNAL_CRYPTO) + \
      defined(MCUBOOT_USE_CC310)) != 1
     #error "One crypto backend must be defined: either CC310/MBED_TLS/TINYCRYPT/PSA_CRYPTO"
 #endif
@@ -206,6 +207,37 @@ static inline int bootutil_sha_finish(bootutil_sha_context *ctx,
 }
 #endif /* MCUBOOT_USE_CC310 */
 
+#if defined(MCUBOOT_USE_NRF_EXTERNAL_CRYPTO)
+
+#include <bl_crypto.h>
+
+typedef bl_sha256_ctx_t bootutil_sha_context;
+
+static inline void bootutil_sha_init(bootutil_sha_context *ctx)
+{
+    bl_sha256_init(ctx);
+}
+
+static inline void bootutil_sha_drop(bootutil_sha_context *ctx)
+{
+    (void)ctx;
+}
+
+static inline int bootutil_sha_update(bootutil_sha_context *ctx,
+                                      const void *data,
+                                      uint32_t data_len)
+{
+    return bl_sha256_update(ctx, data, data_len);
+}
+
+static inline int bootutil_sha_finish(bootutil_sha_context *ctx,
+                                      uint8_t *output)
+{
+    bl_sha256_finalize(ctx, output);
+    return 0;
+}
+#endif /* MCUBOOT_USE_NRF_EXTERNAL_CRYPTO */
+
 #ifdef __cplusplus
 }
 #endif

boot/zephyr/CMakeLists.txt

@@ -171,6 +171,8 @@ if(CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256 OR CONFIG_BOOT_ENCRYPT_EC256)
     zephyr_library_sources(${MCUBOOT_NRF_EXT_DIR}/cc310_glue.c)
     zephyr_library_include_directories(${MCUBOOT_NRF_EXT_DIR})
     zephyr_link_libraries(nrfxlib_crypto)
+  elseif(CONFIG_BOOT_USE_NRF_EXTERNAL_CRYPTO)
+    zephyr_include_directories(${BL_CRYPTO_DIR}/../include)
   endif()
 
   # Since here we are not using Zephyr's mbedTLS but rather our own, we need

boot/zephyr/external_crypto.conf

@@ -0,0 +1,20 @@
+#
+# Copyright (c) 2021 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+# These configurations should be used when using nrf/samples/bootloader
+# as the immutable bootloader (B0), and MCUBoot as the second stage updateable
+# bootloader.
+
+# Set ECDSA as signing mechanism
+CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256=y
+
+# Use crypto backend from B0
+CONFIG_BOOT_NRF_EXTERNAL_CRYPTO=y
+CONFIG_SECURE_BOOT_CRYPTO=y
+CONFIG_SB_CRYPTO_CLIENT_ECDSA_SECP256R1=y
+CONFIG_SB_CRYPTO_CLIENT_SHA256=y
+CONFIG_BL_SHA256_EXT_API_REQUIRED=y
+CONFIG_BL_SECP256R1_EXT_API_REQUIRED=y

boot/zephyr/include/mcuboot_config/mcuboot_config.h

@@ -40,9 +40,18 @@
 #define MCUBOOT_USE_TINYCRYPT
 #elif defined(CONFIG_BOOT_USE_CC310)
 #define MCUBOOT_USE_CC310
-#ifdef CONFIG_BOOT_USE_NRF_CC310_BL
-#define MCUBOOT_USE_NRF_CC310_BL
+#elif defined(CONFIG_MBEDTLS_PSA_CRYPTO_CLIENT)
+#define MCUBOOT_USE_PSA_CRYPTO
+#elif defined(CONFIG_BOOT_USE_NRF_EXTERNAL_CRYPTO)
+#define MCUBOOT_USE_NRF_EXTERNAL_CRYPTO
 #endif
+
+#ifdef CONFIG_BOOT_IMG_HASH_ALG_SHA512
+#define MCUBOOT_SHA512
+#endif
+
+#ifdef CONFIG_BOOT_IMG_HASH_ALG_SHA256
+#define MCUBOOT_SHA256
 #endif
 
 /* Zephyr, regardless of C library used, provides snprintf */