ED25519 implementation with SHA512 + support to calculate SHA512 directly on storage + PureEdDSA #325

de-nordic · 2024-08-02T15:58:36Z

Only top four commits are relevant here, the rest are changes the PR is based on ( #323)

The PR provides:

usage of SHA512 in ED25519 signature verification where PureEdDSA(sha512(image)) is used
support to directly invoke SHA512 calculation on storage, which enabled hardware accelerated SHA512 calculation (when provided by hardware)
support for PureEdDSA(image) where signature is directly calculated over image and there is not hash/digest calculation.

Note that there is upstream PR for imgtool that supports this changes:
mcu-tools/mcuboot#2063
and PR that reserves the TLV
mcu-tools/mcuboot#2029
in upstream, so that we do not get in conflict with definitions before we are able to upstream the code.

Placed on top of #323

boot/bootutil/src/ed25519_psa.c

de-nordic · 2024-08-23T17:43:35Z

I was finally able to develop the imgtool version that does the single hash ed25519. The problem is that while imgtool is able to verify signed image fine, the MCUboot is not. I am trying to figure out what is happening.

nordicjm · 2024-09-26T07:12:22Z

boot/bootutil/zephyr/CMakeLists.txt

+target_include_directories(MCUBOOT_BOOTUTIL INTERFACE
+   ${ZEPHYR_MBEDTLS_MODULE_DIR}/include
+)


2 space indent for cmake

nordicjm · 2024-09-26T07:12:29Z

boot/zephyr/CMakeLists.txt

+zephyr_library_include_directories(
+  ${ZEPHYR_MBEDTLS_MODULE_DIR}/include
+)


nordicjm · 2024-09-26T07:12:40Z

boot/zephyr/Kconfig

@@ -27,6 +27,16 @@ config BOOT_USE_MBEDTLS
 	help
 	  Use mbedTLS for crypto primitives.

+config BOOT_USE_PSA_CRYPTO
+	bool
+	# Hidden option


Suggested change

# Hidden option

nordicjm · 2024-09-26T07:13:03Z

boot/zephyr/Kconfig

@@ -60,6 +70,58 @@ config NRF_CC310_BL
 	bool
 	default n

+if BOOT_USE_PSA_CRYPTO
+config BOOT_PSA_IMG_HASH_ALG_SHA256_DEPENDENCIES


newline gap

nordicjm · 2024-09-26T07:13:08Z

boot/zephyr/Kconfig

+	  Dependencies for ed25519 signature
+
+if BOOT_ENCRYPT_IMAGE
+config BOOT_X25519_PSA_DEPENDENCIES


nordicjm · 2024-09-26T07:14:03Z

boot/bootutil/src/ed25519_psa.c

+                          const uint8_t signature[64],
+                          const uint8_t public_key[32])


use defines from above

nordicjm · 2024-09-26T07:15:22Z

boot/bootutil/src/encrypted_psa.c

+           &buf[EC_CIPHERKEY_INDEX],
+	   sizeof(iv_and_key) - PSA_CIPHER_IV_LENGTH(PSA_KEY_TYPE_AES, PSA_ALG_CTR));
+
+    /* QQQ: are we sure that enckey has the size proper to fit the key ? */


should these comments be addressed/looked at?

Removed. The comments are note for improvement, where MCUboot has very poor "management" of various identifiers/constants that are hard to track.

nordicjm · 2024-09-26T07:16:14Z

boot/bootutil/src/image_validate.c

@@ -126,6 +128,15 @@ bootutil_img_hash(struct enc_key_data *enc_state, int image_index,
    /* If protected TLVs are present they are also hashed. */
    size += hdr->ih_protect_tlv_size;

+#ifdef MCUBOOT_HASH_STORAGE_DIRECTLY
+


Suggested change

nordicjm · 2024-09-26T07:16:19Z

boot/bootutil/src/image_validate.c

+     * be directly given to hashing function.
+     */
+    bootutil_sha_update(&sha_ctx, (void *)flash_area_get_off(fap), size);
+


Suggested change

nordicjm · 2024-09-26T07:16:22Z

boot/bootutil/src/image_validate.c

+    bootutil_sha_update(&sha_ctx, (void *)flash_area_get_off(fap), size);
+
+#else /* MCUBOOT_HASH_STORAGE_DIRECTLY */
+


Suggested change

Not resolved

nordicjm · 2024-09-26T07:17:49Z

boot/bootutil/src/image_ed25519.c

+    uint8_t *pubkey;
+    uint8_t *end;
+
+    if (slen != 64) {


nordicjm · 2024-09-26T07:19:22Z

boot/bootutil/src/image_validate.c

+    uint16_t len;
+    int32_t rc;
+
+    rc = bootutil_tlv_iter_begin(&it, hdr, fap, IMAGE_TLV_SIG_PURE, false);


security vulnerability: this can reside in protected or unprotected TLV section, so someone can manipulate an image to either have or not have this from an update that has the inverse - can that cause problems? And why is this not forced to protected area?

This only indicates that image is build with pure signature, if you turn this off the MCUboot that was build for pure will just not validate image as it expects "pure image"; if you pass image with this to something that does not understand pure, the chances of validation are slim, because it will just try to validate sha against pure signature.
The real reason for this is to be able to distinguish between images, because otherwise you can not tell the signatures apart, when trying to solve issues.

boot/zephyr/Kconfig

Use SHA512 directly calculated over image with the ED25519 signature. Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

nordicjm · 2024-09-30T08:47:29Z

boot/bootutil/src/image_validate.c

+    bootutil_sha_update(&sha_ctx, (void *)flash_area_get_off(fap), size);
+
+#else /* MCUBOOT_HASH_STORAGE_DIRECTLY */
+


Not resolved

nordicjm · 2024-09-30T08:47:47Z

boot/zephyr/include/mcuboot_config/mcuboot_config.h

@@ -137,8 +137,18 @@
 #endif

 #ifdef CONFIG_BOOT_DECOMPRESSION
+


Suggested change

Moved after the ifdef, to separate blocks.

nordicjm · 2024-09-30T08:48:25Z

boot/bootutil/src/image_validate.c

@@ -566,8 +613,12 @@ bootutil_img_validate(struct enc_key_data *enc_state, int image_index,
            }

            image_hash_valid = 1;
+            break;
+        }
+#endif /*def EXPECTED_HASH_TLV */


defined(condition) also missing correct conditions

nordicjm · 2024-09-30T10:38:33Z

boot/zephyr/include/mcuboot_config/mcuboot_config.h

+#ifdef MCUBOOT_ENC_IMAGES
+#error "Direct hash check is currently not supported when encrypted images are enabled"
+#endif


this check can go really, it's already enforced by Kconfig, doesn't make sense to check for something that isn't possible

Removed, although I must admit that I do like to check these things also in code, at compile-time.

nordicjm

OK once unneeded check is dropped

The commit add support for passing storage device address space to hash calculation functions, which allows to use hardware accelerated hash calculation on storage. This feature only works when image encryption is not enabled and all slots are defined within internal storage of device. The feature is enabled using Kconfig option CONFIG_BOOT_IMG_HASH_DIRECTLY_ON_STORAGE Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

The commit adds support for PureEdDSA, which validates signature of image rather than hash. This is most secure, available, ED25519 usage in MCUboot, but due to requirement of PureEdDSA to be able to calculate signature at whole message at once, here image, it only works on setups where entire image can be mapped to device address space, so that PSA functions calculating the signature can see the whole image at once. This option is enabled with Kconfig option: CONFIG_BOOT_SIGNATURE_TYPE_PURE when the ED25519 signature type is already selected. Note that the option will enable SHA512 for calculating public key hash. Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

michalek-no changed the title ~~The proper ED255129 implementation with SHA512~~ The proper ED25519 implementation with SHA512 Aug 5, 2024

de-nordic mentioned this pull request Aug 7, 2024

PSA implementation of ed25519 image verification and x25519 random key encryption/decryption #323

Merged

nvlsianpu approved these changes Aug 12, 2024

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de-nordic commented Aug 23, 2024

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boot/bootutil/src/ed25519_psa.c Outdated Show resolved Hide resolved

de-nordic force-pushed the x25519_enc_pure branch 3 times, most recently from 4631e1b to 8c7f38c Compare September 6, 2024 07:22

de-nordic force-pushed the x25519_enc_pure branch from cd55052 to e44f620 Compare September 13, 2024 15:26

de-nordic marked this pull request as ready for review September 13, 2024 15:31

de-nordic changed the title ~~The proper ED25519 implementation with SHA512~~ ED25519 implementation with SHA512 + support to calculate SHA512 directly on storage + PureEdDSA Sep 13, 2024

de-nordic requested review from nordicjm and michalek-no September 13, 2024 15:41

NordicBuilder mentioned this pull request Sep 18, 2024

manifest: Add PreEdDSA ed25519 image signature verification nrfconnect/sdk-nrf#17369

Merged

de-nordic force-pushed the x25519_enc_pure branch from e44f620 to 6c8f526 Compare September 25, 2024 14:49

nordicjm reviewed Sep 26, 2024

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de-nordic force-pushed the x25519_enc_pure branch 5 times, most recently from c81af6d to 04ae52b Compare September 26, 2024 17:13

[nrf noup] bootutil: Provide support for SHA512 with ED25519

9ef93e7

Use SHA512 directly calculated over image with the ED25519 signature. Signed-off-by: Dominik Ermel <dominik.ermel@nordicsemi.no>

de-nordic force-pushed the x25519_enc_pure branch from 04ae52b to 2fe6162 Compare September 30, 2024 07:32

de-nordic requested a review from nordicjm September 30, 2024 07:40

nordicjm requested changes Sep 30, 2024

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de-nordic force-pushed the x25519_enc_pure branch from 2fe6162 to 5c7304a Compare September 30, 2024 10:34

de-nordic requested a review from nordicjm September 30, 2024 10:35

nordicjm reviewed Sep 30, 2024

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nordicjm approved these changes Sep 30, 2024

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de-nordic added 2 commits October 1, 2024 08:02

de-nordic force-pushed the x25519_enc_pure branch from 5c7304a to 705739c Compare October 1, 2024 08:02

nvlsianpu merged commit de524e9 into nrfconnect:main Oct 1, 2024
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ED25519 implementation with SHA512 + support to calculate SHA512 directly on storage + PureEdDSA #325

ED25519 implementation with SHA512 + support to calculate SHA512 directly on storage + PureEdDSA #325

de-nordic commented Aug 2, 2024 •

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		bootutil_sha_update(&sha_ctx, (void *)flash_area_get_off(fap), size);

		#else /* MCUBOOT_HASH_STORAGE_DIRECTLY */

ED25519 implementation with SHA512 + support to calculate SHA512 directly on storage + PureEdDSA #325

ED25519 implementation with SHA512 + support to calculate SHA512 directly on storage + PureEdDSA #325

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de-nordic commented Aug 2, 2024 • edited Loading

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de-nordic commented Aug 2, 2024 •

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