Hi Poppy,
Some feedback from my understanding on the first question.
1. Import persistent key with a key_id is still supported in the updated PSA crypto spec.
In the version of PSA crypto spec in which psa_open_key is supported, the persistent key can be opened after the reset with the key_id which is specified in the key attributes in key creation. This is not very friendly. The reason is that each time the user calls the psa_open_key, the crypto service loads the key material from slot to running area(ram or flash) thus a new associated resources is allocated. The application must eventually call psa_close_key to release the allocated associated resources. It can happen that multiple applications call psa_open_key multile times as they may do not know whether the key is opened by other applications. So it can happen that multiple copies of associated resources are allocated for the same key. This is not user friendly.
In the updated PSA crypto spec, the key material management strategy is changed. The user does not need to call the psa_open_key to load the key from slot to ram/flash. See the section of "9.4 Key identifies" of the spec:
```
Key identifiers are output from a successful call to one of the key creation functions. For persistent keys,
this is the same identifier as the one specified in the key attributes used to create the key. The key
indenter remains valid until it is invalidated by passing it to psa_destroy_key(). A volatile key identifier
must not be used after it has been invalidated.
```
So I think the user can use the key_id directly to call crypto operations, such as means encrypt, decrypt.
Regards,
Sherry Zhang
From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> On Behalf Of Edward Yang via TF-M
Sent: Wednesday, June 2, 2021 1:30 PM
To: tf-m(a)lists.trustedfirmware.org
Subject: [TF-M] Questions about psa crypto persistent key
Hi Experts,
I have some questions about crypto persisten keys.
1. psa_open_key() is removed in psa crypto spec,so it is impossible to import a persistent key into key slot with key_id,which means encrypt/decrypt data directly with a persistent key is not allowed,these persistent keys can only be
used to derive volatile keys which will be used for encryption/decryption, I am not sure if I understand correctly.
2. Besides,HUK can be used to derive the other crypto keys,such as ps crypto key.HUK may be stored in OTP area of MCU(without crypto element such as cc312),then what's intended flow to derive crypto keys from HUK via calling PSA crypto service?There is no reference implementation in tf-m code.
tfm_plat_get_huk_derived_key(){
get HUK from OTP
||
||
\/
how to derive crypto key from HUK with calling crypto service?
}
3. BTW,HUK has a persistent key id TFM_CRYPTO_KEY_ID_HUK defined in tfm_crypto_defs.h,but I haven't seen any reference to this macro. What's the intended use of this key id?And what's the key owner of HUK?
Best Regards,
Poppy Wu
Macronix Microelectronics (Suzhou) Co.,Ltd
http://www.mxic.com.cn<http://www.mxic.com.cn/>
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=====================================================================
Hi Poppy Wu,
In the v1.0.0 PSA Crypto spec, key handles were removed, and keys are now always referred to by a key identifier.
After creating a persistent key with a key_id specified by the application (by import, generation or derivation), the key can be used in a cryptographic operation by passing the key_id to the operation function. No key handles are needed anymore. See https://armmbed.github.io/mbed-crypto/html/api/keys/lifetimes.html#persiste….
An implementation can provide some built-in keys with a pre-defined key_id. Depending on the key attributes and policy, these can be used by an application in appropriate cryptographic operations. Built-in keys can behave differently to application persistent keys:
* They cannot be destroyed by an application
* They might be accessible to multiple applications
* They might have different values in different applications
The implementation should provide documentation on the expected use of any built-in keys.
We'll need one of the TF-M team to comment on the expected use for TFM_CRYPTO_KEY_ID_HUK.
Regards,
Andrew Thoelke
Andrew Thoelke
Software Systems Architect | Arm
. . . . . . . . . . . . . . . . . . . . . . . . . . .
Arm.com
From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> On Behalf Of Edward Yang via TF-M
Sent: 02 June 2021 06:30
To: tf-m(a)lists.trustedfirmware.org
Subject: [TF-M] Questions about psa crypto persistent key
Hi Experts,
I have some questions about crypto persisten keys.
1. psa_open_key() is removed in psa crypto spec,so it is impossible to import a persistent key into key slot with key_id,which means encrypt/decrypt data directly with a persistent key is not allowed,these persistent keys can only be
used to derive volatile keys which will be used for encryption/decryption, I am not sure if I understand correctly.
2. Besides,HUK can be used to derive the other crypto keys,such as ps crypto key.HUK may be stored in OTP area of MCU(without crypto element such as cc312),then what's intended flow to derive crypto keys from HUK via calling PSA crypto service?There is no reference implementation in tf-m code.
tfm_plat_get_huk_derived_key(){
get HUK from OTP
||
||
\/
how to derive crypto key from HUK with calling crypto service?
}
3. BTW,HUK has a persistent key id TFM_CRYPTO_KEY_ID_HUK defined in tfm_crypto_defs.h,but I haven't seen any reference to this macro. What's the intended use of this key id?And what's the key owner of HUK?
Best Regards,
Poppy Wu
Macronix Microelectronics (Suzhou) Co.,Ltd
http://www.mxic.com.cn<http://www.mxic.com.cn/>
CONFIDENTIALITY NOTE:
This e-mail and any attachments may contain confidential information and/or personal data, which is protected by applicable laws. Please be reminded that duplication, disclosure, distribution, or use of this e-mail (and/or its attachments) or any part thereof is prohibited. If you receive this e-mail in error, please notify us immediately and delete this mail as well as it attachments from your system. In addition, please be informed that collection, processing, and/or use of personal data is prohibited unless expressly permitted by personal data protection laws. Thank you for your attention and cooperation.
Macronix International Co., Ltd.
=====================================================================
Hi,
I want to talk about whether TFM should support the PEM key format in crypto operation. In the PSA crypto spec, it describes:
```
This specification supports a single format for each key type. Implementations may support other formats as long as the standard format is supported.
```
The PEM format is not the standard format described in the spec. However, in the tfm_mbedcrypto_config_default.h, the MBEDTLS_PEM_PARSE_C and the MBEDTLS_PEM_WRITE_C is defined which leads to that PEM key format operation is enabled in TFM crypto service.
In isolation level1, about more than 2000 bytes code is introduced by this feature:
.ER_TFM_CODE 0x2a01c // MBEDTLS_PEM_PARSE_C and the MBEDTLS_PEM_WRITE_C enabled
.ER_TFM_CODE 0x29848 // MBEDTLS_PEM_PARSE_C and the MBEDTLS_PEM_WRITE_C disabled
Is it necessary to support the PEM format in the key operation in crypto service at the cost of more than 2000 bytes?
Any comments on that?
Regards,
Sherry Zhang
Hi Experts,
I have some questions about crypto persisten keys.
1. psa_open_key() is removed in psa crypto spec,so it is impossible to
import a persistent key into key slot with key_id,which means
encrypt/decrypt data directly with a persistent key is not allowed,these
persistent keys can only be
used to derive volatile keys which will be used for encryption/decryption,
I am not sure if I understand correctly.
2. Besides,HUK can be used to derive the other crypto keys,such as ps
crypto key.HUK may be stored in OTP area of MCU(without crypto element
such as cc312),then what's intended flow to derive crypto keys from HUK
via calling PSA crypto service?There is no reference implementation in
tf-m code.
tfm_plat_get_huk_derived_key(){
get HUK from OTP
||
||
\/
how to derive crypto key from HUK with calling crypto service?
}
3. BTW,HUK has a persistent key id TFM_CRYPTO_KEY_ID_HUK defined in
tfm_crypto_defs.h,but I haven't seen any reference to this macro. What's
the intended use of this key id?And what's the key owner of HUK?
Best Regards,
Poppy Wu
Macronix Microelectronics (Suzhou) Co.,Ltd
http://www.mxic.com.cn
============================================================================
CONFIDENTIALITY NOTE:
This e-mail and any attachments may contain confidential information and/or personal data, which is protected by applicable laws. Please be reminded that duplication, disclosure, distribution, or use of this e-mail (and/or its attachments) or any part thereof is prohibited. If you receive this e-mail in error, please notify us immediately and delete this mail as well as it attachments from your system. In addition, please be informed that collection, processing, and/or use of personal data is prohibited unless expressly permitted by personal data protection laws. Thank you for your attention and cooperation.
Macronix International Co., Ltd.
=====================================================================
Hi,
The agenda for the forum:
1. Linker script/scatter file templating (Ken Liu)
2. Discussion on Non-Secure Client ID update (David Wang).
3. AOB
Regards,
Anton
From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> On Behalf Of Anton Komlev via TF-M
Sent: Wednesday, May 19, 2021 6:21 PM
To: tf-m(a)lists.trustedfirmware.org
Cc: nd <nd(a)arm.com>
Subject: [TF-M] Technical Forum call - May 27
Hi,
The next Technical Forum is planned on Thursday, May 27 , 07:00-08:00 UTC (Asia time zone).
Please reply on this email with your proposals for agenda topics.
Recording and slides of previous meetings are here:
https://www.trustedfirmware.org/meetings/tf-m-technical-forum/
Best regards,
Anton
Hi Suresh,
> I am of the belief that MCUboot will be a very thin shim layer over the FWU API to provide the compatibility interface to legacy software and most of the work that was done earlier in MCUboot is pushed down into the FWU partition.
Are you suggesting that the software stack might look like this:
Update client application
|
| Function call
V
MCUBoot user API
Shim layer
|
| Function call
V
FWU API
|
| TF-M psa_call() etc.
V
FWU Partition
|
| Function call
V
MCUBoot user API
MCUBoot engine
This looks like it has one more layer than it needs, as either:
1. The Update client application could Talk directly to the FWU API, or
2. The first MCUBoot user API could interact with an MCUBoot update partition (RoT Service), without having to tunnel the MCUBoot API over the FWU API. The latter might not be straightforward - I am not sure that anyone has reviewed the two APIs for this purpose.
Are you only considering this software stack for a system where touching the update client application source code is not possible (needed for option #1 above)? - and you also cannot introduce a custom MCUBoot RoT Service partition (option #2 above) so you want to reuse TF-M's existing FWU API and partition?
Regards,
Andrew
From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> On Behalf Of Suresh Marisetty via TF-M
Sent: 25 May 2021 02:37
To: Sherry Zhang <Sherry.Zhang2(a)arm.com>; tf-m(a)lists.trustedfirmware.org
Cc: nd <nd(a)arm.com>
Subject: Re: [TF-M] Firmware update API - MCUboot update
Hi Sherry,
Thanks for the info. Wondering if there is some documentation or powerpoint explaining how the MCUBoot is changed to accommodate the FWU API.
Details that would help:
1. How the MCUboot works without the FWU API - natively
2. How the MCUBoot needs to be modified to leverage from FWU API
3. What components are retained in MCUBoot ex: image format, signing, metadata, tools
I am of the belief that MCUboot will be a very thin shim layer over the FWU API to provide the compatibility interface to legacy software and most of the work that was done earlier in MCUboot is pushed down into the FWU partition.
The other way to look at it is: If somebody wants to replace MCUboot with a simple BL to integrate it tightly into TFM, what would that look like?
thanks
Suresh Marisetty
Infineon Semiconductor Corporation
From: Sherry Zhang <Sherry.Zhang2(a)arm.com<mailto:Sherry.Zhang2@arm.com>>
Sent: Thursday, May 13, 2021 7:51 PM
To: Marisetty Suresh (CYSC CSS ICW SW SSE) <Suresh.Marisetty(a)infineon.com<mailto:Suresh.Marisetty@infineon.com>>; tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org>
Cc: nd <nd(a)arm.com<mailto:nd@arm.com>>
Subject: RE: Firmware update API - MCUboot update
Caution: This e-mail originated outside Infineon Technologies. Do not click on links or open attachments unless you validate it is safe<https://goto.infineon.com/SocialEngineering>.
Hi Suresh,
The MCUboot update functionality is about validating the existing images on the device which is different from that of the firmware update service which follows mostly with the PSA Firmware Update API spec<https://developer.arm.com/documentation/ihi0093/latest/>.
We designed a shim layer between the firmware update partition and bootloader. A specific bootloader can be ported into the firmware update partition via that shim layer. Please refer to the firmware update service document<https://git.trustedfirmware.org/TF-M/trusted-firmware-m.git/tree/docs/techn…>. In the MCUboot based shim layer implementation, it calls some user/public APIs provided by MCUboot to achieve its functionality. For example, the Firmware Update API spec describes that psa_fwu_install() API should validate the image or defer the validation to a system reboot. In the MCUboot shim layer implementation, it calls the boot_write_magic() API to mark the image as a candidate image for MCUboot and defers the image validation to a system reboot. Please refer to this link<https://git.trustedfirmware.org/TF-M/trusted-firmware-m.git/tree/secure_fw/…>.
Can you please provide more specific suggestion or questions?
Regards,
Sherry Zhang
From: Suresh.Marisetty(a)infineon.com<mailto:Suresh.Marisetty@infineon.com> <Suresh.Marisetty(a)infineon.com<mailto:Suresh.Marisetty@infineon.com>>
Sent: Thursday, May 13, 2021 11:40 PM
To: Sherry Zhang <Sherry.Zhang2(a)arm.com<mailto:Sherry.Zhang2@arm.com>>; tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org>
Cc: nd <nd(a)arm.com<mailto:nd@arm.com>>
Subject: RE: Firmware update API - MCUboot update
Hi Sherry,
Please take a closer look at the MCUboot and TFM might want to have a clear position/distinction between these two and how to transition from MCUboot update to this mechanism or it could be that they complement each other.
thanks
Suresh Marisetty
Infineon Semiconductor Corporation
From: Sherry Zhang <Sherry.Zhang2(a)arm.com<mailto:Sherry.Zhang2@arm.com>>
Sent: Wednesday, May 12, 2021 8:55 PM
To: Marisetty Suresh (CYSC CSS ICW SW SSE) <Suresh.Marisetty(a)infineon.com<mailto:Suresh.Marisetty@infineon.com>>; tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org>
Cc: nd <nd(a)arm.com<mailto:nd@arm.com>>
Subject: RE: Firmware update API - MCUboot update
Caution: This e-mail originated outside Infineon Technologies. Do not click on links or open attachments unless you validate it is safe<https://goto.infineon.com/SocialEngineering>.
Hi Suresh,
The firmware update service APIs are for updating the firmware. The functionalities of these APIs includes loading the image into its target device(flash), verifying the image and installing it and so on.
The user can call the these APIs to achieve update images. For example, in the integration of TF-M and the FreeRTOS OTA<https://github.com/Linaro/amazon-freertos/blob/tfm-fwu/libraries/abstractio…>, the OTA agent calls the firmware update service APIs to achieve an image update remotely.
I guess that the "MCUboot update services" you mentioned refers to the functionality of MCUboot which acts as a bootloader. As a bootloader, it can verify the image which already exists on the device and chose the right image to start up. But it cannot, for example, load the image into device or control the image update process.
The firmware update partition calls some user APIs provided by MCUboot to cooperate with it. You can refer to https://git.trustedfirmware.org/TF-M/trusted-firmware-m.git/tree/docs/techn….
Regards,
Sherry Zhang
From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org<mailto:tf-m-bounces@lists.trustedfirmware.org>> On Behalf Of Suresh Marisetty via TF-M
Sent: Thursday, May 13, 2021 11:09 AM
To: tf-m(a)lists.trustedfirmware.org<mailto:tf-m@lists.trustedfirmware.org>
Subject: [TF-M] Firmware update API - MCUboot update
Hi,
I would like to see if there is any guidance/documentation on how to coordinate between the firmware update services API with that of MCUboot.
Does the use of this API make the MCUboot update services redundant?
thanks
Suresh Marisetty
Infineon Semiconductor Corporation
Lead Member of Technical Staff
CYSC CSS ICW SW SSE
Mobile: +5103863997
Suresh.Marisetty(a)infineon.com<mailto:Suresh.Marisetty@infineon.com>
Hi Suresh,
The firmware update service APIs are for updating the firmware. The functionalities of these APIs includes loading the image into its target device(flash), verifying the image and installing it and so on.
The user can call the these APIs to achieve update images. For example, in the integration of TF-M and the FreeRTOS OTA<https://github.com/Linaro/amazon-freertos/blob/tfm-fwu/libraries/abstractio…>, the OTA agent calls the firmware update service APIs to achieve an image update remotely.
I guess that the "MCUboot update services" you mentioned refers to the functionality of MCUboot which acts as a bootloader. As a bootloader, it can verify the image which already exists on the device and chose the right image to start up. But it cannot, for example, load the image into device or control the image update process.
The firmware update partition calls some user APIs provided by MCUboot to cooperate with it. You can refer to https://git.trustedfirmware.org/TF-M/trusted-firmware-m.git/tree/docs/techn….
Regards,
Sherry Zhang
From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> On Behalf Of Suresh Marisetty via TF-M
Sent: Thursday, May 13, 2021 11:09 AM
To: tf-m(a)lists.trustedfirmware.org
Subject: [TF-M] Firmware update API - MCUboot update
Hi,
I would like to see if there is any guidance/documentation on how to coordinate between the firmware update services API with that of MCUboot.
Does the use of this API make the MCUboot update services redundant?
thanks
Suresh Marisetty
Infineon Semiconductor Corporation
Lead Member of Technical Staff
CYSC CSS ICW SW SSE
Mobile: +5103863997
Suresh.Marisetty(a)infineon.com<mailto:Suresh.Marisetty@infineon.com>
Hi Poppy,
SPRT requires the shared library shall not own static R/W data. ITS filesystem may not satisfy this requirement.
Usually, a SP, for example Protected Storage, can rely on ITS service to access data in non-volatile memory.
Best regards,
Hu Ziji
From: TF-M <tf-m-bounces(a)lists.trustedfirmware.org> On Behalf Of Edward Yang via TF-M
Sent: Monday, May 24, 2021 12:54 PM
To: tf-m(a)lists.trustedfirmware.org
Subject: [TF-M] A question on tfm its filesystem
Hi,
I'd like to ask a question to see if the filesystem part of tf-m its partition can be moved to lib/sprt folder,to make this filesystem a shared library for PRoT part of tfm.
Therefore,besides its partition, other extra secure partitions can also make use of this filesystem.
Best Regards,
Poppy Wu
Macronix Microelectronics (Suzhou) Co.,Ltd
Http: //www.mxic.com.cn
CONFIDENTIALITY NOTE:
This e-mail and any attachments may contain confidential information and/or personal data, which is protected by applicable laws. Please be reminded that duplication, disclosure, distribution, or use of this e-mail (and/or its attachments) or any part thereof is prohibited. If you receive this e-mail in error, please notify us immediately and delete this mail as well as its attachment(s) from your system. In addition, please be informed that collection, processing, and/or use of personal data is prohibited unless expressly permitted by personal data protection laws. Thank you for your attention and cooperation.
Macronix International Co., Ltd.
=====================================================================
Hi,
There are some out of sync contents in the wiki page (mainly the design chapter), which needs to be cleaned a bit.
https://developer.trustedfirmware.org/w/tf_m/
As the first step, the following article would be removed (Would move to a recyclable place at first):
Cooperative Scheduling Rules - content out of date.
Non-Secure Interrupt Handling - covered in the design document.
Secure Partition Interrupt Handling - covered in the interrupt handling document.
Service IPC compatibility - Attestation - low priority, no need to be a standalone item.
Service IPC compatibility - SST - same as above.
Trusted Firmware-m Isolation Level 2 - covered by document 'FF-M isolation'.
Uniform Secure Service Signature - out of date, as most of related files are changed.
Any comments please feel free to ping me.
Would do this on Thursday (27th May) this week.
Thanks.
/Ken
Hi,
I'd like to ask a question to see if the filesystem part of tf-m its
partition can be moved to lib/sprt folder,to make this filesystem a shared
library for PRoT part of tfm.
Therefore,besides its partition, other extra secure partitions can also
make use of this filesystem.
Best Regards,
Poppy Wu
Macronix Microelectronics (Suzhou) Co.,Ltd
Http: //www.mxic.com.cn
============================================================================
CONFIDENTIALITY NOTE:
This e-mail and any attachments may contain confidential information and/or personal data, which is protected by applicable laws. Please be reminded that duplication, disclosure, distribution, or use of this e-mail (and/or its attachments) or any part thereof is prohibited. If you receive this e-mail in error, please notify us immediately and delete this mail as well as its attachment(s) from your system. In addition, please be informed that collection, processing, and/or use of personal data is prohibited unless expressly permitted by personal data protection laws. Thank you for your attention and cooperation.
Macronix International Co., Ltd.
=====================================================================
