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Re: Writing mbedtls_x509_crt chain to PEM ?

by Nicolas Pillot

Hello Please note that this is a repost from my previous message from yesterday as it seemd to have bugged (empty text + html attachement) when viewed from the archive. Apologies. Short question : how do i output an in-memory mbedtls_x509_crt chain to PEM text ? Context : I have a project where the user provides a PEM bundle to be used for HTTPS As it is provided by a user, may be incomplete or malformed : - no private key - more than 1 private key - no certificate at all - duplicate certificates - no certificate matching the private key - broken chain - extraneous certificates not part of the chain… So i want to full validate user input. Here is what i have succeeded so far : - parse the bundle into atomic parts, based on « BEGIN/END » labels - try to mbedtls_x509_crt_parse / mbedtls_pk_parse_key each part (no chain) - check that i only have one private key in the bundle - search for the certificat C matching the private key - starting from that atomic certificate, verify it against each other candidate certificate - if it validates, add it to the chain of C, and repeat until no candidate validates - then check that there are no remaining certificate (which never validated anything) - finally print and store the chain (as it’s now deemed correct and minimal) Now i want to store it in PEM format for later use. But i do not understand the way to do it : - there are no write functions for mbedtls_x509_crt - the mbedtls_x509write_cert structure shares few members with mbedtls_x509_crt - i have not found yet how to get/convert many of the missing members - as memory is tight i have have cleaned the « atomic parts » text buffers (but if there is no other way, i'll keep and reuse them) I guess it should be pretty simple, but i cannot wrap my head around it. Thanks in advance for your help Nicolas PS : if steps 1-8 could be done more elegantly, please do not hesitate to point me in the right direction.

2 years, 6 months

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Writing mbedtls_x509_crt chain to PEM ?

by Nicolas PILLOT

2 years, 6 months

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Mbed TLS4.0 - Remove legacy cipher APIs

by S Krishnan, Archanaa

Hi, In mbedTLS road map, there is a future task to remove legacy cipher API (https://developer.trustedfirmware.org/w/mbed-tls/roadmap/). Does that mean all existing mbedtls crypto APIs will not be supported anymore? mbedTLS is used for both its TLS and crypto library. I am curious how the planned changes will affect both set of users. * Are the crypto library users expected to only use PSA crypto APIs and key IDs? * Are the TLS library users expected to see API changes to TLS functions to support key IDs? Thank, Archanaa

2 years, 6 months

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Question about handshake MTU

by Martin Man

Hi guys, I use mbedtls for years (since 2.10 IIRC) upgrading to latest available as time goes by. For DTLS that is. I remember a case in the past where a link would have a small MTU (around 500 bytes) and I had to tune ssl_context.handshake.mtu to a lower value to successfully complete handshakes. I do not remember exactly why, but I did not want to actually restrict maximum value via mbedtls_ssl_set_mtu, maybe it was even ignored back then for handshakes… but Now when working on migration to 3.2.1 (gave some time to 3x releases to stabilize) I noticed that the whole ssl_context.handshake member is now private and inaccessible, which I guess is fine. Could somebody with more knowledge of the code recommend what is the best strategy for DTLS app where MTU may not always be 1400? thanks a lot for your time, Martin

2 years, 6 months

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Regarding Connection ID (RFC 9146) support in Mbed TLS

by Jérémy Audiger

Hi everyone, I would like to know what is the current support of Mbed TLS regarding the RFC 9146 (https://datatracker.ietf.org/doc/html/rfc9146) published in March 2022. Mbed TLS is currently supporting a draft version of this RFC (https://datatracker.ietf.org/doc/html/draft-ietf-tls-dtls-connection-id-05) through the define MBEDTLS_SSL_DTLS_CONNECTION_ID, but I just wanted to know the progress on supporting the newly RFC released this year. Are there any plan to support it soon ? If yes, will it be in the coming weeks / months (i.e.: next release) ? I'm asking since I'm currently playing with the Connection ID on both a DTLS 1.2 Server and DTLS 1.2 Client. Anyway, have a nice day, Best regards, Jérémy Audiger [ioterop-your-lwm2m-partner]<https://ioterop.com/> [social-icon-linkedin]<https://www.linkedin.com/company/7955832/> [social-icon-twitter] <https://twitter.com/ioteropcompany> [social-icon-facebook] <https://www.facebook.com/IoteropCompany/>

2 years, 6 months

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Reminder: MBed TLS Technical Forum - US/Europe

by Don Harbin

Hi All, A gentle reminder that the US-Europe timezone-friendly MBed TLS Tech forum is next Monday at 4:30 PM UK time. Invite details can be found on the online calendar here <https://www.trustedfirmware.org/meetings/>. If you have any topics, please let Dave Rodgman know. :) Best regards, Don Harbin TrustedFirmware Community Manager don.harbin(a)linaro.org

2 years, 7 months

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Re: What am I doing wrong?

by Marco Nilsson

We're seeing pretty much the same issue on 3.0.0 ARM. However, if I build the ssh_client2 tool on my host machine (x64) and try to mimic the config as close as possible, it works just fine. Do you think we're seeing the same problem? Will try with a newer version next week.

2 years, 7 months

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HMAC and CMAC Verification

by Ahmed Mohammed

Hello, I am wondering if there are APIs for Hmac and Cmac verification? from md.h and cmac.h, Hmac and Cmac generation functionalities are provided in a single and streaming approach. But is there a plan to add verification APIs for future releases maybe? Kind regards, Ahmed Mohammed

2 years, 7 months

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User configuration

by Ahmed Mohammed

Hello, What is the difference between these two macros in include/mbedtls/build_info.h: MBEDTLS_CONFIG_FILE MBEDTLS_USER_CONFIG_FILE In other words, why would I have two different user configuration files? Or I misunderstand the difference between such files. Kind regards, Ahmed Mohammed

2 years, 7 months

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Slowness in verification of a ecdsa secp256r1 signature using S32K Microcontroller (clock speed 112MHz) - bare metal implementation

by ammar.ahmed.mughal＠gmail.com

I am verifying a signature generated using ecdsa secp256r1. The signature is getting verified but the time taken by the verification step is too long. It takes 4-5 seconds to verify the signature. The implementation is bare metal i.e. no RTOS (one realizes the use of RTOS but still the time is too long). Can you please guide a way around for this issue. How to make it work faster , the ideal verification time would be 30ms - 60ms. Here is a gist of my code mbedtls_ecp_curve_info *curve_info = NULL; mbedtls_ecdsa_context ecdsa_context; /// Initialization mbedtls_ecdsa_init(&ecdsa_context); curve_info = mbedtls_ecp_curve_info_from_tls_id(23); /// 23 is tls_id of secp256r1 mbedtls_ecp_group_load(&ecdsa_context.grp, curve_info->grp_id); /// Processing result = mbedtls_ecp_point_read_binary( &ecdsa_context.grp, &ecdsa_context.Q, public_key_data, // public key data in uncompressed format i.e. including leading 0x04 sizeof(public_key_data) ); /// 32 /// 71 status_verify_signature = mbedtls_ecdsa_read_signature(&ecdsa_context, hash, sizeof(hash), signature, sizeof(sig)); /// converts the signature data to ASN1, verifies the signature Thank you :)

2 years, 7 months

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