- mbed-tls - lists.trustedfirmware.org

Reminder: MBed TLS Tech Forum - Asia/Europe

by Don Harbin

Hi All, A gentle reminder that the Asia-Europe timezone-friendly MBed TLS Tech forum is next Monday at 10:00am 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 ReplyReply to allForward Compose: Community activity: OpenCV, Sensors, AI [image: Minimise][image: Pop-out][image: Close] Compose: Reminder: MBed TLS Tech Forum - Asia/Europe [image: Minimise][image: Pop-out][image: Close] Recipients

9 months, 3 weeks

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Can TLS client send `Encrypted Alert 21` to server

by Satya Prakash Prasad

Hi All, We are using the MBedTLS 3.6.0 release stack and often see the TLS client -> server sending Encrypted Alert 21 packets followed by closing the SSL connection (or rather reconnection starting from new handshake messages). As far as I understand Alert 21 is a fatal message stating Decryption of a TLSCiphertext record is decrypted in an invalid way: either it was not an even multiple of the block length or its padding values, when checked, were not correct - copied from the Internet. But then Handshake and Application Data goes thru fine for a while and then we see our client sending Alert 21 encrypted message Is it legitimate that the client can send Alert 21 messages to the server and close the current connection - we are observing that the server application is waiting for messages from the client and is un-aware that a connection reset has occurred. So the server application states a timeout for receiving messages from the client. Further, how can we assert such a scenario? When and how can it occur? Is there a way we can simulate it and send details to owners of server firmware to fix their issue? Regards, Prakash

10 months

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FIPS 140-3 compliance of MbedTLS Test suites

by Viktor.Ivanets＠infineon.com

Hi All, We are using MbedTLS on our devices and implementing PSA wrappers to use our Crypto hardware. For validating this one we are using MbedTLS test suites. Could you please tell me: 1. Does your test suites compliant to FIPS 140-3? 2. Do you use NIST test vectors to validate your algorithm implementations? Thanks. Viktor Ivanets.

10 months

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3.6.0 library size

by Steven Burck

On a project at my company, we're using mbedtls to encrypt and sign our data. We began the project with mbedtls 2.2.6, and have continuously upgraded until now, 3.6.0. I've noticed my application has grown greatly since then, even though we are only using the following APIs: Encryption:(only decryption on the embedded side) - mbedtls_aes_init - mbedtls_aes_setkey_dec - mbedtls_aes_crypt_cbc Signing (only verification on the embedded side) - mbedtls_ecp_point_read_binary - mbedtls_sha256_init/free - mbedtls_sha256_starts_ret - mbedtls_sha256_update_ret - mbedtls_sha256_finish_ret - mbedtls_ecdsa_init/free - mbedtls_ecp_group_load - mbedtls_ecdsa_read_signature The size of libembedcrypto.a has grown from under 400K to almost 800K. I've tried reducing it with mbedtls_config,h, but it is not entirely clear to me which #defines do what. I tried one of the sample configs which by it;s name looked promising (crypto-config-ccm-aes-sha256.h), and it reduced the size of the library by 90%, but left me with link errors for all of the above functions. Going one #define at a time manually to see if it saves or grows is slow, and so I hoped I could find some assistance here. Thanks in advance

10 months

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Question about random number g

by Zhang, Hao

Hi TF-M and mbedtls community, I am new to TF-M, I have a few questions about CryptoCell and random number generation. Thank you in advance. 1. I figure there seems to have two CryptoCell 312 implementations within TF-M. One under lib/ext/cryptocell-312-runtime and the other under platform/ext/accelerator/cc312/cc312-rom. What are the difference between these two? 2. For lib/ext/cryptocell-312-runtime, it does not define MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG whereas /ext/accelerator/cc312/cc312-rom does. Does that mean cryptocell-312-runtime is initiating RNG cryptodriver by using mbedtls_entropy_add_source whereas cc312-rom is using mbedtls_psa_external_get_random<https://github.com/zephyrproject-rtos/trusted-firmware-m/blob/8df9cc8baf462…>. If so, may I ask why these two cryptocells take two different approaches? I read from one of the documentation that mbedtls_psa_external_get_random is used when entropy is sufficient. So if entropy is sufficient, is it always preferred to have MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG defined and implements mbedtls_psa_external_get_random? What are the differences between the two approaches. 3. I also found cryptocell-312-runtime defines the entry point function cc3xx_init_random<https://github.com/zephyrproject-rtos/trusted-firmware-m/blob/8df9cc8baf462…>. But since PSA random number entry point funciton is not complete, the cc3xx_init_random is not being called anywhere, right? [https://opengraph.githubassets.com/17cdebc400b0ed807c620b586b21f3f77ff9c5d3…]<https://github.com/zephyrproject-rtos/trusted-firmware-m/blob/8df9cc8baf462…> trusted-firmware-m/platform/ext/accelerator/cc312/cc312-rom/psa_driver_api/src/cc3xx_psa_random.c at 8df9cc8baf46252fd188bba1d87333a8daa9a5e8 · zephyrproject-rtos/trusted-firmware-m<https://github.com/zephyrproject-rtos/trusted-firmware-m/blob/8df9cc8baf462…> Zephyr repository tracking https://git.trustedfirmware.org/trusted-firmware-m.git/ - zephyrproject-rtos/trusted-firmware-m github.com 4. I know random number generation PSA entry point function is in development, may I ask when that would be expected to complete? Thank you very much! Best regards, Hao

10 months, 1 week

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Request for feedback about Mbed TLS 4: DRBG interfaces

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4.0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/107 Should TF-PSA-Crypto 1.0 (and thus Mbed TLS 4.0) have an interface for *pseudo*-random generation? It will, of course, still have a pseudorandom generator (= deterministic random bit generator = DRBG) internally, to power psa_generate_random(), psa_generate_key(), etc. The question is whether there will still be a public interface to create other DRBG instances, and if so, with what interface. If you want to be able to create instances of HMAC_DRBG and CTR_DRBG from application code in TF-PSA-Crypto 1.0, please let us know what your use case is. In particular, what parameters do you need (HMAC_DRBG and CTR_DRBG have many)? Do you need reseeding, and if so under whose control (the DRBG, or the caller)? In the absence of feedback, it is likely that HMAC_DRBG and CTR_DRBG will not be publicly available. Best regards, -- Gilles Peskine Mbed TLS developer

10 months, 1 week

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mbedtls 3.6.0: zero-sized array gives compiler warning (is undefined behavior)

by Almut Herzog

Hi all, I have a custom configuration where MBEDTLS_ECDSA_C is defined but MBEDTLS_PSA_CRYPTO_C and MBEDTLS_PSA_CRYPTO_CONFIG are not. This leads to a compiler warning in e.g. psa_util.c because a zero-sized array is declared (because PSA_VENDOR_ECC_MAX_CURVE_BITS is defined as 0). As of C99, §6.7.5.2 Array declarators: "If the expression is a constant expression, it shall have a value greater than zero." psa_util.c: #if defined(MBEDTLS_PSA_UTIL_HAVE_ECDSA) // Line 368 int mbedtls_ecdsa_raw_to_der(...) // Line 433 unsigned char r[PSA_BITS_TO_BYTES(PSA_VENDOR_ECC_MAX_CURVE_BITS)]; // Line 436 --> becomes in my config: unsigned char r[0]; MBEDTLS_PSA_UTIL_HAVE_ECDSA is automatically defined in my configuration due to the following code in config_adjust_legacy_crypto.h: #if defined(MBEDTLS_ECDSA_C) || (defined(MBEDTLS_PSA_CRYPTO_C) && \ (defined(PSA_WANT_ALG_ECDSA) || defined(PSA_WANT_ALG_DETERMINISTIC_ECDSA))) #define MBEDTLS_PSA_UTIL_HAVE_ECDSA #endif PSA_VENDOR_ECC_MAX_CURVE_BITS only receives a non-zero value if a PSA_WANT_<CURVE>, e.g. PSA_WANT_ECC_BRAINPOOL_P_R1_256, is defined. PSA_WANT_<CURVE> only gets defined in crypto_config.h if MBEDTLS_PSA_CRYPTO_CONFIG is defined (which it is not in my configuration). I have worked around it by explicitly defining e.g. PSA_WANT_ECC_BRAINPOOL_P_R1_256 in my configuration. But I believe there is some mismatch in the defines, at least in this example case, because mbedtls_ecdsa_raw_to_der() is only used in pk_wrap.c if MBEDTLS_USE_PSA_CRYPTO is defined. Impact: * In general, zero-sized arrays have undefined behavior in C (but are allowed by some compiler extensions) and thus behave differently for different compilers --> you might want to review PSA_VENDOR_ECC_MAX_CURVE_BITS and PSA_VENDOR_FFDH_MAX_KEY_BITS (and possibly more definitions) that fall through to 0 and are used as array sizes. * In my particular case, I believe code is compiled that is not needed (defines in psa_util.c and pk_wrap.c do not seem to match)

10 months, 1 week

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Request for feedback about Mbed TLS 4: size_t printing with %zu

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (Mbed TLS 4.0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/mbedtls/issues/9307 Mbed TLS requires a C99 platform, with some pragmatic restrictions. One restriction is that we do not require printf and friends to support %zu for size_t printing. Starting with Mbed TLS 4.0, we are considering requiring printf() and friends (or the mbedtls_printf() and friends alternatives if overridden) to support %zu. This only affects the TLS library, not X.509 and crypto. Is it still necessary in 2025 to support platforms where printf() does not support the z modifier? Best regards, -- Gilles Peskine Mbed TLS developer

10 months, 1 week

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Request for feedback about Mbed TLS 4 and TF-PSA-Crypto: build system

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4.0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/106 We are evaluating build systems for TF-PSA-Crypto, and this will influence the Mbed TLS build as well (the Mbed TLS build scripts will call the TF-PSA-Crypto build scripts, whatever they are). Our current thinking is that we would like to have *CMake as the sole build system*. (We're still investigating whether CMake can do all we need.) That would mean that we would no longer provide GNU makefiles or Visual Studio solutions. As this remains a C project, for just building the library, compiling all the .c files with an include path covering all the .h files will keep working in common cases (but, as today, it isn't something we support officially). The main case I can think of where this wouldn't work is when cryptographic accelerator support requires special includes or compiler flags. Are there environments where the use of CMake is a problem? What is the oldest version of CMake that you'd like us to be compatible with? Best regards, -- Gilles Peskine Mbed TLS developer

10 months, 2 weeks

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Request for feedback about Mbed TLS 4: RSA decryption cipher suites

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (Mbed TLS 4.0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/mbedtls/issues/8170 We are considering removing support for RSA and RSA-PSK key exchanges in Mbed TLS 4. These are cipher suites that use RSA encryption, as opposed to cipher suites using a key agreement (ECDHE) plus RSA signature. These key exchanges are hard to implement securely (we believe we got it right, but it's very delicate code), and they add significantly to the complexity of the TLS code. They have been formally deprecated for a long time and were removed in TLS 1.3. However, I'm aware that some ecosystems are clinging to RSA key exchange. Are RSA-encryption key exchanges still relevant for Mbed TLS? If you want Mbed TLS 4 to keep supporting RSA-encryption cipher suites in TLS 1.2, please let us know and tell us about your use cases. Best regards, -- Gilles Peskine Mbed TLS developer

10 months, 2 weeks

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Request for feedback about Mbed TLS 4: AESNI without compiler intrinsics

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4.0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/mbedtls/issues/8231 We currently have two implementations of accelerated AES on x86_64 using AESNI (Intel AES acceleration): using assembly or using compiler intrinsics. The assembly code works with GCC and Clang without any compilation options, but not with MSVC. The intrinsics work with MSVC, but not with ancient GCC/Clang and they require compiling at least aesni.c with suitable CPU variant options (e.g. -maes -mpclmul for Clang). We're considering removing the assembly implementation. Is there still interest in compiling AESNI support with older compilers or with simple build systems that don't pass machine options? Best regards, -- Gilles Peskine Mbed TLS developer

10 months, 2 weeks

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How to read ecp private key

by arun.lal＠intel.com

I am generating a ECP key in following way. And now how do I get the private key? TEE_Result gen_ec_keys(mbedtls_pk_context* pk, mbedtls_entropy_f_source_ptr f_source, __maybe_unused TEE_Param params[TEE_NUM_PARAMS]) { int ret = 1; mbedtls_entropy_context entropy; mbedtls_ctr_drbg_context ctr_drbg; const char* pers = "gen_key"; TEE_Result res = TEE_SUCCESS; unsigned char output_buf[16000]; memset(output_buf, 0, 16000); mbedtls_entropy_init(&entropy); mbedtls_ctr_drbg_init(&ctr_drbg); if ((ret = mbedtls_entropy_add_source(&entropy, f_source, NULL, 48, MBEDTLS_ENTROPY_SOURCE_STRONG)) != 0) { params[2].value.a = 1; goto exit; } if ((ret = mbedtls_ctr_drbg_seed(&ctr_drbg, f_entropy, &entropy, (const unsigned char*)pers, strlen(pers))) != 0) { mbedtls_printf(" failed\n ! mbedtls_ctr_drbg_seed returned -0x%04x\n", (unsigned int)-ret); params[2].value.a = 2; goto exit; } if ((ret = mbedtls_pk_setup(pk, mbedtls_pk_info_from_type(MBEDTLS_PK_ECKEY))) != 0) { EMSG(" failed\n ! mbedtls_pk_setup returned -0x%04x", (unsigned int)-ret); params[2].value.a = 3; goto exit; } if ((ret = mbedtls_ecp_gen_key(MBEDTLS_ECP_DP_SECP384R1, mbedtls_pk_ec(*pk), mbedtls_ctr_drbg_random, &ctr_drbg)) != 0) { EMSG(" failed\n ! mbedtls_ecp_gen_key returned -0x%04x", (unsigned int)-ret); params[2].value.a = 4; goto exit; } exit: mbedtls_ctr_drbg_free(&ctr_drbg); mbedtls_entropy_free(&entropy); return res; }

10 months, 3 weeks

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Re: PSA Cryptoprocessor Driver Interface

by Shebu Varghese Kuriakose

+ Mbed TLS mailing list as well for visibility and any comments. Regards, Shebu From: Zhang, Hao via TF-M <tf-m(a)lists.trustedfirmware.org> Sent: Wednesday, June 5, 2024 12:37 AM To: tf-m(a)lists.trustedfirmware.org Subject: [TF-M] PSA Cryptoprocessor Driver Interface Hi TF-M community, TF-M allows Semiconductor vendors to plug in their HW accelerator using PSA cryptoprocessor driver interface. I have a couple of questions in terms of the driver interface. 1. To port customized HW accelerator to TF-M's Crypto service for TF-M v2.1.0 LTS using driver interface, for the multipart operation, https://github.com/zephyrproject-rtos/mbedtls/blob/zephyr/docs/proposed/psa… states that "A driver that implements a multi-part operation must define all of the entry points in this family as well as a type that represents the operation context." Take aead encrypt as an example, if the underlying hardware does not support aead_abort, could it implements aead_abort by simply return PSA_ERROR_NOT_SUPPORTED? 1. The driver interface depends heavily on psa_crypto_driver_wrappers.h to dispatch operations to customized HW accelerator, where the psa_crypto_driver_wrappers.h file is automatically generated by scripts/data_files/driver_templates/psa_crypto_driver_wrappers.h.jinja. To port customized HW accelerator to TF-M's Crypto service for TF-M v2.1.0 LTS, would the approach be creating a customized psa_crypto_driver_wrappers.h.jinja file, the driver description file in JSON, and entry point functions. If so and we are considering upstreaming TF-M in the future, all these files would go inside platform/ext/accelerator/<vendor name>. Efforts need to be made so files such as psa_crypto_driver_wrappers.h.jinja should point to mbedtls, right? Additionally, as .jinja is retiring (mentioned in another email exchange), how would semi vendors update psa_crypto_driver_wrappers.h in the future? [https://opengraph.githubassets.com/c87e79773a7fb0841ea038f7cf3dfdf4170debb8…]<https://github.com/zephyrproject-rtos/mbedtls/blob/zephyr/docs/proposed/psa…> mbedtls/docs/proposed/psa-driver-interface.md at zephyr * zephyrproject-rtos/mbedtls<https://github.com/zephyrproject-rtos/mbedtls/blob/zephyr/docs/proposed/psa…> mbedtls module for Zephyr, this is not a mirror of the official mbedtls repository. - zephyrproject-rtos/mbedtls github.com Thank you very much! Best regards

10 months, 3 weeks

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mbedtls_x509_dn_gets(): Different DN string for 2.28.8 and 3.6.0

by Almut Herzog

Hi, Not sure whether I should report this as a bug or maybe an enhancement issue or maybe it is as-designed: I recently migrated from 2.28.8 to 3.6.0 and noticed: An X.509 certificate DN coded as T61 string (done automatically so by openssl for a DN that contains an underscore) is returned as a hex string in 3.6.0 while it is returned as a regular, human-readable string in 2.28.8. As this is not working for us I patched mbedtls_c509_dn_gets() locally as shown below. Please feedback whether you want me to report an issue or if the 3.6.0 behavior is as-designed for a good reason. Best regards, /Almut --- mbedtls-3.6.0_orig/library/x509.c 2024-03-28 09:59:12.000000000 +0100 +++ mbedtls-3.6.0/library/x509.c 2024-05-21 10:43:43.327442284 +0200 @@ -840,9 +840,7 @@ MBEDTLS_X509_SAFE_SNPRINTF; } - print_hexstring = (name->val.tag != MBEDTLS_ASN1_UTF8_STRING) && - (name->val.tag != MBEDTLS_ASN1_PRINTABLE_STRING) && - (name->val.tag != MBEDTLS_ASN1_IA5_STRING); + print_hexstring = !MBEDTLS_ASN1_IS_STRING_TAG(name->val.tag); if ((ret = mbedtls_oid_get_attr_short_name(&name->oid, &short_name)) == 0) { ret = mbedtls_snprintf(p, n, "%s=", short_name);

10 months, 3 weeks

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What is the right way to use ecp

by arun.lal＠intel.com

I have a very basic use case, to use a buffer and perform ECDSA encryption in a TA application. I also want to read back the private key which is generated. I see functions like mbedtls_ecp_gen_key but I have failed to find enough details on what steps to follow to use this function. It will be really helpful if I can be pointed to a example. Or let me know If there is some other way to achieve the end goal.

11 months

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Are you requesting feedback about ED25519?

by Christian Huitema

Hello Gilles, I see that you are requesting feedback on a set of issues, but not on support of EdDSA. Yet, support for ED25519 is an important requirement for TLS and QUIC. With other crypto suites, the CPU load is significantly lower for ED25519 than for ECDSA/secp255r1. Somewhat related, but there is also demand for ChaCha20-poly1035, for performance reason on some systems. Are there any plans? -- Christian Huitema

11 months, 1 week

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Request for feedback about Mbed TLS 4: CBC cipher suites

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (Mbed TLS 4.0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/mbedtls/issues/9202 In 2025 (by the time Mbed TLS 4.0 is released), are CBC-based cipher suites still relevant for Mbed TLS? If you still need support for CBC-based cipher suites (as opposed to cipher suites using AEAD: CCM, GCM or ChaChaPoly, or null cipher suites), please let us know. Removing them would allow us to significantly simplify some parts of the TLS code. They are difficult to implement securely due to being very sensitive to side channels; we think we got it right, but at the expense of performance, code size and maintainability. One option we're considering is to keep CBC cipher suites, but only when the encrypt-then-MAC (EtM) extension is enabled. However, this is problematic because the TLS protocol does not allow a client to indicate that it requires EtM support, which could lead to a failed connection even when the server also have an AEAD cipher suite in common. Best regards, -- Gilles Peskine Mbed TLS developer

11 months, 1 week

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Request for feedback about Mbed TLS 4: static ECDH cipher suites

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (Mbed TLS 4.0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/mbedtls/issues/9201 We are considering removing static ECDH cipher suites. (Mbed TLS has never supported static non-EC DH.) They are officially deprecated by RFC 9325. OpenSSL dropped them in 2016. If you want Mbed TLS 4.0 to continue supporting ECDH, please let us know in what ecosystem they're still relevant. Best regards, -- Gilles Peskine Mbed TLS developer

11 months, 1 week

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Request for feedback about Mbed TLS 4: dynamic secure element drivers

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4,0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/mbedtls/issues/8151 We are planning to remove the dynamic secure element interface enabled by MBEDTLS_PSA_CRYPTO_SE_C, in favor of PSA secure element drivers declared at compile time. The functionality is the same, but with a cleaner interface (we learned from the first draft). However, this does mean that all drivers must be declared at compile time. If you are currently using MBEDTLS_PSA_CRYPTO_SE_C and relying on runtime declaration of drivers, please let us know about your use case, so that we can try to find an alternative solution. Best regards, -- Gilles Peskine Mbed TLS developer

11 months, 1 week

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Request for feedback about Mbed TLS 4: partial ECC acceleration

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4,0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/103 We are removing all the ALT interfaces to implement hardware-accelerated cryptography, in favor of PSA drivers. For the most part, PSA accelerator drivers provide equivalent functionality to ALT interface. However, there is one main exception: the ECC code allows replacing just code ECC arithmetic (MBEDTLS_ECP_ALT) or even just selected functions (sub-options of MBEDTLS_ECP_INTERNAL_ALT). On the other hand, the granularity of PSA accelerators is whole mechanisms: ECDH, ECDSA, etc. on a specific set of curves. If you are currently using MBEDTLS_ECP_ALT or MBEDTLS_ECP_INTERNAL_ALT to implement accelerated ECC airthmetic and relying on code from ecp.c, ecdh.c and ecdsa.c to provide ECC mechanisms, please let us know what your requirements are and how much of a pain it would be to have to fully implement ECDH/ECDSA/... in your driver. Best regards, -- Gilles Peskine Mbed TLS developer

11 months, 1 week

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Request for feedback about Mbed TLS 4: RSA private key import

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4,0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/105 Mbed TLS 4 and TF-PSA-Crypto will complete our migration to PSA cryptography APIs. For simplicity, PSA only requires implementations to support complete representations RSA private keys, where all the fields are provided (n, e, d, p, q, dp, dq, u). Thus, with only PSA APIs, it is not possible to import an RSA private key without the public exponent, or an RSA private key without the CRT parameters. Should TF-PSA-Crypto provide an extension to support such private keys? If you need this, please let us know about your use case. Best regards, -- Gilles Peskine Mbed TLS developer

11 months, 1 week

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Request for feedback about Mbed TLS 4: custom ECC mechanisms

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4,0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/102 Mbed TLS 4 and TF-PSA-Crypto will complete our migration to PSA cryptography APIs, which are higher-level than the legacy mbedtls_xxx() APIs in Mbed TLS ≤3.x. As a consequence, the API will only provide access to ECC-based cryptographic mechanisms such as ECDH, ECDSA and ECJPAKE. (ECIES can be implemented on top of ECDH. Support for EdDSA and SPAKE2+ is planned, but might not be ready at the 4.0 release time.) It will not provide access to ECC arithmetic functions such as mbedtls_ecp_muladd(). Do you need custom ECC-based mechanisms (e.g. custom PAKE)? If so, please let us know which mechanisms and what arithmetic they require. We are not currently planning to make it possible to use such mechanisms without patching the TF-PSA-Crypto code. Best regards, -- Gilles Peskine Mbed TLS developer

11 months, 1 week

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Request for feedback about Mbed TLS 4: custom RSA mechanisms

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4,0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/TF-PSA-Crypto/issues/104 Mbed TLS 4 and TF-PSA-Crypto will complete our migration to PSA cryptography APIs, which are higher-level than the legacy mbedtls_xxx() APIs in Mbed TLS ≤3.x. As a consequence, the API will only provide access to RSA-based encryption and signature mechanisms (PKCS#1v1.5 encryption, OAEP, PKCS#1v1.5 signature, RSS), not to the low-level RSA-public and RSA-private operations. Do you need custom RSA-based mechanisms (e.g. full-domain encryption or hashing)? If so, please let us know. We are not currently planning to make it possible to use such mechanisms without patching the TF-PSA-Crypto code. Best regards, -- Gilles Peskine Mbed TLS developer

11 months, 1 week

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Request for feedback about Mbed TLS 4: DES (including 3DES)

by Gilles Peskine

Hello, This is a request for feedback about the next major release of Mbed TLS (TF-PSA-Crypto 1.0 + Mbed TLS 4,0). (Mbed TLS 3.6 LTS will remain supported with its current feature set until at least Q2 2027.) Please reply to this thread or on the GitHub issue linked below. If you wish to leave feedback privately, you can reply privately and your feedback will be anonymized before sharing outside Arm. https://github.com/Mbed-TLS/mbedtls/issues/9164 We are considering fully removing DES, including 3DES, from the library. Is any DES variant still relevant to Mbed TLS users these days? If you want Mbed TLS 4 to include DES, please let us know what you're using it for. Reasons to remove: it's long obsolete, and no longer accepted even by NIST except to handle legacy data. Removing it would be one less module to support and would allow generic block cipher code to focus on modern ciphers with 128-bit blocks. Best regards, -- Gilles Peskine Mbed TLS developer

11 months, 1 week

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MBEDTLS Default Search Path

by Frozen Forest

I am trying to build *https://github.com/ithewei/libhv <https://github.com/ithewei/libhv>* with MBEDTLS on Windows but it doesn't have include and library define options on *CMake*. When I ask them with an issue on *GitHub*, they said I need to use *"Default Search Path"*. I installed it with *cmake --build . --config Release --target INSTALL *and I can see it in *Program Files/MBed TLS. *I think I need to define an environment variable. But what is correct names for includes and libraries ?

11 months, 1 week

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