Hi Ethan and John,

Its difficult getting the environment setup. Would one of you mind sharing a CCS project with me?

I've got wolfSSL building using the instructions at https://www.wolfssl.com/documentation/U … -RTOS.pdf, but having trouble importing the TLS echo example. I may just end up creating a simple wolfCrypt_test project from scratch.

So far I've pushed my cleanups to: https://github.com/dgarske/wolfssl/tree/ti_aes , however no real fixes in AES GCM yet.

Feel free to email support at wolfssl dot come directly with any examples and reference this forum link.

Thanks,
David Garske, wolfSSL

Hi RCuller,

The input password will need to be padded to block size before being encrypted. The block should still decrypt properly even if you use a larger size. If you can explain how the encryption works it will help us guide you. Hopefully the example will provide some clues.

If you'd like to take this to a private channel you can email support at wolfssl dot com and we'll provide free pre-sales support.

Thanks,
David Garske, wolfSSL

Hi mnzdbz,

Because you are using WOLFSSL_SMALL_STACK it uses heap instead. If you remove the small stack option it will use stack and not heap.

Which mode of AES? There are AES tables as you found. Not using the tables slows down the operation because it must compute values. Are you building the .c code with optimizations enabled like "-Os" or "-O2"? Those make a big different.

Besides WOLFSSL_AES_SMALL_TABLES you can also play with WOLFSSL_AES_NO_UNROLL to see how that impacts performance and code size.

Thanks,
David Garske, wolfSSL

Hi mnzdbz,

How is your stack configured? Fast math (tfm.c) uses stack not heap. The correct size for FP_MAX_BITS is your maximum key size * 2 (for multiplication of two big integers).

You would likely need about 8KB of stack with your configuration. If you would like to use heap I recommend the following build settings.

#define WOLFSSL_SP_MATH_ALL
#define WOLFSSL_SP_SMALL
#define WOLFSSL_SMALL_STACK

This will use our sp_int.c with heap allocations.

Thanks,
David Garske, wolfSSL

Hi Richeal C,

Have you tried adjusting the TPM2_SPI_MAX_HZ to a lower value?

Can you try building wolfTPM like:

./configure --enable-infineon=slb9670 CFLAGS="-DTPM2_SPI_MAX_HZ=33000000"

Note you can add --enable-debug=io to see the raw output. Some of the self-test and key creation routines take a while. You might consider looking at XTPM_WAIT.

Can you tell us more about your project? Feel free to email support @ wolfssl.com directly.

Thanks,
David Garske, wolfSSL

Hi mnzdbz,

For validation of certificate begin/end dates we need a time source/RTC. If this is not available you can bypass date checking by adding NO_ASN_TIME to your user_settings.h. If you have an RTC, but your stdlib doesn't expose time() then you can define your own API.

Example:

/* user_settings.h - Override Current Time */

/* Allows custom "custom_time()" function to be used for benchmark */
#define WOLFSSL_USER_CURRTIME
#define WOLFSSL_GMTIME
#define USER_TICKS
extern unsigned long my_time(unsigned long* timer);
#define XTIME my_time

/* example code */

/* This is used by wolfCrypt asn.c for cert time checking */
unsigned long my_time(unsigned long* timer)
{
    (void)timer;
    return hw_get_time_sec();
}

Thanks,
David Garske, wolfSSL

Hi Wangzihao,

Can you share the build settings you are using to compile wolfSSL (like the ./configure or user_settings.h)?

Thanks,
David Garske, wolfSSL

Hi Sebastian,

Building our libraries for bare-metal is the easy part. Both wolfSSL and wolfMQTT are pure C libraries designed for portability and even bare-metal use.

For building you have a few options:
1) Use ./configure and cross-compile the libraries for your target. Something like:

./configure --host=arm-none-eabi CC=gcc AR=ar --disable-shared --disable-examples --disable-crypttests --disable-asm --disable-rsa --disable-dh --enable-tls13 --disable-tlsv12 CFLAGS="-mcpu=cortex-m0 -mthumb" LDFLAGS="-mcpu=cortex-m0 -mthumb"

. The result is a .a static library. You can use --prefix= to specify a custom install path used with "make install". This generates a wolfssl/options.h with the build options used. You'll need to include this in your application

#include <wolfssl/options.h>

.

2) Use our example GCC Makefiles in IDE/GCC-ARM which can be easily setup for Cortex M0

3) Use your own IDE: Import the src/*.c and wolfcrypt/src/*.c files into your project and build directly. Add include to the wolfSSL/wolfMQTT root. Add pre-processor WOLFSSL_USER_SETTINGS and add your own user_settings.h file (examples here: https://github.com/wolfSSL/wolfssl/tree … s/configs)

You'll likely have to do some investigating on how to use LWIP on bare-metal. I don't know of an example we have for this. But google turned up this nice article: https://lwip.fandom.com/wiki/LwIP_with_ … ing_system

Perhaps a short technical call might help you get started?

Thanks,
David Garske, wolfSSL

Hi Shammon,

Each asymmetric algorithm has different total memory requirements. We have several build options for altering where this memory comes from. For example you can put on heap, stack or static memory.

By default the memory comes mostly from the stack. If you'd prefer to use the heap then I would should consider updating to the latest wolfSSL in GitHub and using the `WOLFSSL_SP_SMALL_STACK` option, which is new. Or you could just try `WOLFSSL_SMALL_STACK` with your current release.

The RSA/DH algorithms have a much lager key size and generally use more memory. The ECC (ECDHE/ECDSA) and ED25519 algorithms use much less memory and can also be used with TLS v1.2 and v1.3.

Perhaps you can tell me more about your configuration such as RTOS/bare-metal, available heap/stack and TLS requirements?

Thanks,
David Garske, wolfSSL

Hi Shammon,

This sounds like a stack issue. Please try increasing your stack memory for the thread or adjust in the linker script if using bare-metal. What size DH key are you trying to generate? Have you tried running the wolfCrypt tests first? Make sure you have the right DH parameters enabled via `HAVE_FFDHE_2048`, `HAVE_FFDHE_3072`, `HAVE_FFDHE_4096`, etc.

Thanks,
David Garske, wolfSSL

Hi Luizg473,

I think your issue is not using `wolfTPM2_Init` and `wolfTPM2_Cleanup`. Have you tried that?

wolfTPM should have the WinAPI option enabled by default for windows: https://github.com/wolfSSL/wolfTPM/blob … ts.txt#L86

You can use `WOLFTPM_INTERFACE=WINAPI` to force it.

The build settings for wolfTPM come from here: https://github.com/microsoft/vcpkg/blob … file.cmake

Thanks,
David Garske, wolfSSL