Using Pre-Shared Keys (PSK) with wolfSSL
Ever wondered how to use PSK with the embedded wolfSSL library? PSK is useful in resource constrained devices where public key operations may not be viable. It`s also helpful in closed networks where a Certificate Authority structure isn`t in place. To enable PSK with wolfSSL you can simply do:
$ ./configure --enable-psk
Using PSK on the client side requires one additional function call:
wolfSSL_CTX_set_psk_client_callback()
There`s an example client callback in cyassl/test.h called my_psk_client_cb(). The example sets the client identity which is helpful for the server if there are multiple clients with unique keys and is limited to 128 bytes. It could also examine the server identity hint in case the client is talking to multiple servers with unique keys. Then the pre-shared key is returned to the caller, here that is simply 0x1a2b3c4d, but it could be any key up to 64 bytes in length (512 bits).
On the server side two additional calls are required:
wolfSSL_CTX_set_psk_server_callback()
wolfSSL_CTX_use_psk_identity_hint()
The server stores it`s identity hint to help the client with the 2nd call, in our server example that`s “cyassl server”. An example server psk callback can also be found in my_psk_server_cb() in cyassl/test.h. It verifies the client identity and then returns the key to the caller, which is again 0x1a2b3c4d, but could be any key up to 64 bytes in length. If you have any questions about using PSK with TLS please let us know.
wolfSSL at Sensors Expo 2019
Come visit wolfSSL at the 2019 Sensors Expo & Conference! Sensors Expo & Conference is the premier event for sensors, connectivity and systems, attracting the largest gathering of engineers and professionals of sensing-related technologies. This year the Sensors Expo & Conference will be held in San Jose, CA.
Where Sensors Expo & Conference will be held for 2019:
Venue: McEnery Convention Center, San Jose, CA
Booth #: 1525
When: June 25-27
Directions: https://www.sensorsexpo.com/show-overview/
Stop by to hear more about the wolfSSL embedded SSL/TLS library, the wolfCrypt encryption engine, or to meet the wolfSSL team! Feel free to say hello!
For more information about wolfSSL, its products, or future events, please contact facts@wolfssl.com.
More information about Sensors Expo & Conference can be found here: https://www.sensorsexpo.com/
wolfCrypt Support for Cryptographic Callbacks
wolfCrypt adds support for cryptographic callbacks that can be registered for replacing stock software calls with your own custom implementations. The goal is to make adding hardware cryptographic support easier.
Currently supported crypto callbacks:
- RNG and RNG Seed
- ECC (key gen, sign/verify and shared secret)
- RSA (key gen, sign/verify, encrypt/decrypt)
- AES CBC and GCM
- SHA1 and SHA256
- HMAC
This feature is enabled using “–enable-cryptocb” or “#define WOLF_CRYPTO_CB”.
To register a cryptographic callback function use the “wc_CryptoCb_RegisterDevice” API. This takes a unique device ID (devId), callback function and optional user context.
typedef int (*CryptoDevCallbackFunc)(int devId, wc_CryptoInfo* info, void* ctx);
WOLFSSL_API int wc_CryptoCb_RegisterDevice(
int devId,
CryptoDevCallbackFunc cb,
void* ctx);
To enable use of the crypto callbacks you must supply the “devId” arguments on initialization.
For TLS use:
- wolfSSL_CTX_SetDevId(ctx, devId);
- wolfSSL_SetDevId(ssl, devId);
For wolfCrypt API’s use the init functions that accept “devId” such as:
- wc_InitRsaKey_ex
- wc_ecc_init_ex
- wc_AesInit
- wc_InitSha256_ex
- wc_InitSha_ex
- wc_HmacInit
Examples:
- STSAFE-A100 ECC Crypto Callbacks: https://github.com/wolfSSL/wolfssl/blob/master/wolfcrypt/src/port/st/stsafe.c#L330
- TPM 2.0 wolfTPM Crypto Callbacks: https://github.com/wolfSSL/wolfTPM/blob/master/src/tpm2_wrap.c#L2937
- Generic wolfCrypt tests: https://github.com/wolfSSL/wolfssl/blob/master/wolfcrypt/test/test.c#L24304
For questions please email us at facts@wolfssl.com.
wolfBoot adds RISC-V Support
We have added support for RISC-V hardware in our wolfBoot library. The reference example uses the SiFive HiFive1 FE310 board to demonstrate a secure bootloader and firmware upgrade.
The HiFive1 is a 32-bit E31 RISC-V core capable of running at 320MHz. It includes 4MB of external flash and 16KB of internal RAM.
The wolfBoot library provides:
- Boot validation of the firmware image using hash and signature
- Reliable firmware update (power fail safe).
- Rollback support if application does not report “success”
- Version checking to prevent downgrade attack
- Support for external flash on updates
This adds support for:
- RV32 Hardware Access Layer (HAL) support for:
- PLL Clock configuration
- Flash eSPI
- UART
- RTC
- Firmware update example using the serial interface
Full setup and installation instructions can be found in “docs/Targets.md”.
These new features can be found on GitHub here:
https://github.com/wolfSSL/wolfBoot/pull/14
For questions please email us at facts@wolfssl.com.
Differences between TLS 1.2 and TLS 1.3 (#TLS13)
wolfSSL Adds Support for the Arm® TrustZone® CryptoCell-310
Are you a user of MCU with CryptoCell hardware? If so, you will be happy to know that wolfSSL recently added support for CryptoCell with wolfCrypt and benchmark examples to the wolfSSL embedded SSL/TLS library!
The wolfSSL port supports the following features:
- SHA-256
- AES CBC
- Elliptic Curve Digital Signature Algorithm (ECDSA) – sign and verify
- Elliptic Curve Diffie Hellman (ECDH) – shared secret
- ECC key generation support
- RSA sign and verify
- RSA key generation support
- RSA encrypt and decrypt
These features are tested on nRF52840 hardware platform with Nordic nRF5_SDK_15.2.0.
You can use the WOLFSSL_CRYPTOCELL macro to activate the CryptoCell support in wolfSSL. For instructions on how to build and run the examples on your projects, please see the “<wolfssl-root>/IDE/CRYPTOCELL/README” file. This support is currently located in our GitHub master branch, and will roll into the next stable release of wolfSSL.
wolfSSL provides support for the latest and greatest version of the TLS protocol, TLS 1.3! Using the wolfSSL port will allow your device to connect to the internet in one of the most secure ways possible.
For more information, please contact facts@wolfssl.com.
Resources
The most recent version of wolfSSL can be downloaded from our download page, here: https://www.wolfssl.com/download/
wolfSSL GitHub repository: https://github.com/wolfssl/wolfssl.git
wolfSSL support for TLS 1.3: https://www.wolfssl.com/docs/tls13/
wolfSSL at IoT Tech Expo
This year, wolfSSL is at IoT Tech Expo Europe! Europe’s largest and leading IoT event covers the latest innovations within the IoT and how they impact industries such as Manufacturing, Transport, Supply Chain, Insurance, Logistics, Government, Energy and Automotive. This year’s key topics include smart building and facilities management, building the connected supply chain, smart city and transport management, smart grid data management and analytics, delivering smart connected new products, and much more. For 2019, IoT Tech Expo will be held in Amsterdam, Netherlands.
Where IoT Tech Expo will be held for 2019:
Venue: RAI Amsterdam
Booth #: 631
When: June 19-20
Directions: https://www.iottechexpo.com/europe/event-travel-accommodation/
Stop by to hear more about the wolfSSL embedded SSL/TLS library, the wolfCrypt encryption engine, or to meet the wolfSSL team! Feel free to say hello!
For more information about wolfSSL, its products, or future events, please contact facts@wolfssl.com.
More information about IoT Tech Expo can be found here: https://www.iottechexpo.com/europe/.
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