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Are you looking for an SSL/TLS library which will seamlessly integrate into your bare metal or No-OS environment? If so, continue reading to learn why the wolfSSL lightweight SSL library is a perfect fit for such environments.

wolfSSL has been designed with portability and ease of use in mind, allowing developers to easily integrate it into a bare metal or operating systemless environment. As a large percentage of wolfSSL users are running the library on small, embedded devices, we have added several abstraction layers which make tying wolfSSL into these types of environments an easy task.

Available abstraction layers include:

• Custom Input/Output
• Standard C library / Memory
• File system (Able to use cert/key buffers instead)
• Threading
• Operating System

In addition to abstraction layers, we have tried to keep wolfSSL’s memory usage as low as possible. Build sizes for a complete SSL/TLS stack range from 20-100kB depending on build options, with RAM usage between 1-36kB per connection.

To learn more about how to integrate wolfSSL into your environment or get more information about reducing wolfSSL’s memory usage, please see the wolfSSL Manual or contact us directly.

In early March 2018 we added support for the new Microsoft Azure Sphere microcontroller, which uses Pluton security for ECC P-256 key generation and sign/shared secret (ECDSA/ECDHE). This micro is targeting the embedded IoT space and supports Azure IoT cloud or any of your choosing. This chip uses wolfSSL and wolfCrypt for solving its TLS and Cryptographic security.

https://azure.microsoft.com/en-us/services/azure-sphere/

https://azure.microsoft.com/en-us/blog/introducing-microsoft-azure-sphere-secure-and-power-the-intelligent-edge/

For more questions please email us at facts@wolfssl.com.

We have added ST33TP support for the I2C and SPI version of the TPM 2.0 modules to the wolfTPM library.

STMicroelectronics ST33TP* TPM 2.0 Module Specifications:

• Interfaces: SPI (33MHz) or I2C (400kHz)
• Algorithms: RSA (1024/2048), ECC (224/256), AES (128/192/256), SHA1, SHA2, HMAC
• Certifications: CC EAL4+ and FIPS 140-2 Level 2
• NV Storage: 112KB

wolfTPM Library Features:

• The design allows for easy portability to different platforms.
• Native C code designed for embedded use.
• Single IO callback for hardware interface.
• No external library dependencies.
• Compact code size and minimal memory use.
• HAL IO callback examples for Raspberry Pi, STM32 CubeMX Hal and Atmel ASF.
• Tested on ST ST33TP* SPI/I2C and Infineon Optiga SLB9670.

Wrappers to simplify:

• Key Generation
• RSA encrypt/decrypt
• ECC sign/verify (ECDSA)
• ECC shared secret (ECDH)
• NV access (key and data storage)

Examples for:

• All TPM2 native API’s
• TPM wrappers
• PKCS #7
• Certificate Signing Request (CSR)
• TLS Client/Server
• Benchmarking

For the latest information and sources see GitHub here:
https://github.com/wolfSSL/wolftpm

For more questions please email us at facts@wolfssl.com.

wolfSSL supports the STMicroelectronics STSAFE-A100 I2C cryptographic coprocessor. It's capable of ECC sign/verify (ECDSA) and shared secret (ECDH) operations for 256-bit and 384-bit (NIST Prime and Brainpool) curves. It has 2 key slots and 6KB of non-volatile memory for certificate or data storage. 

Prerequisites:

• Requires the STSAFE-A Device Library from ST
• Requires wolfSSL interface and crypto configuration code (available by request and approval from ST)

Examples:

• wolfSSL uses PK callbacks for the TLS crypto operations
• wolfCrypt uses the WOLFSSL_STSAFEA100 macro to enable native `wc_ecc_*` API support

The README.md and reference PK callbacks can be found here: https://github.com/wolfSSL/wolfssl/tree/master/wolfcrypt/src/port/st

Preprocessor Macros:

• WOLFSSL_STSAFEA100

PK Callbacks:

wolfSSL TLS layer PK callbacks expose API’s to set ECC callbacks.Enabled with: #define HAVE_PK_CALLBACKS or ./configure --enable-pkcallbacks.

Reference API’s:

• SSL_STSAFE_CreateKeyCb
• SSL_STSAFE_SignCertificateCb
• SSL_STSAFE_VerifyPeerCertCb
• SSL_STSAFE_SharedSecretCb

Reference API for loading device certificate:

• SSL_STSAFE_LoadDeviceCertificate

For more questions please email us at facts@wolfssl.com.

wolfSSL embedded SSL/TLS support the latest Microchip ATECC508A and ATECC608A I2C cryptographic coprocessors. The latest round of fixes to support the most recent CryptoAuthLib are in a pull request here (https://github.com/wolfSSL/wolfssl/pull/1815). We have not yet tested with the ATECC608A due to lack of hardware, but wolfSSL is compatible with the latest CryptoAuthLib. We plan on adding support for the new 608A PRF and HKDF for TLS 1.2 and TLS 1.3 speed improvements.

Prerequisites:

• Requires the Microchip CryptoAuthLib (https://github.com/MicrochipTech/cryptoauthlib.git)

Examples:

• wolfSSL uses PK (Public Key) callbacks for the TLS crypto operations
• wolfCrypt uses the WOLFSSL_ATECC508A macro to enable native `wc_ecc_*` API support

The README.md and reference PK callbacks can be found here: https://github.com/wolfSSL/wolfssl/tree/master/wolfcrypt/src/port/atmel

Additional demos for wolfSSL TLS Client/Server and wolfCrypt test/benchmarks can be found:

https://www.wolfssl.com/download/downloadMoreForm.php
https://github.com/dgarske/atmel

Preprocessor Macros:

• WOLFSSL_ATECC508A
• WOLFSSL_ATECC_PKCB
• WOLFSSL_ATMEL

PK Callbacks:

wolfSSL’s TLS layer PK callbacks expose API’s to set ECC callbacks. These are enabled with: #define HAVE_PK_CALLBACKS or ./configure --enable-pkcallbacks.

Reference API’s:

• atcatls_create_key_cb
• atcatls_verify_signature_cb
• atcatls_sign_certificate_cb
• atcatls_create_pms_cb

For more questions please email us at facts@wolfssl.com.

Have you heard talk about SSL 3.0, TLS 1.0, TLS 1.1, TLS 1.2, and TLS 1.3 but never really knew the differences between the different versions? Secure Socket Layer (SSL) and Transport Security Layer (TLS) are both cryptographic protocols which provide secure communication over networks. These different versions are all in widespread use today in applications such as web browsing, e-mail, instant messaging and VoIP, and each is slightly different from the others.wolfSSL supports all three of these ciphers to best suit your needs and requirements. Below you will find the major differences between the different protocol versions.

SSL 3.0
This protocol was released in 1996, but first began with the creation of SSL 1.0 developed by Netscape. Version 1.0 wasn`t released, and version 2.0 had a number of security flaws, thus leading to the release of SSL 3.0. Some major improvements of SSL 3.0 over SSL 2.0 are:
– Separation of the transport of data from the message layer
– Use of a full 128 bits of keying material even when using the Export cipher
– Ability of the client and server to send chains of certificates, thus allowing organizations to use certificate hierarchy which is more than two certificates deep.
– Implementing a generalized key exchange protocol, allowing Diffie-Hellman and Fortezza key exchanges as well as non-RSA certificates.
– Allowing for record compression and decompression
– Ability to fall back to SSL 2.0 when a 2.0 client is encountered

Netscape`s Original SSL 3.0 Draft: http://www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt
Comparison of SSLv2 and SSLv3: http://stason.org/TULARC/security/ssl-talk/4-11-What-is-the-difference-between-SSL-2-0-and-3-0.html

TLS 1.0
This protocol was first defined in RFC 2246 in January of 1999. This was an upgrade from SSL 3.0 and the differences were not dramatic, but they are significant enough that SSL 3.0 and TLS 1.0 don`t interoperate. Some of the major differences between SSL 3.0 and TLS 1.0 are:
– Key derivation functions are different
– MACs are different – SSL 3.0 uses a modification of an early HMAC while TLS 1.0 uses HMAC.
– The Finished messages are different
– TLS has more alerts
– TLS requires DSS/DH support

RFC 2246: http://tools.ietf.org/html/rfc2246

TLS 1.1
This protocol was defined in RFC 4346 in April of 2006, and is an update to TLS 1.0. The major changes are:
– The Implicit Initialization Vector (IV) is replaced with an explicit IV to protect against Cipher block chaining (CBC) attacks.
– Handling of padded errors is changed to use the bad_record_mac alert rather than the decryption_failed alert to protect against CBC attacks.
– IANA registries are defined for protocol parameters
– Premature closes no longer cause a session to be non-resumable.

RFC 4346: http://tools.ietf.org/html/rfc4346#section-1.1

TLS 1.2
This protocol was defined in RFC 5246 in August of 2008. Based on TLS 1.1, TLS 1.2 contains improved flexibility. The major differences include:
– The MD5/SHA-1 combination in the pseudorandom function (PRF) was replaced with cipher-suite-specified PRFs.
– The MD5/SHA-1 combination in the digitally-signed element was replaced with a single hash. Signed elements include a field explicitly specifying the hash algorithm used.
– There was substantial cleanup to the client`s and server`s ability to specify which hash and signature algorithms they will accept.
– Addition of support for authenticated encryption with additional data modes.
– TLS Extensions definition and AES Cipher Suites were merged in.
– Tighter checking of EncryptedPreMasterSecret version numbers.
– Many of the requirements were tightened
– Verify_data length depends on the cipher suite
– Description of Bleichenbacher/Dlima attack defenses cleaned up.

RFC 5246: http://tools.ietf.org/html/rfc5246

TLS 1.3
This protocol is currently being revised, and is in its 28th draft. The major differences from TLS 1.2 include:
– The list of supported symmetric algorithms has been pruned of all legacy algorithms. The remaining algorithms all use Authenticated Encryption with Associated Data (AEAD) algorithms.
– A zero-RTT (0-RTT) mode was added, saving a round-trip at connection setup for some application data at the cost of certain security properties.
– Static RSA and Diffie-Hellman cipher suites have been removed; all public-key based key exchange mechanisms now provide forward secrecy.
– All handshake messages after the ServerHello are now encrypted.
– Key derivation functions have been re-designed, with the HMAC-based Extract-and-Expand Key Derivation Function (HKDF) being used as a primitive.
– The handshake state machine has been restructured to be more consistent and remove superfluous messages.
– ECC is now in the base spec and includes new signature algorithms. Point format negotiation has been removed in favor of single point format for each curve.
– Compression, custom DHE groups, and DSA have been removed, RSA padding now uses PSS.
– TLS 1.2 version negotiation verification mechanism was deprecated in favor of a version list in an extension.
– Session resumption with and without server-side state and the PSK-based ciphersuites of earlier versions of TLS have been replaced by a single new PSK exchange.

RFC 8446: https://tools.ietf.org/html/rfc8446

Resources:
If you would like to read more about SSL or TLS, here are several resources that might be helpful:
TLS – Wikipedia (http://en.wikipedia.org/wiki/Transport_Layer_Security)
SSL versus TLS – What`s the Difference? (http://luxsci.com/blog/ssl-versus-tls-whats-the-difference.html)
Cisco – SSL: Foundation for Web Security (http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_1-1/ssl.html)

As always, if you have any questions or would like to talk to the wolfSSL team about more information, please contact facts@wolfssl.com.