RECENT BLOG NEWS

author: Daniel Stenberg

After another eight week cycle was been completed, curl shipped a new release into the world. 7.65.0 brings some news and some security fixes but is primarily yet again a set of bug-fixes bundled up. Remember 7.64.1?

As always, download it straight from curl.haxx.se!

One fun detail on this release: we have 500 less lines of source code in the lib/ directory compared to the previous release!

Things that happened in curl since last release:

• we announced a new Bug Bounty program and already paid the first rewards
• curl up 2019 happened and was awesome
• at wolfSSL we announced the tinycurl effort
• we’re running the annual curl survey right now
• we’ve welcomed new sponsors

Numbers

the 181st release
3 changes
56 days (total: 7,733)
119 bug fixes (total: 5,148)
215 commits (total: 24,326)
0 new public libcurl function (total: 80)
1 new curl_easy_setopt() option (total: 267)
0 new curl command line option (total: 221)
50 contributors, 24 new (total: 1,953)
32 authors, 12 new (total: 681)
2 security fixes (total: 89)
350 USD paid in Bug Bounties

News

1. libcurl has deprecated support for the global DNS cache.
2. Pipelining support is now completely removed from curl.
3. CURLOPT_MAXAGE_CONN is a new option that controls how long to keep a live connection in the connection cache for reuse.

Security

This release comes with fixes for two separate security problems. Both rated low risk. Both reported via the new bug bounty program.

CVE-2019-5435 is an issue in the recently introduced URL parsing API. It is only a problem in 32 bit architectures and only if an application can be told to pass in ridiculously long (> 2GB) strings to libcurl. This bug is similar in nature to a few other bugs libcurl has had in the past, and to once and for all combat this kind of flaw libcurl now (in 7.65.0 and forward) has a “maximum string length” limit for strings that you can pass to it using its APIs. The maximum size is 8MB. (The reporter was awarded 150 USD for this find.)

CVE-2019-5436 is a problem in the TFTP code. If an application decides to uses a smaller “blksize” than 504 (default is 512), curl would overflow a buffer allocated on the heap with data received from the server. Luckily, very few people actually download data from unknown or even remote TFTP servers. Secondly, asking for a blksize smaller than 512 is rather pointless and also very rare: the primary point in changing that size is to enlarge it. (The reporter was awarded 200 USD for this find.)

Bug-fixes

Over one hundred bug-fixes landed in this release, but some of my favorites from release cycle include…

mark connection for close on TLS close_notify

close_notify is a message in the TLS protocol that means that this connection is about to close. In most circumstances that message doesn’t actually provide information to curl that is needed, but in the case the connection is closed prematurely, understanding that this message preceded the closure helps curl act appropriately. This change was done for the OpenSSL backend only as that’s where we got the bug reported and worked on it this time, but I think we might have reasons to do the same for other backends going forward!

show port in the verbose “Trying …” message

The verbose message that says “Trying 12.34.56.78…” means that curl has sent started a TCP connect attempt to that IP address. This message has now been modified to also include the target port number so when using -v with curl 7.65.0, connecting to that same host for HTTPS will instead say “Trying 12.34.56.78:443…”.

To aid debugging really. I think it gives more information faster at a place you’re already looking.

new SOCKS 4+5 test server

The test suite got a brand new SOCKS server! Previously, all SOCKS tests for both version 4 and version 5 were done by firing up ssh (typically openssh). That method was decent but made it hard to do a range of tests for bad behavior, bad protocol replies and similar. With the new custom test server, we can basically add whatever test we want and we’ve already extended the SOCKS testing to cover more code and use cases than previously.

SOCKS5 user name and passwords must be shorter than 256

curl allows user names and passwords provided in URLs and as separate options to be more or less unrestricted in size and that include if the credentials are used for SOCKS5 authentication – totally ignoring the fact that the protocol SOCKS5 has a maximum size of 255 for the fields. Starting now, curl will return an error if the credentials for SOCKS5 are too long.

Warn if curl and libcurl versions do not match

The command line tool and the library are independent and separable, as in you can run one version of the curl tool with another version of the libcurl library. The libcurl API is solid enough to allow it and the tool is independent enough to not restrict it further.

We always release curl the command line tool and libcurl the library together, using the same version number – with the code for both shipped in the same single file.

There should rarely be a good reason to actually run curl and libcurl with different versions. Starting now, curl will show a little warning if this is detected as we have learned that this is almost always a sign of an installation or setup mistake. Hopefully this message will aid people to detect the mistake earlier and easier.

Better handling of “–no-” prefixed options

curl’s command line parser allows users to switch off boolean options by prefixing them with dash dash no dash. For example we can switch off compressed responses by using “–no-compression” since there regular option “–compression” switches it on.

It turned out we stripped the “–no-” thing no regarding if the option was boolean or not and presumed the logic to handle it – which it didn’t. So users could actually pass a proxy string to curl with the regular option “–proxy” as well as “–no-proxy”. The latter of course not making much sense and was just due to an oversight.

In 7.65.0, only actual boolean command line options can be used with “–no-“. Trying it on other options will cause curl to report error for it.

Add CURLUPART_ZONEID to the URL API

Remember when we added a new URL parsing API to libcurl back in 7.62.0? It wasn’t even a year ago! When we did this, we also changed the internals to use the same code. It turned out we caused a regression when we parsed numerical IPv6 addresses that provide the zone ID within the string. Like this: “https://[ffe80::1%25eth0]/index.html”

Starting in this release, you can both set and get the zone ID in a URL using the API, but of course setting it doesn’t do anything unless the host is a numeric IPv6 address.

parse proxy with the URL parser API

We removed the separate proxy string parsing logic and instead switched that over to more appropriately use the generic URL parser for this purpose as well. This move reduced the code size, made the code simpler and makes sure we have a unified handling of URLs! Everyone is happy!

longer URL schemes

I naively wrote the URL parser to handle scheme names as long as the longest scheme we support in curl: 8 bytes. But since the parser can also be asked to parse URLs with non-supported schemes, that limit was a bit too harsh. I did a quick research, learned that the longest currently registered URI scheme is 36 characters (“microsoft.windows.camera.multipicker”). Starting in this release , curl accepts URL schemes up to 40 bytes long.

Coming up next

There’s several things brewing in the background that might be ready to show in next release. Parallel transfers in the curl tool and deprecating PolarSSL support seem likely to happen for example. Less likely for this release, but still being worked on slowly, is HTTP/3 support.

We’re also likely to get a bunch of changes and fine features we haven’t even thought about from our awesome contributors. In eight weeks I hope to write another one of these blog posts explaining what went into that release…

If you have any questions or run into any issues, contact us at facts@wolfssl.com, or call us at +1 425 245 8247.

You can be a part of the new industry-changing port that integrates wolfSSL into Apache! The port of the wolfSSL embedded SSL/TLS library to be used with the Apache web server is nearing the point of Beta testing and we will be looking for user feedback. Development branches of the work have a basic connection being established and working, along with being able to stand up to a basic TLS test probe of the web server when running. Additional features such as OCSP stapling use and more testing is underway. If interested in getting a Beta version of wolfSSL’s integration to Apache contact us at facts@wolfssl.com.

Here are a few of the many reasons why someone should choose to use wolfSSL with their Apache server: we have FIPS validated code for use with projects that have FIPS requirements, our library was built with support for embedded devices leading to better scaling of connections (think more connections in the same amount of memory due to less memory used per connection),  hardware acceleration support on a wide range of devices, progressive cryptography additions such as the first TLS library with TLS 1.3 support, and the outstanding support we offer.

If you have any questions or run into any issues, contact us at facts@wolfssl.com, or call us at +1 425 245 8247.

wolfSSL's embedded SSL/TLS library has included support for TLS 1.3 since early releases of the TLS 1.3 draft. Since then, wolfSSL has remained up-to-date with the TLS 1.3 specification. In this post, the major upgrades of TLS 1.3 from TLS 1.2 are outlined below:

TLS 1.3

This protocol is defined in RFC 8446. TLS 1.3 contains improved security and speed. The major differences 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.

More information about the TLS 1.3 protocol can be found here: https://www.wolfssl.com/docs/tls13/. If you have any questions or run into any issues, contact us at facts@wolfssl.com, or call us at +1 425 245 8247.

Author: Daniel Stenberg

curl, or libcurl specifically, is probably the world’s most popular and widely used HTTP client side library counting more than six billion installs.

curl is a rock solid and feature-packed library that supports a huge amount of protocols and capabilities that surpass most competitors. But this comes at a cost: it is not the smallest library you can find.

Within a 100K

Instead of being happy with getting told that curl is “too big” for certain use cases, I set a goal for myself: make it possible to build a version of curl that can do HTTPS and fit in 100K (including the wolfSSL TLS library) on a typical 32 bit architecture.

As a comparison, the tiny-curl shared library when built on an x86-64 Linux, is smaller than 25% of the size as the default Debian shipped library is.

FreeRTOS

But let’s not stop there. Users with this kind of strict size requirements are rarely running a full Linux installation or similar OS. If you are sensitive about storage to the exact kilobyte level, you usually run a more slimmed down OS as well – so I decided that my initial tiny-curl effort should be done on FreeRTOS. That’s a fairly popular and free RTOS for the more resource constrained devices.

This port is still rough and I expect us to release follow-up releases soon that improves the FreeRTOS port and ideally also adds support for other popular RTOSes. Which RTOS would you like to support for that isn’t already supported?

Offer the libcurl API for HTTPS on FreeRTOS, within 100 kilobytes.

Maintain API

I strongly believe that the power of having libcurl in your embedded devices is partly powered by the libcurl API. The API that you can use for libcurl on any platform, that’s been around for a very long time and for which you can find numerous examples for on the Internet and in libcurl’s extensive documentation. Maintaining support for the API was of the highest priority.

Patch it

My secondary goal was to patch as clean as possible so that we can upstream patches into the main curl source tree for the changes makes sense and that aren’t disturbing to the general code base, and for the work that we can’t we should be able to rebase on top of the curl code base with as little obstruction as possible going forward.

Keep the HTTPS basics

I just want to do HTTPS GET

That’s the mantra here. My patch disables a lot of protocols and features:

• No protocols except HTTP(S) are supported
• HTTP/1 only
• No cookie support
• No date parsing
• No alt-svc
• No HTTP authentication
• No DNS-over-HTTPS
• No .netrc parsing
• No HTTP multi-part formposts
• No shuffled DNS support
• No built-in progress meter
• Although they’re all disabled individually so it is still easy to enable one or more of these for specific builds.

Downloads and versions?

Tiny-curl 0.9 is the first shot at this and can be downloaded from wolfSSL. It is based on curl 7.64.1.

Most of the patches in tiny-curl are being upstreamed into curl in the #3844 pull request. I intend to upstream most, if not all, of the tiny-curl work over time.

License

The FreeRTOS port of tiny-curl is licensed GPLv3 and not MIT like the rest of curl. This is an experiment to see how we can do curl work like this in a sustainable way. If you want this under another license, we’re open for business over at wolfSSL!

If you have any questions or run into any issues, contact us at facts@wolfssl.com, or call us at +1 425 245 8247.

wolfBoot is wolfSSL's own implementation of a secure bootloader that leverages wolfSSL's underlying wolfCrypt module to provide signature authentication for the running firmware.

The role of a secure bootloader is to effectively prevent the loading of malicious or unauthorized firmware on the target. Additionally, wolfBoot provides a fail-safe update mechanism, that can be interrupted at any time, and resumed at next boot.

wolfBoot is designed to be a portable, OS-agnostic, secure bootloader solution for all 32-bit microcontrollers, relying on wolfCrypt for firmware authentication.

Due to its minimalist design and the tiny Hardware Abstraction Layer (HAL) API, wolfBoot is completely independent of any OS or bare-metal application, and can be easily ported and integrated into existing embedded software solutions.

wolfBoot provides the basis for secure firmware update (OTA) management at boot time, cutting down the development effort needed to implement and validate the required mechanisms to handle the updates. It reduces the development effort to just receiving the image using a secure channel within the application/OS. We recommend using wolfSSL to encrypt the firmware transfer over TLS, to avoid eavesdropping. Once the image is transferred and stored into the update partition, wolfBoot takes care of the update procedure at the next boot.

Remote updates that would lead to a faulty firmware are automatically reverted by wolfBoot after the first 'test' boot, by restoring the original firmware image whenever the update has failed to boot properly. This mechanism protects the target device from accidental updates on the field.

wolfBoot can be downloaded from the wolfSSL download page here: https://www.wolfssl.com/download/

More about boot loaders can be found here: https://en.wikipedia.org/wiki/Booting#BOOT-LOADER
More about wolfSSL: https://www.wolfssl.com/products/wolfssl/
More about wolfCrypt: https://www.wolfssl.com/products/wolfCrypt/

If you have any questions or run into any issues, contact us at facts@wolfssl.com, or call us at +1 425 245 8247.

At wolfSSL we have had customers asking us whether we support the Ed25519 signature algorithm using a hash. We are pleased to announce that we now have available all the signature algorithms in RFC8032 including the prehashed version.

The original Ed25519 signature algorithm, much to the consternation of hardware vendors, has the message being hashed twice - with different prefixes. Signing large messages is therefore bad news for hardware accelerators as the whole message has to be sent rather than a small hash as in RSA and ECDSA.

The designers of the algorithm did this for security reasons. But, the IETF came out with a backward compatible algorithm that hashes the message with SHA-512 first. From RFC8032, the ed25519ph algorithm is: “greatly more vulnerable to weaknesses in hash functions used”. Therefore it should be used with caution.

The other algorithm adds a context that is prepended to the hashed data. But there are also security considerations when using this algorithm. The context should be a fixed value that is not message dependent and all uses in the protocol should use contexts if one of them does. If an attacker can choose the prefix, then this opens up an attack vector where they can try different prefixes until they get the result they want. Using a context in one place and not another has a similar problem.

If you have any questions or run into any issues, contact us at facts@wolfssl.com, or call us at +1 425 245 8247.

With the release of wolfSSL 4.0.0, the wolfSSL team has also released a new product: the wolfSSL FIPS Ready library. This product features new, state of the art concepts and technology. In a single sentence, wolfSSL FIPS Ready is a testable and free to download open source embedded SSL/TLS library with support for FIPS validation, with FIPS enabled cryptography layer code included in the wolfSSL source tree. To further elaborate on what FIPS Ready really means, you do not get a FIPS certificate and you are not FIPS approved. FIPS Ready means that you have included the FIPS code into your build and that you are operating according to the FIPS enforced best practices of default entry point, and Power On Self Test (POST).

FIPS validation is a government certification for cryptographic modules that states that the module in question has undergone thorough and rigorous testing to be certified. FIPS validation specifies that a software/encryption module is able to be used within or alongside government systems. The most recent FIPS specification is 140-2, with various levels of security offered (1-5). Currently, wolfCrypt has FIPS 140-2 validation with certificates #2425 and #3389. When trying to get software modules FIPS validated, this is often a costly and time-consuming effort and as such causes the FIPS validated modules to have high price tags.

Since the majority of wolfSSL products use the wolfCrypt encryption engine, this also means that if wolfSSH, wolfMQTT (with TLS support), wolfBoot, and other wolfSSL products in place can be tested FIPS validated code with their software before committing.

wolfSSL FIPS Ready can be downloaded from the wolfSSL download page, here: https://www.wolfssl.com/download/

If you have any questions or run into any issues, contact us at facts@wolfssl.com, or call us at +1 425 245 8247.

The National Institute of Standards and Technology (NIST) has completed the validation of the wolfCrypt module version 4 for an updated Federal Information and Processing Standards (FIPS) 140-2 certificate in addition to its previous FIPS 140-2 certificate. This new certificate includes updated and more secure algorithms added to the wolfCrypt module's boundary, some of which are listed further below.

FIPS 140-2 is a government standard that specifies a software module is compatible and allowed to be used in government systems. This includes such areas as drone software, government databases, and other high-security/high-power uses.

The new FIPS 140-2 validation has certificate #3389. The Operating Environments (OEs) tested are Ubuntu Linux (16.04) and Windows 10 on Intel Core i5 processors. Full details about the OEs can be found on the CSRC certificate page. Additionally, the certificate also includes the following algorithms: AES (CBC, GCM, CTR, ECB), CVL, Hash DRBG, DSA, DHE, ECDSA (key generation, sign, verify), HMAC, RSA (key generation, sign, verify), SHA-3, SHA-2, SHA-1, and Triple-DES.

For more information about wolfSSL, wolfCrypt, or our FIPS 140-2 validations, please view our resources below.

• wolfSSL FIPS page: https://www.wolfssl.com/license/fips/
• wolfSSL product page: https://www.wolfssl.com/products/wolfssl/
• wolfCrypt product page: https://www.wolfssl.com/products/wolfcrypt/

If you have any questions or run into any issues, contact us at facts@wolfssl.com, or call us at +1 425 245 8247.