82 lines
3.9 KiB
Markdown
82 lines
3.9 KiB
Markdown
# Maintained branches
|
|
|
|
At any point in time, we have a number of maintained branches consisting of:
|
|
|
|
- The [`master`](https://github.com/Mbed-TLS/mbedtls/tree/master) branch:
|
|
this always contains the latest release, including all publicly available
|
|
security fixes.
|
|
- The [`development`](https://github.com/Mbed-TLS/mbedtls/tree/development) branch:
|
|
this is where new features land,
|
|
as well as bug fixes and security fixes.
|
|
- One or more long-time support (LTS) branches:
|
|
these only get bug fixes and security fixes.
|
|
|
|
We use [Semantic Versioning](https://semver.org/). In particular, we maintain
|
|
API compatibility in the `master` branch between major version changes. We
|
|
also maintain ABI compatibility within LTS branches; see the next section for
|
|
details.
|
|
|
|
Every major version will become an LTS branch when the next major version is
|
|
released. We may occasionally create LTS branches from other releases at our
|
|
discretion.
|
|
When a new LTS branch is created, it usually remains supported for three years.
|
|
|
|
## Backwards Compatibility for application code
|
|
|
|
We maintain API compatibility in released versions of Mbed TLS. If you have
|
|
code that's working and secure with Mbed TLS x.y.z and does not rely on
|
|
undocumented features, then you should be able to re-compile it without
|
|
modification with any later release x.y'.z' with the same major version
|
|
number, and your code will still build, be secure, and work.
|
|
|
|
Note that this guarantee only applies if you either use the default
|
|
compile-time configuration (`mbedtls/config.h`) or the same modified
|
|
compile-time configuration. Changing compile-time configuration options can
|
|
result in an incompatible API or ABI, although features will generally not
|
|
affect unrelated features (for example, enabling or disabling a
|
|
cryptographic algorithm does not break code that does not use that
|
|
algorithm).
|
|
|
|
There are rare exceptions: code that was relying on something that became
|
|
insecure in the meantime (for example, crypto that was found to be weak) may
|
|
need to be changed. In case security comes in conflict with backwards
|
|
compatibility, we will put security first, but always attempt to provide a
|
|
compatibility option.
|
|
|
|
For the LTS branches, additionally we try very hard to also maintain ABI
|
|
compatibility (same definition as API except with re-linking instead of
|
|
re-compiling) and to avoid any increase in code size or RAM usage, or in the
|
|
minimum version of tools needed to build the code. The only exception, as
|
|
before, is in case those goals would conflict with fixing a security issue, we
|
|
will put security first but provide a compatibility option. (So far we never
|
|
had to break ABI compatibility in an LTS branch, but we occasionally had to
|
|
increase code size for a security fix.)
|
|
|
|
For contributors, see the [Backwards Compatibility section of
|
|
CONTRIBUTING](CONTRIBUTING.md#backwards-compatibility).
|
|
|
|
## Backward compatibility for the key store
|
|
|
|
We maintain backward compatibility with previous versions of the
|
|
PSA Crypto persistent storage since Mbed TLS 2.25.0, provided that the
|
|
storage backend (PSA ITS implementation) is configured in a compatible way.
|
|
We intend to maintain this backward compatibility throughout a major version
|
|
of Mbed TLS (for example, all Mbed TLS 3.y versions will be able to read
|
|
keys written under any Mbed TLS 3.x with x <= y).
|
|
|
|
Mbed TLS 3.x can also read keys written by Mbed TLS 2.25.0 through 2.28.x
|
|
LTS, but future major version upgrades (for example from 2.28.x/3.x to 4.y)
|
|
may require the use of an upgrade tool.
|
|
|
|
## Current Branches
|
|
|
|
The following branches are currently maintained:
|
|
|
|
- [master](https://github.com/Mbed-TLS/mbedtls/tree/master)
|
|
- [`development`](https://github.com/Mbed-TLS/mbedtls/)
|
|
- [`mbedtls-2.28`](https://github.com/Mbed-TLS/mbedtls/tree/mbedtls-2.28)
|
|
maintained until at least the end of 2024, see
|
|
<https://github.com/Mbed-TLS/mbedtls/releases/tag/v2.28.5>.
|
|
|
|
Users are urged to always use the latest version of a maintained branch.
|