Add post about rustup 1.25.2 (#1073)

Author: pietroalbini

posts/2023-02-01-Rustup-1.25.2.md

@@ -0,0 +1,56 @@
+---
+layout: post
+title: "Announcing Rustup 1.25.2"
+author: The rustup working group
+---
+
+The rustup working group is announcing the release of rustup version 1.25.2.
+Rustup is the recommended tool to install Rust, a programming language that is
+empowering everyone to build reliable and efficient software.
+
+If you have a previous version of rustup installed, getting rustup 1.25.2 is as
+easy as stopping any programs which may be using Rustup (e.g. closing your IDE)
+and running:
+
+```
+rustup self update
+```
+
+Rustup will also automatically update itself at the end of a normal toolchain
+update:
+
+```
+rustup update
+```
+
+If you don't have it already, you can [get rustup](https://rustup.rs/) from the
+appropriate page on our website.
+
+## What's new in rustup 1.25.2
+
+This version of rustup fixes a warning incorrectly saying that signature
+verification failed for Rust releases. The warning was due to a dependency of
+Rustup including a time-based check preventing the use of SHA-1 from February
+1st, 2023 onwards.
+
+Unfortunately Rust's release signing key uses SHA-1 to sign its subkeys, which
+resulted in all signatures being marked as invalid. Rustup 1.25.2 temporarily
+fixes the problem by allowing again the use of SHA-1.
+
+## Why is signature verification failure only a warning?
+
+Signature verification is currently an experimental and incomplete feature
+included in rustup, as it's still missing crucial features like key rotation.
+Until the feature is complete and ready for use, its outcomes are only
+displayed as warnings without a way to turn them into errors.
+
+This is done to avoid potentially breaking installations of rustup. Signature
+verification will error out on failure only after the design and implementation
+of the feature will be finished.
+
+## Thanks
+
+Thanks again to all the contributors who made rustup 1.25.2 possible!
+
+ * Daniel Silverstone (kinnison)
+ * Pietro Albini (pietroalbini)