brew/docs/Checksum_Deprecation.md
2017-10-22 05:31:53 +01:00

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# MD5 and SHA-1 Deprecation
In early 2015 Homebrew started the process of deprecating _SHA1_ for package
integrity verification. Since then formulae under the Homebrew organisation
have been moved onto using _SHA256_ for verification; this includes both source
packages and our precompiled packages (bottles).
Homebrew has since stopped supporting _SHA1_ and _MD5_ entirely.
_MD5_ checksums were removed from core formulae in 2012 and as of April 2015
installing a formula verified by _MD5_ is actively blocked.
We removed _SHA1_ support in **November 2016**,
21 months after we started warning people to move away from it for verification.
This is enforced in the same way _MD5_ is, by blocking the installation of that
individual formula until the checksum is migrated.
This means custom taps, local custom formulae, etc need to be migrated to use
_SHA256_ before you can install them.