import-certificate.sh

#!/bin/bash

set -euo pipefail

security create-keychain -p "" build.keychain
security list-keychains -s build.keychain
security default-keychain -s build.keychain
security unlock-keychain -p "" build.keychain
security set-keychain-settings
security import <(echo $SIGNING_CERTIFICATE_P12_DATA | base64 --decode) \
                -f pkcs12 \
                -k build.keychain \
                -P $SIGNING_CERTIFICATE_PASSWORD \
                -T /usr/bin/codesign
security set-key-partition-list -S apple-tool:,apple: -s -k "" build.keychain

This has stopped working with the error

security: SecKeychainItemImport: One or more parameters passed to a function were not valid.
bad decrypt

Does anyone know if something has changed recently in github actions?

Check if you're passing the right environment to github action. That was the error for me

jobs:
  build_with_signing:
    runs-on: macos-latest

    ###This fixed it for me###
    environment: stage

    steps:
      - name: Checkout repository
        uses: actions/checkout@v4