Manually copying login keychain files from one Mac to another no longer works on Secure Enclave-equipped Macs running macOS Tahoe
Summary
Der Flounder reports that copying login keychains between Macs fails on Secure Enclave-equipped Macs under macOS Tahoe. The login keychain is protected by two AES-256-GCM keys, with the secret key requiring an SG enclave trip; copying the file to another Mac or VM cannot unlock it, leading macOS to create a new login keychain. The post includes test steps and logs illustrating the failure and fallback behavior.