The mbedtls backend was only one of several optional cryptography backends supported by unicrypto. The package already implements a complete backend using python3-cryptography (unicrypto/backends/cryptography/), which covers all supported ciphers: AES, DES, TDES and RC4.
The backend selection logic in unicrypto/__init__.py uses a preference table that already lists 'cryptography' before 'mbedtls', so removing the mbedtls backend causes no functional regression — the cryptography backend is silently selected instead. To fix the RC bug #1090176, three patches have been applied: - 001-remove-mbedtls-backend.patch: removes mbedtls from pref_to_module and preftable in unicrypto/__init__.py, so it is no longer attempted as a backend. - 002-remove-unavailable-backend-tests.patch: removes test functions that reference mbedtls, pycryptodome, pycryptodomex and pycrypto backends directly at module collection time, which caused ModuleNotFoundError during pytest collection in the Debian build environment. - 003-fix-cryptography-deprecation.patch: updates the cryptography backend to import ARC4 and TripleDES from cryptography.hazmat.decrepit, where they were moved since python3-cryptography 43.0.0, avoiding DeprecationWarning and ensuring forward compatibility with version 48.0.0 which will remove them from the old location. Nilson F. Silva
