Deprecated Features
========================

Certain functionality is deprecated and is likely to be removed in
a future major release.

To help warn users, macros are used to annotate deprecated functions
and headers. These warnings are enabled by default, but can be
disabled by defining the macro ``BOTAN_NO_DEPRECATED_WARNINGS`` prior
to including any Botan headers.

.. warning::
    Not all of the functionality which is currently deprecated has an
    associated warning.

If you are using something which is currently deprecated and there
doesn't seem to be an obvious alternative, contact the developers to
explain your use case if you want to make sure your code continues to
work.

Platform Support Deprecations
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

* Support for building for Windows systems prior to Windows 10 is deprecated.

TLS Protocol Deprecations
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The following TLS protocol features are deprecated and will be removed
in a future major release:

- Support for point compression in TLS. This is supported in v1.2 but
  removed in v1.3. For simplicity it will be removed in v1.2 also.

- All CBC mode ciphersuites. This includes all available 3DES ciphersuites.
  This implies also removing Encrypt-then-MAC extension.

- All DHE ciphersuites

- Support for renegotiation in TLS v1.2

- All ciphersuites using static RSA key exchange

- ``Credentials_Manager::psk()`` to provide various TLS-specific keys and
  secrets, most notably "session-ticket", "dtls-cookie-secret" and the actual
  TLS PSKs for given identities and hosts. Instead, use the dedicated methods in
  ``Credentials_Manager`` and do not override the ``psk()`` method any longer.

Deprecated Functionality
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This section lists cryptographic functionality which will be removed
in a future major release.

- Kyber 90s mode is deprecated and will be removed.

- Currently it is possible to create an EC_Group with cofactor > 1.
  None of the builtin groups have composite order, and in the future
  it will be impossible to create composite order EC_Groups.

- Prior to 2.8.0, SM2 algorithms were implemented as two distinct key
  types, one used for encryption and the other for signatures. In 2.8,
  the two types were merged. However it is still possible to refer to
  SM2 using the split names of "SM2_Enc" or "SM2_Sig". In a future major
  release this will be removed, and only "SM2" will be recognized.

- DSA, ECDSA, ECGDSA, ECKCDSA, and GOST-34.10 previously (before Botan 3)
  required that the hash be named as "EMSA1(HASH_NAME)". This is no longer
  required. In a future major release, only "HASH_NAME" will be accepted.

- Block cipher GOST 28147, Noekeon, Lion

- Hash function GOST 34.11-94, Streebog, MD4

- GOST 34.10 signature scheme

- Stream cipher SHAKE (this does not affect SHAKE used as a HashFunction or XOF)

- The utility functions in cryptobox.h

- X9.42 KDF

- The current McEliece implementation (in ``pubkey/mce``) will be
  replaced by a more modern code-based KEM from the NIST
  competition. (Probably the "Classic McEliece" submission.)

- DLIES

- GCM support for 64-bit tags

- Weak or rarely used ECC builtin groups including "secp160k1", "secp160r1",
  "secp160r2", "secp192k1", "secp224k1",
  "brainpool160r1", "brainpool192r1", "brainpool224r1", "brainpool320r1",
  "x962_p192v2", "x962_p192v3", "x962_p239v1", "x962_p239v2", "x962_p239v3".

- All built in MODP groups < 2048 bits

- Support for explicit ECC curve parameters and ImplicitCA encoded parameters in
  EC_Group and all users (including X.509 certificates and PKCS#8 private keys).

- All pre-created DSA groups

- All support for loading, generating or using RSA keys with a public
  exponent larger than 2**64-1

Deprecated Headers
^^^^^^^^^^^^^^^^^^^^^^

  PBKDF headers: ``bcrypt_pbkdf.h``, ``pbkdf2.h``, ``pgp_s2k.h``, ``scrypt.h``,
  and ``argon2.h``: Use the ``PasswordHash`` interface instead.

  Internal implementation headers - seemingly no reason for applications to use:
  ``curve_gfp.h``,
  ``reducer.h``,
  ``tls_algos.h``,
  ``tls_magic.h``

  Utility headers, nominally useful in applications but not a core part of
  the library API and most are just sufficient for what the library needs
  to implement other functionality.
  ``compiler.h``,
  ``uuid.h``,

Other API deprecations
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

- The ``PBKDF`` class is deprecated in favor of ``PasswordHash`` and
  ``PasswordHashFamily``.

- The ``Buffered_Computation`` base class. In a future release the
  class will be removed, and all of member functions instead declared
  directly on ``MessageAuthenticationCode`` and ``HashFunction``. So
  this only affects you if you are directly referencing
  ``Botan::Buffered_Computation`` in some way.