Bug fixes

• std::void_t was introduced only in C++17; switched to using a custom implementation (Issue 180).
• Fixed two independent bugs in native/src/CMakeConfig.cmd: The first prevented SEAL to be built in a directory with spaces in the path due to missing quotation marks. Another issue caused MSVC to fail when building SEAL for multiple architectures.
• RNSBase::decompose_array had incorrect semantics that caused Evaluator::multiply_plain_normal and Evaluator::transform_to_ntt_inplace (for Plaintext) to behave incorrectly for some plaintexts.

Other

• Added pkg-config support (PR 181).
• seal::util::PtrIter<T *> now dereferences correctly to T & instead of T *.
  This results in simpler code, where inside SEAL_ITERATE lambda functions dereferences of seal::util::PtrIter<T *> do not need to be dereferenced a second time, as was particularly common when iterating over ModulusIter and NTTTablesIter types.
• seal::util::IterTuple now dereferences to an std::tuple of dereferences of its component iterators, so it is no longer possible to directly pass a dereferenced seal::util::IterTuple to an inner lambda function in nested SEAL_ITERATE calls.
  Instead, the outer lambda function parameter should be wrapped inside another call to seal::util::iter before passed on to the inner SEAL_ITERATE to produce an appropriate seal::util::IterTuple.

Bug fixes

• Fixed a bug in seal::util::IterTuple<...> where a part of the value_type was constructed incorrectly.
• Fixed a bug in Evaluator::mod_switch_drop_to_next that caused non-inplace modulus switching to fail (Issue 179). Thanks s0l0ist!

Bug fixes

• Merged pull request PR 178 to fix a lambda capture issue when building on GCC 7.5.
• Fixed issue where SEAL.vcxproj could not be compiled with MSBuild outside the solution (Issue 171).
• SEAL 3.5.1 required CMake 3.13 instead of 3.12; this has now been fixed and 3.12 works again (Issue 167).
• Fixed issue in NuSpec file that made local NuGet package generation fail.
• Fixed issue in NuSpec where XML documentation was not included into the package.

New features

• Huge improvements to SEAL iterators, including seal::util::iter and seal::util::reverse_iter functions that can create any type of iterator from appropriate parameters.
• Added seal::util::SeqIter<T> iterator for iterating a sequence of numbers for convenient iteration indexing.
• Switched functions in seal/util/polyarithsmallmod.* to use iterators; this is to reduce the layers of iteration in higher level code.
• Added macro SEAL_ITERATE that should be used instead of for_each_n.

Other

• Added note in README.md about known performance issues when compiling with GNU G++ compared to Clang++ (Issue 173).
• Merged pull requests that improve the performance of keyswitching (PR #177) and rescale (PR #176) in CKKS.

Version 3.5.1

Changed version to 3.5.1.

Hotfix - 4/30/2020

• Fixed a critical bug (Issue 166) in Evaluator::multiply_plain_inplace. Thanks s0l0ist!

Hotfix - 4/29/2020

• Switched to using Microsoft GSL v3.0.1 and fixed minor GSL related issues in CMakeLists.txt.
• Fixed some typos in README.md.
• Fixes bugs in ADO pipelines files.

New Features

• Microsoft SEAL officially supports Android (Xamarin.Android) on ARM64.
• Microsoft SEAL is a CMake project (UNIX-like systems only):
  • There is now a top-level CMakeLists.txt that builds all native components.
  • The following CMake targets are created: SEAL::seal (static library), SEAL::seal_shared (shared library; optional), SEAL::sealc (C export library; optional).
  • Examples and unit tests are built if enabled through CMake (see README.md).
  • ZLIB is downloaded and compiled by CMake and automatically included in the library.
  • Microsoft GSL is downloaded by CMake. Its header files are copied to native/src/gsl and installed with Microsoft SEAL.
  • Google Test is downloaded and compiled by CMake.
• Improved serialization:
  • Serialization::SEALHeader layout has been changed. SEAL 3.4 objects can still be loaded by SEAL 3.5, and the headers are automatically converted to SEAL 3.5 format.
  • Serialization::SEALHeader captures version number information.
  • Added examples for serialization.
  • The seeded versions of Encryptor's symmetric-key encryption and KeyGenerator's RelinKeys and GaloisKeys generation now output Serializable objects. See more details in API Changes below.

For Library Developers and Contributors

We have created a set of C++ iterators that easily allows looping over polynomials in a ciphertext, over RNS components in a polynomial, and over coefficients in an RNS component. There are also a few other iterators that can come in handy. Currently Evaluator fully utilizes these, and in the future the rest of the library will as well.
The iterators are primarily intended to be used with std::for_each_n to simplify existing code and help with code correctness. Please see native/src/seal/util/iterator.h for guidance on how to use these.

We have also completely rewritten the RNS tools that were previously in the util::BaseConverter class. This functionality is now split between two classes: util::BaseConverter whose sole purpose is to perform the FastBConv computation of [BEHZ16] and util::RNSTool that handles almost everything else. RNS bases are now represented by the new util::RNSBase class.

API Changes

The following changes are explained in C++ syntax and are introduced to .NET wrappers similarly:

• New generic class Serializable wraps Ciphertext, RelinKeys, and GaloisKeys objects to provide a more flexible approach to the functionality provided in release 3.4 by KeyGenerator::[relin|galois]_keys_save and Encryptor::encrypt_[zero_]symmetric_save functions. Specifically, these functions have been removed and replaced with overloads of KeyGenerator::[relin|galois]_keys and Encryptor::encrypt_[zero_]symmetric that return Serializable objects. The KeyGenerator::[relin|galois]_keys methods in release 3.4 are renamed to KeyGenerator::[relin|galois]_keys_local. The Serializable objects cannot be used directly by the API, and are only intended to be serialized, which activates the compression functionalities introduced earlier in release 3.4.
• SmallModulus class is renamed to Modulus, and is relocated to native/src/seal/modulus.h.
• *coeff_mod_count* methods are renamed to *coeff_modulus_size*, which applies to many classes.
• parameter_error_name and parameter_error_message methods are added to EncryptionParameterQualifiers and SEALContext classes to explain why an EncryptionParameters object is invalid.
• The data members and layout of Serialization::SEALHeader have changed.

The following changes are specific to C++:

• New bounds in native/src/seal/util/defines.h:
  • SEAL_POLY_MOD_DEGREE_MAX is increased to 131072; values bigger than 32768 require the security check to be disabled by passing sec_level_type::none to SEALContext::Create.
  • SEAL_COEFF_MOD_COUNT_MAX is increased to 64.
  • SEAL_MOD_BIT_COUNT_MAX and SEAL_MOD_BIT_COUNT_MIN are added and set to 61 and 2, respectively.
  • SEAL_INTERNAL_MOD_BIT_COUNT is added and set to 61.
• EncryptionParameterQualifiers now has an error code parameter_error that interprets the reason why an EncryptionParameters object is invalid.
• bool parameters_set() is added to replace the previous bool parameters_set member.

The following changes are specific to .NET:

• Version numbers are retrievable in .NET through SEALVersion class.

Other Changes

• Releases are now listed on releases page.
• The native library can serialize (save and load) objects larger than 4 GB. Please be aware that compressed serialization requires an additional temporary buffer roughly the size of the object to be allocated, and the streambuffer for the output stream may consume some non-trivial amount of memory as well. In the .NET library, objects are limited to 2 GB, and loading an object larger than 2 GB will throw an exception.(Issue 142)
• Larger-than-suggested parameters are supported for expert users. To enable that, please adjust SEAL_POLY_MOD_DEGREE_MAX and SEAL_COEFF_MOD_COUNT_MAX in native/src/seal/util/defines.h.(Issue 150, Issue 84)
• Serialization now clearly indicates an insufficient buffer size error.(Issue 117)
• Unsupported compression mode now throws std::invalid_argument (native) or ArgumentException (.NET).
• There is now a .clang-format for automated formatting of C++ (.cpp and .h) files. Execute tools/scripts/clang-format-all.sh for easy formatting (UNIX-like systems only). This is compatible with clang-format-9 and above. Formatting for C# is not yet supported.(Issue 93)
• The C export library previously in dotnet/native/ is moved to native/src/seal/c/ and renamed to SEAL_C to support building of wrapper libraries in languages like .NET, Java, Python, etc.
• The .NET wrapper library targets .NET Standard 2.0, but the .NET example and test projects use C# 8.0 and require .NET Core 3.x. Therefore, Visual Studio 2017 is no longer supported for building the .NET example and test projects.
• Fixed issue when compiling in FreeBSD.(PR 113)
• A bug in the [BEHZ16]-style RNS operations is fixed; proper unit tests are added.
• Performance of methods in Evaluator are in general improved.(PR 148) This is compiler-dependent, however, and currently Clang seems to produce the fastest running code for Microsoft SEAL.

File Changes

Renamed files and directories:

• dotnet/examples/7_Performance.cs was previously dotnet/examples/6_Performance.cs
• native/examples/7_performance.cpp was previously native/examples/6_performance.cpp
• native/src/seal/c/ was previously dotnet/native/sealnet.
• native/src/seal/util/ntt.h was previously native/src/seal/util/smallntt.h.
• native/src/seal/util/ntt.cpp was previously native/src/seal/util/smallntt.cpp.
• native/tests/seal/util/ntt.cpp was previously native/tests/seal/util/smallntt.cpp.

New files:

• android/
• dotnet/examples/6_Serialization.cs
• dotnet/src/Serializable.cs
• dotnet/src/Version.cs
• dotnet/tests/SerializationTests.cs
• native/examples/6_serialization.cpp
• native/src/seal/c/version.h
• native/src/seal/c/version.cpp
• native/src/seal/util/galois.h
• native/src/seal/util/galois.cpp
• native/src/seal/util/hash.cpp
• native/src/seal/util/iterator.h
• native/src/seal/util/rns.h
• native/src/seal/util/rns.cpp
• native/src/seal/util/streambuf.h
• native/src/seal/util/streambuf.cpp
• native/src/seal/serializable.h
• native/tests/seal/util/iterator.cpp
• native/tests/seal/util/galois.cpp
• native/tests/seal/util/rns.cpp

Removed files:

• dotnet/src/SmallModulus.cs is merged to dotnet/src/ModulusTests.cs.
• dotnet/tests/SmallModulusTests.cs is merged to dotnet/tests/ModulusTests.cs.
• native/src/seal/util/baseconverter.h
• native/src/seal/util/baseconverter.cpp
• native/src/seal/smallmodulus.h is merged to native/src/seal/modulus.h.
• native/src/seal/smallmodulus.cpp is merged to [native...

Changes

• Fixed a concurrency issue in SEALNet: the unordered_map storing SEALContext pointers was
  not locked appropriately on construction and destruction of new SEALContext objects.
• Fixed a few typos in examples (PR 71).
• Added include guard to config.h.in.

Changes

• Fixed issues with SEALNet.targets file and SEALNet.nuspec.in.
• Updated README.md with information about existing multi-platform
  NuGet package.

Changes

• Fixed bug in .NET serialization code where an incorrect number of bytes was written when using
  ZLIB compression.
• Fixed an issue with .NET functions Encryptor.EncryptSymmetric..., where asymmetric encryption
  was done instead of symmetric encryption.
• Prevented KeyGenerator::galois_keys and KeyGenerator::relin_keys from being called when the
  encryption parameters do not support keyswitching.
• Fixed a bug in Decryptor::invariant_noise_budget where the computed noise budget was
  log(plain_modulus) bits smaller than it was supposed to be.
• Removed support for Microsoft GSL gsl::multi_span, as it was recently deprecated in GSL.

Changes

• Fixed bug reported in Issue 66 on GitHub.
• CMake does version matching now (correctly) only on major and minor version, not patch version,
  so writing find_package(SEAL 3.4) works correctly and selects the newest version 3.4.x it can
  find.

Changes

This patch fixes a few issues with ZLIB support on Windows. Specifically,

• Fixed a mistake in native/src/CMakeConfig.cmd where the CMake library search path
  suffix was incorrect.
• Switched to using a static version of ZLIB on Windows.
• Corrected instructions in README.md for enabling ZLIB support on Windows.