How To Migrate A User Project From Palisade To OpenFHE

This migration guide describes how to migrate user projects from Palisade to OpenFHE. The guide uses src/pke/examples/simple-integers.cpp as an example.

Before making any changes to simple-integers.cpp:

  • Install OpenFHE (see instructions here)

  • Change the CMakeLists.txt for your project: replace all instances of Palisade and PALISADE with OpenFHE

Code changes (in src/pke/examples/simple-integers.cpp):

1. Generate CryptoContext (see instructions here). You don’t need to set multiple arguments anymore to generate CryptoContext. A separate parameter object is required instead and every parameter in the object has a default value. So, set only those parameters that you want to change. For this example, we changed two of them:

// declare the parameter object
CCParams<CryptoContextBFVRNS> parameters;
// set the desired parameter values
parameters.SetPlaintextModulus(65537);
parameters.SetMultiplicativeDepth(2);

All parameter values can be seen by simply printing the parameter object:

// print all parameters for CryptoContext
std::cout << parameters << std::endl;

And you get something similar to this line:
scheme: BFVRNS; ptModulus: 65537; digitSize: 0; standardDeviation: 3.19; secretKeyDist: UNIFORM_TERNARY; maxRelinSkDeg: 2; ksTech: BV; scalTech: NORESCALE; batchSize: 0; firstModSize: 60; numLargeDigits: 0; multiplicativeDepth:2; scalingModSize: 60; securityLevel: HEStd_128_classic; ringDim: 0; evalAddCount: 0; keySwitchCount: 0; encryptionTechnique: STANDARD; multiplicationTechnique: HPSPOVERQLEVELED; multiHopModSize: 0; PREMode: INDCPA; multipartyMode: FIXED_NOISE_MULTIPARTY; executionMode: EXEC_EVALUATION; decryptionNoiseMode: FIXED_NOISE_DECRYPT; noiseEstimate: 0; desiredPrecision: 0; statisticalSecurity: 30; numAdversarialQueries: 1

The parameter object is created using a template and for BFV it should be

CCParams<CryptoContextBFVRNS> parameters;

  1. All other changes are mostly cosmetic as some types and functions were renamed:

  • KeyPair<DCRTPoly> instead of LPKeyPair<DCRTPoly>

  • EvalRotateKeyGen() instead of EvalAtIndexKeyGen()

  • EvalRotate() instead of EvalAtIndex()

  • GetScheme() instead of GetEncryptionAlgorithm()

  • GetNoiseScaleDeg() instead of GetDepth()

After you make all the changes mentioned above, you can link and run the example.

Palisade-OpenFHE type mappings and new parameter types

In Palisade

In OpenFHE

Arguments to cryptoContext->Enable()

ENCRYPTION

PKE

PRE

PRE

SHE

LEVELEDSHE

ADVANCEDSHE

ADVANCEDSHE

MULTIPARTY

MULTIPARTY

FHE

FHE

MODE

SecretKeyDist

RLWE

GAUSSIAN

OPTIMIZED

UNIFORM_TERNARY

SPARSE

SPARSE_TERNARY

KeySwitchTechnique

KeySwitchTechnique

HYBRID

HYBRID

BV

BV

GHS

No longer supported

RescalingTechnique

ScalingTechnique

APPROXRESCALE

FIXEDMANUAL

APPROXAUTO

FIXEDAUTO

EXACTRESCALE

FLEXIBLEAUTO

FLEXIBLEAUTOEXT (new)

NORESCALE (new)

BFV CryptoContext Call

MultiplicationTechnique (BFV only)

genCryptoContextBFVrnsB

BEHZ

genCryptoContextBFVrns

HPS

HPSPOVERQ (new)

HPSPOVERQLEVELED (new)

If your project includes serialization, then the following files should be included in addition to “openfhe.h”:

  1. To serialize ciphertext:

#include "ciphertext-ser.h"

  1. To serialize cryptocontext:

#include "cryptocontext-ser.h"

  1. To serialize key(s):

#include "key/key-ser.h"

  1. … and the scheme-related serialization header file

  • for CKKS

#include "scheme/ckksrns/ckksrns-ser.h"

  • for BGV

#include "scheme/bgvrns/bgvrns-ser.h"

  • for BFV

#include "scheme/bfvrns/bfvrns-ser.h"

See the code difference in simple-integers.cpp before and after the migration.

For advanced users: see the code difference in openfhe-genomic-examples before and after the migration.