node-seal example

index.js

// https://github.com/s0l0ist/node-seal/blob/main/FULL-EXAMPLE.md
// https://github.com/s0l0ist/node-seal/blob/main/USAGE.md
// See also https://inferati.com/blog/fhe-schemes-bfv
;(async () => {

  const SEAL = require('node-seal')
  const seal = await SEAL()
  const schemeType = seal.SchemeType.bgv
  const securityLevel = seal.SecurityLevel.tc128
  const polyModulusDegree = 4096

  // Bit sizes for each prime of the coeffModulus
  const bitSizes = [36, 36, 37]

  // Bit size representing plainModulus
  const bitSize = 20

  const parms = seal.EncryptionParameters(schemeType)

  // Set the PolyModulusDegree
  parms.setPolyModulusDegree(polyModulusDegree)

  // Create a suitable set of CoeffModulus primes
  parms.setCoeffModulus(
    seal.CoeffModulus.Create(polyModulusDegree, Int32Array.from(bitSizes))
  )

  // Set the PlainModulus to a prime of bitSize 20.
  // i.e. plaintext modulus, of bit size 20 (i.e < 1,048,576)
  parms.setPlainModulus(
    seal.PlainModulus.Batching(polyModulusDegree, bitSize)
  )

  console.log(parms.plainModulus.value)
  console.log(parms.coeffModulus)

  const context = seal.Context(
    parms, // Encryption Parameters
    true, // ExpandModChain
    securityLevel // Enforce a security level
  )

  if (!context.parametersSet()) {
    throw new Error(
      'Could not set the parameters in the given context. Please try different encryption parameters.'
    )
  }

  const encoder = seal.BatchEncoder(context)
  const keyGenerator = seal.KeyGenerator(context)
  const publicKey = keyGenerator.createPublicKey()
  const secretKey = keyGenerator.secretKey()
  const encryptor = seal.Encryptor(context, publicKey)
  const decryptor = seal.Decryptor(context, secretKey)
  const evaluator = seal.Evaluator(context)

  var in1 = "2,5,3,4,5"
  var in2 = "3,5,9,11,2"

  const array1 = Int32Array.from(in1.split(','))
  const array2 = Int32Array.from(in2.split(','))

  const plainText1 = encoder.encode(array1)
  const plainText2 = encoder.encode(array2)

  var cipherText1 = encryptor.encrypt(plainText1)
  var cipherText2 = encryptor.encrypt(plainText2)

  console.log('Plaintext 1:', array1)
  console.log('Plaintext 2:', array2)

  evaluator.add(cipherText1, cipherText2, cipherText1)

  var decryptedPlainText = decryptor.decrypt(cipherText1)
  var decodedArray = encoder.decode(decryptedPlainText)
  console.log('Decrypted (Homomorphic Add): ', decodedArray)

  cipherText1 = encryptor.encrypt(plainText1)
  cipherText2 = encryptor.encrypt(plainText2)

  evaluator.sub(cipherText1, cipherText2, cipherText1)

  decryptedPlainText = decryptor.decrypt(cipherText1)
  decodedArray = encoder.decode(decryptedPlainText)
  console.log('Decrypted (Homomorphic Subtract): ', decodedArray)

  cipherText1 = encryptor.encrypt(plainText1)
  cipherText2 = encryptor.encrypt(plainText2)

  evaluator.multiply(cipherText1, cipherText2, cipherText1)

  decryptedPlainText = decryptor.decrypt(cipherText1)
  decodedArray = encoder.decode(decryptedPlainText)
  console.log('Decrypted (Homomorphic Multiplication): ', decodedArray)

})()