# CKKS

Load libraries that will be used.

    library(polynom)
    library(HomomorphicEncryption)

Set some parameters.

    d  =   4
    n  =   2^d
    p  =   (n/2)-1
    q  = 874
    pm = GenPolyMod(n)

Set a working seed for random numbers

    set.seed(123)

Create the secret key and the polynomials a and e, which will go into the public key

    # generate a secret key
    s = GenSecretKey(n)

    # generate a
    a = GenA(n, q)

    # generate the error
    e = GenError(n)

Generate the public key.

    pk0 = GenPubKey0(a, s, e, pm, q)
    pk1 = GenPubKey1(a)

Create a polynomial message

    # create a message
    m = polynomial( coef=c(500, 600, 100) )

Create polynomials for the encryption

    # polynomials for encryption
    e1 = GenError(n)
    e2 = GenError(n)
    u  = GenU(n)

Generate the ciphertext

    ct0 = CoefMod((pk0*u + e1 + m) %% pm, q)
    ct1 = EncryptPoly1(pk1, u, e2, pm, q)

Decrypt

    decrypt = (ct1 * s) + ct0
    decrypt = decrypt %% pm
    decrypt = CoefMod(decrypt, q)
    print(decrypt[1:length(coef(m))])
    #> [1] 523 619 103