# 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 = CoefMod((-a*s + e) %% pm, q)
pk1 = GenPubKey1(a)

Create a polynomial message

# create a message
m = polynomial( coef=c(1, 1, 1) )

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)
#> 20 + 2*x + 870*x^2 + 871*x^3 + 32*x^4 + 861*x^5 + 2*x^6 + 27*x^7 + 32*x^8 +
#> 856*x^9 + 868*x^10 + 861*x^11 + 867*x^12 + 2*x^13 + 861*x^14 + 38*x^15