library(polynom)
library(HomomorphicEncryption)Set some parameters.
d = 4
n = 2^d
p = (n/2)-1
t = p
q = 868
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*p, pm, q)
pk1 = GenPubKey1(a)Create a polynomial message
# create a message
m1 = polynomial( coef=c(1, 1, 1) )
m2 = polynomial( coef=c(0, 1 ) )Create polynomials for the encryption
# polynomials for encryption
e1 = GenError(n)
e2 = GenError(n)
u = GenU(n)Generate the ciphertext
m1_ct0 = pk0*u + p*e1 + m1
m1_ct0 = m1_ct0 %% pm
m1_ct0 = CoefMod(m1_ct0, q)
m1_ct1 = pk1*u + p*e2
m1_ct1 = m1_ct1 %% pm
m1_ct1 = CoefMod(m1_ct1, q)
m2_ct0 = pk0*u + p*e1 + m2
m2_ct0 = m2_ct0 %% pm
m2_ct0 = CoefMod(m2_ct0, q)
m2_ct1 = pk1*u + p*e2
m2_ct1 = m2_ct1 %% pm
m2_ct1 = CoefMod(m2_ct1, q)EvalAdd
sum_ct0 = m1_ct0 + m2_ct0
sum_ct1 = m1_ct1 + m2_ct1Decrypt
decrypt = (sum_ct1 * s) + sum_ct0
decrypt = decrypt %% pm
decrypt = CoefMod(decrypt, q)
decrypt = CoefMod(round(decrypt), p)
print(decrypt)
#> 1 + 2*x + x^2