coppersmith_padding.gp

padding.gp

default(realprecision,9000);
setrand(1);
p=nextprime(random(2^15));
q=nextprime(random(2^15));
N=p*q;

print("N=p*q="N);
P = random(N);    \\ le padding
print("padding="P)
e = 3;            \\ expo public
print("expo="e)
X = floor(N^(1/3)); \\ N^(1/e - epsilon)
print("X="X)
x0 = random(X);   \\ le message inconnu
print("X0="x0)
C = lift( (Mod(x0,N) + P)^e ); \\ le chiffré
print("C="C)
print("coppersmith........")
print(zncoppersmith((P + x)^3 - C, N, X))
print(" = X0 ")