Reverse Iteration Cipher in Python 3

# Reverse iterate
def revpow2(z, c, b):
     if b == 1:
            return -((z-c)**(0.5));
     else:
            return (z-c)**(0.5);

# Forward iterate
def fowpow2(z, c):
     return z * z + c;

# Encrypts a byte
def encrypt_byte(z, c, pt):
    for b in pt:
        z=revpow2(z,c,int(b));
        print(z);
    return z;

# Decrypts a byte
def decrypt_byte(z, c):
    s = ""
    for b in range(8):
        print(z);
        s += "0" if z.real > 0 else "1";
        z=fowpow2(z,c);
    s = s[::-1]; # reverse the bits
    return s;




# The secret key (c), and origin point (z)
c = (-.75+.09j);
z = (0+0j);
pt0 = "01000001";

print("Encrypt: " + pt0);
print("______________________________________");
ct = encrypt_byte(z, c, pt0);
print("______________________________________");

print("");

print("Decrypt");
print("______________________________________");
pt1 = decrypt_byte(ct, c);
print("______________________________________");

print("");

print("decrypted: " + pt1);