/// <summary>
/// Creates a new modulus
/// </summary>
/// <param name="path">filepath where modulus is written, default is</param>
/// <param name="length">modulus length in bits</param>
/// <returns></returns>
static byte[] CreateNewModulus(string path, int length = 2048)
{
MakwaPrivateKey privateKey = MakwaPrivateKey.Generate(length);
byte[] modulus = Tools.I2OSP(privateKey.Modulus);
WriteToFile(path, modulus);
return(modulus);
}
/// <summary>
/// Creates a new private key class, writes modulus and primes p,q to file
/// </summary>
/// <param name="path">
/// filepath, primes are appended with "-p" and "-q" respectively
/// </param>
/// <param name="length">modulus length in bits, default is 2048</param>
/// <returns>MakwaPrivateKey</returns>
static MakwaPrivateKey CreateNewPrivateKey(string path, int length = 2048)
{
MakwaPrivateKey privateKey = MakwaPrivateKey.Generate(length);
byte[] modulus = Tools.I2OSP(privateKey.Modulus);
byte[] p = Tools.I2OSP(privateKey.p);
byte[] q = Tools.I2OSP(privateKey.q);
WriteToFile(path, modulus);
WriteToFile(path + "-p", p);
WriteToFile(path + "-q", q);
return(privateKey);
}
/// <summary>
/// Generate a new private key. A secure PRNG is used to produce
/// the new private key. The target modulus size (in bits) is
/// provided as parameter; it must be no smaller than 1273 bits,
/// and no greater than 32768 bits. The normal and recommended
/// modulus size is 2048 bits.
/// </summary>
/// <param name="size"> the target modulus size </param>
/// <returns> the new private key </returns>
/// <exception cref="Exception"> on error </exception>
public static MakwaPrivateKey Generate(int size)
{
if (size < 1273 || size > 32768)
{
throw new Exception("invalid modulus size: " + size);
}
int sizeP = (size + 1) >> 1;
int sizeQ = size - sizeP;
BigInteger p = MakeRandPrime(sizeP);
BigInteger q = MakeRandPrime(sizeQ);
MakwaPrivateKey k = new MakwaPrivateKey(p, q);
if (k.Modulus.BitLength != size)
{
throw new Exception("key generation error");
}
return(k);
}