private byte[] OAEPDecrypt(byte[] cipher)
{
var modLen = rsaParameters.Modulus.GetByteCount();
var msize = modLen - HashOutputSize - 1;
var X = new byte[msize];
var Y = new byte[HashOutputSize];
Array.Copy(cipher, 0, X, 0, msize);
Array.Copy(cipher, msize, Y, 0, Y.Length);
using var sha256 = new SHA256C();
var r = XorArray(Y, sha256.ComputeHash(X));
sha256.Initialize();
var m = XorArray(X, sha256.ComputeHash(r));
var i = m.Length - 1;
while (m[i] == 0)
{
--i;
}
return(m.Take(i + 1).ToArray());
}
private byte[] OAEPEncrypt(byte[] message)
{
var modLen = rsaParameters.Modulus.GetByteCount();
byte[] r = new byte[HashOutputSize];
RandomNumberGenerator.Fill(r);
var msize = modLen - r.Length - 1;
var m = new byte[msize];
m.Initialize();
Array.Copy(message, m, message.Length);
using var sha256 = new SHA256C();
var X = XorArray(m, sha256.ComputeHash(r));
sha256.Initialize();
var Y = XorArray(r, sha256.ComputeHash(X));
return(X.Concat(Y).ToArray());
}
