/// <summary>
/// Low level RSA Process function for use with private key.
/// Should never be used; Because without padding RSA is vulnerable to attacks. Use with caution.
/// </summary>
/// <param name="plainText">Data to encrypt. Length must be less than Modulus size in octets.</param>
/// <param name="usePrivate">True to use Private key, else Public.</param>
/// <returns>Encrypted Data</returns>
private byte[] RSAProcess(byte[] plainText, bool usePrivate)
{
if (usePrivate && !rsaParams.HasPrivateInfo)
{
throw new CryptographicException("RSA Process: Incomplete Private Key Info");
}
if (usePrivate == false && !rsaParams.HasPublicInfo)
{
throw new CryptographicException("RSA Process: Incomplete Public Key Info");
}
BigInteger e = usePrivate ? rsaParams.D : rsaParams.E;
BigInteger pt = RSAxUtils.OS2IP(plainText, false);
BigInteger m = BigInteger.ModPow(pt, e, rsaParams.N);
if (m.Sign == -1)
{
return(RSAxUtils.I2OSP(m + rsaParams.N, rsaParams.OctetsInModulus, false));
}
else
{
return(RSAxUtils.I2OSP(m, rsaParams.OctetsInModulus, false));
}
}
/// <summary>
/// Low level RSA Decryption function for use with private key. Uses CRT and is Much faster.
/// Should never be used; Because without padding RSA is vulnerable to attacks. Use with caution.
/// </summary>
/// <param name="data">Data to encrypt. Length must be less than Modulus size in octets.</param>
/// <returns>Encrypted Data</returns>
private byte[] RSADecryptPrivateCRT(byte[] data)
{
if (rsaParams.HasPrivateInfo && rsaParams.HasCRTInfo)
{
BigInteger c = RSAxUtils.OS2IP(data, false);
BigInteger m1 = BigInteger.ModPow(c, rsaParams.DP, rsaParams.P);
BigInteger m2 = BigInteger.ModPow(c, rsaParams.DQ, rsaParams.Q);
BigInteger h = (m1 - m2) * rsaParams.InverseQ % rsaParams.P;
BigInteger m = m2 + rsaParams.Q * h;
if (m.Sign == -1)
{
return(RSAxUtils.I2OSP(m + rsaParams.N, rsaParams.OctetsInModulus, false));
}
else
{
return(RSAxUtils.I2OSP(m, rsaParams.OctetsInModulus, false));
}
}
else
{
throw new CryptographicException("RSA Decrypt CRT: Incomplete Key Info");
}
}
/// <summary>
/// Initialize the RSA class. Only the public parameters.
/// </summary>
/// <param name="modulus">Modulus of the RSA key.</param>
/// <param name="exponent">Exponent of the RSA key</param>
/// <param name="modulusSize">Modulus size in number of bits. Ex: 512, 1024, 2048, 4096 etc.</param>
public RSAxParameters(byte[] modulus, byte[] exponent, int modulusSize)
{
// rsaParams;
OctetsInModulus = modulusSize / 8;
E = RSAxUtils.OS2IP(exponent, false);
N = RSAxUtils.OS2IP(modulus, false);
HasPublicInfo = true;
}
/// <summary>
/// Initialize the RSA class. For CRT.
/// </summary>
/// <param name="modulus">Modulus of the RSA key.</param>
/// <param name="exponent">Exponent of the RSA key</param>
/// /// <param name="d">Exponent of the RSA key</param>
/// <param name="p">P paramater of RSA Algorithm.</param>
/// <param name="q">Q paramater of RSA Algorithm.</param>
/// <param name="dp">DP paramater of RSA Algorithm.</param>
/// <param name="dq">DQ paramater of RSA Algorithm.</param>
/// <param name="inverseQ">InverseQ paramater of RSA Algorithm.</param>
/// <param name="modulusSize">Modulus size in number of bits. Ex: 512, 1024, 2048, 4096 etc.</param>
public RSAxParameters(byte[] modulus, byte[] exponent, byte[] d, byte[] p, byte [] q, byte [] dp, byte [] dq, byte [] inverseQ, int modulusSize)
{
// rsaParams;
OctetsInModulus = modulusSize / 8;
E = RSAxUtils.OS2IP(exponent, false);
N = RSAxUtils.OS2IP(modulus, false);
D = RSAxUtils.OS2IP(d, false);
P = RSAxUtils.OS2IP(p, false);
Q = RSAxUtils.OS2IP(q, false);
DP = RSAxUtils.OS2IP(dp, false);
DQ = RSAxUtils.OS2IP(dq, false);
InverseQ = RSAxUtils.OS2IP(inverseQ, false);
HasCRTInfo = true;
HasPublicInfo = true;
HasPrivateInfo = true;
}
/// <summary>
/// Initialize the RSA class. It's assumed that both the Public and Extended Private info are there.
/// </summary>
/// <param name="rsaParams">Preallocated RSAParameters containing the required keys.</param>
/// <param name="modulusSize">Modulus size in bits</param>
public RSAxParameters(RSAParameters rsaParams, int modulusSize)
{
// rsaParams;
OctetsInModulus = modulusSize / 8;
E = RSAxUtils.OS2IP(rsaParams.Exponent, false);
D = RSAxUtils.OS2IP(rsaParams.D, false);
N = RSAxUtils.OS2IP(rsaParams.Modulus, false);
P = RSAxUtils.OS2IP(rsaParams.P, false);
Q = RSAxUtils.OS2IP(rsaParams.Q, false);
DP = RSAxUtils.OS2IP(rsaParams.DP, false);
DQ = RSAxUtils.OS2IP(rsaParams.DQ, false);
InverseQ = RSAxUtils.OS2IP(rsaParams.InverseQ, false);
HasCRTInfo = true;
HasPublicInfo = true;
HasPrivateInfo = true;
}
