RSA create PublicKey and PrivateKey in xml or pub

Question

Hello I have a question. For example I have: P: 5 Q: 17 phiN: 64 N: 85 e:5 d: 13 How can I generate the following from these values: PublicKey.xml and PrivateKey.xml ? In the source code below the parameters are created automatically. How can I insert my own parameters here e.g. from above? public ICommand GenerateNewKey { get { return generateNewKey ?? (generateNewKey = new DelegateCommand(a => { var rsaCryptoServiceProvider = new RSACryptoServiceProvider(); XmlRsaPublic = rsaCryptoServiceProvider.ToXmlString(false); XmlRsaPrivate = rsaCryptoServiceProvider.ToXmlString(true); var rsaPrivateKey = new OpenSSL.Crypto.RSA { SecretPrimeFactorP = BigNumber.FromArray(rsaCryptoServiceProvider.ExportParameters(true).P) SecretPrimeFactorQ = BigNumber.FromArray(rsaCryptoServiceProvider.ExportParameters(true).Q) DmodP1 = BigNumber.FromArray(rsaCryptoServiceProvider.ExportParameters(true).DP) DmodQ1 = BigNumber.FromArray(rsaCryptoServiceProvider.ExportParameters(true).DQ) IQmodP = BigNumber.FromArray(rsaCryptoServiceProvider.ExportParameters(true).InverseQ) PrivateExponent = BigNumber.FromArray(rsaCryptoServiceProvider.ExportParameters(true).D) PublicExponent = BigNumber.FromArray(rsaCryptoServiceProvider.ExportParameters(true).Exponent) PublicModulus = BigNumber.FromArray(rsaCryptoServiceProvider.ExportParameters(true).Modulus) }; PemRsaPrivate = rsaPrivateKey.PrivateKeyAsPEM; PemRsaPublic = rsaPrivateKey.PublicKeyAsPEM; DerRsaPrivate = BitConverter.ToString(Convert.FromBase64String(PemRsaPrivate.Trim().Substring(31 PemRsaPrivate.Length - 61).Trim())); DerRsaPublic = BitConverter.ToString(Convert.FromBase64String(PemRsaPublic.Trim().Substring(26 PemRsaPublic.Length - 51).Trim())); })); } }

Tuhin Paul · Answer

Part - 2 The flowchart will show: Start of key generation. Input parameters (P Q D Exponent Modulus). Calculation of derived parameters (DP DQ InverseQ). Importing RSA parameters. Generating XML for public and private keys. End process.

Tuhin Paul · Answer

Part - 1 using System; using System.Security.Cryptography; using System.Xml; public class CustomRSAKeyGenerator { public static void GenerateCustomRSAKey( byte[] p byte[] q byte[] d byte[] exponent byte[] modulus out string publicKeyXml out string privateKeyXml) { // Create RSA parameters manually RSAParameters rsaParameters = new RSAParameters { P = p Q = q D = d Exponent = exponent Modulus = modulus // Calculate additional required parameters DP = CalculateDP(d p) DQ = CalculateDQ(d q) InverseQ = CalculateInverseQ(p q) }; // Create RSA instance with custom parameters using (RSACryptoServiceProvider rsa = new RSACryptoServiceProvider()) { rsa.ImportParameters(rsaParameters); // Generate XML representations publicKeyXml = rsa.ToXmlString(false); privateKeyXml = rsa.ToXmlString(true); } } private static byte[] CalculateDP(byte[] d byte[] p) { // d mod (p-1) return ModularReduction(d SubtractOne(p)); } private static byte[] CalculateDQ(byte[] d byte[] q) { // d mod (q-1) return ModularReduction(d SubtractOne(q)); } private static byte[] CalculateInverseQ(byte[] p byte[] q) { // Compute modular multiplicative inverse of q mod p return ComputeModularInverse(q p); } private static byte[] SubtractOne(byte[] number) { byte[] result = (byte[])number.Clone(); for (int i = result.Length - 1; i >= 0; i--) { if (result[i] > 0) { result[i]--; break; } result[i] = 255; } return result; } private static byte[] ModularReduction(byte[] dividend byte[] divisor) { // Simple modular reduction (you might want to use a more robust BigInteger implementation) // This is a simplified example System.Numerics.BigInteger dividendBI = new System.Numerics.BigInteger(dividend); System.Numerics.BigInteger divisorBI = new System.Numerics.BigInteger(divisor); return (dividendBI % divisorBI).ToByteArray(); } private static byte[] ComputeModularInverse(byte[] a byte[] m) { // Simplified modular multiplicative inverse calculation // In practice use a more robust algorithm System.Numerics.BigInteger aBI = new System.Numerics.BigInteger(a); System.Numerics.BigInteger mBI = new System.Numerics.BigInteger(m); for (System.Numerics.BigInteger x = 1; x The GenerateCustomRSAKey method allows you to manually input your RSA key parameters: P: Prime factor p (5) Q: Prime factor q (17) D: Private exponent (13) Exponent: Public exponent (5) Modulus: N (85) It calculates additional required RSA parameters: DP: d mod (p-1) DQ: d mod (q-1) InverseQ: Modular multiplicative inverse of q mod p The method generates both PublicKey.xml and PrivateKey.xml using rsa.ToXmlString() An example usage method Example() demonstrates how to use the key generation with your specific values Caveats: The modular arithmetic methods are simplified. For production use consider more robust BigInteger implementations. Check your input parameters are mathematically consistent for a valid RSA key pair. To use in your existing code replace the key generation logic with a call to CustomRSAKeyGenerator.GenerateCustomRSAKey()  passing your specific byte arrays for each parameter.