(C# UWP/WinRT) Generate RSA Key and Export to PKCS1 / PKCS8

C# UWP/WinRT example code showing how to generate an RSA public/private key and save to PKCS1 and PKCS8 format files. In a PKCS1 or PKCS8 formatted file, the key is stored in binary ASN.1 format (and ASN.1 is itself written according to DER -- Distinguished Encoding Rules). A PEM file simply contains the binary ASN.1 base64 encoded and delimited by BEGIN/END lines. PKCS1 format files are never encrypted. PKCS8 can be encrypted or unencrypted. Public keys are never encrypted (there is no need). Private keys *should* always be encrypted - unless perhaps the unencrypted private key is obtained and itself stored in some sort of secure place.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

// This example assumes the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

Chilkat.Rsa rsa = new Chilkat.Rsa();

// Generate a 2048-bit key.  Chilkat RSA supports
// key sizes ranging from 512 bits to 8192 bits.
bool success = rsa.GenerateKey(2048);
if (success != true) {
    Debug.WriteLine(rsa.LastErrorText);
    return;
}

// Get the public and private key parts:
Chilkat.PublicKey pubKey = rsa.ExportPublicKeyObj();
Chilkat.PrivateKey privKey = rsa.ExportPrivateKeyObj();

// Get the public key as a PKCS8 PEM string
string pubKeyPem = pubKey.GetOpenSslPem();
Debug.WriteLine(pubKeyPem);

// Get the public key in PKCS8 format, in a Base64 encoded string.
string pubKeyPkcs8Base64 = pubKey.GetPkcs8ENC("base64");
Debug.WriteLine(pubKeyPkcs8Base64);

// Get the public key in PKCS1 format, in a Base64 encoded string.
string pubKeyPkcs1Base64 = pubKey.GetPkcs1ENC("base64");
Debug.WriteLine(pubKeyPkcs1Base64);

// Get the private key in a PKCS8 PEM string.
string privKeyPem = privKey.GetPkcs8Pem();
Debug.WriteLine(privKeyPem);

// Get the private key in a PKCS8 encrypted PEM string.
string privKeyEncPem = privKey.GetPkcs8EncryptedPem("myPassword");
Debug.WriteLine(privKeyEncPem);

// Get the private key in PKCS1 Base64 format
string privKeyPkcs1Base64 = privKey.GetPkcs1ENC("base64");
Debug.WriteLine(privKeyPkcs1Base64);

// Get the private key in PKCS8 Base64 format
string privKeyPkcs8Base64 = privKey.GetPkcs8ENC("base64");
Debug.WriteLine(privKeyPkcs8Base64);

// Save to PKCS1 / PKCS8 / PEM files...

// Save the public key to PKCS8 binary DER
// Note: Chilkat is confusingly using the substring "OpenSsl" in the method name.
// A better choice would've been "SavePkcs8DerFile". When you see "OpenSsl" referring to
// a key format in a Chilkat method name, assume "PKCS8".
success = pubKey.SaveOpenSslDerFile("pubKey_pkcs8.der");

// Save the public key to PKCS1 binary DER
success = pubKey.SaveRsaDerFile("pubKey_pkcs1.der");

// Save the private key to unencrypted binary PKCS1 DER.
// Note: PKCS1 is never found in an encrypted format. 
success = privKey.SaveRsaDerFile("privKey_pkcs1.der");

// Save the private key to unencrypted binary PKCS8
success = privKey.SavePkcs8File("privKey_pkcs8.der");

// Save the private key to encrypted binary PKCS8
success = privKey.SavePkcs8EncryptedFile("myPassword","privKey_enc_pkcs8.der");

// Save the private key to unencrypted PKCS8 PEM
success = privKey.SavePkcs8PemFile("privKey.pem");

// Save the private key to encrypted PKCS8 PEM
success = privKey.SavePkcs8EncryptedPemFile("myPassword","privKey_enc.pem");