/// <summary>
/// Import a public key into the provider whose context
/// has been obtained.
/// </summary>
/// <param name="publicKey">Base64 encoded public key to import.</param>
internal void ImportPublicKeyFromBase64EncodedString(string publicKey)
{
Dbg.Assert(!string.IsNullOrEmpty(publicKey), "key cannot be null or empty");
byte[] publicKeyBlob = Convert.FromBase64String(publicKey);
_rsa = PSCryptoNativeConverter.FromCapiPublicKeyBlob(publicKeyBlob);
}
/// <summary>
/// Get the public key, in CAPI-compatible form, as a base64 encoded string.
/// </summary>
/// <returns>Public key as base64 encoded string.</returns>
internal string GetPublicKeyAsBase64EncodedString()
{
Dbg.Assert(_rsa != null, "No public key available.");
byte[] capiPublicKeyBlob = PSCryptoNativeConverter.ToCapiPublicKeyBlob(_rsa);
return(Convert.ToBase64String(capiPublicKeyBlob));
}
/// <summary>
/// Import a session key from the remote side into
/// the current CSP.
/// </summary>
/// <param name="sessionKey">encrypted session key as a
/// base64 encoded string</param>
internal void ImportSessionKeyFromBase64EncodedString(string sessionKey)
{
Dbg.Assert(!string.IsNullOrEmpty(sessionKey), "key cannot be null or empty");
byte[] sessionKeyBlob = Convert.FromBase64String(sessionKey);
byte[] rsaEncryptedKey = PSCryptoNativeConverter.FromCapiSimpleKeyBlob(sessionKeyBlob);
_aes.Key = _rsa.Decrypt(rsaEncryptedKey, RSAEncryptionPadding.Pkcs1);
// now we have imported the key and will be able to
// encrypt using the session key
_canEncrypt = true;
}
/// <summary>
/// 1. Generate a AES-256 session key
/// 2. Encrypt the session key with the Imported
/// RSA public key
/// 3. Encode result above as base 64 string and export.
/// </summary>
/// <returns>Session key encrypted with receivers public key
/// and encoded as a base 64 string.</returns>
internal string SafeExportSessionKey()
{
Dbg.Assert(_rsa != null, "No public key available.");
// generate one if not already done.
GenerateSessionKey();
// encrypt it
byte[] encryptedKey = _rsa.Encrypt(_aes.Key, RSAEncryptionPadding.Pkcs1);
// convert the key to capi simpleblob format before exporting
byte[] simpleKeyBlob = PSCryptoNativeConverter.ToCapiSimpleKeyBlob(encryptedKey);
return(Convert.ToBase64String(simpleKeyBlob));
}
