/// <summary>Creates a Secret Box</summary>
/// <param name="message">The message.</param>
/// <param name="nonce">The 24 byte nonce.</param>
/// <param name="key">The 32 byte key.</param>
/// <returns>The encrypted message.</returns>
/// <exception cref="KeyOutOfRangeException"></exception>
/// <exception cref="NonceOutOfRangeException"></exception>
/// <exception cref="CryptographicException"></exception>
public static byte[] Create(byte[] message, byte[] nonce, byte[] key)
{
//validate the length of the key
if (key == null || key.Length != KEY_BYTES)
{
throw new KeyOutOfRangeException("key", key == null ? 0 : key.Length,
string.Format("key must be {0} bytes in length.", KEY_BYTES));
}
//validate the length of the nonce
if (nonce == null || nonce.Length != NONCE_BYTES)
{
throw new NonceOutOfRangeException("nonce", nonce == null ? 0 : nonce.Length,
string.Format("nonce must be {0} bytes in length.", NONCE_BYTES));
}
byte[] buffer = new byte[MAC_BYTES + message.Length];
SodiumCore.Init();
int ret = SodiumLibrary.crypto_secretbox_easy(buffer, message, message.Length, nonce, key);
if (ret != 0)
{
throw new CryptographicException("Failed to create SecretBox");
}
return(buffer);
}
/// <summary>Opens a Secret Box</summary>
/// <param name="cipherText">The cipherText.</param>
/// <param name="nonce">The 24 byte nonce.</param>
/// <param name="key">The 32 byte nonce.</param>
/// <returns>The decrypted text.</returns>
/// <exception cref="KeyOutOfRangeException"></exception>
/// <exception cref="NonceOutOfRangeException"></exception>
/// <exception cref="CryptographicException"></exception>
public static byte[] Open(byte[] cipherText, byte[] nonce, byte[] key)
{
//validate the length of the key
if (key == null || key.Length != KEY_BYTES)
{
throw new KeyOutOfRangeException("key", key == null ? 0 : key.Length,
string.Format("key must be {0} bytes in length.", KEY_BYTES));
}
//validate the length of the nonce
if (nonce == null || nonce.Length != NONCE_BYTES)
{
throw new NonceOutOfRangeException("nonce", nonce == null ? 0 : nonce.Length,
string.Format("nonce must be {0} bytes in length.", NONCE_BYTES));
}
//check to see if there are MAC_BYTES of leading nulls, if so, trim.
//this is required due to an error in older versions.
if (cipherText[0] == 0)
{
//check to see if trim is needed
bool trim = true;
for (int i = 0; i < MAC_BYTES - 1; i++)
{
if (cipherText[i] != 0)
{
trim = false;
break;
}
}
//if the leading MAC_BYTES are null, trim it off before going on.
if (trim)
{
byte[] temp = new byte[cipherText.Length - MAC_BYTES];
Array.Copy(cipherText, MAC_BYTES, temp, 0, cipherText.Length - MAC_BYTES);
cipherText = temp;
}
}
byte[] buffer = new byte[cipherText.Length - MAC_BYTES];
SodiumCore.Init();
int ret = SodiumLibrary.crypto_secretbox_open_easy(buffer, cipherText, cipherText.Length, nonce, key);
if (ret != 0)
{
throw new CryptographicException("Failed to open SecretBox");
}
return(buffer);
}
/// <summary>Generates a random 24 byte nonce.</summary>
/// <returns>Returns a byte array with 24 random bytes</returns>
public static byte[] GenerateNonce()
{
return(SodiumCore.GetRandomBytes(NONCE_BYTES));
}
/// <summary>Generates a random 32 byte key.</summary>
/// <returns>Returns a byte array with 32 random bytes</returns>
public static byte[] GenerateKey()
{
return(SodiumCore.GetRandomBytes(KEY_BYTES));
}
