/// <summary>
/// Submits a message to a <see cref="Convo"/>.
/// </summary>
/// <param name="convo">The <see cref="Convo"/> to post the message into.</param>
/// <param name="messageType">The type of message (e.g. "TEXT=UTF8", "FILE=example.png", etc...).</param>
/// <param name="message">The message body to encrypt and post.</param>
/// <returns>Whether the message could be submitted successfully or not.</returns>
private async Task <bool> PostMessageToConvo(Convo convo, string messageType, byte[] message)
{
if (message.NullOrEmpty())
{
return(false);
}
Task <IDictionary <string, string> > publicKeys = userService.GetUserPublicKeys(user.Id, convo.GetParticipantIdsCommaSeparated(), user.Token.Item2);
byte[] compressedMessage = await compressionUtility.Compress(message, CompressionSettings.Default).ConfigureAwait(false);
using var encryptionResult = await aes.EncryptAsync(compressedMessage).ConfigureAwait(false);
byte[] key = new byte[48];
for (int i = 0; i < 32; i++)
{
key[i] = encryptionResult.Key[i];
}
for (int i = 0; i < 16; i++)
{
key[i + 32] = encryptionResult.IV[i];
}
// Encrypt the message decryption key for every convo participant individually.
var encryptedKeys = new ConcurrentBag <string>();
Parallel.ForEach(await publicKeys.ConfigureAwait(false), kvp =>
{
(string userId, string userPublicKey) = kvp;
if (userId.NotNullNotEmpty() && userPublicKey.NotNullNotEmpty())
{
string decompressedPublicKey = keyExchange.DecompressPublicKey(userPublicKey);
encryptedKeys.Add(userId + ':' + Convert.ToBase64String(rsa.Encrypt(key, decompressedPublicKey)));
}
});
try
{
var postParamsDto = new PostMessageParamsDto
{
Type = messageType,
SenderName = userSettings.Username,
ConvoId = convo.Id,
ConvoPasswordSHA512 = convoPasswordProvider.GetPasswordSHA512(convo.Id),
EncryptedKeys = encryptedKeys.ToCommaSeparatedString(),
EncryptedBody = Convert.ToBase64String(encryptionResult.EncryptedData)
};
var body = new EpistleRequestBody
{
UserId = user.Id,
Auth = user.Token.Item2,
Body = JsonSerializer.Serialize(postParamsDto)
};
return(await convoService.PostMessage(body.Sign(rsa, user.PrivateKeyPem)).ConfigureAwait(false));
}
catch
{
return(false);
}
}
