public static Result <Argon2Kdf, InvalidDataException> Deserialize(IDictionary <string, object> properties)
{
var ret = new Argon2Kdf();
if (!properties.TryGet <string>("kdf", out var kdf))
{
return(new InvalidDataException("The kdf dictionary does not have the required 'kdf' field."));
}
if (kdf != KdfName)
{
return(new InvalidDataException($"The kdf needs to be '{KdfName}' (was '{kdf}')."));
}
if (!properties.TryGet <int>("version", out var version))
{
return(new InvalidDataException("The kdf dictionary does not have the required 'version' field."));
}
if (version != Version)
{
return(new InvalidDataException(
$"Only version 0x{Version:X4} is supported at the moment (was 0x{version:X4})"));
}
if (!properties.TryGet <int>("opslimit", out var opslimit))
{
return(new InvalidDataException("The kdf dictionary does not have the required 'opslimit' field."));
}
ret.OpsLimit = opslimit;
if (!properties.TryGet <int>("memlimit", out var memlimit))
{
return(new InvalidDataException("The kdf dictionary does not have the required 'memlimit' field."));
}
ret.MemLimit = memlimit;
if (!properties.TryGet <string>("salt", out var salt))
{
return(new InvalidDataException("The kdf dictionary does not have the required 'salt' field."));
}
var fb64 = salt.FromBase64();
if (!fb64)
{
return(new InvalidDataException("The salt is not a valid base64 string."));
}
ret.Salt = fb64.Value;
return(ret);
}
public static Result <InvalidDataException> Decrypt(Stream input, Stream output, string password)
{
var header = input.GetBytes(4);
if (!header.SequenceEqual(MagicHeader))
{
return(new InvalidDataException("The magic header was not present in the input data."));
}
var cipherInfoRes = _readDict(input);
if (!cipherInfoRes)
{
return(new InvalidDataException("Failed to read cipher info from stream.", cipherInfoRes.Error));
}
var(cipherInfo, cipherBytes) = cipherInfoRes.Value;
if (!cipherInfo.TryGet <string>("iv", out var ivRaw))
{
return(new InvalidDataException("Failed to read initialization vector from initial dictionary. Most likely the data is corrupt."));
}
var ivRes = ivRaw.FromBase64();
if (!ivRes)
{
return(new InvalidDataException("The initialization vector was not a valid base64 string.", ivRes.Error));
}
var iv = ivRes.Value;
if (!cipherInfo.TryGet <string>("cipher", out var cipherVal))
{
return(new InvalidDataException("The cipher string was not present in the cipher info dictionary."));
}
ICipher cipher;
switch (cipherVal)
{
case Aes256GcmCipher.CipherNameStatic:
cipher = new Aes256GcmCipher();
break;
default:
return(new InvalidDataException($"The cipher '{cipherVal}' is not supported."));
}
if (!cipherInfo.TryGet <string>("kdf", out var kdfVal))
{
return(new InvalidDataException("The kdf string was not present in the cipher info dictionary."));
}
IKdf kdf;
switch (kdfVal)
{
case Argon2Kdf.KdfName:
{
var kdfRes = Argon2Kdf.Deserialize(cipherInfo);
if (!kdfRes)
{
return(new InvalidDataException("Failed to initialize argon2 kdf.", kdfRes.Error));
}
kdf = kdfRes.Value;
}
break;
default:
return(new InvalidDataException($"The kdf '{kdfVal}' is not supported."));
}
var checksumRes = _readDict(input);
if (!checksumRes)
{
return(new InvalidDataException("Failed to read checksum from stream.", checksumRes.Error));
}
var(checksum, checksumBytes) = checksumRes.Value;
if (!checksum.TryGet <string>("algo", out var checksumAlgo))
{
return(new InvalidDataException("No algorithm field from checksum dictionary."));
}
byte[] dictChecksum;
switch (checksumAlgo)
{
case "sha256":
dictChecksum = Sha256(cipherBytes);
break;
default:
return(new InvalidDataException($"The given checksum algorithm '{checksumAlgo}' is not supported."));
}
if (!checksum.TryGet <string>("checksum", out var checksumString))
{
return(new InvalidDataException("No checksum field from checksum dictionary."));
}
var expChecksum = checksumString.FromBase64();
if (!expChecksum)
{
return(new InvalidDataException("The checksum field was not a valid base64 string.", expChecksum.Error));
}
if (!dictChecksum.SequenceEqual(expChecksum.Value))
{
return(new InvalidDataException("Header checksum mismatch."));
}
byte[] key = Array.Empty <byte>();
try
{
key = kdf.Derive(password.ToUtf8Bytes(), 32);
cipher.Decrypt(input, output, key, iv);
return(Result <InvalidDataException> .Success);
}
catch (Exception e)
{
return(new InvalidDataException("Failed to process the data.", e));
}
finally
{
Array.Clear(key, 0, key.Length);
Array.Clear(iv, 0, iv.Length);
}
}
