private string GetSignature(string path)
{
if (_binaryKey == null || _binarySalt == null)
{
return("insecure");
}
var pathBytes = Encoding.UTF8.GetBytes(path);
var passwordWithSaltByteArray = new byte[pathBytes.Length + _binarySalt.Length];
Buffer.BlockCopy(_binarySalt, 0, passwordWithSaltByteArray, 0, _binarySalt.Length);
Buffer.BlockCopy(pathBytes, 0, passwordWithSaltByteArray, _binarySalt.Length, pathBytes.Length);
using var hmac = new HMACSHA256(_binaryKey);
var digestBytes = hmac.ComputeHash(passwordWithSaltByteArray);
return(HexHelper.ByteArrayToUrlSafeBase64(digestBytes));
}
protected string BuildWithFormatAndOptions(string url, bool encode, Dictionary <string, ImgProxyOption> dict, FormatOption formatOption)
{
var processingOptions = string.Join("/", dict.Values);
string path;
if (encode)
{
path = formatOption != null
? $"/{processingOptions}/{HexHelper.StringToSafeBase64(url)}.{formatOption.Format}"
: $"/{processingOptions}/{HexHelper.StringToSafeBase64(url)}";
}
else
{
path = formatOption != null
? $"/{processingOptions}/plain/{url}@{formatOption.Format}"
: $"/{processingOptions}/plain/{url}";
}
var signature = GetSignature(path);
return($"{_host}/{signature}{path}");
}
protected void WithCredentials(string key, string salt)
{
if (string.IsNullOrEmpty(key))
{
throw new ArgumentNullException(nameof(key));
}
if (string.IsNullOrEmpty(salt))
{
throw new ArgumentNullException(nameof(salt));
}
if (key.Length % 2 == 1)
{
throw new ArgumentException("Invalid key. The key cannot have an odd number of digits", nameof(key));
}
if (salt.Length % 2 == 1)
{
throw new ArgumentException("Invalid salt. The salt cannot have an odd number of digits", nameof(salt));
}
_binaryKey = HexHelper.HexStringToByteArray(key);
_binarySalt = HexHelper.HexStringToByteArray(salt);
}
public WatermarkUrlOption(string url)
{
Url = HexHelper.StringToSafeBase64(url);
}
public StyleOption(string url)
{
Style = HexHelper.StringToSafeBase64(url);
}
