public string Decrypt(string secureString)
{
string result = null;
try
{
byte[] secureBytes = Convert.FromBase64String(secureString);
uint saltBytesCount = 0;
uint initiaVectorBytesCount = 0;
SecureHead.DecodeByteCounts(secureBytes, 0, out saltBytesCount, out initiaVectorBytesCount);
SecureHead secureHead = SecureHead.Decode(
secureBytes,
2 * sizeof(uint),
saltBytesCount,
initiaVectorBytesCount);
byte[] plainBytes = Decrypt(secureBytes, secureHead.TotalBytesCount, secureHead.SecureBytesCount, secureHead);
if (plainBytes != null)
{
result = BytesHelper.GetUTF8String(plainBytes, 0, (uint)plainBytes.Length);
}
}
catch (Exception e)
{
//ignore all exceptions according to requirements
}
return(result);
}
public static SecureHead Decode(byte[] bytes, uint offset, uint saltBytesCount, uint initiaVectorBytesCount)
{
uint totalBytesCount = GetPart2BytesCount() + saltBytesCount + initiaVectorBytesCount;
if (BytesHelper.IsNullOrEmptyArray(bytes) == true ||
bytes.Length - offset < totalBytesCount)
{
throw new ArgumentException(
string.Format("bytes array should have {0} bytes at least.",
totalBytesCount));
}
//part 2 (4 uints):
uint beginIndex = offset;
uint length = sizeof(uint);
uint saltIterations = BytesHelper.GetUInt32(bytes, beginIndex);
beginIndex += length;
length = sizeof(uint);
uint saltedInitiaVectorBytesCount = BytesHelper.GetUInt32(bytes, beginIndex);
beginIndex += length;
length = sizeof(uint);
uint saltedPasswordBytesCount = BytesHelper.GetUInt32(bytes, beginIndex);
beginIndex += length;
length = sizeof(uint);
uint secureDataBytes = BytesHelper.GetUInt32(bytes, beginIndex);
//part 3 (2 byte arraries):
beginIndex += length;
length = saltBytesCount;
string salt = BytesHelper.GetUTF8String(bytes, beginIndex, length);
beginIndex += length;
length = initiaVectorBytesCount;
string initiaVector = BytesHelper.GetUTF8String(bytes, beginIndex, length);
return(new SecureHead(
salt,
initiaVector,
saltIterations,
saltedInitiaVectorBytesCount,
saltedPasswordBytesCount,
secureDataBytes));
}
