before:
```rust
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        let mut read_buf = vec![0; buf.len();
        let bytes_read = self.0.read(&mut read_buf)?;

        if bytes_read == 0 {
            return Ok(0);
        }

        read_buf.truncate(bytes_read);

       decryption stuff

        Ok(bytes_read)
    }
```
after:
```rust
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
        let mut read_buf = Vec::with_capacity(buf.len());

        let bytes_read =
            (&self.0).take((buf.len()) as u64).read_to_end(&mut read_buf)?;

        if bytes_read == 0 {
            return Ok(0)
        }

        decryption stuff, doesnt matter.
        Ok(bytes_read)
    }
```