def METHOD_NAME(self, der):
    '''
    Builds a new DER that only includes N/E/D/P/Q RSA parameters;
    standard DER private bytes provided by OpenSSL also includes
    CRT params (DP/DQ/QP) which can be removed.
    '''
    OFFSET_N = 7  # N is always located at this offset
    b = bytearray(der)
    off = OFFSET_N
    if b[off + 1] != 0x82:
        raise RSAUsageError("Error parsing N while minimizing")
    len_N = (b[off + 2] << 8) + b[off + 3] + 4
    off += len_N
    if b[off + 1] != 0x03:
        raise RSAUsageError("Error parsing E while minimizing")
    len_E = b[off + 2] + 4
    off += len_E
    if b[off + 1] != 0x82:
        raise RSAUsageError("Error parsing D while minimizing")
    len_D = (b[off + 2] << 8) + b[off + 3] + 4
    off += len_D
    if b[off + 1] != 0x81:
        raise RSAUsageError("Error parsing P while minimizing")
    len_P = b[off + 2] + 3
    off += len_P
    if b[off + 1] != 0x81:
        raise RSAUsageError("Error parsing Q while minimizing")
    len_Q = b[off + 2] + 3
    off += len_Q
    # adjust DER size for removed elements
    b[2] = (off - 4) >> 8
    b[3] = (off - 4) & 0xff
    return b[:off]