I do not use Python, but I wrote my own library in C for reading/writing DER. (I have made a variant, which adds a few new types such as: key/value list, BCD, T

I do not use Python, but I wrote my own library in C for reading/writing DER. (I have made a variant, which adds a few new types such as: key/value list, BCD, TRON character code, etc. The program works even if you do not use these new types.) DER does have the advantages they mention in that article, and other advantages. Some people mention that DER is not compact or not efficient; but often what is used instead is formats that are even less compact or less efficient than DER, and/or that are significantly more complicated to handle.