Amazing dex1, it works!
Can you explain
PRE_STRING=302e0201010420
secp256k1_ID=a00706052b8104000a
I searched more details but I don't find good resources
it is all the "stuff" you want to give OpenSSL in one place encoded using ASN.1 DER encoding.
302e02010104202d7238106df87d7b70f9d7cc4ff833ff9fad86aa5e50f8cf42689c238d70f723a00706052b8104000a
which is:
30 : sequence tag
2e : length = 46
02 : int tag
01 : length = 1
01 : int value = 1
04 : octet string tag
20 : length = 32
2d7238106df87d7b70f9d7cc4ff833ff9fad86aa5e50f8cf42689c238d70f723 : the string (key hex)
a0 : context specific tag
07 : length = 7
06 : object identifier tag
05 : length = 5
2b8104000a : sekp256k1 identifier