$ openssl asn1parse -i < [EXTENSIONS]
    0:d=0  hl=2 l=  18 cons: SEQUENCE          
    2:d=1  hl=2 l=  14 cons:  SEQUENCE          
    4:d=2  hl=2 l=   3 prim:   OBJECT            :X509v3 Key Usage
    9:d=2  hl=2 l=   1 prim:   BOOLEAN           :255
   12:d=2  hl=2 l=   4 prim:   OCTET STRING      [HEX DUMP]:030203B8
   18:d=1  hl=2 l=   0 prim:  NULL              
-----BEGIN EXTENSIONS-----
MBIwDgYDVR0PAQH/BAQDAgO4BQA=
-----END EXTENSIONS-----