The key, message, and signature come from wycheproof ecdsa_secp256r1_sha256_test.json

The signature was wrapped in an additional BITSTRING.


$ openssl asn1parse -i < [PUBLIC KEY]
    0:d=0  hl=2 l=  89 cons: SEQUENCE          
    2:d=1  hl=2 l=  19 cons:  SEQUENCE          
    4:d=2  hl=2 l=   7 prim:   OBJECT            :id-ecPublicKey
   13:d=2  hl=2 l=   8 prim:   OBJECT            :prime256v1
   23:d=1  hl=2 l=  66 prim:  BIT STRING        

-----BEGIN PUBLIC KEY-----
MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEBKrsc2NXJvIT+4qeZNo7hjLkFJWpRNAEW1IuunJ
A+tWH2TFXmKqjpboBd1eHztBeqve04J/IHW0apUboNl1SXQ==
-----END PUBLIC KEY-----


$ openssl asn1parse -i < [ALGORITHM]
    0:d=0  hl=2 l=  10 cons: SEQUENCE          
    2:d=1  hl=2 l=   8 prim:  OBJECT            :ecdsa-with-SHA256

-----BEGIN ALGORITHM-----
MAoGCCqGSM49BAMC
-----END ALGORITHM-----

-----BEGIN DATA-----
MTIzNDAw
-----END DATA-----


$ openssl asn1parse -i < [SIGNATURE]
    0:d=0  hl=2 l=  73 prim: BIT STRING        

-----BEGIN SIGNATURE-----
A0kAMEYCIQCo6hUMuAEl1zgcTB8dqOneJxH5kXBgQGpz15BFGeUTiAIhAPOrn6aL1HlzpzstQEg
MK6UMIsnXbsIXJXKIKTKFRJuG
-----END SIGNATURE-----
