- ecdsa_sign(+Key, 
+Data, -Signature, +Options)
- Create an ECDSA signature for Data with EC private key Key. 
Among the most common cases is signing a hash that was created with crypto_data_hash/3 
or other predicates of this library. For this reason, the default 
encoding (hex) assumes that Data is an atom, 
string, character list or code list representing the data in hexadecimal 
notation. See rsa_sign/4 for an 
example.
Options:
 
- encoding(+Encoding)
- Encoding to use for Data. Default is hex. 
Alternatives areoctet,utf8andtext.
 
- [semidet]ecdsa_verify(+Key, 
+Data, +Signature, +Options)
- True iff Signature can be verified as the ECDSA signature for
Data, using the EC public key Key.
Options:
 
- encoding(+Encoding)
- Encoding to use for Data. Default is hex. 
Alternatives areoctet,utf8andtext.