CREATE_ASYMMETRIC_PUB_KEY

Syntax:
create_asymmetric_pub_key(algorithm, priv_key_str)

Derives a public key from the given private key using the given
algorithm, and returns the key as a binary string in PEM format. If key
derivation fails, the result is NULL.

priv_key_str must be a valid key string in PEM format. algorithm
indicates the encryption algorithm used to create the key.

Supported algorithm values: 'RSA', 'DSA', 'DH'

For a usage example, see the description of
create_asymmetric_priv_key().