Create Read Only SNMPv3 user – IOS

snmp-server group viewers v3 auth
snmp-server user snmpView viewers v3 auth md5 uHNKmuLP0lXOp8ODFkmJ
snmp-server group viewers v3 auth read viewConfig
snmp-server view viewConfig system included
snmp-server view viewConfig internet included
snmp-server view viewConfig mib-2 included
snmp-server view viewConfig cisco included
snmp-server view viewConfig ciscoConfig included
snmp-server view viewConfig ciscoImageMIB included
snmp-server view viewConfig snmpMIB included

Create Read Write SNMPv3 user – IOS

snmp-server group writers v3 auth
snmp-server user snmpWrite writers v3 auth md5 jB7HCiNBoGsk5qgfasHQ
snmp-server group writers v3 auth write writeConfig
snmp-server view writeConfig system included
snmp-server view writeConfig internet included
snmp-server view writeConfig mib-2 included
snmp-server view writeConfig cisco included
snmp-server view writeConfig ciscoConfig included
snmp-server view writeConfig ciscoImageMIB included
snmp-server view writeConfig snmpMIB included

Create Read Only SNMPv3 user – ASA

snmp-server group viewers v3 auth
snmp-server user snmpView viewers v3 auth md5 uHNKmuLP0lXOp8ODFkmJ
snmp-server host inside 0.0.0.0 version 3 snmpView

NOTE: Please keep in mind that certain ACLs might require modification in order to allow SNMP protocol access.