path: root/docs/Chapter4/Security.rst

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.. Copyright 2017 AT&T Intellectual Property.  All rights reserved.

VNF Security
----------------------

The objective of this section is to provide the key security
requirements that need to be met by VNFs. The security requirements are
grouped into five areas as listed below. Other security areas will be
addressed in future updates. These security requirements are applicable
to all VNFs. Additional security requirements for specific types of VNFs
will be applicable and are outside the scope of these general
requirements.

Section 5.a Security in *VNF Guidelines* outlines
the five broad security areas for VNFs that are detailed in the
following sections:

-  **VNF General Security**: This section addresses general security
   requirements for the VNFs that the VNF provider will need to address.

-  **VNF Identity and Access Management**: This section addresses
   security requirements with respect to Identity and Access Management
   as these pertain to generic VNFs.

-  **VNF API Security**: This section addresses the generic security
   requirements associated with APIs. These requirements are applicable
   to those VNFs that use standard APIs for communication and data
   exchange.

-  **VNF Security Analytics**: This section addresses the security
   requirements associated with analytics for VNFs that deal with
   monitoring, data collection and analysis.

-  **VNF Data Protection**: This section addresses the security
   requirements associated with data protection.

VNF General Security Requirements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This section provides details on the VNF general security requirements
on various security areas such as user access control, network security,
ACLs, infrastructure security, and vulnerability management. These
requirements cover topics associated with compliance, security patching,
logging/accounting, authentication, encryption, role-based access
control, least privilege access/authorization. The following security
requirements need to be met by the solution in a virtual environment:

General Security Requirements

Integration and operation within a robust security environment is necessary
and expected. The security architecture will include one or more of the
following: IDAM (Identity and Access Management) for all system and
applications access, Code scanning, network vulnerability scans, OS,
Database and application patching, malware detection and cleaning,
DDOS prevention, network security gateways (internal and external)
operating at various layers, host and application based tools for
security compliance validation, aggressive security patch application,
tightly controlled software distribution and change control processes
and other state of the art security solutions. The VNF is expected to
function reliably within such an environment and the developer is
expected to understand and accommodate such controls and can expected
to supply responsive interoperability support and testing throughout
the product’s lifecycle.

* R-23740 The VNF **MUST** accommodate the security principle of
  “least privilege” during development, implementation and operation.
  The importance of “least privilege” cannot be overstated and must be
  observed in all aspects of VNF development and not limited to security.
  This is applicable to all sections of this document.
* R-61354 The VNF **MUST** implement access control list for OA&M
  services (e.g., restricting access to certain ports or applications).
* R-85633 The VNF **MUST** implement Data Storage Encryption
  (database/disk encryption) for Sensitive Personal Information (SPI)
  and other subscriber identifiable data. Note: subscriber’s SPI/data
  must be encrypted at rest, and other subscriber identifiable data
  should be encrypted at rest. Other data protection requirements exist
  and should be well understood by the developer.
* R-92207 The VNF **SHOULD** implement a mechanism for automated and
  frequent "system configuration (automated provisioning / closed loop)"
  auditing.
* R-23882 The VNF **SHOULD** be scanned using both network scanning
  and application scanning security tools on all code, including underlying
  OS and related configuration. Scan reports shall be provided. Remediation
  roadmaps shall be made available for any findings.
* R-46986 The VNF **SHOULD** have source code scanned using scanning
  tools (e.g., Fortify) and provide reports.
* R-55830 The VNF **MUST** distribute all production code from NCSP
  internal sources only. No production code, libraries, OS images, etc.
  shall be distributed from publically accessible depots.
* R-99771 The VNF **MUST** provide all code/configuration files in a
  "Locked down" or hardened state or with documented recommendations for
  such hardening. All unnecessary services will be disabled. VNF provider
  default credentials, community strings and other such artifacts will be
  removed or disclosed so that they can be modified or removed during
  provisioning.
* R-19768 The VNF **SHOULD** support L3 VPNs that enable segregation of
  traffic by application (dropping packets not belonging to the VPN) (i.e.,
  AVPN, IPSec VPN for Internet routes).
* R-33981 The VNF **SHOULD** interoperate with various access control
  mechanisms for the Network Cloud execution environment (e.g.,
  Hypervisors, containers).
* R-40813 The VNF **SHOULD** support the use of virtual trusted platform
  module, hypervisor security testing and standards scanning tools.
* R-56904 The VNF **MUST** interoperate with the ONAP (SDN) Controller so that
  it can dynamically modify the firewall rules, ACL rules, QoS rules, virtual
  routing and forwarding rules.
* R-26586 The VNF **SHOULD** support the ability to work with aliases
  (e.g., gateways, proxies) to protect and encapsulate resources.
* R-49956 The VNF **MUST** pass all access to applications (Bearer,
  signaling and OA&M) through various security tools and platforms from
  ACLs, stateful firewalls and application layer gateways depending on
  manner of deployment. The application is expected to function (and in
  some cases, interwork) with these security tools.
* R-69649 The VNF **MUST** have all vulnerabilities patched as soon
  as possible. Patching shall be controlled via change control process
  with vulnerabilities disclosed along with mitigation recommendations.
* R-78010 The VNF **MUST** use the NCSP’s IDAM API for Identification,
  authentication and access control of customer or VNF application users.
* R-42681 The VNF **MUST** use the NCSP’s IDAM API or comply with
  the requirements if not using the NCSP’s IDAM API, for identification,
  authentication and access control of OA&M and other system level
  functions.
* R-68589 The VNF **MUST**, if not using the NCSP’s IDAM API, support
  User-IDs and passwords to uniquely identify the user/application. VNF
  needs to have appropriate connectors to the Identity, Authentication
  and Authorization systems that enables access at OS, Database and
  Application levels as appropriate.
* R-52085 The VNF **MUST**, if not using the NCSP’s IDAM API, provide
  the ability to support Multi-Factor Authentication (e.g., 1st factor =
  Software token on device (RSA SecureID); 2nd factor = User Name+Password,
  etc.) for the users.
* R-98391 The VNF **MUST**, if not using the NCSP’s IDAM API, support
  Role-Based Access Control to permit/limit the user/application to
  performing specific activities.
* R-63217 The VNF **MUST**, if not using the NCSP’s IDAM API, support
  logging via ONAP for a historical view of “who did what and when”.
* R-62498 The VNF **MUST**, if not using the NCSP’s IDAM API, encrypt
  OA&M access (e.g., SSH, SFTP).
* R-79107 The VNF **MUST**, if not using the NCSP’s IDAM API, enforce
  a configurable maximum number of Login attempts policy for the users.
  VNF provider must comply with "terminate idle sessions" policy.
  Interactive sessions must be terminated, or a secure, locking screensaver
  must be activated requiring authentication, after a configurable period
  of inactivity. The system-based inactivity timeout for the enterprise
  identity and access management system must also be configurable.
* R-35144 The VNF **MUST**, if not using the NCSP’s IDAM API, comply
  with the NCSP’s credential management policy.
* R-75041 The VNF **MUST**, if not using the NCSP’s IDAM API, expire
  passwords at regular configurable intervals.
* R-46908 The VNF **MUST**, if not using the NCSP’s IDAM API, comply
  with "password complexity" policy. When passwords are used, they shall
  be complex and shall at least meet the following password construction
  requirements: (1) be a minimum configurable number of characters in
  length, (2) include 3 of the 4 following types of characters:
  upper-case alphabetic, lower-case alphabetic, numeric, and special,
  (3) not be the same as the UserID with which they are associated or
  other common strings as specified by the environment, (4) not contain
  repeating or sequential characters or numbers, (5) not to use special
  characters that may have command functions, and (6) new passwords must
  not contain sequences of three or more characters from the previous
  password.
* R-39342 The VNF **MUST**, if not using the NCSP’s IDAM API, comply
  with "password changes (includes default passwords)" policy. Products
  will support password aging, syntax and other credential management
  practices on a configurable basis.
* R-40521 The VNF **MUST**, if not using the NCSP’s IDAM API, support
  use of common third party authentication and authorization tools such
  as TACACS+, RADIUS.
* R-41994 The VNF **MUST**, if not using the NCSP’s IDAM API, comply
  with "No Self-Signed Certificates" policy. Self-signed certificates
  must be used for encryption only, using specified and approved
  encryption protocols such as TLS 1.2 or higher or equivalent security
  protocols such as IPSec, AES.
* R-23135 The VNF **MUST**, if not using the NCSP’s IDAM API,
  authenticate system to system communications where one system
  accesses the resources of another system, and must never conceal
  individual accountability.

VNF Identity and Access Management Requirements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The following security requirements for logging, identity, and access
management need to be met by the solution in a virtual environment:


Identity and Access Management Requirements

* R-95105 The VNF **MUST** host connectors for access to the application
  layer.
* R-45496 The VNF **MUST** host connectors for access to the OS
  (Operating System) layer.
* R-05470 The VNF **MUST** host connectors for access to the database layer.
* R-99174 The VNF **MUST** comply with Individual Accountability
  (each person must be assigned a unique ID) when persons or non-person
  entities access VNFs.
* R-42874 The VNF **MUST** comply with Least Privilege (no more
  privilege than required to perform job functions) when persons
  or non-person entities access VNFs.
* R-71787 The VNF **MUST** comply with Segregation of Duties (access to a
  single layer and no developer may access production without special
  oversight) when persons or non-person entities access VNFs.
* R-86261 The VNF **MUST NOT** allow VNF provider access to VNFs remotely.
* R-49945 The VNF **MUST** authorize VNF provider access through a
  client application API by the client application owner and the resource
  owner of the VNF before provisioning authorization through Role Based
  Access Control (RBAC), Attribute Based Access Control (ABAC), or other
  policy based mechanism.
* R-31751 The VNF **MUST** subject VNF provider access to privilege
  reconciliation tools to prevent access creep and ensure correct
  enforcement of access policies.
* R-34552 The VNF **MUST** provide or support the Identity and Access
  Management (IDAM) based threat detection data for OWASP Top 10.
* R-29301 The VNF **MUST** provide or support the Identity and Access
  Management (IDAM) based threat detection data for Password Attacks.
* R-72243 The VNF **MUST** provide or support the Identity and Access
  Management (IDAM) based threat detection data for Phishing / SMishing.
* R-58998 The VNF **MUST** provide or support the Identity and Access
  Management (IDAM) based threat detection data for Malware (Key Logger).
* R-14025 The VNF **MUST** provide or support the Identity and Access
  Management (IDAM) based threat detection data for Session Hijacking.
* R-31412 The VNF **MUST** provide or support the Identity and Access
  Management (IDAM) based threat detection data for XSS / CSRF.
* R-51883 The VNF **MUST** provide or support the Identity and Access
  Management (IDAM) based threat detection data for Replay.
* R-44032 The VNF **MUST** provide or support the Identity and Access
  Management (IDAM) based threat detection data for Man in the Middle (MITM).
* R-58977 The VNF **MUST** provide or support the Identity and Access
  Management (IDAM) based threat detection data for Eavesdropping.
* R-24825 The VNF **MUST** provide Context awareness data (device,
  location, time, etc.) and be able to integrate with threat detection system.
* R-59391 The VNF provider **MUST**, where a VNF provider requires
  the assumption of permissions, such as root or administrator, first
  log in under their individual user login ID then switch to the other
  higher level account; or where the individual user login is infeasible,
  must login with an account with admin privileges in a way that
  uniquely identifies the individual performing the function.
* R-85028 The VNF **MUST** authenticate system to system access and
  do not conceal a VNF provider user’s individual accountability for
  transactions.
* R-80335 The VNF **MUST** make visible a Warning Notice: A formal
  statement of resource intent, i.e., a warning notice, upon initial
  access to a VNF provider user who accesses private internal networks
  or Company computer resources, e.g., upon initial logon to an internal
  web site, system or application which requires authentication.
* R-73541 The VNF **MUST** use access controls for VNFs and their
  supporting computing systems at all times to restrict access to
  authorized personnel only, e.g., least privilege. These controls
  could include the use of system configuration or access control
  software.
* R-64503 The VNF **MUST** provide minimum privileges for initial
  and default settings for new user accounts.
* R-86835 The VNF **MUST** set the default settings for user access
  to sensitive commands and data to deny authorization.
* R-77157 The VNF **MUST** conform to approved request, workflow
  authorization, and authorization provisioning requirements when
  creating privileged users.
* R-81147 The VNF **MUST** have greater restrictions for access and
  execution, such as up to 3 factors of authentication and restricted
  authorization, for commands affecting network services, such as
  commands relating to VNFs.
* R-49109 The VNF **MUST** encrypt TCP/IP--HTTPS (e.g., TLS v1.2)
  transmission of data on internal and external networks.
* R-39562 The VNF **MUST** disable unnecessary or vulnerable cgi-bin programs.
* R-15671 The VNF **MUST NOT** provide public or unrestricted access
  to any data without the permission of the data owner. All data
  classification and access controls must be followed.
* R-89753 The VNF **MUST NOT** install or use systems, tools or
  utilities capable of capturing or logging data that was not created
  by them or sent specifically to them in production, without
  authorization of the VNF system owner.
* R-19082 The VNF **MUST NOT** run security testing tools and
  programs, e.g., password cracker, port scanners, hacking tools
  in production, without authorization of the VNF system owner.
* R-19790 The VNF **MUST NOT** include authentication credentials
  in security audit logs, even if encrypted.
* R-85419 The VNF **SHOULD** use REST APIs exposed to Client
  Applications for the implementation of OAuth 2.0 Authorization
  Code Grant and Client Credentials Grant, as the standard interface
  for a VNF.
* R-48080 The VNF **SHOULD** support SCEP (Simple Certificate
  Enrollment Protocol).


VNF API Security Requirements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This section covers API security requirements when these are used by the
VNFs. Key security areas covered in API security are Access Control,
Authentication, Passwords, PKI Authentication Alarming, Anomaly
Detection, Lawful Intercept, Monitoring and Logging, Input Validation,
Cryptography, Business continuity, Biometric Authentication,
Identification, Confidentiality and Integrity, and Denial of Service.

The solution in a virtual environment needs to meet the following API
security requirements:


API Requirements

* R-37608 The VNF **MUST** provide a mechanism to restrict access based
  on the attributes of the VNF and the attributes of the subject.
* R-43884 The VNF **MUST** integrate with external authentication
  and authorization services (e.g., IDAM).
* R-25878 The VNF **MUST** use certificates issued from publicly
  recognized Certificate Authorities (CA) for the authentication process
  where PKI-based authentication is used.
* R-19804 The VNF **MUST** validate the CA signature on the certificate,
  ensure that the date is within the validity period of the certificate,
  check the Certificate Revocation List (CRL), and recognize the identity
  represented by the certificate where PKI-based authentication is used.
* R-47204 The VNF **MUST** protect the confidentiality and integrity of
  data at rest and in transit from unauthorized access and modification.
* R-33488 The VNF **MUST** protect against all denial of service
  attacks, both volumetric and non-volumetric, or integrate with external
  denial of service protection tools.
* R-21652 The VNF **MUST** implement the following input validation
  control: Check the size (length) of all input. Do not permit an amount
  of input so great that it would cause the VNF to fail. Where the input
  may be a file, the VNF API must enforce a size limit.
* R-54930 The VNF **MUST** implement the following input validation
  control: Do not permit input that contains content or characters
  inappropriate to the input expected by the design. Inappropriate input,
  such as SQL insertions, may cause the system to execute undesirable
  and unauthorized transactions against the database or allow other
  inappropriate access to the internal network.
* R-21210 The VNF **MUST** implement the following input validation
  control: Validate that any input file has a correct and valid
  Multipurpose Internet Mail Extensions (MIME) type. Input files
  should be tested for spoofed MIME types.
* R-23772 The VNF **MUST** validate input at all layers implementing VNF APIs.
* R-87135 The VNF **MUST** comply with NIST standards and industry
  best practices for all implementations of cryptography.
* R-02137 The VNF **MUST** implement all monitoring and logging as
  described in the Security Analytics section.
* R-15659 The VNF **MUST** restrict changing the criticality level of
  a system security alarm to administrator(s).
* R-19367 The VNF **MUST** monitor API invocation patterns to detect
  anomalous access patterns that may represent fraudulent access or
  other types of attacks, or integrate with tools that implement anomaly
  and abuse detection.
* R-78066 The VNF **MUST** support requests for information from law
  enforcement and government agencies.


VNF Security Analytics Requirements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This section covers VNF security analytics requirements that are mostly
applicable to security monitoring. The VNF Security Analytics cover the
collection and analysis of data following key areas of security
monitoring:

-  Anti-virus software

-  Logging

-  Data capture

-  Tasking

-  DPI

-  API based monitoring

-  Detection and notification

-  Resource exhaustion detection

-  Proactive and scalable monitoring

-  Mobility and guest VNF monitoring

-  Closed loop monitoring

-  Interfaces to management and orchestration

-  Malformed packet detections

-  Service chaining

-  Dynamic security control

-  Dynamic load balancing

-  Connection attempts to inactive ports (malicious port scanning)

The following requirements of security monitoring need to be met by the
solution in a virtual environment.

Security Analytics Requirements

* R-48470 The VNF **MUST** support Real-time detection and
  notification of security events.
* R-22286 The VNF **MUST** support Integration functionality via
  API/Syslog/SNMP to other functional modules in the network (e.g.,
  PCRF, PCEF) that enable dynamic security control by blocking the
  malicious traffic or malicious end users
* R-32636 The VNF **MUST** support API-based monitoring to take care of
  the scenarios where the control interfaces are not exposed, or are
  optimized and proprietary in nature.
* R-61648 The VNF **MUST** support event logging, formats, and delivery
  tools to provide the required degree of event data to ONAP
* R-22367 The VNF **MUST** support detection of malformed packets due to
  software misconfiguration or software vulnerability.
* R-31961 The VNF **MUST** support integrated DPI/monitoring functionality
  as part of VNFs (e.g., PGW, MME).
* R-20912 The VNF **MUST** support alternative monitoring capabilities
  when VNFs do not expose data or control traffic or use proprietary and
  optimized protocols for inter VNF communication.
* R-73223 The VNF **MUST** support proactive monitoring to detect and
  report the attacks on resources so that the VNFs and associated VMs can
  be isolated, such as detection techniques for resource exhaustion, namely
  OS resource attacks, CPU attacks, consumption of kernel memory, local
  storage attacks.
* R-58370 The VNF **MUST** coexist and operate normally with commercial
  anti-virus software which shall produce alarms every time when there is a
  security incident.
* R-56920 The VNF **MUST** protect all security audit logs (including
  API, OS and application-generated logs), security audit software, data,
  and associated documentation from modification, or unauthorized viewing,
  by standard OS access control mechanisms, by sending to a remote system,
  or by encryption.
* R-54520 The VNF **MUST** log successful and unsuccessful login attempts.
* R-55478 The VNF **MUST** log logoffs.
* R-08598 The VNF **MUST** log successful and unsuccessful changes to
  a privilege level.
* R-13344 The VNF **MUST** log starting and stopping of security
  logging.
* R-07617 The VNF **MUST** log creating, removing, or changing the
  inherent privilege level of users.
* R-94525 The VNF **MUST** log connections to a network listener of the
  resource.
* R-31614 The VNF **MUST** log the field “event type” in the security
  audit logs.
* R-97445 The VNF **MUST** log the field “date/time” in the security
  audit logs.
* R-25547 The VNF **MUST** log the field “protocol” in the security audit logs.
* R-06413 The VNF **MUST** log the field “service or program used for
  access” in the security audit logs.
* R-15325 The VNF **MUST** log the field “success/failure” in the
  security audit logs.
* R-89474 The VNF **MUST** log the field “Login ID” in the security audit logs.
* R-04982 The VNF **MUST NOT** include an authentication credential,
  e.g., password, in the security audit logs, even if encrypted.
* R-63330 The VNF **MUST** detect when the security audit log storage
  medium is approaching capacity (configurable) and issue an alarm via
  SMS or equivalent as to allow time for proper actions to be taken to
  pre-empt loss of audit data.
* R-41252 The VNF **MUST** support the capability of online storage of
  security audit logs.
* R-41825 The VNF **MUST** activate security alarms automatically when
  the following event is detected: configurable number of consecutive
  unsuccessful login attempts
* R-43332 The VNF **MUST** activate security alarms automatically when
  the following event is detected: successful modification of critical
  system or application files
* R-74958 The VNF **MUST** activate security alarms automatically when
  the following event is detected: unsuccessful attempts to gain permissions
  or assume the identity of another user
* R-15884 The VNF **MUST** include the field “date” in the Security alarms
  (where applicable and technically feasible).
* R-23957 The VNF **MUST** include the field “time” in the Security alarms
  (where applicable and technically feasible).
* R-71842 The VNF **MUST** include the field “service or program used for
  access” in the Security alarms (where applicable and technically feasible).
* R-57617 The VNF **MUST** include the field “success/failure” in the
  Security alarms (where applicable and technically feasible).
* R-99730 The VNF **MUST** include the field “Login ID” in the Security
  alarms (where applicable and technically feasible).
* R-29705 The VNF **MUST** restrict changing the criticality level of a
  system security alarm to administrator(s).
* R-13627 The VNF **MUST** monitor API invocation patterns to detect
  anomalous access patterns that may represent fraudulent access or other
  types of attacks, or integrate with tools that implement anomaly and
  abuse detection.
* R-21819 The VNF **MUST** support requests for information from law
  enforcement and government agencies.
* R-56786 The VNF **MUST** implement “Closed Loop” automatic implementation
  (without human intervention) for Known Threats with detection rate in low
  false positives.
* R-25094 The VNF **MUST** perform data capture for security functions.
* R-04492 The VNF **MUST** generate security audit logs that must be sent
  to Security Analytics Tools for analysis.
* R-19219 The VNF **MUST** provide audit logs that include user ID, dates,
  times for log-on and log-off, and terminal location at minimum.
* R-30932 The VNF **MUST** provide security audit logs including records
  of successful and rejected system access data and other resource access
  attempts.
* R-54816 The VNF **MUST** support the storage of security audit logs
  for agreed period of time for forensic analysis.
* R-57271 The VNF **MUST** provide the capability of generating security
  audit logs by interacting with the operating system (OS) as appropriate.
* R-84160 The VNF **MUST** have security logging for VNFs and their
  OSs be active from initialization. Audit logging includes automatic
  routines to maintain activity records and cleanup programs to ensure
  the integrity of the audit/logging systems.

VNF Data Protection Requirements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This section covers VNF data protection requirements that are mostly
applicable to security monitoring.


Data Protection Requirements

* R-58964 The VNF **MUST** provide the capability to restrict read
  and write access to data.
* R-99112 The VNF **MUST** provide the capability to restrict access
  to data to specific users.
* R-83227 The VNF **MUST** Provide the capability to encrypt data in
  transit on a physical or virtual network.
* R-32641 The VNF **MUST** provide the capability to encrypt data on
  non-volatile memory.
* R-13151 The VNF **SHOULD** disable the paging of the data requiring
  encryption, if possible, where the encryption of non-transient data is
  required on a device for which the operating system performs paging to
  virtual memory. If not possible to disable the paging of the data
  requiring encryption, the virtual memory should be encrypted.
* R-93860 The VNF **MUST** provide the capability to integrate with an
  external encryption service.
* R-73067 The VNF **MUST** use industry standard cryptographic algorithms
  and standard modes of operations when implementing cryptography.
* R-22645 The VNF **SHOULD** use commercial algorithms only when there
  are no applicable governmental standards for specific cryptographic
  functions, e.g., public key cryptography, message digests.
* R-12467 The VNF **MUST NOT** use the SHA, DSS, MD5, SHA-1 and
  Skipjack algorithms or other compromised encryption.
* R-02170 The VNF **MUST** use, whenever possible, standard implementations
  of security applications, protocols, and format, e.g., S/MIME, TLS, SSH,
  IPSec, X.509 digital certificates for cryptographic implementations.
  These implementations must be purchased from reputable vendors and must
  not be developed in-house.
* R-70933 The VNF **MUST** provide the ability to migrate to newer
  versions of cryptographic algorithms and protocols with no impact.
* R-44723 The VNF **MUST** use symmetric keys of at least 112 bits in length.
* R-25401 The VNF **MUST** use asymmetric keys of at least 2048 bits in length.
* R-95864 The VNF **MUST** use commercial tools that comply with X.509
  standards and produce x.509 compliant keys for public/private key generation.
* R-12110 The VNF **MUST NOT** use keys generated or derived from
  predictable functions or values, e.g., values considered predictable
  include user identity information, time of day, stored/transmitted data.
* R-52060 The VNF **MUST** provide the capability to configure encryption
  algorithms or devices so that they comply with the laws of the jurisdiction
  in which there are plans to use data encryption.
* R-69610 The VNF **MUST** provide the capability of using certificates
  issued from a Certificate Authority not provided by the VNF provider.
* R-83500 The VNF **MUST** provide the capability of allowing certificate
  renewal and revocation.
* R-29977 The VNF **MUST** provide the capability of testing the validity
  of a digital certificate by validating the CA signature on the certificate.
* R-24359 The VNF **MUST** provide the capability of testing the validity
  of a digital certificate by validating the date the certificate is being
  used is within the validity period for the certificate.
* R-39604 The VNF **MUST** provide the capability of testing the
  validity of a digital certificate by checking the Certificate Revocation
  List (CRL) for the certificates of that type to ensure that the
  certificate has not been revoked.
* R-75343 The VNF **MUST** provide the capability of testing the
  validity of a digital certificate by recognizing the identity represented
  by the certificate — the "distinguished name".