internal/cvss/cvss.go: hide internals

1 files changed, 741 insertions, 663 deletions

diff --git a/internal/cvss/cvss.go b/internal/cvss/cvss.go
index e50f718..f260ce2 100644
--- a/internal/cvss/cvss.go
+++ b/internal/cvss/cvss.go
@@ -7,11 +7,11 @@ import (
 )
 
 //go:generate stringer -linecomment -type=Version
-//go:generate stringer -linecomment -type=MetricCategory
-//go:generate stringer -linecomment -type=V2MetricKey
-//go:generate stringer -linecomment -type=V2Metric
-//go:generate stringer -linecomment -type=V3MetricKey
-//go:generate stringer -linecomment -type=V3Metric
+//go:generate stringer -linecomment -type=Category
+//go:generate stringer -linecomment -type=v2MetricKey
+//go:generate stringer -linecomment -type=v2Metric
+//go:generate stringer -linecomment -type=v3MetricKey
+//go:generate stringer -linecomment -type=v3Metric
 
 // CVSS version
 type Version byte
@@ -23,330 +23,340 @@ const (
 )
 
 // CVSS metric category.
-type MetricCategory byte
+type Category byte
 
 const (
-  Base MetricCategory = iota // Base
+  Base Category = iota // Base
   Temporal // Temporal
   Environmental // Environmental
 )
 
-// CVSS metric key
-type V2MetricKey byte
+// CVSS metric key.
+type v2MetricKey byte
 
 const (
-  V2AccessVector V2MetricKey = iota // AV
-  V2AccessComplexity // AC
-  V2Authentication // Au
-  V2ConfidentialityImpact // C
-  V2IntegrityImpact // I
-  V2AvailabilityImpact // A
-  V2Exploitability // E
-  V2RemediationLevel // RL
-  V2ReportConfidence // RC
-  V2CollateralDamagePotential // CDP
-  V2TargetDistribution // TD
-  V2ConfidentialityRequirement // CR
-  V2IntegrityRequirement // IR
-  V2AvailabilityRequirement // AR
+  v2AccessVector v2MetricKey = iota // AV
+  v2AccessComplexity // AC
+  v2Authentication // Au
+  v2ConfidentialityImpact // C
+  v2IntegrityImpact // I
+  v2AvailabilityImpact // A
+  v2Exploitability // E
+  v2RemediationLevel // RL
+  v2ReportConfidence // RC
+  v2CollateralDamagePotential // CDP
+  v2TargetDistribution // TD
+  v2ConfidentialityRequirement // CR
+  v2IntegrityRequirement // IR
+  v2AvailabilityRequirement // AR
+
+  v2InvalidMetricKey // invalid
 )
 
 // CVSS V2 metric key info lut
-var v2MetricKeys = map[V2MetricKey]struct {
+var v2MetricKeys = map[v2MetricKey]struct {
   Name string
-  Category MetricCategory
+  Category Category
 } {
-  V2AccessVector: { "Access Vector", Base },
-  V2AccessComplexity: { "Access Complexity", Base },
-  V2Authentication: { "Authentication", Base },
-  V2ConfidentialityImpact: { "Confidentiality Impact", Base },
-  V2IntegrityImpact: { "Integrity Impact", Base },
-  V2AvailabilityImpact: { "Availability Impact", Base },
-  V2Exploitability: { "Exploitability", Temporal },
-  V2RemediationLevel: { "Remediation Level", Temporal },
-  V2ReportConfidence: { "Report Confidence", Temporal },
-  V2CollateralDamagePotential: { "Collateral Damage Potential", Environmental },
-  V2TargetDistribution: { "Target Distribution", Environmental },
-  V2ConfidentialityRequirement: { "Confidentiality Requirement", Environmental },
-  V2IntegrityRequirement: { "Integrity Requirement", Environmental },
-  V2AvailabilityRequirement: { "Availability Requirement", Environmental },
+  v2AccessVector: { "Access Vector", Base },
+  v2AccessComplexity: { "Access Complexity", Base },
+  v2Authentication: { "Authentication", Base },
+  v2ConfidentialityImpact: { "Confidentiality Impact", Base },
+  v2IntegrityImpact: { "Integrity Impact", Base },
+  v2AvailabilityImpact: { "Availability Impact", Base },
+  v2Exploitability: { "Exploitability", Temporal },
+  v2RemediationLevel: { "Remediation Level", Temporal },
+  v2ReportConfidence: { "Report Confidence", Temporal },
+  v2CollateralDamagePotential: { "Collateral Damage Potential", Environmental },
+  v2TargetDistribution: { "Target Distribution", Environmental },
+  v2ConfidentialityRequirement: { "Confidentiality Requirement", Environmental },
+  v2IntegrityRequirement: { "Integrity Requirement", Environmental },
+  v2AvailabilityRequirement: { "Availability Requirement", Environmental },
 }
 
 // v2 metric key IDs lut
-var v2MetricKeyIds = map[string]V2MetricKey {
-  "AV": V2AccessVector,
-  "AC": V2AccessComplexity,
-  "Au": V2Authentication,
-  "C": V2ConfidentialityImpact,
-  "I": V2IntegrityImpact,
-  "A": V2AvailabilityImpact,
-  "E": V2Exploitability,
-  "RL": V2RemediationLevel,
-  "RC": V2ReportConfidence,
-  "CDP": V2CollateralDamagePotential,
-  "TD": V2TargetDistribution,
-  "CR": V2ConfidentialityRequirement,
-  "IR": V2IntegrityRequirement,
-  "AR": V2AvailabilityRequirement,
+var v2MetricKeyIds = map[string]v2MetricKey {
+  "AV": v2AccessVector,
+  "AC": v2AccessComplexity,
+  "Au": v2Authentication,
+  "C": v2ConfidentialityImpact,
+  "I": v2IntegrityImpact,
+  "A": v2AvailabilityImpact,
+  "E": v2Exploitability,
+  "RL": v2RemediationLevel,
+  "RC": v2ReportConfidence,
+  "CDP": v2CollateralDamagePotential,
+  "TD": v2TargetDistribution,
+  "CR": v2ConfidentialityRequirement,
+  "IR": v2IntegrityRequirement,
+  "AR": v2AvailabilityRequirement,
 }
 
 // Get metric key from string.
-func GetV2MetricKeyFromString(s string) (V2MetricKey, error) {
+func getV2MetricKeyFromString(s string) (v2MetricKey, error) {
   k, ok := v2MetricKeyIds[s]
   if ok {
     return k, nil
   } else {
-    return V2AccessVector, fmt.Errorf("unknown metric key: %s", s)
+    return v2InvalidMetricKey, fmt.Errorf("invalid metric key: %s", s)
   }
 }
 
 // Get metric key name.
-func (k V2MetricKey) Name() string {
+func (k v2MetricKey) Name() string {
   return v2MetricKeys[k].Name
 }
 
 // Get metric key category.
-func (k V2MetricKey) Category() MetricCategory {
+func (k v2MetricKey) Category() Category {
   return v2MetricKeys[k].Category
 }
 
 // CVSS v2 metric value
-type V2Metric byte
+type v2Metric byte
 
 const (
-  V2AVNetwork V2Metric = iota // AV:N
-  V2AVAdjacentNetwork // AV:A
-  V2AVLocal // AV:L
-
-  V2ACLow // AC:L
-  V2ACMedium // AC:L
-  V2ACHigh // AC:H
-
-  V2AuMultiple // Au:M
-  V2AuSingle // Au:S
-  V2AuNone // Au:N
-
-  V2CNone // C:N
-  V2CPartial // C:P
-  V2CComplete // C:C
-
-  V2INone // I:N
-  V2IPartial // I:P
-  V2IComplete // I:C
-
-  V2ANone // A:N
-  V2APartial // A:P
-  V2AComplete // A:C
-
-  V2ENotDefined // E:ND
-  V2EUnproven // E:U
-  V2EProofOfConcept // E:POC
-  V2EFunctional // E:F
-  V2EHigh // E:H
-
-  V2RLOfficialFix // RL:OF
-  V2RLTemporaryFix // RL:TF
-  V2RLWorkaround // RL:W
-  V2RLUnavailable // RL:U
-  V2RLNotDefined // RL:ND
-
-  V2RCUnconfirmed // RC:UC
-  V2RCUncorroborated // RC:UR
-  V2RCConfirmed // RC:C
-  V2RCNotDefined // RC:ND
-
-  V2CDPNone // CDP:N
-  V2CDPLow // CDP:L
-  V2CDPLowMedium // CDP:LM
-  V2CDPMediumHigh // CDP:MH
-  V2CDPHigh // CDP:H
-  V2CDPNotDefined // CDP:ND
-
-  V2TDNone // TD:N
-  V2TDLow // TD:L
-  V2TDMedium // TD:M
-  V2TDHigh // TD:H
-  V2TDNotDefined // TD:ND
-
-  V2CRLow // CR:L
-  V2CRMedium // CR:M
-  V2CRHigh // CR:H
-  V2CRNotDefined // CR:ND
-
-  V2IRLow // IR:L
-  V2IRMedium // IR:M
-  V2IRHigh // IR:H
-  V2IRNotDefined // IR:ND
-
-  V2ARLow // AR:L
-  V2ARMedium // AR:M
-  V2ARHigh // AR:H
-  V2ARNotDefined // AR:ND
+  v2AVNetwork v2Metric = iota // AV:N
+  v2AVAdjacentNetwork // AV:A
+  v2AVLocal // AV:L
+
+  v2ACLow // AC:L
+  v2ACMedium // AC:L
+  v2ACHigh // AC:H
+
+  v2AuMultiple // Au:M
+  v2AuSingle // Au:S
+  v2AuNone // Au:N
+
+  v2CNone // C:N
+  v2CPartial // C:P
+  v2CComplete // C:C
+
+  v2INone // I:N
+  v2IPartial // I:P
+  v2IComplete // I:C
+
+  v2ANone // A:N
+  v2APartial // A:P
+  v2AComplete // A:C
+
+  v2ENotDefined // E:ND
+  v2EUnproven // E:U
+  v2EProofOfConcept // E:POC
+  v2EFunctional // E:F
+  v2EHigh // E:H
+
+  v2RLOfficialFix // RL:OF
+  v2RLTemporaryFix // RL:TF
+  v2RLWorkaround // RL:W
+  v2RLUnavailable // RL:U
+  v2RLNotDefined // RL:ND
+
+  v2RCUnconfirmed // RC:UC
+  v2RCUncorroborated // RC:UR
+  v2RCConfirmed // RC:C
+  v2RCNotDefined // RC:ND
+
+  v2CDPNone // CDP:N
+  v2CDPLow // CDP:L
+  v2CDPLowMedium // CDP:LM
+  v2CDPMediumHigh // CDP:MH
+  v2CDPHigh // CDP:H
+  v2CDPNotDefined // CDP:ND
+
+  v2TDNone // TD:N
+  v2TDLow // TD:L
+  v2TDMedium // TD:M
+  v2TDHigh // TD:H
+  v2TDNotDefined // TD:ND
+
+  v2CRLow // CR:L
+  v2CRMedium // CR:M
+  v2CRHigh // CR:H
+  v2CRNotDefined // CR:ND
+
+  v2IRLow // IR:L
+  v2IRMedium // IR:M
+  v2IRHigh // IR:H
+  v2IRNotDefined // IR:ND
+
+  v2ARLow // AR:L
+  v2ARMedium // AR:M
+  v2ARHigh // AR:H
+  v2ARNotDefined // AR:ND
+
+  v2InvalidMetric // invalid
 )
 
 // map of metrics to metric keys
-var v2MetricKeyLut = map[V2Metric]V2MetricKey {
-  V2AVNetwork: V2AccessVector,
-  V2AVAdjacentNetwork: V2AccessVector,
-  V2AVLocal: V2AccessVector,
-
-  V2ACLow: V2AccessComplexity,
-  V2ACMedium: V2AccessComplexity,
-  V2ACHigh: V2AccessComplexity,
-
-  V2AuMultiple: V2Authentication,
-  V2AuSingle: V2Authentication,
-  V2AuNone: V2Authentication,
-
-  V2CNone: V2ConfidentialityImpact,
-  V2CPartial: V2ConfidentialityImpact,
-  V2CComplete: V2ConfidentialityImpact,
-
-  V2INone: V2IntegrityImpact,
-  V2IPartial: V2IntegrityImpact,
-  V2IComplete: V2IntegrityImpact,
-
-  V2ANone: V2AvailabilityImpact,
-  V2APartial: V2AvailabilityImpact,
-  V2AComplete: V2AvailabilityImpact,
-
-  V2ENotDefined: V2Exploitability,
-  V2EUnproven: V2Exploitability,
-  V2EProofOfConcept: V2Exploitability,
-  V2EFunctional: V2Exploitability,
-  V2EHigh: V2Exploitability,
-
-  V2RLOfficialFix: V2RemediationLevel,
-  V2RLTemporaryFix: V2RemediationLevel,
-  V2RLWorkaround: V2RemediationLevel,
-  V2RLUnavailable: V2RemediationLevel,
-  V2RLNotDefined: V2RemediationLevel,
-
-  V2RCUnconfirmed: V2ReportConfidence,
-  V2RCUncorroborated: V2ReportConfidence,
-  V2RCConfirmed: V2ReportConfidence,
-  V2RCNotDefined: V2ReportConfidence,
-
-  V2CDPNone: V2CollateralDamagePotential,
-  V2CDPLow: V2CollateralDamagePotential,
-  V2CDPLowMedium: V2CollateralDamagePotential,
-  V2CDPMediumHigh: V2CollateralDamagePotential,
-  V2CDPHigh: V2CollateralDamagePotential,
-  V2CDPNotDefined: V2CollateralDamagePotential,
-
-  V2TDNone: V2TargetDistribution,
-  V2TDLow: V2TargetDistribution,
-  V2TDMedium: V2TargetDistribution,
-  V2TDHigh: V2TargetDistribution,
-  V2TDNotDefined: V2TargetDistribution,
-
-  V2CRLow: V2ConfidentialityRequirement,
-  V2CRMedium: V2ConfidentialityRequirement,
-  V2CRHigh: V2ConfidentialityRequirement,
-  V2CRNotDefined: V2ConfidentialityRequirement,
-
-  V2IRLow: V2IntegrityRequirement,
-  V2IRMedium: V2IntegrityRequirement,
-  V2IRHigh: V2IntegrityRequirement,
-  V2IRNotDefined: V2IntegrityRequirement,
-
-  V2ARLow: V2AvailabilityRequirement,
-  V2ARMedium: V2AvailabilityRequirement,
-  V2ARHigh: V2AvailabilityRequirement,
-  V2ARNotDefined: V2AvailabilityRequirement,
+var v2MetricKeyLut = map[v2Metric]v2MetricKey {
+  v2AVNetwork: v2AccessVector,
+  v2AVAdjacentNetwork: v2AccessVector,
+  v2AVLocal: v2AccessVector,
+
+  v2ACLow: v2AccessComplexity,
+  v2ACMedium: v2AccessComplexity,
+  v2ACHigh: v2AccessComplexity,
+
+  v2AuMultiple: v2Authentication,
+  v2AuSingle: v2Authentication,
+  v2AuNone: v2Authentication,
+
+  v2CNone: v2ConfidentialityImpact,
+  v2CPartial: v2ConfidentialityImpact,
+  v2CComplete: v2ConfidentialityImpact,
+
+  v2INone: v2IntegrityImpact,
+  v2IPartial: v2IntegrityImpact,
+  v2IComplete: v2IntegrityImpact,
+
+  v2ANone: v2AvailabilityImpact,
+  v2APartial: v2AvailabilityImpact,
+  v2AComplete: v2AvailabilityImpact,
+
+  v2ENotDefined: v2Exploitability,
+  v2EUnproven: v2Exploitability,
+  v2EProofOfConcept: v2Exploitability,
+  v2EFunctional: v2Exploitability,
+  v2EHigh: v2Exploitability,
+
+  v2RLOfficialFix: v2RemediationLevel,
+  v2RLTemporaryFix: v2RemediationLevel,
+  v2RLWorkaround: v2RemediationLevel,
+  v2RLUnavailable: v2RemediationLevel,
+  v2RLNotDefined: v2RemediationLevel,
+
+  v2RCUnconfirmed: v2ReportConfidence,
+  v2RCUncorroborated: v2ReportConfidence,
+  v2RCConfirmed: v2ReportConfidence,
+  v2RCNotDefined: v2ReportConfidence,
+
+  v2CDPNone: v2CollateralDamagePotential,
+  v2CDPLow: v2CollateralDamagePotential,
+  v2CDPLowMedium: v2CollateralDamagePotential,
+  v2CDPMediumHigh: v2CollateralDamagePotential,
+  v2CDPHigh: v2CollateralDamagePotential,
+  v2CDPNotDefined: v2CollateralDamagePotential,
+
+  v2TDNone: v2TargetDistribution,
+  v2TDLow: v2TargetDistribution,
+  v2TDMedium: v2TargetDistribution,
+  v2TDHigh: v2TargetDistribution,
+  v2TDNotDefined: v2TargetDistribution,
+
+  v2CRLow: v2ConfidentialityRequirement,
+  v2CRMedium: v2ConfidentialityRequirement,
+  v2CRHigh: v2ConfidentialityRequirement,
+  v2CRNotDefined: v2ConfidentialityRequirement,
+
+  v2IRLow: v2IntegrityRequirement,
+  v2IRMedium: v2IntegrityRequirement,
+  v2IRHigh: v2IntegrityRequirement,
+  v2IRNotDefined: v2IntegrityRequirement,
+
+  v2ARLow: v2AvailabilityRequirement,
+  v2ARMedium: v2AvailabilityRequirement,
+  v2ARHigh: v2AvailabilityRequirement,
+  v2ARNotDefined: v2AvailabilityRequirement,
 }
 
 // map of metric strings to metrics
-var v2MetricStrLut = map[string]V2Metric {
-  "AV:N": V2AVNetwork,
-  "AV:A": V2AVAdjacentNetwork,
-  "AV:L": V2AVLocal,
-
-  "AC:L": V2ACLow,
-  "AC:M": V2ACMedium,
-  "AC:H": V2ACHigh,
-
-  "Au:M": V2AuMultiple,
-  "Au:S": V2AuSingle,
-  "Au:N": V2AuNone,
-
-  "C:N": V2CNone,
-  "C:P": V2CPartial,
-  "C:C": V2CComplete,
-
-  "I:N": V2INone,
-  "I:P": V2IPartial,
-  "I:C": V2IComplete,
-
-  "A:N": V2ANone,
-  "A:P": V2APartial,
-  "A:C": V2AComplete,
-
-  "E:ND": V2ENotDefined,
-  "E:U": V2EUnproven,
-  "E:POC": V2EProofOfConcept,
-  "E:F": V2EFunctional,
-  "E:H": V2EHigh,
-
-  "RL:OF": V2RLOfficialFix,
-  "RL:TF": V2RLTemporaryFix,
-  "RL:W": V2RLWorkaround,
-  "RL:U": V2RLUnavailable,
-  "RL:ND": V2RLNotDefined,
-
-  "RC:UC": V2RCUnconfirmed,
-  "RC:UR": V2RCUncorroborated,
-  "RC:C": V2RCConfirmed,
-  "RC:ND": V2RCNotDefined,
-
-  "CDP:N": V2CDPNone,
-  "CDP:L": V2CDPLow,
-  "CDP:LM": V2CDPLowMedium,
-  "CDP:MH": V2CDPMediumHigh,
-  "CDP:H": V2CDPHigh,
-  "CDP:ND": V2CDPNotDefined,
-
-  "TD:N": V2TDNone,
-  "TD:L": V2TDLow,
-  "TD:M": V2TDMedium,
-  "TD:H": V2TDHigh,
-  "TD:ND": V2TDNotDefined,
-
-  "CR:L": V2CRLow,
-  "CR:M": V2CRMedium,
-  "CR:H": V2CRHigh,
-  "CR:ND": V2CRNotDefined,
-
-  "IR:L": V2IRLow,
-  "IR:M": V2IRMedium,
-  "IR:H": V2IRHigh,
-  "IR:ND": V2IRNotDefined,
-
-  "AR:L": V2ARLow,
-  "AR:M": V2ARMedium,
-  "AR:H": V2ARHigh,
-  "AR:ND": V2ARNotDefined,
+var v2MetricStrLut = map[string]v2Metric {
+  "AV:N": v2AVNetwork,
+  "AV:A": v2AVAdjacentNetwork,
+  "AV:L": v2AVLocal,
+
+  "AC:L": v2ACLow,
+  "AC:M": v2ACMedium,
+  "AC:H": v2ACHigh,
+
+  "Au:M": v2AuMultiple,
+  "Au:S": v2AuSingle,
+  "Au:N": v2AuNone,
+
+  "C:N": v2CNone,
+  "C:P": v2CPartial,
+  "C:C": v2CComplete,
+
+  "I:N": v2INone,
+  "I:P": v2IPartial,
+  "I:C": v2IComplete,
+
+  "A:N": v2ANone,
+  "A:P": v2APartial,
+  "A:C": v2AComplete,
+
+  "E:ND": v2ENotDefined,
+  "E:U": v2EUnproven,
+  "E:POC": v2EProofOfConcept,
+  "E:F": v2EFunctional,
+  "E:H": v2EHigh,
+
+  "RL:OF": v2RLOfficialFix,
+  "RL:TF": v2RLTemporaryFix,
+  "RL:W": v2RLWorkaround,
+  "RL:U": v2RLUnavailable,
+  "RL:ND": v2RLNotDefined,
+
+  "RC:UC": v2RCUnconfirmed,
+  "RC:UR": v2RCUncorroborated,
+  "RC:C": v2RCConfirmed,
+  "RC:ND": v2RCNotDefined,
+
+  "CDP:N": v2CDPNone,
+  "CDP:L": v2CDPLow,
+  "CDP:LM": v2CDPLowMedium,
+  "CDP:MH": v2CDPMediumHigh,
+  "CDP:H": v2CDPHigh,
+  "CDP:ND": v2CDPNotDefined,
+
+  "TD:N": v2TDNone,
+  "TD:L": v2TDLow,
+  "TD:M": v2TDMedium,
+  "TD:H": v2TDHigh,
+  "TD:ND": v2TDNotDefined,
+
+  "CR:L": v2CRLow,
+  "CR:M": v2CRMedium,
+  "CR:H": v2CRHigh,
+  "CR:ND": v2CRNotDefined,
+
+  "IR:L": v2IRLow,
+  "IR:M": v2IRMedium,
+  "IR:H": v2IRHigh,
+  "IR:ND": v2IRNotDefined,
+
+  "AR:L": v2ARLow,
+  "AR:M": v2ARMedium,
+  "AR:H": v2ARHigh,
+  "AR:ND": v2ARNotDefined,
 }
 
 // Convert string to CVSS 2.0 metric.
-func GetV2MetricFromString(s string) (V2Metric, error) {
+func getV2MetricFromString(s string) (v2Metric, error) {
   // get metric
   m, ok := v2MetricStrLut[s]
   if !ok {
-    return V2AVNetwork, fmt.Errorf("invalid metric: %s", s)
+    return v2InvalidMetric, fmt.Errorf("invalid metric: %s", s)
   }
 
   // return success
   return m, nil
 }
 
+// Get CVSS 2.0 metric key.
+func (m v2Metric) Key() MetricKey {
+  k, _ := v2MetricKeyLut[m]
+  return k
+}
+
 // CVSS 2.0 vector.
-type v2Vector []V2Metric
+type v2Vector []v2Metric
 
 // Convert vector to string
 func (v v2Vector) String() string {
   // convert to slice of metrics
-  metrics := []V2Metric(v)
+  metrics := []v2Metric(v)
 
   // build vector
   r := make([]string, len(metrics))
@@ -362,16 +372,27 @@ func (v v2Vector) String() string {
 func (v2Vector) Version() Version {
   return V20
 }
+// Return metrics in this vector.
+func (v v2Vector) Metrics() []Metric {
+  // build result
+  r := make([]Metric, len(v))
+  for i, m := range(v) {
+    r[i] = m
+  }
+
+  // return result
+  return r
+}
 
 // create CVSS 2.0 vector from string
-func NewV2VectorFromString(s string) (Vector, error) {
+func newV2Vector(s string) (Vector, error) {
   strs := strings.Split(s, "/")
-  r := make([]V2Metric, len(strs))
+  r := make([]v2Metric, len(strs))
 
   // walk metric strings
   for i, ms := range(strs) {
     // convert string to vector
-    m, err := GetV2MetricFromString(ms)
+    m, err := getV2MetricFromString(ms)
     if err != nil {
       return nil, err
     }
@@ -385,423 +406,432 @@ func NewV2VectorFromString(s string) (Vector, error) {
 }
 
 // CVSS v3 metric key
-type V3MetricKey byte
+type v3MetricKey byte
 
 const (
-  V3AttackVector V3MetricKey = iota // AV
-  V3AttackComplexity // AC
-  V3PrivilegesRequired // PR
-  V3UserInteraction // UI
-  V3Scope // S
-  V3Confidentiality // C
-  V3Integrity // I
-  V3Availability // A
-  V3ExploitCodeMaturity // E
-  V3RemediationLevel // RL
-  V3ReportConfidence // RC
-  V3ConfidentialityRequirement // CR
-  V3IntegrityRequirement // IR
-  V3AvailabilityRequirement // AR
-  V3ModifiedAttackVector // MAV
-  V3ModifiedAttackComplexity // MAC
-  V3ModifiedPrivilegesRequired // MPR
-  V3ModifiedUserInteraction // MUI
-  V3ModifiedScope // MS
-  V3ModifiedConfidentiality // MC
-  V3ModifiedIntegrity // MI
-  V3ModifiedAvailability // MA
+  v3AttackVector v3MetricKey = iota // AV
+  v3AttackComplexity // AC
+  v3PrivilegesRequired // PR
+  v3UserInteraction // UI
+  v3Scope // S
+  v3Confidentiality // C
+  v3Integrity // I
+  v3Availability // A
+  v3ExploitCodeMaturity // E
+  v3RemediationLevel // RL
+  v3ReportConfidence // RC
+  v3ConfidentialityRequirement // CR
+  v3IntegrityRequirement // IR
+  v3AvailabilityRequirement // AR
+  v3ModifiedAttackVector // MAV
+  v3ModifiedAttackComplexity // MAC
+  v3ModifiedPrivilegesRequired // MPR
+  v3ModifiedUserInteraction // MUI
+  v3ModifiedScope // MS
+  v3ModifiedConfidentiality // MC
+  v3ModifiedIntegrity // MI
+  v3ModifiedAvailability // MA
+
+  v3InvalidMetricKey // invalid
 )
 
-// CVSS V3 metric key info lut
-var v3MetricKeys = map[V3MetricKey]struct {
+// CVSS v3 metric key info lut
+var v3MetricKeys = map[v3MetricKey]struct {
   Name string
-  Category MetricCategory
+  Category Category
 } {
-  V3AttackVector: { "Attack Vector", Base },
-  V3AttackComplexity: { "Attack Complexity", Base },
-  V3PrivilegesRequired: { "Privileges Required", Base },
-  V3UserInteraction: { "User Interaction", Base },
-  V3Scope: { "Scope", Base },
-  V3Confidentiality: { "Confidentiality", Base },
-  V3Integrity: { "Integrity", Base },
-  V3Availability: { "Availability", Base },
-  V3ExploitCodeMaturity: { "Exploit Code Maturity", Temporal },
-  V3RemediationLevel: { "Remediation Level", Temporal },
-  V3ReportConfidence: { "Report Confidence", Temporal },
-  V3ConfidentialityRequirement: { "Confidentiality Requirement", Environmental },
-  V3IntegrityRequirement: { "Integrity Requirement", Environmental },
-  V3AvailabilityRequirement: { "Availability Requirement", Environmental },
-  V3ModifiedAttackVector: { "Modified Attack Vector", Environmental },
-  V3ModifiedAttackComplexity: { "Modified Attack Complexity", Environmental },
-  V3ModifiedPrivilegesRequired: { "Modified Privileges Required", Environmental },
-  V3ModifiedUserInteraction: { "Modified User Interaction", Environmental },
-  V3ModifiedScope: { "Modified Scope", Environmental },
-  V3ModifiedConfidentiality: { "Modified Confidentiality", Environmental },
-  V3ModifiedIntegrity: { "Modified Integrity", Environmental },
-  V3ModifiedAvailability: { "Modified Availability", Environmental },
+  v3AttackVector: { "Attack Vector", Base },
+  v3AttackComplexity: { "Attack Complexity", Base },
+  v3PrivilegesRequired: { "Privileges Required", Base },
+  v3UserInteraction: { "User Interaction", Base },
+  v3Scope: { "Scope", Base },
+  v3Confidentiality: { "Confidentiality", Base },
+  v3Integrity: { "Integrity", Base },
+  v3Availability: { "Availability", Base },
+  v3ExploitCodeMaturity: { "Exploit Code Maturity", Temporal },
+  v3RemediationLevel: { "Remediation Level", Temporal },
+  v3ReportConfidence: { "Report Confidence", Temporal },
+  v3ConfidentialityRequirement: { "Confidentiality Requirement", Environmental },
+  v3IntegrityRequirement: { "Integrity Requirement", Environmental },
+  v3AvailabilityRequirement: { "Availability Requirement", Environmental },
+  v3ModifiedAttackVector: { "Modified Attack Vector", Environmental },
+  v3ModifiedAttackComplexity: { "Modified Attack Complexity", Environmental },
+  v3ModifiedPrivilegesRequired: { "Modified Privileges Required", Environmental },
+  v3ModifiedUserInteraction: { "Modified User Interaction", Environmental },
+  v3ModifiedScope: { "Modified Scope", Environmental },
+  v3ModifiedConfidentiality: { "Modified Confidentiality", Environmental },
+  v3ModifiedIntegrity: { "Modified Integrity", Environmental },
+  v3ModifiedAvailability: { "Modified Availability", Environmental },
 }
 
 // metric key IDs lut
-var v3MetricKeyIds = map[string]V3MetricKey {
-  "AV": V3AttackVector,
-  "AC": V3AttackComplexity,
-  "PR": V3PrivilegesRequired,
-  "UI": V3UserInteraction,
-  "S": V3Scope,
-  "C": V3Confidentiality,
-  "I": V3Integrity,
-  "A": V3Availability,
-  "E": V3ExploitCodeMaturity,
-  "RL": V3RemediationLevel,
-  "RC": V3ReportConfidence,
-  "CR": V3ConfidentialityRequirement,
-  "IR": V3IntegrityRequirement,
-  "AR": V3AvailabilityRequirement,
-  "MAV": V3ModifiedAttackVector,
-  "MAC": V3ModifiedAttackComplexity,
-  "MPR": V3ModifiedPrivilegesRequired,
-  "MUI": V3ModifiedUserInteraction,
-  "MS": V3ModifiedScope,
-  "MC": V3ModifiedConfidentiality,
-  "MI": V3ModifiedIntegrity,
-  "MA": V3ModifiedAvailability,
+var v3MetricKeyIds = map[string]v3MetricKey {
+  "AV": v3AttackVector,
+  "AC": v3AttackComplexity,
+  "PR": v3PrivilegesRequired,
+  "UI": v3UserInteraction,
+  "S": v3Scope,
+  "C": v3Confidentiality,
+  "I": v3Integrity,
+  "A": v3Availability,
+  "E": v3ExploitCodeMaturity,
+  "RL": v3RemediationLevel,
+  "RC": v3ReportConfidence,
+  "CR": v3ConfidentialityRequirement,
+  "IR": v3IntegrityRequirement,
+  "AR": v3AvailabilityRequirement,
+  "MAV": v3ModifiedAttackVector,
+  "MAC": v3ModifiedAttackComplexity,
+  "MPR": v3ModifiedPrivilegesRequired,
+  "MUI": v3ModifiedUserInteraction,
+  "MS": v3ModifiedScope,
+  "MC": v3ModifiedConfidentiality,
+  "MI": v3ModifiedIntegrity,
+  "MA": v3ModifiedAvailability,
 }
 
 // Get metric key from string.
-func GetV3MetricKeyFromString(s string) (V3MetricKey, error) {
+func getV3MetricKeyFromString(s string) (v3MetricKey, error) {
   k, ok := v3MetricKeyIds[s]
   if ok {
     return k, nil
   } else {
-    return V3AttackVector, fmt.Errorf("unknown metric key: %s", s)
+    return v3InvalidMetricKey, fmt.Errorf("invalid metric key: %s", s)
   }
 }
 
 // Get metric key name.
-func (k V3MetricKey) Name() string {
+func (k v3MetricKey) Name() string {
   return v3MetricKeys[k].Name
 }
 
 // Get metric key category.
-func (k V3MetricKey) Category() MetricCategory {
+func (k v3MetricKey) Category() Category {
   return v3MetricKeys[k].Category
 }
 
 // metric value
-type V3Metric byte
+type v3Metric byte
 
 const (
-  V3AVNetwork V3Metric = iota // AV:N
-  V3AVAdjacentNetwork // AV:A
-  V3AVLocal // AV:L
-  V3AVPhysical // AV:P
-
-  V3ACLow // AC:L
-  V3ACHigh // AC:H
-
-  V3PRNone // PR:N
-  V3PRLow // PR:L
-  V3PRHigh // PR:H
-
-  V3UINone // UI:N
-  V3UIRequired // UI:R
-
-  V3SUnchanged // S:U
-  V3SChanged // S:C
-
-  V3CHigh // C:H
-  V3CLow // C:L
-  V3CNone // C:N
-
-  V3IHigh // I:H
-  V3ILow // I:L
-  V3INone // I:N
-
-  V3AHigh // A:H
-  V3ALow // A:L
-  V3ANone // A:N
-
-  V3ENotDefined // E:X
-  V3EHigh // E:H
-  V3EFunctional // E:F
-  V3EProofOfConcept // E:P
-  V3EUnproven // E:U
-
-  V3RLNotDefined // RL:X
-  V3RLUnavailable // RL:U
-  V3RLWorkaround // RL:W
-  V3RLTemporaryFix // RL:T
-  V3RLOfficialFix // RL:O
-
-  V3RCNotDefined // RC:X
-  V3RCConfirmed // RC:C
-  V3RCReasonable // RC:R
-  V3RCUnknown // RC:U
-
-  V3CRNotDefined // CR:X
-  V3CRHigh // CR:H
-  V3CRMedium // CR:M
-  V3CRLow // CR:L
-
-  V3IRNotDefined // IR:X
-  V3IRHigh // IR:H
-  V3IRMedium // IR:M
-  V3IRLow // IR:L
-
-  V3ARNotDefined // AR:X
-  V3ARHigh // AR:H
-  V3ARMedium // AR:M
-  V3ARLow // AR:L
-
-  V3MAVNotDefined // MAV:X
-  V3MAVNetwork // MAV:N
-  V3MAVAdjacentNetwork // MAV:A
-  V3MAVLocal // MAV:L
-  V3MAVPhysical // MAV:P
-
-  V3MACNotDefined // MAC:X
-  V3MACLow // MAC:L
-  V3MACHigh // MAC:H
-
-  V3MMRNotDefined // MPR:X
-  V3MPRLow // MPR:L
-  V3MPRHigh // MPR:H
-
-  V3MUINotDefined // MUI:X
-  V3MUINone // MUI:N
-  V3MUIRequired // MUI:R
-
-  V3MSNotDefined // MMS:X
-  V3MSUnchanged // MMS:U
-  V3MSChanged // MMS:C
-
-  V3MCNotDefined // MC:X
-  V3MCHigh // MC:H
-  V3MCLow // MC:L
-  V3MCNone // MC:N
-
-  V3MINotDefined // MI:X
-  V3MIHigh // MI:H
-  V3MILow // MI:L
-  V3MINone // MI:N
-
-  V3MANotDefined // MA:X
-  V3MAHigh // MA:H
-  V3MALow // MA:L
-  V3MANone // MA:N
-  V3UnknownMetric // unknown
+  v3AVNetwork v3Metric = iota // AV:N
+  v3AVAdjacentNetwork // AV:A
+  v3AVLocal // AV:L
+  v3AVPhysical // AV:P
+
+  v3ACLow // AC:L
+  v3ACHigh // AC:H
+
+  v3PRNone // PR:N
+  v3PRLow // PR:L
+  v3PRHigh // PR:H
+
+  v3UINone // UI:N
+  v3UIRequired // UI:R
+
+  v3SUnchanged // S:U
+  v3SChanged // S:C
+
+  v3CHigh // C:H
+  v3CLow // C:L
+  v3CNone // C:N
+
+  v3IHigh // I:H
+  v3ILow // I:L
+  v3INone // I:N
+
+  v3AHigh // A:H
+  v3ALow // A:L
+  v3ANone // A:N
+
+  v3ENotDefined // E:X
+  v3EHigh // E:H
+  v3EFunctional // E:F
+  v3EProofOfConcept // E:P
+  v3EUnproven // E:U
+
+  v3RLNotDefined // RL:X
+  v3RLUnavailable // RL:U
+  v3RLWorkaround // RL:W
+  v3RLTemporaryFix // RL:T
+  v3RLOfficialFix // RL:O
+
+  v3RCNotDefined // RC:X
+  v3RCConfirmed // RC:C
+  v3RCReasonable // RC:R
+  v3RCUnknown // RC:U
+
+  v3CRNotDefined // CR:X
+  v3CRHigh // CR:H
+  v3CRMedium // CR:M
+  v3CRLow // CR:L
+
+  v3IRNotDefined // IR:X
+  v3IRHigh // IR:H
+  v3IRMedium // IR:M
+  v3IRLow // IR:L
+
+  v3ARNotDefined // AR:X
+  v3ARHigh // AR:H
+  v3ARMedium // AR:M
+  v3ARLow // AR:L
+
+  v3MAVNotDefined // MAV:X
+  v3MAVNetwork // MAV:N
+  v3MAVAdjacentNetwork // MAV:A
+  v3MAVLocal // MAV:L
+  v3MAVPhysical // MAV:P
+
+  v3MACNotDefined // MAC:X
+  v3MACLow // MAC:L
+  v3MACHigh // MAC:H
+
+  v3MMRNotDefined // MPR:X
+  v3MPRLow // MPR:L
+  v3MPRHigh // MPR:H
+
+  v3MUINotDefined // MUI:X
+  v3MUINone // MUI:N
+  v3MUIRequired // MUI:R
+
+  v3MSNotDefined // MMS:X
+  v3MSUnchanged // MMS:U
+  v3MSChanged // MMS:C
+
+  v3MCNotDefined // MC:X
+  v3MCHigh // MC:H
+  v3MCLow // MC:L
+  v3MCNone // MC:N
+
+  v3MINotDefined // MI:X
+  v3MIHigh // MI:H
+  v3MILow // MI:L
+  v3MINone // MI:N
+
+  v3MANotDefined // MA:X
+  v3MAHigh // MA:H
+  v3MALow // MA:L
+  v3MANone // MA:N
+
+  v3InvalidMetric // invalid
 )
 
 // map of metrics to metric keys
-var v3MetricKeyLut = map[V3Metric]V3MetricKey {
-  V3AVNetwork: V3AttackVector, // AV:N
-  V3AVAdjacentNetwork: V3AttackVector, // AV:A
-  V3AVLocal: V3AttackVector, // AV:L
-  V3AVPhysical: V3AttackVector, // AV:P
-
-  V3ACLow: V3AttackComplexity, // AC:L
-  V3ACHigh: V3AttackComplexity, // AC:H
-
-  V3PRNone: V3PrivilegesRequired, // PR:N
-  V3PRLow: V3PrivilegesRequired, // PR:L
-  V3PRHigh: V3PrivilegesRequired, // PR:H
-
-  V3UINone: V3UserInteraction, // UI:N
-  V3UIRequired: V3UserInteraction, // UI:R
-
-  V3SUnchanged: V3Scope, // S:U
-  V3SChanged: V3Scope, // S:C
-
-  V3CHigh: V3Confidentiality, // C:H
-  V3CLow: V3Confidentiality, // C:L
-  V3CNone: V3Confidentiality, // C:N
-
-  V3IHigh: V3Integrity, // I:H
-  V3ILow: V3Integrity, // I:L
-  V3INone: V3Integrity, // I:N
-
-  V3AHigh: V3Availability, // A:H
-  V3ALow: V3Availability, // A:L
-  V3ANone: V3Availability, // A:N
-
-  V3ENotDefined: V3ExploitCodeMaturity, // E:X
-  V3EHigh: V3ExploitCodeMaturity, // E:H
-  V3EFunctional: V3ExploitCodeMaturity, // E:F
-  V3EProofOfConcept: V3ExploitCodeMaturity, // E:P
-  V3EUnproven: V3ExploitCodeMaturity, // E:U
-
-  V3RLNotDefined: V3RemediationLevel, // RL:X
-  V3RLUnavailable: V3RemediationLevel, // RL:U
-  V3RLWorkaround: V3RemediationLevel, // RL:W
-  V3RLTemporaryFix: V3RemediationLevel, // RL:T
-  V3RLOfficialFix: V3RemediationLevel, // RL:O
-
-  V3RCNotDefined: V3ReportConfidence, // RC:X
-  V3RCConfirmed: V3ReportConfidence, // RC:C
-  V3RCReasonable: V3ReportConfidence, // RC:R
-  V3RCUnknown: V3ReportConfidence, // RC:U
-
-  V3CRNotDefined: V3ConfidentialityRequirement, // CR:X
-  V3CRHigh: V3ConfidentialityRequirement, // CR:H
-  V3CRMedium: V3ConfidentialityRequirement, // CR:M
-  V3CRLow: V3ConfidentialityRequirement, // CR:L
-
-  V3IRNotDefined: V3IntegrityRequirement, // IR:X
-  V3IRHigh: V3IntegrityRequirement, // IR:H
-  V3IRMedium: V3IntegrityRequirement, // IR:M
-  V3IRLow: V3IntegrityRequirement, // IR:L
-
-  V3ARNotDefined: V3AvailabilityRequirement, // AR:X
-  V3ARHigh: V3AvailabilityRequirement, // AR:H
-  V3ARMedium: V3AvailabilityRequirement, // AR:M
-  V3ARLow: V3AvailabilityRequirement, // AR:L
-
-  V3MAVNotDefined: V3ModifiedAttackVector, // MAV:X
-  V3MAVNetwork: V3ModifiedAttackVector, // MAV:N
-  V3MAVAdjacentNetwork: V3ModifiedAttackVector, // MAV:A
-  V3MAVLocal: V3ModifiedAttackVector, // MAV:L
-  V3MAVPhysical: V3ModifiedAttackVector, // MAV:P
-
-  V3MACNotDefined: V3ModifiedAttackComplexity, // MAC:X
-  V3MACLow: V3ModifiedAttackComplexity, // MAC:L
-  V3MACHigh: V3ModifiedAttackComplexity, // MAC:H
-
-  V3MMRNotDefined: V3ModifiedPrivilegesRequired, // MPR:X
-  V3MPRLow: V3ModifiedPrivilegesRequired, // MPR:L
-  V3MPRHigh: V3ModifiedPrivilegesRequired, // MPR:H
-
-  V3MUINotDefined: V3ModifiedUserInteraction, // MUI:X
-  V3MUINone: V3ModifiedUserInteraction, // MUI:N
-  V3MUIRequired: V3ModifiedUserInteraction, // MUI:R
-
-  V3MSNotDefined: V3ModifiedScope, // MMS:X
-  V3MSUnchanged: V3ModifiedConfidentiality, // MMS:U
-  V3MSChanged: V3ModifiedIntegrity, // MMS:C
-
-  V3MCNotDefined: V3ModifiedConfidentiality, // MC:X
-  V3MCHigh: V3ModifiedConfidentiality, // MC:H
-  V3MCLow: V3ModifiedConfidentiality, // MC:L
-  V3MCNone: V3ModifiedConfidentiality, // MC:N
-
-  V3MINotDefined: V3ModifiedIntegrity, // MI:X
-  V3MIHigh: V3ModifiedIntegrity, // MI:H
-  V3MILow: V3ModifiedIntegrity, // MI:L
-  V3MINone: V3ModifiedIntegrity, // MI:N
-
-  V3MANotDefined: V3ModifiedAvailability, // MA:X
-  V3MAHigh: V3ModifiedAvailability, // MA:H
-  V3MALow: V3ModifiedAvailability, // MA:L
-  V3MANone: V3ModifiedAvailability, // MA:N
+var v3MetricKeyLut = map[v3Metric]v3MetricKey {
+  v3AVNetwork: v3AttackVector, // AV:N
+  v3AVAdjacentNetwork: v3AttackVector, // AV:A
+  v3AVLocal: v3AttackVector, // AV:L
+  v3AVPhysical: v3AttackVector, // AV:P
+
+  v3ACLow: v3AttackComplexity, // AC:L
+  v3ACHigh: v3AttackComplexity, // AC:H
+
+  v3PRNone: v3PrivilegesRequired, // PR:N
+  v3PRLow: v3PrivilegesRequired, // PR:L
+  v3PRHigh: v3PrivilegesRequired, // PR:H
+
+  v3UINone: v3UserInteraction, // UI:N
+  v3UIRequired: v3UserInteraction, // UI:R
+
+  v3SUnchanged: v3Scope, // S:U
+  v3SChanged: v3Scope, // S:C
+
+  v3CHigh: v3Confidentiality, // C:H
+  v3CLow: v3Confidentiality, // C:L
+  v3CNone: v3Confidentiality, // C:N
+
+  v3IHigh: v3Integrity, // I:H
+  v3ILow: v3Integrity, // I:L
+  v3INone: v3Integrity, // I:N
+
+  v3AHigh: v3Availability, // A:H
+  v3ALow: v3Availability, // A:L
+  v3ANone: v3Availability, // A:N
+
+  v3ENotDefined: v3ExploitCodeMaturity, // E:X
+  v3EHigh: v3ExploitCodeMaturity, // E:H
+  v3EFunctional: v3ExploitCodeMaturity, // E:F
+  v3EProofOfConcept: v3ExploitCodeMaturity, // E:P
+  v3EUnproven: v3ExploitCodeMaturity, // E:U
+
+  v3RLNotDefined: v3RemediationLevel, // RL:X
+  v3RLUnavailable: v3RemediationLevel, // RL:U
+  v3RLWorkaround: v3RemediationLevel, // RL:W
+  v3RLTemporaryFix: v3RemediationLevel, // RL:T
+  v3RLOfficialFix: v3RemediationLevel, // RL:O
+
+  v3RCNotDefined: v3ReportConfidence, // RC:X
+  v3RCConfirmed: v3ReportConfidence, // RC:C
+  v3RCReasonable: v3ReportConfidence, // RC:R
+  v3RCUnknown: v3ReportConfidence, // RC:U
+
+  v3CRNotDefined: v3ConfidentialityRequirement, // CR:X
+  v3CRHigh: v3ConfidentialityRequirement, // CR:H
+  v3CRMedium: v3ConfidentialityRequirement, // CR:M
+  v3CRLow: v3ConfidentialityRequirement, // CR:L
+
+  v3IRNotDefined: v3IntegrityRequirement, // IR:X
+  v3IRHigh: v3IntegrityRequirement, // IR:H
+  v3IRMedium: v3IntegrityRequirement, // IR:M
+  v3IRLow: v3IntegrityRequirement, // IR:L
+
+  v3ARNotDefined: v3AvailabilityRequirement, // AR:X
+  v3ARHigh: v3AvailabilityRequirement, // AR:H
+  v3ARMedium: v3AvailabilityRequirement, // AR:M
+  v3ARLow: v3AvailabilityRequirement, // AR:L
+
+  v3MAVNotDefined: v3ModifiedAttackVector, // MAV:X
+  v3MAVNetwork: v3ModifiedAttackVector, // MAV:N
+  v3MAVAdjacentNetwork: v3ModifiedAttackVector, // MAV:A
+  v3MAVLocal: v3ModifiedAttackVector, // MAV:L
+  v3MAVPhysical: v3ModifiedAttackVector, // MAV:P
+
+  v3MACNotDefined: v3ModifiedAttackComplexity, // MAC:X
+  v3MACLow: v3ModifiedAttackComplexity, // MAC:L
+  v3MACHigh: v3ModifiedAttackComplexity, // MAC:H
+
+  v3MMRNotDefined: v3ModifiedPrivilegesRequired, // MPR:X
+  v3MPRLow: v3ModifiedPrivilegesRequired, // MPR:L
+  v3MPRHigh: v3ModifiedPrivilegesRequired, // MPR:H
+
+  v3MUINotDefined: v3ModifiedUserInteraction, // MUI:X
+  v3MUINone: v3ModifiedUserInteraction, // MUI:N
+  v3MUIRequired: v3ModifiedUserInteraction, // MUI:R
+
+  v3MSNotDefined: v3ModifiedScope, // MMS:X
+  v3MSUnchanged: v3ModifiedConfidentiality, // MMS:U
+  v3MSChanged: v3ModifiedIntegrity, // MMS:C
+
+  v3MCNotDefined: v3ModifiedConfidentiality, // MC:X
+  v3MCHigh: v3ModifiedConfidentiality, // MC:H
+  v3MCLow: v3ModifiedConfidentiality, // MC:L
+  v3MCNone: v3ModifiedConfidentiality, // MC:N
+
+  v3MINotDefined: v3ModifiedIntegrity, // MI:X
+  v3MIHigh: v3ModifiedIntegrity, // MI:H
+  v3MILow: v3ModifiedIntegrity, // MI:L
+  v3MINone: v3ModifiedIntegrity, // MI:N
+
+  v3MANotDefined: v3ModifiedAvailability, // MA:X
+  v3MAHigh: v3ModifiedAvailability, // MA:H
+  v3MALow: v3ModifiedAvailability, // MA:L
+  v3MANone: v3ModifiedAvailability, // MA:N
 }
 
 // map of metric strings to metrics
-var v3MetricStrLut = map[string]V3Metric {
-  "AV:N": V3AVNetwork,
-  "AV:A": V3AVAdjacentNetwork,
-  "AV:L": V3AVLocal,
-  "AV:P": V3AVPhysical,
-
-  "AC:L": V3ACLow,
-  "AC:H": V3ACHigh,
-
-  "PR:N": V3PRNone,
-  "PR:L": V3PRLow,
-  "PR:H": V3PRHigh,
-
-  "UI:N": V3UINone,
-  "UI:R": V3UIRequired,
-
-  "S:U": V3SUnchanged,
-  "S:C": V3SChanged,
-
-  "C:H": V3CHigh,
-  "C:L": V3CLow,
-  "C:N": V3CNone,
-
-  "I:H": V3IHigh,
-  "I:L": V3ILow,
-  "I:N": V3INone,
-
-  "A:H": V3AHigh,
-  "A:L": V3ALow,
-  "A:N": V3ANone,
-
-  "E:X": V3ENotDefined,
-  "E:H": V3EHigh,
-  "E:F": V3EFunctional,
-  "E:P": V3EProofOfConcept,
-  "E:U": V3EUnproven,
-
-  "RL:X": V3RLNotDefined,
-  "RL:U": V3RLUnavailable,
-  "RL:W": V3RLWorkaround,
-  "RL:T": V3RLTemporaryFix,
-  "RL:O": V3RLOfficialFix,
-
-  "RC:X": V3RCNotDefined,
-  "RC:C": V3RCConfirmed,
-  "RC:R": V3RCReasonable,
-  "RC:U": V3RCUnknown,
-
-  "CR:X": V3CRNotDefined,
-  "CR:H": V3CRHigh,
-  "CR:M": V3CRMedium,
-  "CR:L": V3CRLow,
-
-  "IR:X": V3IRNotDefined,
-  "IR:H": V3IRHigh,
-  "IR:M": V3IRMedium,
-  "IR:L": V3IRLow,
-
-  "AR:X": V3ARNotDefined,
-  "AR:H": V3ARHigh,
-  "AR:M": V3ARMedium,
-  "AR:L": V3ARLow,
-
-  "MAV:X": V3MAVNotDefined,
-  "MAV:N": V3MAVNetwork,
-  "MAV:A": V3MAVAdjacentNetwork,
-  "MAV:L": V3MAVLocal,
-  "MAV:P": V3MAVPhysical,
-
-  "MAC:X": V3MACNotDefined,
-  "MAC:L": V3MACLow,
-  "MAC:H": V3MACHigh,
-
-  "MPR:X": V3MMRNotDefined,
-  "MPR:L": V3MPRLow,
-  "MPR:H": V3MPRHigh,
-
-  "MUI:X": V3MUINotDefined,
-  "MUI:N": V3MUINone,
-  "MUI:R": V3MUIRequired,
-
-  "MMS:X": V3MSNotDefined,
-  "MMS:U": V3MSUnchanged,
-  "MMS:C": V3MSChanged,
-
-  "MC:X": V3MCNotDefined,
-  "MC:H": V3MCHigh,
-  "MC:L": V3MCLow,
-  "MC:N": V3MCNone,
-
-  "MI:X": V3MINotDefined,
-  "MI:H": V3MIHigh,
-  "MI:L": V3MILow,
-  "MI:N": V3MINone,
-
-  "MA:X": V3MANotDefined,
-  "MA:H": V3MAHigh,
-  "MA:L": V3MALow,
-  "MA:N": V3MANone,
+var v3MetricStrLut = map[string]v3Metric {
+  "AV:N": v3AVNetwork,
+  "AV:A": v3AVAdjacentNetwork,
+  "AV:L": v3AVLocal,
+  "AV:P": v3AVPhysical,
+
+  "AC:L": v3ACLow,
+  "AC:H": v3ACHigh,
+
+  "PR:N": v3PRNone,
+  "PR:L": v3PRLow,
+  "PR:H": v3PRHigh,
+
+  "UI:N": v3UINone,
+  "UI:R": v3UIRequired,
+
+  "S:U": v3SUnchanged,
+  "S:C": v3SChanged,
+
+  "C:H": v3CHigh,
+  "C:L": v3CLow,
+  "C:N": v3CNone,
+
+  "I:H": v3IHigh,
+  "I:L": v3ILow,
+  "I:N": v3INone,
+
+  "A:H": v3AHigh,
+  "A:L": v3ALow,
+  "A:N": v3ANone,
+
+  "E:X": v3ENotDefined,
+  "E:H": v3EHigh,
+  "E:F": v3EFunctional,
+  "E:P": v3EProofOfConcept,
+  "E:U": v3EUnproven,
+
+  "RL:X": v3RLNotDefined,
+  "RL:U": v3RLUnavailable,
+  "RL:W": v3RLWorkaround,
+  "RL:T": v3RLTemporaryFix,
+  "RL:O": v3RLOfficialFix,
+
+  "RC:X": v3RCNotDefined,
+  "RC:C": v3RCConfirmed,
+  "RC:R": v3RCReasonable,
+  "RC:U": v3RCUnknown,
+
+  "CR:X": v3CRNotDefined,
+  "CR:H": v3CRHigh,
+  "CR:M": v3CRMedium,
+  "CR:L": v3CRLow,
+
+  "IR:X": v3IRNotDefined,
+  "IR:H": v3IRHigh,
+  "IR:M": v3IRMedium,
+  "IR:L": v3IRLow,
+
+  "AR:X": v3ARNotDefined,
+  "AR:H": v3ARHigh,
+  "AR:M": v3ARMedium,
+  "AR:L": v3ARLow,
+
+  "MAV:X": v3MAVNotDefined,
+  "MAV:N": v3MAVNetwork,
+  "MAV:A": v3MAVAdjacentNetwork,
+  "MAV:L": v3MAVLocal,
+  "MAV:P": v3MAVPhysical,
+
+  "MAC:X": v3MACNotDefined,
+  "MAC:L": v3MACLow,
+  "MAC:H": v3MACHigh,
+
+  "MPR:X": v3MMRNotDefined,
+  "MPR:L": v3MPRLow,
+  "MPR:H": v3MPRHigh,
+
+  "MUI:X": v3MUINotDefined,
+  "MUI:N": v3MUINone,
+  "MUI:R": v3MUIRequired,
+
+  "MMS:X": v3MSNotDefined,
+  "MMS:U": v3MSUnchanged,
+  "MMS:C": v3MSChanged,
+
+  "MC:X": v3MCNotDefined,
+  "MC:H": v3MCHigh,
+  "MC:L": v3MCLow,
+  "MC:N": v3MCNone,
+
+  "MI:X": v3MINotDefined,
+  "MI:H": v3MIHigh,
+  "MI:L": v3MILow,
+  "MI:N": v3MINone,
+
+  "MA:X": v3MANotDefined,
+  "MA:H": v3MAHigh,
+  "MA:L": v3MALow,
+  "MA:N": v3MANone,
+}
+
+// Get CVSS 3.x metric key.
+func (m v3Metric) Key() MetricKey {
+  k, _ := v3MetricKeyLut[m]
+  return k
 }
 
 // Convert string to CVSS 3.1 metric.
-func GetV3MetricFromString(s string) (V3Metric, error) {
+func getV3Metric(s string) (v3Metric, error) {
   // get metric
   m, ok := v3MetricStrLut[s]
   if !ok {
-    return V3AVNetwork, fmt.Errorf("invalid metric: %s", s)
+    return v3InvalidMetric, fmt.Errorf("invalid metric: %s", s)
   }
 
   // return success
@@ -812,12 +842,12 @@ func GetV3MetricFromString(s string) (V3Metric, error) {
 var v30Prefix = "CVSS:3.0/"
 
 // CVSS 3.0 vector.
-type v30Vector []V3Metric
+type v30Vector []v3Metric
 
 // Convert vector to string
 func (v v30Vector) String() string {
   // convert to slice of metrics
-  metrics := []V3Metric(v)
+  metrics := []v3Metric(v)
 
   // build vector
   r := make([]string, len(metrics))
@@ -834,15 +864,27 @@ func (v30Vector) Version() Version {
   return V30
 }
 
+// Return metrics in this vector.
+func (v v30Vector) Metrics() []Metric {
+  // build result
+  r := make([]Metric, len(v))
+  for i, m := range(v) {
+    r[i] = m
+  }
+
+  // return result
+  return r
+}
+
 // create CVSS 3.0 vector from string
-func NewV30VectorFromString(s string) (Vector, error) {
+func newV30Vector(s string) (Vector, error) {
   strs := strings.Split(s, "/")
-  r := make([]V3Metric, len(strs))
+  r := make([]v3Metric, len(strs))
 
   // walk metric strings
   for i, ms := range(strs) {
-    // convert string to vector
-    m, err := GetV3MetricFromString(ms)
+    // convert metric string to metric
+    m, err := getV3Metric(ms)
     if err != nil {
       return nil, err
     }
@@ -859,12 +901,12 @@ func NewV30VectorFromString(s string) (Vector, error) {
 var v31Prefix = "CVSS:3.1/"
 
 // CVSS 3.1 vector.
-type v31Vector []V3Metric
+type v31Vector []v3Metric
 
 // Convert vector to string
 func (v v31Vector) String() string {
   // convert to slice of metrics
-  metrics := []V3Metric(v)
+  metrics := []v3Metric(v)
 
   // build vector
   r := make([]string, len(metrics))
@@ -881,15 +923,27 @@ func (v31Vector) Version() Version {
   return V31
 }
 
+// Return metrics in this vector.
+func (v v31Vector) Metrics() []Metric {
+  // build result
+  r := make([]Metric, len(v))
+  for i, m := range(v) {
+    r[i] = m
+  }
+
+  // return result
+  return r
+}
+
 // create CVSS 3.1 vector from string
-func NewV31VectorFromString(s string) (Vector, error) {
+func newV31Vector(s string) (Vector, error) {
   strs := strings.Split(s, "/")
-  r := make([]V3Metric, len(strs))
+  r := make([]v3Metric, len(strs))
 
   // walk metric strings
   for i, ms := range(strs) {
-    // convert string to vector
-    m, err := GetV3MetricFromString(ms)
+    // get metric from string
+    m, err := getV3Metric(ms)
     if err != nil {
       return nil, err
     }
@@ -902,25 +956,49 @@ func NewV31VectorFromString(s string) (Vector, error) {
   return v31Vector(r), nil
 }
 
-// CVSS vector
+// Metric key.
+type MetricKey interface {
+  // Get full name.
+  Name() string
+
+  // Get category.
+  Category() Category
+
+  // Return string representation.
+  String() string
+}
+
+// CVSS metric.
+type Metric interface {
+  // Get metric key.
+  Key() MetricKey
+
+  // Return string representation of metric.
+  String() string
+}
+
+// CVSS metric vector.
 type Vector interface {
   // Get CVSS version.
   Version() Version
 
   // Get CVSS vector string.
   String() string
+
+  // Return metrics in this vector.
+  Metrics() []Metric
 }
 
 // Create new CVSS vector from vector string.
 func NewVector(s string) (Vector, error) {
   if len(s) > len(v31Prefix) && s[:len(v31Prefix)] == v31Prefix {
     // create CVSS v2.0 vector.
-    return NewV31VectorFromString(s[len(v31Prefix):])
+    return newV31Vector(s[len(v31Prefix):])
   } else if len(s) > len(v30Prefix) && s[:len(v30Prefix)] == v30Prefix {
     // create CVSS v3.0 vector.
-    return NewV30VectorFromString(s[len(v30Prefix):])
+    return newV30Vector(s[len(v30Prefix):])
   } else {
     // create CVSS V2 vector
-    return NewV2VectorFromString(s)
+    return newV2Vector(s)
   }
 }