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submission.go
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submission.go
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package exchange
import (
"fmt"
"reflect"
"regexp"
"strings"
"github.com/goccy/go-json"
"github.com/google/uuid"
"github.com/oliveagle/jsonpath"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"github.com/TBD54566975/ssi-sdk/credential"
"github.com/TBD54566975/ssi-sdk/credential/signing"
"github.com/TBD54566975/ssi-sdk/cryptosuite"
"github.com/TBD54566975/ssi-sdk/util"
)
// EmbedTarget describes where a presentation_submission is located in an object model
// https://identity.foundation/presentation-exchange/#embed-targets
type EmbedTarget string
const (
// JWTVPTarget is an embed target where a presentation submission is represented alongside a Verifiable Presentation
// in a JWT value. `presentation_submission` is a top-level claim alongside `vc` for the VP
JWTVPTarget EmbedTarget = "jwt_vp"
// JWTTarget EmbedTarget = "jwt"
// LDPVPTarget EmbedTarget = "ldp_vp"
PresentationSubmissionContext string = "https://identity.foundation/presentation-exchange/submission/v1"
PresentationSubmissionType string = "PresentationSubmission"
)
// PresentationClaim 's may be of any claim format designation, including LD or JWT variations of VCs or VPs
// https://identity.foundation/presentation-exchange/#claim-format-designations
// This object must be constructed for each claim before processing of a Presentation Definition
type PresentationClaim struct {
// If we have a Credential or Presentation value, we assume we have a LDP_VC or LDP_VP respectively
Credential *credential.VerifiableCredential
Presentation *credential.VerifiablePresentation
LDPFormat *LinkedDataFormat
// If we have a token, we assume we have a JWT format value
Token *string
JWTFormat *JWTFormat
// The algorithm or Linked Data proof type by which the claim was signed must be present
SignatureAlgorithmOrProofType string
}
func (pc *PresentationClaim) IsEmpty() bool {
if pc == nil || (pc.Credential == nil && pc.Presentation == nil && pc.Token == nil) {
return true
}
return reflect.DeepEqual(pc, &PresentationClaim{})
}
// GetClaimValue returns the value of the claim, since PresentationClaim is a union type. An error is returned if
// no value is present in any of the possible embedded types.
func (pc *PresentationClaim) GetClaimValue() (interface{}, error) {
if pc.Credential != nil {
return *pc.Credential, nil
}
if pc.Presentation != nil {
return *pc.Presentation, nil
}
if pc.Token != nil {
return *pc.Token, nil
}
return nil, errors.New("claim is empty")
}
// GetClaimFormat returns the value of the format depending on the claim type.
// Since PresentationClaim is a union type. An error is returned if
// no value is present in any of the possible embedded types.
func (pc *PresentationClaim) GetClaimFormat() (string, error) {
if pc.Credential != nil {
if pc.LDPFormat == nil {
return "", errors.New("credential claim has no LDP format set")
}
return string(*pc.LDPFormat), nil
}
if pc.Presentation != nil {
if pc.LDPFormat == nil {
return "", errors.New("presentation claim has no LDP format set")
}
return string(*pc.LDPFormat), nil
}
if pc.Token != nil {
if pc.JWTFormat == nil {
return "", errors.New("JWT claim has no JWT format set")
}
return string(*pc.JWTFormat), nil
}
return "", errors.New("claim is empty")
}
// GetClaimJSON gets the claim value and attempts to turn it into a generic go-JSON object represented by an interface{}
func (pc *PresentationClaim) GetClaimJSON() (map[string]interface{}, error) {
claimValue, err := pc.GetClaimValue()
if err != nil {
return nil, err
}
jsonClaim := make(map[string]interface{})
// need to handle the case where we already have a string, since we won't need to marshal it
var claimBytes []byte
if claimStr, ok := claimValue.(string); ok {
claimBytes = []byte(claimStr)
} else {
claimBytes, err = json.Marshal(claimValue)
if err != nil {
return nil, err
}
}
if err := json.Unmarshal(claimBytes, &jsonClaim); err != nil {
return nil, err
}
return jsonClaim, nil
}
// BuildPresentationSubmission constructs a submission given a presentation definition, set of claims, and an
// embed target format.
// https://identity.foundation/presentation-exchange/#presentation-submission
func BuildPresentationSubmission(signer cryptosuite.Signer, def PresentationDefinition, claims []PresentationClaim, et EmbedTarget) ([]byte, error) {
if !IsSupportedEmbedTarget(et) {
err := fmt.Errorf("unsupported presentation submission embed target type: %s", et)
logrus.WithError(err).Error()
return nil, err
}
normalizedClaims := normalizePresentationClaims(claims)
if len(normalizedClaims) == 0 {
err := errors.New("no claims remain after normalization; cannot continue processing")
logrus.WithError(err).Error()
return nil, err
}
switch et {
case JWTVPTarget:
jwkSigner, ok := signer.(*cryptosuite.JSONWebKeySigner)
if !ok {
err := fmt.Errorf("signer not valid for request type: %s", et)
logrus.WithError(err).Error()
return nil, err
}
vpSubmission, err := BuildPresentationSubmissionVP(def, normalizedClaims)
if err != nil {
err := errors.Wrap(err, "unable to fulfill presentation definition with given credentials")
logrus.WithError(err).Error()
return nil, err
}
return signing.SignVerifiablePresentationJWT(*jwkSigner, *vpSubmission)
default:
err := fmt.Errorf("presentation submission embed target <%s> is not implemented", et)
logrus.WithError(err).Error()
return nil, err
}
}
type normalizedClaim struct {
// id for the claim
claimID string
// go-json representation of the claim
claimData map[string]interface{}
// JWT_VC, JWT_VP, LDP_VC, LDP_VP, etc.
format string
// Signing algorithm used for the claim (e.g. EdDSA, ES256, PS256, etc.).
// OR the Linked Data Proof Type (e.g. JsonWebSignature2020)
algOrProofType string
}
// normalizePresentationClaims takes a set of Presentation Claims and turns them into map[string]interface{} as
// go-JSON representations. The claim format and signature algorithm type are noted as well.
// This method is greedy, meaning it returns the set of claims it was able to normalize.
func normalizePresentationClaims(claims []PresentationClaim) []normalizedClaim {
var normalizedClaims []normalizedClaim
for _, claim := range claims {
ae := util.NewAppendError()
claimJSON, err := claim.GetClaimJSON()
if err != nil {
ae.Append(err)
}
claimFormat, err := claim.GetClaimFormat()
if err != nil {
ae.Append(err)
}
if ae.Error() != nil {
logrus.WithError(ae.Error()).Error("could not normalize claim")
continue
}
var id string
if claimID, ok := claimJSON["id"]; ok {
id = claimID.(string)
}
normalizedClaims = append(normalizedClaims, normalizedClaim{
claimID: id,
claimData: claimJSON,
format: claimFormat,
algOrProofType: claim.SignatureAlgorithmOrProofType,
})
}
return normalizedClaims
}
// processedClaim represents a claim that has been processed for an input descriptor along with relevant
// information for building a valid descriptor_map in the resulting presentation submission
type processedClaim struct {
Claim map[string]interface{}
SubmissionDescriptor
}
// BuildPresentationSubmissionVP takes a presentation definition and a set of claims. According to the presentation
// definition, and the algorithm defined - https://identity.foundation/presentation-exchange/#input-evaluation - in
// the specification, a presentation submission is constructed as a Verifiable Presentation.
func BuildPresentationSubmissionVP(def PresentationDefinition, claims []normalizedClaim) (*credential.VerifiablePresentation, error) {
if err := canProcessDefinition(def); err != nil {
return nil, errors.Wrap(err, "feature not supported in processing given presentation definition")
}
builder := credential.NewVerifiablePresentationBuilder()
if err := builder.AddContext(PresentationSubmissionContext); err != nil {
return nil, err
}
if err := builder.AddType(PresentationSubmissionType); err != nil {
return nil, err
}
submission := PresentationSubmission{
ID: uuid.NewString(),
DefinitionID: def.ID,
}
// begin to process to presentation definition against the available claims
var processedClaims []processedClaim
claimIndex := 0
// keep track of claims we've already added, to avoid duplicates
seenClaims := make(map[string]int)
for _, id := range def.InputDescriptors {
processedInputDescriptor, err := processInputDescriptor(id, claims)
if err != nil {
err := errors.Wrapf(err, "error processing input descriptor: %s", id.ID)
logrus.WithError(err).Error()
return nil, err
}
if processedInputDescriptor == nil {
err := fmt.Errorf("input descrpitor<%s> could not be fulfilled; could not build a valid presentation submission", id.ID)
logrus.WithError(err).Error()
return nil, err
}
// check if claim already exists. if it has, we won't duplicate the claim
var currIndex int
var claim map[string]interface{}
claimID := processedInputDescriptor.ClaimID
if seen, ok := seenClaims[claimID]; ok {
currIndex = seen
} else {
currIndex = claimIndex
claimIndex++
claim = processedInputDescriptor.Claim
seenClaims[claimID] = currIndex
}
processedClaims = append(processedClaims, processedClaim{
Claim: claim,
SubmissionDescriptor: SubmissionDescriptor{
ID: processedInputDescriptor.ID,
Format: processedInputDescriptor.Format,
Path: fmt.Sprintf("$.verifiableCredential[%d]", currIndex),
},
})
}
// set descriptor map in submission and credentials to the VP
var descriptorMap []SubmissionDescriptor
for _, claim := range processedClaims {
descriptorMap = append(descriptorMap, claim.SubmissionDescriptor)
// on the case we've seen the claim, we need to check as to not add a nil claim value
if len(claim.Claim) > 0 {
if err := builder.AddVerifiableCredentials(claim.Claim); err != nil {
err := errors.Wrap(err, "could not add claim value to verifiable presentation")
logrus.WithError(err).Error()
return nil, err
}
}
}
// add the built descriptor map to the submission
submission.DescriptorMap = descriptorMap
// set submission in vp, build, and return
if err := builder.SetPresentationSubmission(submission); err != nil {
return nil, err
}
return builder.Build()
}
// processedInputDescriptor
type processedInputDescriptor struct {
// input descriptor id
ID string
// ID of the claim
ClaimID string
// generic claim
Claim map[string]interface{}
// claim format
Format string
}
// limitedInputDescriptor is the claim data after being filtered/limited via JSON path
type limitedInputDescriptor struct {
Path string
Data interface{}
}
// processInputDescriptor runs the input evaluation algorithm described in the spec for a specific input descriptor
// https://identity.foundation/presentation-exchange/#input-evaluation
func processInputDescriptor(id InputDescriptor, claims []normalizedClaim) (*processedInputDescriptor, error) {
constraints := id.Constraints
if constraints == nil {
err := fmt.Errorf("unable to process input descriptor without constraints")
logrus.WithError(err).Error()
return nil, err
}
fields := constraints.Fields
if len(fields) == 0 {
err := fmt.Errorf("unable to process input descriptor without fields: %s", id.ID)
logrus.WithError(err).Error()
return nil, err
}
// bookkeeping to check whether we've fulfilled all required fields, and whether we need to limit disclosure
fieldsToProcess := len(fields)
limitDisclosure := false
disclosure := constraints.LimitDisclosure
if disclosure != nil && (*disclosure == Required || *disclosure == Preferred) {
limitDisclosure = true
}
// first, reduce the set of claims that conform with the format required by the input descriptor
filteredClaims := filterClaimsByFormat(claims, id.Format)
if len(filteredClaims) == 0 {
err := fmt.Errorf("no claims match the required format, and signing alg/proof type requirements "+
"for input descriptor: %s", id.ID)
logrus.WithError(err).Error()
return nil, err
}
// for the input descriptor to be successfully processed each field needs to yield a result for a given claim,
// so we need to iterate through each claim, and test it against each field, and each path within each field.
// if we find a match for each field, we know a claim can fulfill the given input descriptor.
for _, claim := range filteredClaims {
fieldsProcessed := 0
var limited []limitedInputDescriptor
claimValue := claim.claimData
for _, field := range fields {
// apply the field to the claim, and return the processed value, which we only care about for
// filtering and/or limit_disclosure settings
limitedClaim, fulfilled := processInputDescriptorField(field, claimValue)
if !fulfilled {
// we know this claim is not sufficient to fulfill the input descriptor
break
}
// we've fulfilled the field, so note it
fieldsProcessed++
if limitDisclosure {
limited = append(limited, *limitedClaim)
}
}
// if a claim has matched all fields, we can fulfill the input descriptor with this claim
if fieldsProcessed == fieldsToProcess {
// because the `limit_disclosure` property is present, we must merge the limited fields
resultClaim := claimValue
if limitDisclosure {
limitedClaim := constructLimitedClaim(limited)
resultClaim = limitedClaim
}
return &processedInputDescriptor{
ID: id.ID,
ClaimID: claim.claimID,
Claim: resultClaim,
Format: claim.format,
}, nil
}
}
err := fmt.Errorf("no claims could fulfill the input descriptor: %s", id.ID)
logrus.WithError(err).Error("could not fulfill input descriptor")
return nil, err
}
// filterClaimsByFormat returns a set of claims that comply with a given ClaimFormat according to its
// supported format(s) and signature types per format
func filterClaimsByFormat(claims []normalizedClaim, format *ClaimFormat) []normalizedClaim {
// no format, which is an optional property
if format == nil {
return claims
}
formatValues := format.FormatValues()
var filteredClaims []normalizedClaim
for _, claim := range claims {
// if the format matches, check the alg type
if util.Contains(claim.format, formatValues) {
// get the supported alg or proof types for this format
algOrProofTypes := format.AlgOrProofTypePerFormat(claim.format)
if util.Contains(claim.algOrProofType, algOrProofTypes) {
filteredClaims = append(filteredClaims, claim)
}
}
}
return filteredClaims
}
// constructLimitedClaim builds a limited disclosure/filtered claim from a set of filtered input descriptors
func constructLimitedClaim(limitedDescriptors []limitedInputDescriptor) map[string]interface{} {
result := make(map[string]interface{})
for _, ld := range limitedDescriptors {
curr := result
// normalize the current path to build JSON from
normalizedPath := normalizeJSONPath(ld.Path)
splitPath := strings.Split(normalizedPath, ".")
for i := 0; i < len(splitPath)-1; i++ {
// get and normalize the current section of the path
part := splitPath[i]
normalizedPart := normalizeJSONPartPath(part)
// if it's empty, we continue to the next piece of the path
if normalizedPart == "" {
continue
}
// if the path is not contained in the resulting JSON, create it
if _, ok := curr[normalizedPart]; !ok {
curr[normalizedPart] = make(map[string]interface{})
}
// make sure the value is represented in curr
currVal, _ := curr[normalizedPart]
curr = currVal.(map[string]interface{})
}
// since we've gone to one short of the end, we need to repeat the process for the last element in the path
// this is where we set the data value for the limited descriptor
lastPartName := normalizeJSONPartPath(splitPath[len(splitPath)-1])
curr[lastPartName] = ld.Data
}
return result
}
func normalizeJSONPartPath(partPath string) string {
partRegex := regexp.MustCompile(`[^a-zA-Z]`)
return partRegex.ReplaceAllString(partPath, "")
}
func normalizeJSONPath(path string) string {
pathRegex := regexp.MustCompile(`\[.*\]`)
return pathRegex.ReplaceAllString(path, "")
}
// processInputDescriptorField applies all possible path values to a claim, and checks to see if any match.
// if a path matches fulfilled will be set to true and no processed value will be returned. if limitDisclosure is
// set to true, the processed value will be returned as well.
func processInputDescriptorField(field Field, claimData map[string]interface{}) (limited *limitedInputDescriptor, fulfilled bool) {
for _, path := range field.Path {
pathedData, err := jsonpath.JsonPathLookup(claimData, path)
if err == nil {
limited = &limitedInputDescriptor{
Path: path,
Data: pathedData,
}
fulfilled = true
return
}
}
return nil, false
}
// TODO(gabe) https://github.com/TBD54566975/ssi-sdk/issues/56
// check for certain features we may not support yet: submission requirements, predicates, relational constraints,
// credential status, JSON-LD framing from https://identity.foundation/presentation-exchange/#features
func canProcessDefinition(def PresentationDefinition) error {
submissionRequirementsErr := errors.New("submission requirements feature not supported")
if len(def.SubmissionRequirements) > 0 {
logrus.WithError(submissionRequirementsErr).Error("submission requirements present")
return submissionRequirementsErr
}
for _, id := range def.InputDescriptors {
if id.Constraints != nil {
if len(id.Group) > 0 {
logrus.WithError(submissionRequirementsErr).Error("input descriptor group present")
return submissionRequirementsErr
}
if len(id.Constraints.Fields) > 0 {
for _, field := range id.Constraints.Fields {
if field.Predicate != nil || field.Filter != nil {
err := errors.New("predicate feature not supported")
logrus.WithError(err).Error("predicate and/or filter present")
return err
}
}
}
}
}
for _, id := range def.InputDescriptors {
if hasRelationalConstraint(id.Constraints) {
err := errors.New("relational constraint feature not supported")
logrus.WithError(err).Error()
return err
}
}
for _, id := range def.InputDescriptors {
if id.Constraints != nil && id.Constraints.Statuses != nil {
err := errors.New("credential status constraint feature not supported")
logrus.WithError(err).Error()
return err
}
}
if def.Frame != nil {
err := errors.New("JSON-LD framing feature not supported")
logrus.WithError(err).Error()
return err
}
return nil
}
// hasRelationalConstraint checks a constraint property for relational constraint field values
func hasRelationalConstraint(constraints *Constraints) bool {
if constraints == nil {
return false
}
return constraints.IsHolder != nil || constraints.SameSubject != nil || constraints.SubjectIsIssuer != nil
}
func IsSupportedEmbedTarget(et EmbedTarget) bool {
supported := GetSupportedEmbedTargets()
for _, t := range supported {
if et == t {
return true
}
}
return false
}
func GetSupportedEmbedTargets() []EmbedTarget {
return []EmbedTarget{JWTVPTarget}
}