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PEX: Provide ParseEnvelope to correctly parse PEX VP envelopes
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,137 @@ | ||
| /* | ||
| * Copyright (C) 2023 Nuts community | ||
| * | ||
| * This program is free software: you can redistribute it and/or modify | ||
| * it under the terms of the GNU General Public License as published by | ||
| * the Free Software Foundation, either version 3 of the License, or | ||
| * (at your option) any later version. | ||
| * | ||
| * This program is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| * GNU General Public License for more details. | ||
| * | ||
| * You should have received a copy of the GNU General Public License | ||
| * along with this program. If not, see <https://www.gnu.org/licenses/>. | ||
| * | ||
| */ | ||
|
|
||
| package pe | ||
|
|
||
| import ( | ||
| "encoding/json" | ||
| "fmt" | ||
| "github.com/lestrrat-go/jwx/v2/jwt" | ||
| "github.com/nuts-foundation/go-did/vc" | ||
| ) | ||
|
|
||
| type Envelope struct { | ||
| Interface interface{} | ||
| Presentations []vc.VerifiablePresentation | ||
| } | ||
|
|
||
| // ParseEnvelope parses a Presentation Exchange envelope, which is a JSON type that encompasses zero or more Verifiable Presentations. | ||
| // It returns the envelope as interface{} for use in PresentationSubmission.Validate() and PresentationSubmission.Resolve(). | ||
| // It also returns the parsed Verifiable Presentations. | ||
| // Parsing is complicated since a Presentation Submission has multiple ways to reference a Verifiable Credential: | ||
| // - single VP as JSON object: $.verifiableCredential | ||
| // - multiple VPs as JSON array (with path_nested): $[0] -> $.verifiableCredential | ||
| // And since JWT VPs aren't JSON objects, we need to parse them separately. | ||
| func ParseEnvelope(envelopeBytes []byte) (*Envelope, error) { | ||
| jsonArray := tryParseJSONArray(envelopeBytes) | ||
| if jsonArray != nil { | ||
| // Array of Verifiable Presentations | ||
| asInterface, presentations, err := parseJSONArrayEnvelope(jsonArray) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return &Envelope{ | ||
| Interface: asInterface, | ||
| Presentations: presentations, | ||
| }, nil | ||
| } | ||
| // Single Verifiable Presentation | ||
| asInterface, presentation, err := parseJSONObjectOrStringEnvelope(envelopeBytes) | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
| return &Envelope{ | ||
| Interface: asInterface, | ||
| Presentations: []vc.VerifiablePresentation{*presentation}, | ||
| }, nil | ||
| } | ||
|
|
||
| // parseEnvelopeEntry parses a single Verifiable Presentation in a Presentation Exchange envelope. | ||
| // It takes into account custom unmarshalling required for JWT VPs. | ||
| func parseJSONArrayEnvelope(arr []interface{}) (interface{}, []vc.VerifiablePresentation, error) { | ||
| var presentations []vc.VerifiablePresentation | ||
| var asInterfaces []interface{} | ||
| for _, entry := range arr { | ||
| // Each entry can be a VP as JWT (string) or JSON (object) | ||
| var entryBytes []byte | ||
| switch entry.(type) { | ||
| case string: | ||
| // JWT | ||
| entryBytes = []byte(entry.(string)) | ||
| default: | ||
| var err error | ||
| entryBytes, err = json.Marshal(entry) | ||
| if err != nil { | ||
| return nil, nil, err | ||
| } | ||
| } | ||
| asInterface, presentation, err := parseJSONObjectOrStringEnvelope(entryBytes) | ||
| if err != nil { | ||
| return nil, nil, err | ||
| } | ||
| asInterfaces = append(asInterfaces, asInterface) | ||
| presentations = append(presentations, *presentation) | ||
| } | ||
| return asInterfaces, presentations, nil | ||
| } | ||
|
|
||
| // parseJSONObjectOrStringEnvelope parses a single Verifiable Presentation in a Presentation Exchange envelope. | ||
| // It takes into account custom unmarshalling required for JWT VPs (since they're JSON strings, not objects). | ||
| func parseJSONObjectOrStringEnvelope(envelopeBytes []byte) (interface{}, *vc.VerifiablePresentation, error) { | ||
| presentation, err := vc.ParseVerifiablePresentation(string(envelopeBytes)) | ||
| if err != nil { | ||
| return nil, nil, fmt.Errorf("unable to parse PEX envelope as verifiable presentation: %w", err) | ||
| } | ||
| // TODO: This should be part of go-did library; we need to decode a JWT VP (and maybe later VC) and get the properties | ||
| // (in this case as map) without losing original cardinality. | ||
| // Part of https://github.com/nuts-foundation/go-did/issues/85 | ||
| if presentation.Format() == vc.JWTPresentationProofFormat { | ||
| token, err := jwt.Parse(envelopeBytes, jwt.WithVerify(false), jwt.WithValidate(false)) | ||
| if err != nil { | ||
| return nil, nil, fmt.Errorf("unable to parse PEX envelope as JWT verifiable presentation: %w", err) | ||
| } | ||
| asMap := make(map[string]interface{}) | ||
| // use the 'vp' claim as base Verifiable Presentation properties | ||
| innerVPAsMap, _ := token.PrivateClaims()["vp"].(map[string]interface{}) | ||
| for key, value := range innerVPAsMap { | ||
| asMap[key] = value | ||
| } | ||
| if jti, ok := token.Get(jwt.JwtIDKey); ok { | ||
| asMap["id"] = jti | ||
| } | ||
| return asMap, presentation, nil | ||
| } | ||
| // For other formats, we can just parse the JSON to get the interface{} for JSON Path to work on | ||
| var asMap interface{} | ||
| if err := json.Unmarshal(envelopeBytes, &asMap); err != nil { | ||
| // Can't actually fail? | ||
| return nil, nil, err | ||
| } | ||
| return asMap, presentation, nil | ||
| } | ||
|
|
||
| // tryParseJSONArray tries to parse the given bytes as a JSON array. | ||
| // It returns the array as []interface{} if the bytes are a JSON array, or nil otherwise. | ||
| func tryParseJSONArray(bytes []byte) []interface{} { | ||
| var asInterface interface{} | ||
| if err := json.Unmarshal(bytes, &asInterface); err != nil { | ||
| return nil | ||
| } | ||
| arr, _ := asInterface.([]interface{}) | ||
| return arr | ||
| } |
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