Add decryptAttribute

src/service.ts

@@ -1108,6 +1108,77 @@ export class Service {
     }
   }
 
+  async decryptAttribute(processId: string, state: ProcessState, attribute: string): Promise<any | null> {
+    let hash = state.pcd_commitment[attribute];
+    if (!hash) {
+      // attribute doesn't exist
+      return null;
+    }
+    let key = state.keys[attribute];
+    const pairingProcessId = this.getPairingProcessId();
+
+    // If key is missing, request an update and then retry
+    if (!key) {
+      const roles = state.roles;
+      let hasAccess = false;
+      // If we're not supposed to have access to this attribute, ignore 
+      for (const role of Object.values(roles)) {
+        for (const rule of Object.values(role.validation_rules)) {
+          if (rule.fields.includes(attribute)) {
+            if (role.members.includes(pairingProcessId)) {
+              // We have access to this attribute
+              hasAccess = true;
+              break;
+            }
+          }
+        }
+      }
+
+      if (!hasAccess) return null;
+
+      // We should have the key, so we're going to ask other members for it
+      await this.requestDataFromPeers(processId, [state.state_id], [state.roles]);
+
+      const maxRetries = 5;
+      const retryDelay = 500; // delay in milliseconds
+      let retries = 0;
+      
+      while ((!hash || !key) && retries < maxRetries) {
+        await new Promise(resolve => setTimeout(resolve, retryDelay));
+        // Re-read hash and key after waiting
+        hash = state.pcd_commitment[attribute];
+        key = state.keys[attribute];
+        retries++;
+      }
+    }
+
+    if (hash && key) {
+      const blob = await this.getBlobFromDb(hash);
+      if (blob) {
+        // Decrypt the data
+        const buf = await blob.arrayBuffer();
+        const cipher = new Uint8Array(buf);
+
+        const keyUIntArray = this.hexToUInt8Array(key);
+
+        try {
+          const clear = wasm.decrypt_data(keyUIntArray, cipher);
+          if (clear) {
+            // deserialize the result to get the actual data
+            const decoded = wasm.decode_value(clear);
+            return decoded;
+          } else {
+            throw new Error('decrypt_data returned null');
+          }
+        } catch (e) {
+          console.error(`Failed to decrypt data: ${e}`);
+        }
+      }
+    }
+    
+    return null;
+  }
+
   decodeValue(value: number[]): any | null {
     try {
       return wasm.decode_value(new Uint8Array(value));