secret-wrap : Return null in case of error

src/secret-wrap.ts

@@ -71,11 +71,28 @@ export class SecretWrap {
       type: this.type
     })
   }
-  public static fromString(data: string): SecretWrap {
+  public static fromString(data: string): SecretWrap | null {
     log.trace('fromString')
-    const obj = JSON.parse(data)
-    const cipher = b642a(obj.cipher).expect('Failed to decode cipher')
-    const iv = b642a(obj.iv).expect('Failed to decode IV')
-    return new SecretWrap(cipher, obj.algorithm, obj.usages, obj.type, iv)
+
+    const obj = this.parseJSON(data)
+    if (obj === null) return null
+
+    const cipher = b642a(obj.cipher)
+    if (cipher.is_err()) return null
+    const iv = b642a(obj.iv)
+    if (iv.is_err()) return null
+
+    return new SecretWrap(cipher.unwrap(), obj.algorithm, obj.usages, obj.type, iv.unwrap())
+  }
+
+  private static parseJSON(data: string): {cipher: string, iv: string, algorithm: KeyAlgorithm, usages: KeyUsage[], type: 'raw' | 'pkcs8'} | null {
+    log.trace('parseJSON')
+    try {
+      // TODO : Check the fields
+      return JSON.parse(data)
+    } catch (e) {
+      log.warn('Failed to parse JSON')
+      return null
+    }
   }
 }