- anonymize COSE content according to debug mode rules; (#60)

Author: MykhailoNester

decoder/src/main/java/dgca/verifier/app/decoder/cose/CoseService.kt

@@ -31,4 +31,6 @@ import dgca.verifier.app.decoder.model.VerificationResult
 interface CoseService {
 
     fun decode(input: ByteArray, verificationResult: VerificationResult): CoseData?
+
+    fun anonymizeCose(input: ByteArray): ByteArray?
 }

decoder/src/main/java/dgca/verifier/app/decoder/cose/DefaultCoseService.kt

@@ -23,6 +23,7 @@
 package dgca.verifier.app.decoder.cose
 
 import COSE.HeaderKeys
+import com.google.common.primitives.Bytes
 import com.upokecenter.cbor.CBORObject
 import dgca.verifier.app.decoder.model.CoseData
 import dgca.verifier.app.decoder.model.VerificationResult
@@ -60,4 +61,35 @@ class DefaultCoseService : CoseService {
             unprotectedHeader.get(key)
         }
     }
+
+    override fun anonymizeCose(input: ByteArray): ByteArray? {
+        return try {
+            val messageObject = CBORObject.DecodeFromBytes(input)
+
+            val content = messageObject[2].EncodeToBytes()
+            val index = Bytes.indexOf(input, content)
+
+            val newArray = ByteArray(input.size)
+
+            val anonymize = ByteArray(content.size)
+            anonymize.forEachIndexed { i, _ ->
+                anonymize[i] = 0x58
+            }
+
+            System.arraycopy(input, 0, newArray, 0, index)
+            System.arraycopy(anonymize, 0, newArray, index, anonymize.size)
+            System.arraycopy(
+                input,
+                index + anonymize.size,
+                newArray,
+                index + anonymize.size,
+                input.size - (anonymize.size + index)
+            )
+
+            newArray
+
+        } catch (e: Throwable) {
+            null
+        }
+    }
 }