feat:replace md5 checksum

packages/at_commons/lib/at_commons.dart

@@ -32,3 +32,4 @@ export 'package:at_commons/src/enroll/enrollment.dart';
 @experimental
 export 'package:at_commons/src/telemetry/at_telemetry.dart';
 export 'package:at_commons/src/utils/string_utils.dart';
+export 'package:at_commons/src/keystore/public_key_hash.dart';

packages/at_commons/lib/src/at_constants.dart

@@ -62,6 +62,9 @@ class AtConstants {
   static const String sharedKeyStatus = 'sharedKeyStatus';
   static const String sharedKeyEncrypted = 'sharedKeyEnc';
   static const String sharedWithPublicKeyCheckSum = 'pubKeyCS';
+  static const String sharedWithPublicKeyHash = 'pubKeyHash';
+  static const String sharedWithPublicKeyHashValue = 'hash';
+  static const String sharedWithPublicKeyHashAlgo = 'algo';
   static const String sharedKeyEncryptedEncryptingKeyName = 'skeEncKeyName';
   static const String sharedKeyEncryptedEncryptingAlgo = 'skeEncAlgo';
   static const String firstByte = '#';

packages/at_commons/lib/src/keystore/at_key.dart

@@ -1,6 +1,7 @@
 import 'package:at_commons/src/keystore/at_key_builder_impl.dart';
 import 'package:at_commons/src/utils/at_key_regex_utils.dart';
 import 'package:at_commons/src/utils/string_utils.dart';
+import 'package:at_commons/src/keystore/public_key_hash.dart';
 import 'package:meta/meta.dart';
 
 import '../at_constants.dart';
@@ -489,8 +490,13 @@ class Metadata {
 
   /// Stores the checksum of the encryption public key used to encrypt the [sharedKeyEnc]. We use this
   /// to verify that the encryption key-pair used to encrypt and decrypt the value are same
+  @Deprecated('Use pubKeyHash')
   String? pubKeyCS;
 
+  /// Stores the hash of the encryption public key used to encrypt the [sharedKeyEnc]
+  /// The hash is used to verify whether the current atsign's public key used for encrypting data by another atsign, has changed while decrypting the data
+  PublicKeyHash? pubKeyHash;
+
   /// If the [AtValue] is public data (i.e. it is not encrypted) and contains one or more new line (\n) characters,
   /// then the data will be encoded, and the encoding will be set to type of encoding (e.g. "base64")
   String? encoding;
@@ -553,7 +559,7 @@ class Metadata {
         ', refreshAt : ${refreshAt?.toUtc().toString()}, createdAt : ${createdAt?.toUtc().toString()}'
         ', updatedAt : ${updatedAt?.toUtc().toString()}, isBinary : $isBinary, isEncrypted : $isEncrypted'
         ', isCached : $isCached, dataSignature: $dataSignature, sharedKeyStatus: $sharedKeyStatus'
-        ', encryptedSharedKey: $sharedKeyEnc, pubKeyCheckSum: $pubKeyCS, encoding: $encoding'
+        ', encryptedSharedKey: $sharedKeyEnc, pubKeyHash: $pubKeyHash, encoding: $encoding'
         ', encKeyName: $encKeyName, encAlgo: $encAlgo, ivNonce: $ivNonce'
         ', skeEncKeyName: $skeEncKeyName, skeEncAlgo: $skeEncAlgo}';
   }
@@ -595,6 +601,14 @@ class Metadata {
     if (pubKeyCS.isNotNullOrEmpty) {
       sb.write(':${AtConstants.sharedWithPublicKeyCheckSum}:$pubKeyCS');
     }
+    if (pubKeyHash != null && pubKeyHash!.hash.isNotNullOrEmpty) {
+      sb.write(
+          ':${AtConstants.sharedWithPublicKeyHashValue}:${pubKeyHash!.hash}');
+    }
+    if (pubKeyHash != null && pubKeyHash!.publicKeyHashingAlgo != null) {
+      sb.write(
+          ':${AtConstants.sharedWithPublicKeyHashAlgo}:${pubKeyHash!.publicKeyHashingAlgo}');
+    }
     if (encoding.isNotNullOrEmpty) {
       sb.write(':${AtConstants.encoding}:$encoding');
     }
@@ -667,6 +681,9 @@ class Metadata {
     if (fullJson || pubKeyCS != null) {
       map[AtConstants.sharedWithPublicKeyCheckSum] = pubKeyCS;
     }
+    if (fullJson || pubKeyHash != null) {
+      map[AtConstants.sharedWithPublicKeyHash] = pubKeyHash!.toJson();
+    }
     if (fullJson || encoding != null) {
       map[AtConstants.encoding] = encoding;
     }
@@ -734,6 +751,7 @@ class Metadata {
     metaData.sharedKeyStatus = json[AtConstants.sharedKeyStatus];
     metaData.sharedKeyEnc = json[AtConstants.sharedKeyEncrypted];
     metaData.pubKeyCS = json[AtConstants.sharedWithPublicKeyCheckSum];
+    metaData.pubKeyHash = json[AtConstants.sharedWithPublicKeyHash];
     metaData.encoding = json[AtConstants.encoding];
     metaData.encKeyName = json[AtConstants.encryptingKeyName];
     metaData.encAlgo = json[AtConstants.encryptingAlgo];
@@ -769,6 +787,7 @@ class Metadata {
           isCached == other.isCached &&
           sharedKeyEnc == other.sharedKeyEnc &&
           pubKeyCS == other.pubKeyCS &&
+          pubKeyHash == other.pubKeyHash &&
           encoding == other.encoding &&
           encKeyName == other.encKeyName &&
           encAlgo == other.encAlgo &&
@@ -797,6 +816,7 @@ class Metadata {
       isCached.hashCode ^
       sharedKeyEnc.hashCode ^
       pubKeyCS.hashCode ^
+      pubKeyHash.hashCode ^
       encoding.hashCode ^
       encKeyName.hashCode ^
       encAlgo.hashCode ^

packages/at_commons/lib/src/keystore/public_key_hash.dart

@@ -0,0 +1,30 @@
+/// Represents hash of an atsign's public encryption key and the hashing algorithm used
+class PublicKeyHash {
+  String? hash;
+  PublicKeyHashingAlgo? publicKeyHashingAlgo;
+
+  @override
+  String toString() {
+    return 'PublicKeyHash{hash: $hash, publicKeyHashingAlgo: $publicKeyHashingAlgo}';
+  }
+
+  Map toJson() {
+    var map = {};
+    map['hash'] = hash;
+    map['algo'] = publicKeyHashingAlgo;
+    return map;
+  }
+
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is PublicKeyHash &&
+          runtimeType == other.runtimeType &&
+          hash == other.hash &&
+          publicKeyHashingAlgo == other.publicKeyHashingAlgo;
+
+  @override
+  int get hashCode => hash.hashCode ^ publicKeyHashingAlgo.hashCode;
+}
+
+enum PublicKeyHashingAlgo { sha256, sha512 }