diff --git a/packages/flutter_tools/lib/src/base/utils.dart b/packages/flutter_tools/lib/src/base/utils.dart
index 62a9b8f1d18..cdbdec19f63 100644
--- a/packages/flutter_tools/lib/src/base/utils.dart
+++ b/packages/flutter_tools/lib/src/base/utils.dart
@@ -7,10 +7,15 @@ import 'dart:io';
 
 import 'package:crypto/crypto.dart';
 
+String hex(List<int> bytes) {
+  StringBuffer result = new StringBuffer();
+  for (int part in bytes)
+    result.write('${part < 16 ? '0' : ''}${part.toRadixString(16)}');
+  return result.toString();
+}
+
 String calculateSha(File file) {
-  SHA1 sha1 = new SHA1();
-  sha1.add(file.readAsBytesSync());
-  return CryptoUtils.bytesToHex(sha1.close());
+  return hex(sha1.convert(file.readAsBytesSync()).bytes);
 }
 
 /// Convert `foo_bar` to `fooBar`.
diff --git a/packages/flutter_tools/pubspec.yaml b/packages/flutter_tools/pubspec.yaml
index 05dbe459bdd..da787cee2e8 100644
--- a/packages/flutter_tools/pubspec.yaml
+++ b/packages/flutter_tools/pubspec.yaml
@@ -11,7 +11,7 @@ dependencies:
   analyzer: '>=0.26.1+17' # see note below
   archive: ^1.0.20
   args: ^0.13.4
-  crypto: ^0.9.1
+  crypto: ^0.9.2
   den_api: ^0.1.0
   file: ^0.1.0
   mustache4dart: ^1.0.0
diff --git a/packages/flx/lib/signing.dart b/packages/flx/lib/signing.dart
index 802aecfd1ad..522ca511ec9 100644
--- a/packages/flx/lib/signing.dart
+++ b/packages/flx/lib/signing.dart
@@ -3,13 +3,13 @@
 // found in the LICENSE file.
 
 import 'dart:async';
-import 'dart:convert' hide BASE64;
+import 'dart:convert';
 import 'dart:io';
 import 'dart:typed_data';
 
 import 'package:asn1lib/asn1lib.dart';
 import 'package:bignum/bignum.dart';
-import 'package:crypto/crypto.dart';
+import 'package:crypto/crypto.dart' hide BASE64, Digest;
 import 'package:pointycastle/pointycastle.dart';
 
 export 'package:pointycastle/pointycastle.dart' show AsymmetricKeyPair, PublicKey, PrivateKey;
@@ -82,9 +82,7 @@ Uint8List serializeManifest(Map<String, dynamic> manifestDescriptor, ECPublicKey
   if (publicKey != null)
     outputManifest['key'] = BASE64.encode(publicKey.Q.getEncoded());
 
-  SHA256 sha = new SHA256();
-  sha.add(zipBytes);
-  List<int> hash = sha.close();
+  List<int> hash = sha256.convert(zipBytes).bytes;
 
   BigInteger zipHashInt = new BigInteger.fromBytes(1, hash);
   outputManifest['content-hash'] = zipHashInt.intValue();
diff --git a/packages/flx/pubspec.yaml b/packages/flx/pubspec.yaml
index f0f30fc8289..00cd7e2037e 100644
--- a/packages/flx/pubspec.yaml
+++ b/packages/flx/pubspec.yaml
@@ -7,7 +7,7 @@ dependencies:
   bignum: ^0.1.0
   asn1lib: ^0.4.1
   pointycastle: 0.10.0
-  crypto: ^0.9.1
+  crypto: ^0.9.2
 
 environment:
   sdk: '>=1.12.0 <2.0.0'