crypto
- Dart course
- Advanced
- Lesson 67/83
- 5 min
Learn hashing with the crypto package.
The crypto package
crypto is Dart's hash function package. It is imported with import 'package:crypto/crypto.dart';. It offers SHA-256, SHA-512 and MD5 algorithms. It turns data into a fixed-length hash digest.
Example: final hash = sha256.convert(utf8.encode('Merhaba'));. Here utf8.encode turns the text into bytes; sha256.convert computes the SHA-256 digest of those bytes. The result is a 64-character hexadecimal string. A hash is one-way; you produce a hash from data but cannot recover data from the hash.
Using SHA-256
SHA-256 produces a 256-bit (32-byte) hash. It is shown as a 64-character hexadecimal string. The same input always gives the same hash; so it is used for file integrity and fingerprinting.
Usage: import 'dart:convert'; import 'package:crypto/crypto.dart';. Then final hash = sha256.convert(utf8.encode('Merhaba')); print(hash);. The hash variable is a Digest object; toString() or direct print gives the hex string. Hash computation is deterministic; the same input always produces the same output.
Practice Compute a SHA-256 hash
Add import 'dart:convert'; and import 'package:crypto/crypto.dart';. In main compute the hash with final hash = sha256.convert(utf8.encode('Merhaba')); and print with print(hash).
Starter code
// import dart:convert and the crypto package
void main() {
// compute the sha256 hash of 'Merhaba' and print it
}Sample solution
import 'dart:convert';
import 'package:crypto/crypto.dart';
void main() {
final hash = sha256.convert(utf8.encode('Merhaba'));
print(hash);
}Expected output
7fdc9f4717c5fe66df286c700fab969b4d6209d03aa84624c5f8f58c17c9c058
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does the crypto package provide?
- HTTP client
- Database
- Hash functions Correct answer
- DOM manipulation
Explanation: the crypto package provides hash functions.
2 The sha256 call
final hash = ____.convert(utf8.encode('Merhaba'));final hash = sha256.convert(utf8.encode('Merhaba'));Explanation: sha256.convert(...) computes the SHA-256 digest.
3 Match the crypto parts
| Term | Meaning |
|---|---|
crypto |
Hash package |
sha256 |
256 bit |
utf8.encode |
Turns to bytes |
convert |
Computes |