Add an AES encryption and decryption example #111

stevenroose · 2017-01-27T19:15:32Z

No description provided.

Cretezy

Great work! I think this library definitely needs example of common use case, and this is a great start to that goal

Cretezy · 2018-08-17T00:06:37Z

example/aes.dart

+void main() {
+  // Key must be multiple of block size (16 bytes).
+  var key = new Digest("SHA-256").process(
+      UTF8.encode("correct horse battery staple"));


Use new utf8 (lowercase). I would also highly recommend to set any non-reassigned values (like this one) as final instead, which is generally considered a good practice.

Also, since we're now in the Dart 2 age, I would remove all instances of new.

Cretezy · 2018-08-17T00:07:30Z

example/aes.dart

+  encryptionCipher.init(true, params);
+  Uint8List encrypted = encryptionCipher.process(UTF8.encode(message));
+
+  print("Encrypted: \n" + HEX.encode(encrypted));


Lower cased hex.

Cretezy · 2018-08-17T00:07:38Z

example/aes.dart

+
+  BlockCipher decryptionCipher = new PaddedBlockCipher("AES/CBC/PKCS7");
+  decryptionCipher.init(false, params);
+  String decrypted = UTF8.decode(decryptionCipher.process(encrypted));


utf8 again

Cretezy · 2018-08-17T00:08:25Z

example/aes.dart

+import "dart:convert";
+import "dart:typed_data";
+
+import "package:hex/hex.dart";


No need, use standard library (included in dart:convert).

I can't seem to find hex in here: https://api.dartlang.org/stable/2.0.0/dart-convert/dart-convert-library.html

Cretezy · 2018-08-17T00:08:34Z

pubspec.yaml

@@ -16,6 +16,7 @@ dependencies:
 dev_dependencies:
  benchmark_harness: ">=1.0.4 <2.0.0"
  browser: ">=0.9.0 <0.10.0"
+  hex: ">=0.1.1 <1.0.0"


Use stdlib.

stevenroose · 2018-08-19T13:33:02Z

If you want, I'd accept a PR from you with the suggested changes :)

stevenroose · 2018-10-04T15:30:47Z

If someone could review the example, that would be appreciated!

Cretezy · 2018-10-04T15:43:21Z

I'll take a good look and fix/add to it when I have time! I have yet to upgrade to the newer version of the registry (was using the "take 1" re-implementation).

hoboris · 2018-10-23T00:04:01Z

Apologies for hijacking this pull request. I used your example code to encrypt a message with aes 256 and md5

// Key must be multiple of block size (16 bytes).
    var key = new Digest("MD5").process(
        utf8.encode("correcthorsebatterystaple"));
    // Can be anything.
    var message = "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed d o eiusmod tempor incididunt ut labore et dolore magna aliqua.";
    // The initialization vector must be unique for every message, so it is a
    // good idea to use a message digest as the IV.
    // IV must be equal to block size (16 bytes).
    var iv = new Digest("MD5").process(utf8.encode(message)).sublist(0, 16);
    // The parameters your cipher will need. (PKCS7 does not need params.)
    CipherParameters params = new PaddedBlockCipherParameters(
        new ParametersWithIV(new KeyParameter(key), iv), null);
    print("Message: \n$message");
    ////////////////
    // Encrypting //
    ////////////////
    // As for why you would need CBC mode and PKCS7 padding, consult the internet
    // (f.e. http://www.di-mgt.com.au/properpassword.html).
    BlockCipher encryptionCipher = new PaddedBlockCipher("AES/CBC/PKCS7");
    encryptionCipher.init(true, params);
    Uint8List encrypted = encryptionCipher.process(utf8.encode(message));
    print("Encrypted: \n" + HEX.encode(encrypted));

It does decrypt well with your decryption method. But I tried to decrypt it with openssl with

echo "$encrypted" | openssl enc -d -aes-256-cbc -k $key -a -md md5
encrypted being the hexa encrypted message

But I get a bad magic number error. Am I mising something ?

stevenroose · 2018-10-23T11:55:03Z

I have no idea, tbh. Did that command work with an openssl encrypted message? (f.e. echo adds a newline, not sure if that could break things -- try printf)

It's quite possible that there is an issue with our implementation that we're not aware off. Did you try decrypting with BouncyCastle, f.e.?

hoboris · 2018-10-29T23:59:14Z

I have just tried with javax.crypto library and it is the same, so it must be something else I haven't figured out yet, but the problem does not lie with with PointyCastle or your example.

guoyuanzhuang · 2019-01-15T09:58:48Z

@Cretezy AES result is different with Java.
`public class AESUtil {

private static String AES_ALGORITHM = "AES/ECB/PKCS5Padding";
private static String CHAR_ENCODING = "UTF-8";

public static byte[] encrypt(byte[] data, byte[] key) {
	try {
		SecretKeySpec secretKey = new SecretKeySpec(key, "AES");
		byte[] enCodeFormat = secretKey.getEncoded();
		SecretKeySpec seckey = new SecretKeySpec(enCodeFormat, "AES");
		Cipher cipher = Cipher.getInstance(AES_ALGORITHM);
		cipher.init(Cipher.ENCRYPT_MODE, seckey);
		byte[] result = cipher.doFinal(data);
		return result; // 加密
	} catch (Exception e) {
		e.printStackTrace();
	}
	return null;
}

public static byte[] decrypt(byte[] data, byte[] key) {
	try {
		SecretKeySpec secretKey = new SecretKeySpec(key, "AES");
		byte[] enCodeFormat = secretKey.getEncoded();
		SecretKeySpec seckey = new SecretKeySpec(enCodeFormat, "AES");
		Cipher cipher = Cipher.getInstance(AES_ALGORITHM);
		cipher.init(Cipher.DECRYPT_MODE, seckey);
		byte[] result = cipher.doFinal(data);
		return result; // 加密
	} catch (Exception e) {
		e.printStackTrace();
	}
	return null;
}

public static String encrypt(String data, String key) {
	try {
		byte[] valueByte = encrypt(data.getBytes(CHAR_ENCODING),
				key.getBytes(CHAR_ENCODING));
		return new String(Base64.encode(valueByte, Base64.DEFAULT));
	} catch (Exception e) {
		e.printStackTrace();
	}
	return null;
}

public static String decrypt(String data, String key) {
	try {
		byte[] originalData = Base64.decode(data.getBytes(), Base64.DEFAULT);
		byte[] valueByte = decrypt(originalData,
				key.getBytes(CHAR_ENCODING));
		return new String(valueByte, CHAR_ENCODING);
	} catch (UnsupportedEncodingException e) {
		e.printStackTrace();
	}
	return null;
}

public static String parseByte2HexStr(byte buf[]) {
	StringBuffer sb = new StringBuffer();
	for (int i = 0; i < buf.length; i++) {
		String hex = Integer.toHexString(buf[i] & 0xFF);
		if (hex.length() == 1) {
			hex = '0' + hex;
		}
		sb.append(hex.toUpperCase());
	}
	return sb.toString();
}

}
`
What went wrong? thank you

guoyuanzhuang · 2019-01-16T11:00:13Z

It's solved
thank you

SopheapSK · 2019-04-20T08:56:49Z

@Cretezy AES result is different with Java.
`public class AESUtil {

private static String AES_ALGORITHM = "AES/ECB/PKCS5Padding";
private static String CHAR_ENCODING = "UTF-8";

public static byte[] encrypt(byte[] data, byte[] key) {
	try {
		SecretKeySpec secretKey = new SecretKeySpec(key, "AES");
		byte[] enCodeFormat = secretKey.getEncoded();
		SecretKeySpec seckey = new SecretKeySpec(enCodeFormat, "AES");
		Cipher cipher = Cipher.getInstance(AES_ALGORITHM);
		cipher.init(Cipher.ENCRYPT_MODE, seckey);
		byte[] result = cipher.doFinal(data);
		return result; // 加密
	} catch (Exception e) {
		e.printStackTrace();
	}
	return null;
}

public static byte[] decrypt(byte[] data, byte[] key) {
	try {
		SecretKeySpec secretKey = new SecretKeySpec(key, "AES");
		byte[] enCodeFormat = secretKey.getEncoded();
		SecretKeySpec seckey = new SecretKeySpec(enCodeFormat, "AES");
		Cipher cipher = Cipher.getInstance(AES_ALGORITHM);
		cipher.init(Cipher.DECRYPT_MODE, seckey);
		byte[] result = cipher.doFinal(data);
		return result; // 加密
	} catch (Exception e) {
		e.printStackTrace();
	}
	return null;
}

public static String encrypt(String data, String key) {
	try {
		byte[] valueByte = encrypt(data.getBytes(CHAR_ENCODING),
				key.getBytes(CHAR_ENCODING));
		return new String(Base64.encode(valueByte, Base64.DEFAULT));
	} catch (Exception e) {
		e.printStackTrace();
	}
	return null;
}

public static String decrypt(String data, String key) {
	try {
		byte[] originalData = Base64.decode(data.getBytes(), Base64.DEFAULT);
		byte[] valueByte = decrypt(originalData,
				key.getBytes(CHAR_ENCODING));
		return new String(valueByte, CHAR_ENCODING);
	} catch (UnsupportedEncodingException e) {
		e.printStackTrace();
	}
	return null;
}

public static String parseByte2HexStr(byte buf[]) {
	StringBuffer sb = new StringBuffer();
	for (int i = 0; i < buf.length; i++) {
		String hex = Integer.toHexString(buf[i] & 0xFF);
		if (hex.length() == 1) {
			hex = '0' + hex;
		}
		sb.append(hex.toUpperCase());
	}
	return sb.toString();
}

}
`
What went wrong? thank you

my code in java is exactly the same as yours. but I still cannot find the way to configure code in dart to work as java yet. the result is different.

simbados · 2019-09-04T11:00:45Z

example/aes.dart

+  // The initialization vector must be unique for every message, so it is a
+  // good idea to use a message digest as the IV.
+  // IV must be equal to block size (16 bytes).
+  var iv = new Digest("SHA-256").process(utf8.encode(message)).sublist(0, 16);


Taking the hash of the plaintext for the IV might not be a good idea, as it leaks information about the plaintext. If the text is encrypted twice the IV will be the same. Might be better to use a PRNG.

izaera · 2020-12-23T09:16:06Z

I'm archiving this repo as per #239 (see the issue for more info).

Cretezy suggested changes Aug 17, 2018

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stevenroose force-pushed the aes-example branch from 2a6412f to 9974354 Compare October 4, 2018 15:30

Add an AES encryption and decryption example

9974354

This was referenced Oct 4, 2018

AES result is different with aes-js or nodejs #154

Closed

AES Encrypt、Decrypt #142

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Add an AES encryption and decryption example #111

Add an AES encryption and decryption example #111

stevenroose commented Jan 27, 2017

Cretezy left a comment

Cretezy Aug 17, 2018

Cretezy Aug 17, 2018

Cretezy Aug 17, 2018

Cretezy Aug 17, 2018

Cretezy Aug 17, 2018

stevenroose Sep 14, 2018

Cretezy Aug 17, 2018

stevenroose commented Aug 19, 2018

stevenroose commented Oct 4, 2018

Cretezy commented Oct 4, 2018

hoboris commented Oct 23, 2018 •

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stevenroose commented Oct 23, 2018

hoboris commented Oct 29, 2018 •

edited

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guoyuanzhuang commented Jan 15, 2019

guoyuanzhuang commented Jan 16, 2019

SopheapSK commented Apr 20, 2019

simbados Sep 4, 2019

izaera commented Dec 23, 2020

Add an AES encryption and decryption example #111

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Add an AES encryption and decryption example #111

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stevenroose commented Jan 27, 2017

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stevenroose commented Aug 19, 2018

stevenroose commented Oct 4, 2018

Cretezy commented Oct 4, 2018

hoboris commented Oct 23, 2018 • edited Loading

stevenroose commented Oct 23, 2018

hoboris commented Oct 29, 2018 • edited Loading

guoyuanzhuang commented Jan 15, 2019

guoyuanzhuang commented Jan 16, 2019

SopheapSK commented Apr 20, 2019

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izaera commented Dec 23, 2020

hoboris commented Oct 23, 2018 •

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hoboris commented Oct 29, 2018 •

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