A pure JavaScript implementation of the AES block cipher algorithm and all common modes of operation (CBC, CFB, CTR, ECB and OFB).
- Pure JavaScript (with no dependencies)
- Supports all key sizes (128-bit, 192-bit and 256-bit)
- Supports all common modes of operation (CBC, CFB, CTR, ECB and OFB)
- Works in either node.js or web browsers
The utility functions have been renamed in the 3.x branch, since they were causing a great deal of confusion converting between bytes and string.
The examples have also been updated to encode binary data as printable hex strings.
Strings and Bytes
Strings should NOT be used as keys. UTF-8 allows variable length, multi-byte characters, so a string that is 16 characters long may not be 16 bytes long.
Also, UTF8 should NOT be used to store arbitrary binary data as it is a string encoding format, not a binary encoding format.
// aesjs.util.convertStringToBytes(aString)// Becomes:aesjs.utils.utf8.toBytes(aString)// aesjs.util.convertBytesToString(aString)// Becomes:aesjs.utils.utf8.fromBytes(aString)Bytes and Hex strings
Binary data, such as encrypted bytes, can safely be stored and printed as hexidecimal strings.
// aesjs.util.convertStringToBytes(aString, 'hex')// Becomes:aesjs.utils.hex.toBytes(aString)// aesjs.util.convertBytesToString(aString, 'hex')// Becomes:aesjs.utils.hex.fromBytes(aString)Typed Arrays
The 3.x and above versions of aes-js use Uint8Array instead of Array, which reduces code size when used with Browserify (it no longer pulls in Buffer) and is also about twice the speed.
However, if you need to support browsers older than IE 10, you should continue using version 2.x.
To install aes-js in your node.js project:
npm install aes-js And to access it from within node, simply add:
varaesjs=require('aes-js');To use aes-js in a web page, add the following:
<scripttype="text/javascript" src="https://cdn.rawgit.com/ricmoo/aes-js/e27b99df/index.js"></script>All keys must be 128 bits (16 bytes), 192 bits (24 bytes) or 256 bits (32 bytes) long.
The library work with Array, Uint8Array and Buffer objects as well as any array-like object (i.e. must have a length property, and have a valid byte value for each entry).
// 128-bit, 192-bit and 256-bit keysvarkey_128=[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15];varkey_192=[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23];varkey_256=[0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31];// or, you may use Uint8Array:varkey_128_array=newUint8Array(key_128);varkey_192_array=newUint8Array(key_192);varkey_256_array=newUint8Array(key_256);// or, you may use Buffer in node.js:varkey_128_buffer=Buffer.from(key_128);varkey_192_buffer=Buffer.from(key_192);varkey_256_buffer=Buffer.from(key_256);To generate keys from simple-to-remember passwords, consider using a password-based key-derivation function such as scrypt or bcrypt.
There are several modes of operations, each with various pros and cons. In general though, the CBC and CTR modes are recommended. The ECB is NOT recommended., and is included primarily for completeness.
// An example 128-bit key (16 bytes * 8 bits/byte = 128 bits)varkey=[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16];// Convert text to bytesvartext='Text may be any length you wish, no padding is required.';vartextBytes=aesjs.utils.utf8.toBytes(text);// The counter is optional, and if omitted will begin at 1varaesCtr=newaesjs.ModeOfOperation.ctr(key,newaesjs.Counter(5));varencryptedBytes=aesCtr.encrypt(textBytes);// To print or store the binary data, you may convert it to hexvarencryptedHex=aesjs.utils.hex.fromBytes(encryptedBytes);console.log(encryptedHex);// "a338eda3874ed884b6199150d36f49988c90f5c47fe7792b0cf8c7f77eeffd87// ea145b73e82aefcf2076f881c88879e4e25b1d7b24ba2788"// When ready to decrypt the hex string, convert it back to bytesvarencryptedBytes=aesjs.utils.hex.toBytes(encryptedHex);// The counter mode of operation maintains internal state, so to// decrypt a new instance must be instantiated.varaesCtr=newaesjs.ModeOfOperation.ctr(key,newaesjs.Counter(5));vardecryptedBytes=aesCtr.decrypt(encryptedBytes);// Convert our bytes back into textvardecryptedText=aesjs.utils.utf8.fromBytes(decryptedBytes);console.log(decryptedText);// "Text may be any length you wish, no padding is required."// An example 128-bit keyvarkey=[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16];// The initialization vector (must be 16 bytes)variv=[21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36];// Convert text to bytes (text must be a multiple of 16 bytes)vartext='TextMustBe16Byte';vartextBytes=aesjs.utils.utf8.toBytes(text);varaesCbc=newaesjs.ModeOfOperation.cbc(key,iv);varencryptedBytes=aesCbc.encrypt(textBytes);// To print or store the binary data, you may convert it to hexvarencryptedHex=aesjs.utils.hex.fromBytes(encryptedBytes);console.log(encryptedHex);// "104fb073f9a131f2cab49184bb864ca2"// When ready to decrypt the hex string, convert it back to bytesvarencryptedBytes=aesjs.utils.hex.toBytes(encryptedHex);// The cipher-block chaining mode of operation maintains internal// state, so to decrypt a new instance must be instantiated.varaesCbc=newaesjs.ModeOfOperation.cbc(key,iv);vardecryptedBytes=aesCbc.decrypt(encryptedBytes);// Convert our bytes back into textvardecryptedText=aesjs.utils.utf8.fromBytes(decryptedBytes);console.log(decryptedText);// "TextMustBe16Byte"// An example 128-bit keyvarkey=[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16];// The initialization vector (must be 16 bytes)variv=[21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36];// Convert text to bytes (must be a multiple of the segment size you choose below)vartext='TextMustBeAMultipleOfSegmentSize';vartextBytes=aesjs.utils.utf8.toBytes(text);// The segment size is optional, and defaults to 1varsegmentSize=8;varaesCfb=newaesjs.ModeOfOperation.cfb(key,iv,segmentSize);varencryptedBytes=aesCfb.encrypt(textBytes);// To print or store the binary data, you may convert it to hexvarencryptedHex=aesjs.utils.hex.fromBytes(encryptedBytes);console.log(encryptedHex);// "55e3af2638c560b4fdb9d26a630733ea60197ec23deb85b1f60f71f10409ce27"// When ready to decrypt the hex string, convert it back to bytesvarencryptedBytes=aesjs.utils.hex.toBytes(encryptedHex);// The cipher feedback mode of operation maintains internal state,// so to decrypt a new instance must be instantiated.varaesCfb=newaesjs.ModeOfOperation.cfb(key,iv,8);vardecryptedBytes=aesCfb.decrypt(encryptedBytes);// Convert our bytes back into textvardecryptedText=aesjs.utils.utf8.fromBytes(decryptedBytes);console.log(decryptedText);// "TextMustBeAMultipleOfSegmentSize"// An example 128-bit keyvarkey=[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16];// The initialization vector (must be 16 bytes)variv=[21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36];// Convert text to bytesvartext='Text may be any length you wish, no padding is required.';vartextBytes=aesjs.utils.utf8.toBytes(text);varaesOfb=newaesjs.ModeOfOperation.ofb(key,iv);varencryptedBytes=aesOfb.encrypt(textBytes);// To print or store the binary data, you may convert it to hexvarencryptedHex=aesjs.utils.hex.fromBytes(encryptedBytes);console.log(encryptedHex);// "55e3af2655dd72b9f32456042f39bae9accff6259159e608be55a1aa313c598d// b4b18406d89c83841c9d1af13b56de8eda8fcfe9ec8e75e8"// When ready to decrypt the hex string, convert it back to bytesvarencryptedBytes=aesjs.utils.hex.toBytes(encryptedHex);// The output feedback mode of operation maintains internal state,// so to decrypt a new instance must be instantiated.varaesOfb=newaesjs.ModeOfOperation.ofb(key,iv);vardecryptedBytes=aesOfb.decrypt(encryptedBytes);// Convert our bytes back into textvardecryptedText=aesjs.utils.utf8.fromBytes(decryptedBytes);console.log(decryptedText);// "Text may be any length you wish, no padding is required."This mode is not recommended. Since, for a given key, the same plaintext block in produces the same ciphertext block out, this mode of operation can leak data, such as patterns. For more details and examples, see the Wikipedia article, Electronic Codebook.
// An example 128-bit keyvarkey=[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16];// Convert text to bytesvartext='TextMustBe16Byte';vartextBytes=aesjs.utils.utf8.toBytes(text);varaesEcb=newaesjs.ModeOfOperation.ecb(key);varencryptedBytes=aesEcb.encrypt(textBytes);// To print or store the binary data, you may convert it to hexvarencryptedHex=aesjs.utils.hex.fromBytes(encryptedBytes);console.log(encryptedHex);// "a7d93b35368519fac347498dec18b458"// When ready to decrypt the hex string, convert it back to bytesvarencryptedBytes=aesjs.utils.hex.toBytes(encryptedHex);// Since electronic codebook does not store state, we can// reuse the same instance.//var aesEcb = new aesjs.ModeOfOperation.ecb(key);vardecryptedBytes=aesEcb.decrypt(encryptedBytes);// Convert our bytes back into textvardecryptedText=aesjs.utils.utf8.fromBytes(decryptedBytes);console.log(decryptedText);// "TextMustBe16Byte"You should usually use one of the above common modes of operation. Using the block cipher algorithm directly is also possible using ECB as that mode of operation is merely a thin wrapper.
But this might be useful to experiment with custom modes of operation or play with block cipher algorithms.
// the AES block cipher algorithm works on 16 byte bloca ks, no more, no lessvartext="ABlockIs16Bytes!";vartextAsBytes=aesjs.utils.utf8.toBytes(text)console.log(textAsBytes);// [65, 66, 108, 111, 99, 107, 73, 115, 49, 54, 66, 121, 116, 101, 115, 33]// create an instance of the block cipher algorithmvarkey=[3,1,4,1,5,9,2,6,5,3,5,8,9,7,9,3];varaes=newaesjs.AES(key);// encrypt...varencryptedBytes=aes.encrypt(textAsBytes);console.log(encryptedBytes);// [136, 15, 199, 174, 118, 133, 233, 177, 143, 47, 42, 211, 96, 55, 107, 109] // To print or store the binary data, you may convert it to hexvarencryptedHex=aesjs.utils.hex.fromBytes(encryptedBytes);console.log(encryptedHex);// "880fc7ae7685e9b18f2f2ad360376b6d"// When ready to decrypt the hex string, convert it back to bytesvarencryptedBytes=aesjs.utils.hex.toBytes(encryptedHex);// decrypt...vardecryptedBytes=aes.decrypt(encryptedBytes);console.log(decryptedBytes);// [65, 66, 108, 111, 99, 107, 73, 115, 49, 54, 66, 121, 116, 101, 115, 33]// decode the bytes back into our original textvardecryptedText=aesjs.utils.utf8.fromBytes(decryptedBytes);console.log(decryptedText);// "ABlockIs16Bytes!"This seems to be a point of confusion for many people new to using encryption. You can think of the key as the "password". However, these algorithms require the "password" to be a specific length.
With AES, there are three possible key lengths, 128-bit (16 bytes), 192-bit (24 bytes) or 256-bit (32 bytes). When you create an AES object, the key size is automatically detected, so it is important to pass in a key of the correct length.
Often, you wish to provide a password of arbitrary length, for example, something easy to remember or write down. In these cases, you must come up with a way to transform the password into a key of a specific length. A Password-Based Key Derivation Function (PBKDF) is an algorithm designed for this exact purpose.
Here is an example, using the popular (possibly obsolete?) pbkdf2:
varpbkdf2=require('pbkdf2');varkey_128=pbkdf2.pbkdf2Sync('password','salt',1,128/8,'sha512');varkey_192=pbkdf2.pbkdf2Sync('password','salt',1,192/8,'sha512');varkey_256=pbkdf2.pbkdf2Sync('password','salt',1,256/8,'sha512');Another possibility, is to use a hashing function, such as SHA256 to hash the password, but this method is vulnerable to Rainbow Attacks, unless you use a salt.
Todo...
A test suite has been generated (test/test-vectors.json) from a known correct implementation, pycrypto. To generate new test vectors, run python generate-tests.py.
To run the node.js test suite:
npm test To run the web browser tests, open the test/test.html file in your browser.
E-mail me at [email protected] with any questions, suggestions, comments, et cetera.
Obviously, it's all licensed under the MIT license, so use it as you wish; but if you'd like to buy me a coffee, I won't complain. =)
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