見つけました!
<script type="text/javascript" src="http://crypto-js.googlecode.com/files/2.5.3-crypto-sha1-hmac-pbkdf2-blockmodes-DES.js"></script>
<script type="text/javascript">
// CBC with default padding scheme (iso7816)
var crypted = Crypto.DES.encrypt("Message", "Secret Passphrase", { mode: new Crypto.mode.CBC });
var plain = Crypto.DES.decrypt(crypted, "Secret Passphrase", { mode: new Crypto.mode.CBC });
// CBC with ansix923 padding scheme
var crypted = Crypto.DES.encrypt("Message", "Secret Passphrase", { mode: new Crypto.mode.CBC(Crypto.pad.ansix923) });
var plain = Crypto.DES.decrypt(crypted, "Secret Passphrase", { mode: new Crypto.mode.CBC(Crypto.pad.ansix923) });
</script>