function CryptoJSAesDecrypt(passphrase,encrypted_json_string){
var obj_json = JSON.parse(encrypted_json_string);
var encrypted = obj_json.ciphertext;
var salt = CryptoJS.enc.Hex.parse(obj_json.salt);
var iv = CryptoJS.enc.Hex.parse(obj_json.iv);
var key = CryptoJS.PBKDF2(passphrase, salt, { hasher: CryptoJS.algo.SHA512, keySize: 64/8, iterations: 999});
var decrypted = CryptoJS.AES.decrypt(encrypted, key, { iv: iv});
return decrypted.toString(CryptoJS.enc.Utf8);
}
console.log(CryptoJSAesDecrypt('your passphrase','<?php echo $string_json_fromPHP?>'));