If the length of iv is less than 16, how does 'crypto-js' pad it (make the iv length expanded to the length of 16)

[ZHAO-Clara]

If the length of iv is less than 16, how does 'crypto-js' pad it (make the iv length expanded to the length of 16)？

for example i use the following code, what is the ’iv‘ actually used during the encryption process? like '432100000000'?

const CryptoJS = require('crypto-js')
const key = CryptoJS.enc.Utf8.parse('12345678ABCD')
const iv = CryptoJS.enc.Utf8.parse('4321')
let srcs = CryptoJS.enc.Utf8.parse(word)
let encrypted = CryptoJS.AES.encrypt(srcs, key, { iv: iv, mode: CryptoJS.mode.CBC, padding: CryptoJS.pad.Pkcs7 })

Thank you so much

[ZHAO-Clara]

I have the answer. Actually it uses the "null" in ascii to pad iv, in other words, 0x00 in Hex.