Definition - What does Initialization Vector mean?
An initialization vector is a random number used in combination with a secret key as a means to encrypt data. This number is sometimes referred to as a nonce, or “number occuring once,” as an encryption program uses it only once per session.
Techopedia explains Initialization Vector
An initialization vector is used to avoid repetition during the data encryption process, making it impossible for hackers who use dictionary attack to decrypt the exchanged encrypted message by discovering a pattern.
A particular binary sequence may be repeated more than once in a message, and the more it appears, the more the encryption method is discoverable. For example if a one-letter word exists in a message, it may be either “a” or “I” but it can’t be “e” because the word “e” is non-sensical in English, while “a” has a meaning and “I” has a meaning. Repeating the words and letters makes it possible for software to apply a dictionary and discover the binary sequence corresponding to each letter.
Using an initialization vector changes the binary sequence corresponding to each letter, enabling the letter “a” to be represented by a particular sequence in the first instance, and then represented by a completely different binary sequence in the second instance.