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What is the use of IV in AES?
The AES-CTR algorithm involves encryption of Initialization Vector (IV) with a secret key for generation of ciphertext. A unique IV is required in the AES-CTR algorithm for maintaining the secrecy of data and generation of unique ciphertext.
What is the need to encrypt IV in CBC mode?
The IV need not be secret; however, for the CBC and CFB modes, the IV for any particular execution of the encryption process must be unpredictable, and, for the OFB mode, unique IVs must be used for each execution of the encryption process. In Electronic Codebook (ECB) mode, each block is encrypted independently.
When to use a mode instead of an AES?
(The core AES operation only works on 16-byte blocks. A mode is a way to extend this to longer messages.) For example, with CBC, the encryption of each block is computed from the key, the plaintext block and the ciphertext of the previous block; for the very first block, the IV is used instead of the ciphertext…
Do you need an IV for each encrypted message?
If you use a key multiple times you should use a different IV each time, so a (key, IV) pair isn’t reused. The exact requirements for the IV depend on the chosen chaining mode, but a random 128 bit value is usually fine. It should be different for each message you encrypt.
Do you need a different IV for each key?
If you use a key multiple times you should use a different IV each time, so a (key, IV) pair isn’t reused. The exact requirements for the IV depend on the chosen chaining mode, but a random 128 bit value is usually fine. It should be different for each message you encrypt. Store it alongside the ciphertext, typically as a prefix.
How to find the unique prefix of a string?
The shortest unique prefix for first and last string can be found by comparing them with only 1 most similar neighbor on right and left, respectively. We can sort the array of strings and keep on doing this for every string of the array.