Original Name - Rijndael

Efficient Algorithm that supports both hardware & Software

Supports a block length of 128 bits data and key lengths of 128, 192, and 256 bits.

Supersedes DES – Data Encryption Standard

Supports Symmetric key Encryption.

Result of the encryption is base64 encoded to prevent character encoding problems.

AES encryption is used by U.S. for securing sensitive but unclassified material, so we can say it is enough secure.

Six time faster than triple DES.

It replaced DES as key size was too small (key length of 64 bits, however 8 bits are used for parity, therefore the effective key length is 56 bits.

based on ‘substitution–permutation network - series of linked operations, some of which involve replacing inputs by specific outputs (substitutions) and others involve shuffling bits around (permutations).

Performs all its computations on bytes rather than bits. Hence, AES treats the 128 bits of a plaintext block as 16 bytes. These 16 bytes are arranged in four columns and four rows for processing as a matrix

The number of rounds in AES is variable and depends on the length of the key. AES uses 10 rounds for 128-bit keys, 12 rounds for 192-bit keys and 14 rounds for 256-bit keys. Each of these rounds uses a different 128-bit round key, which is calculated from the original AES key

four processes conducted – [Add round key -Mix columns -Shift rows -Byte substitution]

Decryption – Reverse process –[ Byte substitution - Shift rows - Mix columns Add round key ]

Built-in flexibility of key length, which allows a degree of ‘future-proofing’ against progress in the ability to perform exhaustive key searches.

What are AES – Modes

Procedural rules for a generic block cipher. Different modes of operation of a block cipher.

Different modes result in different properties being achieved which add to the security of the underlying block cipher.

Modes are - ECB, CBC, CFB, OFB, CTR

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