The document describes the Advanced Encryption Standard (AES) algorithm. AES uses 128, 192, or 256-bit secret keys to encrypt plaintext into ciphertext. It operates on bytes and arranges them in a two-dimensional array called the state. The algorithm consists of 10 to 14 rounds depending on the key size, with each round comprising four processing steps: SubBytes, ShiftRows, MixColumns, and AddRoundKey. The final round is slightly different by omitting the MixColumns step.

1. ADVANCED ENCRYPTION
STANDARD
AES
FIPS-197
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3. AES Design
128 bit
Secret Key
192 bit
Plain Text
256 bit
Cipher
128 bit
192 bit
Cipher Text
256 bit
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4. Bytes
• The basic unit for processing in the AES
algorithm is a byte.
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5. Array of Bytes
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6. The State
• Internally, the AES algorithm’s operations are
performed on a two-dimensional array of
bytes called the State
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7. Rounds
• 10, 12, 14 rounds for 128, 192, 256 bit keys
– Regular Rounds (9, 11, 13)
Sub
– Final Round is different (10th, 12th, 14thBytes
)
ShiftRows
Rounds
MixColumns
AddRoundKey
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8. AES Design Flow
Plaintext (128)
AddROundKey
Subkey0
9 rounds
ByteSub
ShiftRow
Mix Column
Ciphertext (128)
AddRoundKey
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Subkey10

9. AES cipher
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10. The SubBytes Step
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11. The ShiftRows Step
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12. The Mix Column Step
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13. The AddRoundKey step
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14. Inverse Cipher
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InvShiftRows()
InvSubBytes()
InvMixColumns()
AddRoundKey()
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15. References
• fips-197
• Wiki
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16. More Protocol Tutorials
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SSL Protocol Click here
DHCPv6 Protocol Click Here
CHAP Protocol Click Here
ISCSI Protocol Tutorial Click Here
BGP Tutorial Click Here
RADIUS Protocol Click Here
PPP Protocol Click Here
PPPoE Protocol Click Here
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