AES Voice Encryption

1
AES Voice Encryption

• Group 228
• Steve Jones
• Jeremy Graham
• Jacob Wirtzfeld
• Advisor Dr. Rajendra Katti

2
Main Highlights

• Goal
• Solution
• Block Diagram
• AES 128
• Flow Charts

• Budget
• Testing
• Demonstration
• Future Implementation

3
Goal

• Capture Voice Signal
• Encrypt Voice Signal Using AES
• Output Encrypted Signal
• Decrypt Signal
• Output Original Voice Signal

4
Solution

• Input Voice into PC
• Save File
• Encrypt Signal (use C to implement AES )
• Save File
• Decrypt (using C)
• Save File
• Output Voice

5
Block Diagram
Input -Microphone
PC
Power
Save
Encrypt
Save
Decrypt
Save
Output -Speaker
6
AES 128

• Add Round Key
• Sub Bytes
• Shift Rows
• Mix Columns

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Add Round Key

• State State Key

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Sub Bytes

• bibi b(i4)mod8 b(i5)mod8 b(i6)mod8
  b(i6)mod8 b(i7)mod8 ci
• Where ci63 in Hex or 01100011 in Binary

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Shift Rows
10
Mix Columns
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Encryption Algorithm Consists of 10 Rounds

• Main Round
• Sub Bytes
• Shift Rows
• Mix Columns
• Add Round Key

• Algorithm
• 1. Add Round Key
• 2. Main Round 9xs
• 3. Main Round without Mix Columns Command

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Encryption Flow Chart
Input
Add Round Key
Sub Bytes
Shift Rows
No
Mix Columns
10th Time?
Yes
Add Round Key
Save
13
Inverse Shift Rows
14
Inverse Sub Bytes
15
Inverse Mix Columns
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Decryption Algorithm Consists of 10 Rounds

• Main Round
• Inverse Shift Rows
• Inverse Sub Bytes
• Add Round Key
• Inverse Mix Columns

• Algorithm
• 1. Add Round Key
• 2. Main Round 9xs
• 3. Main Round without Inverse Mix Columns Command

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Decryption Flow Chart
Input
Add Round Key
Inv Shift Row
Inv Sub Bytes
Add Round Key
No
Mix Columns
10th Time?
Yes
Save
18
Sampling Voice

• Used MATLAB
• wavread(file.wav)
• wavwrite(file.wav)
• Samples between -1 and 1
• (Data 1) 128

19
Budget

• Cost
• Speaker- 49.99
• Microphone- 11.49
• -------------------------------------------
• Total/unit 61.48

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Testing and Evaluation

• Testing Encryption
• Testing Decryption
• Testing with wrong Key
• Testing with Errors

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Plots
Original Decrypted
22
Encrypted Decrypted with Wrong Key
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Original vs. Decrypted
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Demo

• Original
• Mixed
• Final
• Wrong Key

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Problems

• Change of Requirements
• Capturing a voice signal as an array
• C multiplication in mix columns

26
Future Work
Real Time Wireless Transmission

• Advanced Key Exchange Protocol
• Fast
• Processor
• A/D D/A Converters
• High Quality Microphone
• Slight change in Code

27
Thank you for listening.
http//snrdes2.ece.ndsu.nodak.edu/grp228