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Tony Nguyen. Symmetric key encryption performance analysis. Symmetric vs. Asymmetric. Symmetric encryption: known as secret key cryptography, which requires the sender and receiver of a message to share the use of a single, common key for encryption and decryption.

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symmetric vs asymmetric
Symmetric vs. Asymmetric
  • Symmetric encryption: known as secret key cryptography, which requires the sender and receiver of a message to share the use of a single, common key for encryption and decryption.
  • Asymmetric encryption: known as public key cryptography, which employs two keys: public key to encrypt message and private key to decrypt them.
  • Advantages: Symmetric encryption is much faster than asymmetric and required less computation power.
  • Disadvantages: Private key must be shared among parties involved encryption and decryption.

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symmetric vs asymmetric 2
Symmetric vs. Asymmetric [2]

[KetuFile White Papers]

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data encryption standard des
Data Encryption Standard (DES)
  • Invented in 1976 by IBM based on the Lucifer Algorithm.
  • Original key size was 128 bits but reduced to 56 bits. (NSA controversy)
  • Encrypts and decrypts data in 64-bit blocks.
  • Total keys = 2 ^ 56 = 72,057,594,037,927,936.
  • Broken by brute force attack using DES Crackers within 22 hours. (245 billion keys/sec)

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key generation
Key Generation

Permutation

  • Initial input key for DES is 64 bits long.
  • Right most bit is parity big and it is being ignored.
  • Pass through permutation and produced 56 bits key length.

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generate sub keys
Generate sub-keys
  • Use 56-bit key to generate 16 48-bit sub-keys.
  • Use 16 48-bit sub-keys to encrypt and decrypt 16 rounds for DES.
  • Current 56-bit keys split into two 28-bit blocks left and right.
  • Rotate left and right by the number of bits specified in the table.
  • Join left and right to get the new K.
  • Apply Permuted Choice 2 to get the final sub-key.

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plaintext preparation
Plaintext Preparation
  • Passing plain text through a permutation called the Initial Permutation.
  • Then pass it through the Final Permutation or Inverse Initial Permutation.

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des core function
DES Core Function
  • 64-bit block of input data split into two halves, L and R.
  • Data from R[I-1] is XOR with K[I] (16 sub-keys) and stored in the buffer.
  • Data is split into 8 segments of 6 bits each and submit to S-boxes.
  • Results passed into the Permutation.
  • Data is now XOR with L[I-1] and moved into R[I]. R[I-1] is moved into L[I].
  • Repeat the core function until we have completed 16 rounds.
  • When L[16] and R[16] obtained, they join back in the same fashion as they were split apart.
  • Apply the Inverse Permutation to the pre-output which results in encrypted text.

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modes of operation
Modes of Operation
  • Electronic Code Book (ECB): Data is divided into 64-bit blocks and encrypted one at a time. It is fastest and easy to implement but cannot detect re-order contents.
  • Cipher Block Chaining (CBC): Each block of encrypted cipher text is XOR with the next plaintext block. All blocks dependent on previous blocks. More secure than ECB because the extra XOR step.

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triple des
Triple DES
  • Similar to DES.
  • Invented by IBM in 1978.
  • Encrypts and decrypts data in 64-bit blocks.
  • Key size: 192 bits.
  • Modes of Operation: ECB and CBC.
  • Very secure if implemented correctly.
  • Safe to use until 2035.

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blowfish
Blowfish
  • Invented in 1993 by Bruce Schneier.
  • 64-bit block cipher.
  • Key length: 32 to 448 bits.
  • No effective cryptanalysis on the full-round version of Blowfish as of 2008.

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advanced encryption standard aes
Advanced Encryption Standard (AES)
  • Invented by Vincent Rijmen and Joan Daemen in 1998.
  • Encrypts and decrypts data in 128-bit blocks.
  • Key size: 128, 192 or 256 bits.
  • Structure: substitution-permutation network.
  • Most popular and secure for symmetric key cryptography.
  • No effective cryptanalysis of it has been found to date.

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slide13

Milliseconds

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slide14

Milliseconds

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slide15
Demo
  • Java GUI application.
  • Java Security Library.
  • Maximum file size: 50 MB
  • File restriction: Jar file
  • Algorithms: DES, 3DES, Blowfish, AES

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references
References
  • DES Encryption, http://www.tropsoft.com/strongenc/des.htm
  • Triple Data Encryption Standard (TDES), http://www.vocal.com/tdes.html
  • The Blowfish Encryption Algorithm, http://www.schneier.com/blowfish.html
  • The Advanced Encryption Standard (Rijndael), http://www.quadibloc.com/crypto/co040401.htm
  • The Enduring Value of Symmetric Encryption, http://etoken.mikrobeta.com.tr/PDF/WP-SymmetricEncryption.pdf
  • KetuFile White Papers,

http://www.ketufile.com/Symmetric_vs_Asymmetric_Encryption.pdf

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