1

Comparative Survey of the PublicDomain Implementations of

Cryptography

Himabindu Sajja Shujia Gong Mengbing Shen

Objective

♦ Study three ciphers:

Triple DES, RC5 and RSA

♦ Find different implementations from publicdomain. Compare their performance.

♦ Analyze the advantage and disadvantage ofeach implementation

2

Testing Environment

♦ Windows

Pentium III 533MHz , 128M memory andWindows 2000

♦ Unix

Ultra 5, 256M memory and Sun Solaris 7.0

♦ C/C++ Visual C++ 6.0

♦ Java JDK1.3 (Win)/JDK1.1 (Unix)

Software design

Read in the file to alarge buffer

Call the en/decryption function toprocess the data buffer

Get startTime

Get endTimeElapsed=endTime-startTime

Write data to theoutput file

End

Start

3

Input and output

♦ Input file: large plain text file

♦ Intermediate file: encrypted file

♦ Output file: restore to plain text file

File size: 29,963,808 bytes (3DES, RC5)

1,100 bytes (RSA)

Time measurement

Precision: millisecond

Java:

long System.currentTimeMillis()

// Returns the current time inmilliseconds.

4

C/C++:ftime(struct timeb *timeptr)

struct timeb { time_t time;

//long, the seconds portion of the current time

unsigned short millitm;//the milliseconds portion of the current time

short timezone;//the local timezone in minutes west of Greenwich

short dstflag;//TRUE if Daylight Savings Time is in effect

};

Time measurement (cont.)

♦ Encryption and decryption:

Use large file to control the processing timein second.

Repeat testing for 3 times, record theaverage time for comparison.

5

Time measurement (cont.)

♦ Key generation and expansion:

Use loop, repeat for a 10000 times, get theaverage time.

For C/C++, insert some assembly code tomeasure the clock cycle.

Testing result

♦Triple DES

♦RC5

♦RSA

6

Libraries

♦ Ciphers.de www.ciphers.de/crypto (in C)implemented by by Richard Outerbridge

♦ Crypto++ version 4.1www.eskimo.com/~weidai/cryptlib.html(in C++)

♦ Acme www.acme.com (in Java)

♦ Cryptix www.cryptix.com (in Java)

DES-EDE3 and DES-EDE2

♦ DES-EDE3

C=EK3[DK2[EK1[P]]]

Effective key length is 168 bit

♦ DES-EDE2

C=EK1[DK2[EK1[P]]]

Effective key length is 112 bit

7

3DESKey generation (168 bit vs. 112 bit)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

C Crypto+ + Acme Crypt ix

milli

sec

ond

1 6 8 - b i t k e y 1 1 2 - b i t k e y

3DESEncryption (168 bit vs. 112 bit)

0 .0

0 .5

1 .0

1 .5

2 .0

2 .5

3 .0

C Crypt o+ + A c m e Crypt ix

Mb

yte

s/se

c

En c r y p t i o n ( 1 6 8 - b i t k e y ) En c r y p t i o n ( 1 1 2 - b i t k e y )

8

3DESDecryption (168 bit vs. 112 bit)

0 .0

0 .5

1 .0

1 .5

2 .0

2 .5

3 .0

C Crypt o+ + A c m e Crypt ix

Mb

yte

s/se

cDe c r y p t i o n ( 1 6 8 - b i t k e y ) De c r y p t i o n ( 1 1 2 - b i t k e y )

DES-EDE3Encryption and decryption

0 .0

0 .5

1 .0

1 .5

2 .0

2 .5

3 .0

C Crypt o+ + A c me Crypt ix

Mb

yte

s/se

c

En c r y p t i o n De c r y p t i o n

9

DES-EDE2Encryption and decryption

0 .0

0 .5

1 .0

1 .5

2 .0

2 .5

3 .0

C Crypt o+ + A c m e Crypt ix

Mb

yte

s/se

cEn c r y p t i o n De c r y p t i o n

DES-EDE3 vs. DES-EDE2

♦ Key generation speed

DES-EDE2 is 2/3 of DES-EDE3

♦ Encryption/decryption speed

Almost the same

DES-EDE3 is more secure while notspending much more time

10

Encryption vs. decryption

♦ Almost have the same speed

Encrytpion EDE Æ decryption DED

Feistel structure is completely reversible

C/C++ vs. Java

♦ Speed of C/C++ is 2-3 time fast as of Java

C/C++ is a compiled language

Java is an interpreter language

Java classes offer sophisticated features(not really required, resource consuming)

11

All the libraries

Ciphers.de www.ciphers.de/crypto (in C)

• Simple C program

• Use straightforward functions

• Only logical bit operations and shifting

• Combine the S-box and permutation toone lookup array SP-box

• Call the DES function 3 times to realizeDES-EDE

All the libraries (cont.)

Crypto++ 4. 1 (in C++)

• A library has all things

• Use class to implement each algorithm

• The triple-DES object instantiates 3different DES objects

• Optimization using specialized EDE. Iteliminate the intermediate IP and IP-1

12

All the libraries (cont.)

Acme (in Java)

• Java JCE (cryptography extension)

• Each algorithm is encapsulated in a class

• The tripleDES object instantiates 3 differentDES objects

• Apply the same algorithm as before

All the libraries (cont.)

Cryptix (in Java)

• Highly structural, complicated classinheritance relationship.

• Have more validation checks

• Easy to use for end users. Choose amongsuite names

13

Testing result

♦Triple DES

♦RC5

♦RSA

Libraries

♦ http://tirnanog.ls.fi.upm.es/Servicios/Software/ap_crypt/indice.html(There are two Cprograms in this library. One is written byJohn Kelsey, and the other is written byRSADSI)

♦ Java program was written by Shujia GONG

14

RC5 128 bits and RC5 168 bits♦ RC5 128 bits

C=EK [P]

Effective key length is 128 bit

♦ RC5 168 bits

C=EK[P]

Effective key length is 168 bit

RC5 is a flexible algorithm and its keyRC5 is a flexible algorithm and its keylength can be chosen to be 0 to 255 Octets.length can be chosen to be 0 to 255 Octets.

Comprehensive comparison on different libraries(128 bits)

Com prehensive Com parision: 128 bit ke ys

14.7212.17 12.52

8.01

15.50 15.26

43.66

2.63 2.03

73.56

1.38 1.02

0

10

20

30

40

50

60

70

80

Key Ex pans ion Encryption Decryption

Jo h n K e ls e y C p ro g ra m R S AD S I C p ro g ra m Ja va P ro g ra m in W in 2 0 0 0 Ja va in S u n

In µs In ΜΒ/s In ΜΒ/s

15

Comprehensive comparison on different libraries(168 bits)

Com pre he nsive com pa rision fo r 168 b its ke y

15.4211.87 12.63

14.2211.42 10.54

49.67

2 .60 2 .03

84

1 .39 1 .00

0

10

20

30

40

50

60

70

80

90

Key Expans ion Enc ry ption Dec ryp tion

Mic

rose

cond

s

John K els ey 's C program RS A DS I's C program Java on W in2000 Java on S un

In µs In ΜΒ/s In ΜΒ/s

Key Expansion (168 bit vs. 128 bit)

Ke y e x pa nsion , 128 b its vs. 168 b its

14 .72

8 .01

43 .66

73 .56

15 .42 14 .22

49 .67

84

0

10

20

30

40

50

60

70

80

90

John Ke ls ey 's C p rogram RS A DS I's C p rogram Jav a on W in2000 Jav a on S UN

Mic

rose

cond

s

128 b its 168 b its

16

Encryption (168 bit vs. 128 bit)

Encryption, 128 bits vs. 168 bits

12 .17

15 .50

2 .63

1 .38

11 .8711 .42

2 .60

1 .39

0 .00

2 .00

4 .00

6 .00

8 .00

10 .00

12 .00

14 .00

16 .00

18 .00

John K e ls ey 's C p rogram RS A DSI's C p rogram Jav a on W in2000 Jav a on S UN

Mic

rose

cond

s

128 bits 168 bitsMB/sec

Decryption (168 bit vs. 128 bit)

De cryp tion , 128 bits vs. 168 bits

1 2 .5 2

1 5 .2 6

2 .0 3

1 .0 2

1 2 .6 3

1 0 .5 4

2 .0 3

1 .0 0

0 .0 0

2 .0 0

4 .0 0

6 .0 0

8 .0 0

1 0 .0 0

1 2 .0 0

1 4 .0 0

1 6 .0 0

1 8 .0 0

Jo h n K e ls e y 's C p ro g r a m RS A DS I's C p ro g r a m Ja v a o n W in 2 0 0 0 Ja v a o n S UN

Mic

rose

cond

s

128 bits 168 bitsMB/sec

17

Encryption and decryption (128 bit key)

128 bits RC5

12 .17

15 .50

2 .63

1 .38

12 .52

15 .26

2 .03

1 .02

0 .00

2 .00

4 .00

6 .00

8 .00

10 .00

12 .00

14 .00

16 .00

18 .00

John Ke ls ey 's C p rogram RS A DS I's C p rogram Jav a on W in2000 Jav a on S UN

Mic

rose

cond

s

Enc ry p tion Dec ry p tionMB/sec

Encryption and decryption (168 bit key)

RC5 168 bits

11 .8711 .42

2 .60

1 .39

12 .63

10 .54

2 .03

1 .00

0 .00

2 .00

4 .00

6 .00

8 .00

10 .00

12 .00

14 .00

John Ke ls ey 's C p rogram RS A DS I's C p rogram Jav a on W in2000 Jav a on S UN

Mic

rose

cond

s

Enc ry p tion Dec ry p tionMB/sec

18

Encryption and decryption (168 bit key)

Java is a special program, because Java doesntsupport unsigned integer and unsigned char.Therefore, the subtraction operation indecryption takes longer time in Java

RC5 128 bits vs. 168 bits

♦ Key expansion speed128 bits key is faster than 168 bits key in mostcases

♦ Encryption/decryption speedalmost no change in most case.

Basically, the key length should not influence thespeed of encryption and decryption.

19

C vs. Java

♦ Speed of C is 5 times as fast as Java

C/C++ is a compiled language

Java is an interpreter language

Java classes offer sophisticated features(not really required, resource consuming)

All the libraries

♦ C program

http://tirnanog.ls.fi .upm.es/Servicios/Software/ap_crypt/indice.html(There are two C programs inthis library. One is written by John Kelsey, and theother is written by RSADSI)

• Simple C program• Use straightforward functions• Only logical bit operations, addition, substraction and

shifting♦ Java program

Written by Shujia GONG

20

Testing result

♦Triple DES

♦RC5

♦RSA

RSA:

• Analyze the public domain implementations ofRSA public Key cryptosystem.

• Analyze both Java and C or C++implementations and find out whichimplementations are faster.

• Choosing the Fastest implementation of all.

21

Implementations Found:

Java• Cryptix32-pgp:Written by Cryptix(www.cryptix.com).

• JRSA:Written by Jared T .Klett.

C• RSAref:Written by RSA laboratories(www.RSA.com).

C++• Crypto++4.1:Written by WeiDai(www.eskimo.com).

Timing diagram:

Key Generation:

0

5

10

15

20

25

30

768 1024 2048

RSARef( C )Crypto++( C++)

Key Length

Tim

e (se

cs)

22

Timing diagram:

Encryption: Decryption:

0

20

40

60

80

100

120

768 2048

RSARef(C )Crypto++(C++)

0

1

2

3

4

5

6

768 2048

RSARef(C )Crypto++( C++)

Key Length

Kbyte

/ sec

Key Length

Kbyte

/sec

Conclusions:

Key generation:• Cypto++ is faster

Reasons:• Crypto++ is precomputing some of the data to increase the

speed.

• Still needs some analyzing.

Encryption:• Crypto++ is faster.

Reasons:• Crypto++ is using assembly language for some operations like

add and subtract which speeds up the process by 10 to 20% .

23

Conclusions:

Decryption:• CRYPTO++ is faster.

Reasons:• Same as for encryption

Timing Diagrams:

Key generation:

0

20

40

60

80

100

120

128 512 768

JRSACRYPTIX

24

Timing Diagrams

Encryption: Decryption:

0

0.2

0.4

0.6

0.8

512

JRSA

CRYPTIX

0

0.05

0.1

0.15

0.2

512

JRSA

CRYPTIX

Key Length Key Length

Kbyte

/sec

Kbyte

/sec

Conclusions

Key Generation:• JRSA is faster

Reasons:• CRYPTIX uses Maurers algorithm for testing the

prime numbers where as JRSA uses Miller RabinTest.

• Miller Rabin Test is quite faster than Maurersalgorithm.

• Complex class hierarchy of Cryptix.

25

Conclusions:

Encryption:• JRSA is very slow compared to Cryptix

Reasons:• Encryption method in JRSA takes the input as a string and

converts to byte array and byte array to big integer and encryptseach big integer separately.

• JRSA encrypts byte by byte.

Decryption:• JRSA is again very slow compared to Cryptix.

Reasons:• Cryptix uses Chinese Remainder theorem where as JRSA

doesnt .

Timing Diagram.

Key Generation:

0

20

40

60

80

100

120

512 768

Cryptix(Java)RSARef( C )Crypto++( C++ )

Key Length

Tim

e (se

cs)

26

Timing Diagram:

Encryption: Decryption:

0

20

40

60

80

100

120

768

CRYPTIX(java)RSARef( C )

Crypto++(C++) 0

1

2

3

4

5

6

768

CRYPTIX(Java)RSARef( C )

Crpto++(C++)

Key lengthKey Length

Kbyte

/sec

Kbyte

/sec

Conclusions:

• C and C++ libraries are faster than Java libraries.

• Crypto++ is the fastest library.

27

Encryption/DecryptionRC5 vs. 3DES vs. RSA

RC5 vs. 3DES vs. RS A

11 .8716

12 .6270

2 .2752 2 .3140

0 .0550 0 .00330 .0000

2 .0000

4 .0000

6 .0000

8 .0000

10 .0000

12 .0000

14 .0000

Enc ry p tion Dec ry p tion

Meg

aByt

es/s

econ

d

RC5 168bits 3DES 168 bits RS A 1024 bits

Key expansion, scheduling and GenerationRC5 vs. 3DES vs. RSA

20000000

(512 bits)

RSA

96 (168 bits)3DES

14.22 (168 bits)RC5

Time (µs)Algorithm

28

Conclusion

RC5 is much faster than 3DES because RC5only takes 16 rounds operation while 3DEStakes 48 rounds operation.

Both RC5 and 3DES are 40~200 times as fast asRSA in terms of encryption and 700~3600 timesas fast as RSA in terms of decryption. That isbecause RC5 and 3DES doesnt have theexponential and multiplicative modulationoperation as in RSA.