Structural Properties of Cryptographic Sequences - Computational Intelligence in Security for Information Systems - page 165

Table 2. JCOP 41 encryption and decryption time in milliseconds
Encryption Decryption
Message length (bytes) Message length (bytes)
64 96 128 160 64 96 128 160
Key 131 433.79 463.97 498.25 531.29 279.02 280.32 296.01 297.87
JCOP 41 length 163 461.07 491.89 525.60 554.59 291.71 293.15 309.11 310.76
(bits) 193 499.28 529.95 563.75 593.98 311.19 313.08 328.78 331.00
Key 128 489.58 498.19 517.37 520.19 436.72 439.72 453.35 455.42
JCOP J3A length 160 532.51 535.03 549.06 551.17 459.89 462.83 476.58 479.01
(bits) 192 597.85 601.28 615.44 617.52 523.09 525.75 539.93 542.82
is 0 . 81 milliseconds, which provides useful information about the stability of
the smart card performance. Due to this stability, we decided that it was not
necessary to perform additional tests, as the measures taken are concentrated
around each average value and the CV in the worst-case scenario is 0 . 00286.
The results depend on the Java Card applet and the particular software op-
timizations applied (size of the arrays, variable usage and sharing, etc.), which
means that a different applet could produce different values.
Figures 1 and 2 present the performance of JCOP 41 and JCOP J3A when
encrypting and decrypting messages of 64 and 160 bytes, respectively. Those
figures include the processing results for key lengths of 131, 163, and 193 bits
(JCOP 41), and 128, 160, and 192 bits (JCOP J3A).
After reviewing the data, it can be stated that the encryption time is relatively
similar in JCOP 41 and JCOP J3A cards. However, it seems that the JCOP J3A
implementation is more sensible to an increase in the key size than the JCOP
41 applet when maintaining the length of the plaintext.
Fig. 1. Processing time in JCOP 41 and JCOP J3A for messages of 64 bytes