We developed and evaluated several cryptographic system libraries for Palm OS? which include stream and block ciphers, hash functions and multiple-precision integer arithmetic operations. We noted that the encryption speed of SSC2 outperforms both ARC4 (Alleged RC4) and SEAL 3.0 if the plaintext is small. On the other hand, SEAL 3.0 almost doubles the speed of SSC2 when the plaintext is considerably large. We also observed that the optimized Rijn-dael with 8KB of lookup tables is 4 times faster than DES. In addition, our results show that implementing the cryptographic algorithms as system libraries does not degrade their performance significantly. Instead, they provide great flexibility and code management to the algorithms. Furthermore, the test results presented in this paper provide a basis for performance estimation of cryptosystems implemented on PalmPilot^TM.