In recent years, some cryptographic algorithms have gained popularity due to properties that make them suitable for use in constrained environments like mobile information appliances, where computing resources and power availability are limited. In this paper, we select a set of public-key, symmetric-key and hash algorithms suitable for such environments and study their workload characteristics. In particular, we study elliptic-curve versions of public-key cryptography algorithms, which allow fast software implementations while reducing the key size needed for a desired level of security compared to previous integer-based public-key algorithms. We characterize the operations needed by elliptic-curve analogs of Diffie-Hellman key exchange, ElGamal and the Digital Signature Algorithm for public-key cryptography, for different key sizes and different levels of software optimization. We also include characterizations for the Advanced Encryption Standard (AES) for symmetric-key cryptography, and SHA as a hash algorithm. We show that all these algorithms can be implemented efficiently with a very simple processor.