Cryptanalysts have developed certain measures for analyzing the strength of a cryptographic algorithm. Some of these measures and their desired values are:

These Cryptographic measures offer some insight into the difficulty of cryptanalysis for various schemes. Normally, these measures are calculated for different file types and an average value is computed that determines the classification category of a proposed scheme. Table 1 shows the vertical classification of algorithms based on some of these measures.

The encryption methods that fall in the weak category can usually be broken by hand. Encryption methods classified as moderate are considered non-trivial and require computer methods to break. Encryption methods that fall within the strong category require a considerable amount of computer effort to break while the methods listed as very strong may require massive computer resources or may not be breakable within this lifetime. The methods that fall into the Ultimate category can only be broken through torture, bribery, making an offer that cannot be refused, or simply by theft, surveillance, or trickery.

Most of the methods commercially employed are not strong in all categories. For instance, Blowfish falls in the strong category for it's Shannon File Entropy, Index of Coincidence, and the Compression Factor. However, Blowfish falls in the weak category in the File Randomness Test.

Table 2 shows a comparison of some of the popular software encryption systems with Dynacrypt® and where they fall in the classification system defined in Table 1.