- Advanced Encryption Standard (AES), Digital Signature Standard (DSS) [includes description of Digital Signature Algorithm (DSA)], Secure Hash Standard (SHS) - National Institute of Standards and Technology's official descriptions of the named algorithms among others.
- Bruce Schneier's Cryptography Page - Has descriptions of numerous encryption algorithms including Blowfish, Twofish, Solitaire, Helix, Phelix, Yarrow, Threefish, Skein and more. Offers source code for a variety of platforms.
- KremlinEncrypt - Cryptography site provides an overview of cryptography algorithms and links to published descriptions where available.
- PowerBASIC Crypto Archives - Offers PowerBASIC source code for many algorithms including:
- Hashing - RIPEMD-160, MD5, SHA-1, SHA-256, CRC-16, CRC-32, Adler-32, FNV-32, ELF-32
- Encryption - RSA-64, Diffie-Hellman-Merkle Secure Key Exchange, Rijndael, Serpent, Twofish, CAST-128, CAST-256, Skipjack, TEA, RC4, PC1, GOST, Blowfish, Caesar Substitutional Shift, ROT13
- Encoding - Base64, MIME Base64, UUEncode, yEnc, Neuronal Network, URLEncode, URLDecode
- Compression - LZ78, LZSS, LZW, RLE, Huffman, Supertiny
- Psuedo-Random Number Generation (PRNG) - Mersenne Twister Number Generator, Cryptographic PRNG, MPRNG, MOAPRNG, L'Ecuyer LCG3 Composite PRNG, W32.SQL-Slammer
- Artificial Life - Offers executable and source for ant food collection and the travelling salesman problems using genetic algorithms
- Genetic Ant Algorithm - Source code for a Java applet that implements the Genetic Ant Algorithm based upon the model given in Koza, Genetic Programming, MIT Press
- Introduction to Genetic Algorithms - Introduces fundamentals, offers Java applet examples
- Jaga - Offers a free, open source API for implementing genetic algorithms (GA) and genetic programming (GP) applications in Java
GIS (Geographic Information Systems) Algorithms
- Andrew Kitchen's Sorting Algorithms - Describes parallel sorting algorithms:
- Odd-Even Transposition Sort has a worst case time of O(n), running on n processors. Its absolute speed up is O(log n), so its efficiency is O((log n)/n)
- Shear Sort has a worst case time of O(n½ log n), running on n processors. Its absolute speed up is O(n½), so its efficiency is O(1/n½)
- Ariel Faigon's Library of Sorting Algorithms - C source code for a variety of sorting algorithms including Insertion Sort, Quick Sort, Shell Sort, Gamasort, Heap Sort and Sedgesort (Robert Sedgewick quicksort optimization)
- David Martin's Sorting Algorithms - Source code and simple animations showing how they work for several algorithms - Insertion Selection. Bubble, Shell, Merge, Heap, Quick, Quick3
- Flash Sort - Describes the FlashSort algorithm which sorts n elements in O(n) time
- Michael Lamont's Sorting Algorithms - Describes common sorting algorithms:
- O(n²) Sorts - bubble, insertion, selection and shell sorts
- O(n log n) Sorts - heap, merge and quick sorts
- Sequential and Parallel Sorting Algorithms - Describes many sorting algorithms:
- Sorting Networks
- Bitonic Sort
- Odd-Even Mergesort
- 4-way Mergesort
- Rotate Sort
- s^2-way Mergesort
Computational Geometry Algorithms
- GeoLib - Downloadable Gnu GPL (free for non-commercial use) library of C++ computational geometry algorithms. Included in the library is a class representing a latitude and longitude position which provides conversion to Cartesian co-ordinates allowing Geospatial polygon representation.
- CGAL - Offers open source C++ library of computational geometry algorithms.
- FastGEO - Offers source code for a library of computational geometry algorithms such as geometrical primitives and predicates, hull construction, triangulation, clipping, rotations and projections using the Object Pascal language.
- Wykobi - FastGEO library ported to C++.
Project Management Algorithms
- AI Horizon - Has a variety of algorithms, from basic computer science data structures such as 2-3 trees to AI-related algorithms such as minimax and a discussion of machine learning algorithms.
- CS Animated - Describes a variety of algorithms using narrated slideshow presentations (videos).
- Global Optimization Algorithms - Theory and Application - This is a free ebook (600+ page - 12.6MB .PDF file) that focuses on evolutionary computation by discussing evolutionary algorithms, genetic algorithms, genetic programming, learning classifier systems, evolution strategy, differential evolution, particle swarm optimization, and ant colony optimization. It also elaborates on meta-heuristics like simulated annealing, hill climbing, tabu search, and random optimization. It contains many pseudocode descriptions for the algorithms.
- Hash Algorithms - Overview and source code (in C, Pascal and Java) for many general purpose hashing algorithms.
- Porter Stemming Algorithm - Describes a process for removing the commoner morphological and inflexional endings from words in English. Its main use is as part of a term normalisation process that is usually done when setting up Information Retrieval systems.
- Rubik's Cube - Solves a Rubic's Cube using the BestFast search algorithm and profile tables.
- Simulated Annealing - The fundamental idea is to allow moves resulting in solutions of worse quality than the current solution (uphill moves) in order to escape from local minima. The probability of doing such a move is decreased during the search.
- The Stony Brook Algorithm Repository - Offers a collection of algorithm implementations for over seventy of the most fundamental problems in combinatorial algorithms:
- Data Structures - Dictionaries, Priority Queues, Suffix Trees and Arrays, Graph Data Structures, Set Data Structures, Kd-Trees
- Numerical Problems - Solving Linear Equations, Bandwidth Reduction, Matrix Multiplication, Determinants and Permanents, Linear Programming/Simplex Method, Random Number Generation, Factoring and Primality Testing, Arbitrary Precision Arithmetic, Knapsack Problem, Discrete Fourier Transform
- Combinatorial Problems - Sorting, Searching, Median and Selection, Permutations, Subsets, Partitions, Graphs, Calendrical Calculations, Job Scheduling, Satisfiability
- Graph Problems - Polynomial Time Problems (Connected Components, Topological Sorting, Minimum Spanning Tree, Shortest Path, Transitive Closure and Reduction, Matching, Eulerian Cycle / Chinese Postman, Edge and Vertex Connectivity, Network Flow, Drawing Graphs Nicely, Drawing Trees, Planarity Detection and Embedding)
- Graph Problems - Hard Problems (Clique, Independent Set, Vertex Cover, Traveling Salesman Problem, Hamiltonian Cycle, Graph Partition, Vertex Coloring, Edge Coloring, Graph Isomorphism, Steiner Tree, Feedback Edge/Vertex Set
- Computational Geometry - Robust Geometric Primitives, Convex Hull, Triangulation, Voronoi Diagrams, Nearest Neighbor Search, Range Search, Point Location, Intersection Detection, Bin Packing, Medial-Axis Transformation, Polygon Partitioning, Simplifying Polygons, Shape Similarity, Motion Planning, Maintaining Line Arrangements, Minkowski Sum
- Set and String Problems - Set Cover, Set Packing, String Matching, Approximate String Matching, Text Compression, Cryptography, Finite State Machine Minimization, Longest Common Substring, Shortest Common Superstring
- Introduction to Neural Networks - Describes the Back Propagation algorithm for neural networks.
- NIST Dictionary of Algorithms and Data Structures - Some entries have links to implementations.