**Don Coppersmith** (born c. 1950) is a cryptographer and mathematician. He was involved in the design of the Data Encryption Standard block cipher at IBM, particularly the design of the S-boxes, strengthening them against differential cryptanalysis. He has also worked on algorithms for computing discrete logarithms, the cryptanalysis of RSA, methods for rapid matrix multiplication (see Coppersmithâ€“Winograd algorithm) and IBM's MARS cipher. Don is also a co-designer of the SEAL and Scream ciphers.

In 1972, Coppersmith obtained a Bachelor's degree in mathematics at the Massachusetts Institute of Technology, and a Masters and PhD in mathematics from Harvard University in 1975 and 1977 respectively. He was a Putnam Fellow each year from 1968â€“1971, becoming the first four-time Putnam Fellow in history. In 1998, he started *Ponder This*, an online monthly column on mathematical puzzles and problems. In October 2005, the column was taken over by James Shearer.

In 2002, Coppersmith won the RSA Security Award for Mathematics.