Trapdoor Function

An easily computed function whose inverse is extremely difficult to compute. An example is the multiplication of twolarge Primes. Finding and verifying two large Primes is easy, as is their multiplication. But factorization of theresultant product is very difficult.

References

Gardner, M. Chs. 13-14 in Penrose Tiles and Trapdoor Ciphers...and the Return of Dr. Matrix, reissue ed. New York: W. H. Freeman, pp. 299-300, 1989.

• Radix
• Radon-Nikodym Theorem
• Radon Transform
• Radon Transform--Cylinder
• Radon Transform--Delta Function
• Radon Transform--Gaussian
• Radon Transform--Square
• Rado's Sigma Function
• Railroad Track Problem
• Ramanujan 6-10-8 Identity
• Ramanujan Constant
• Ramanujan Continued Fraction
• Ramanujan Cos/Cosh Identity
• Ramanujan-Eisenstein Series
• Ramanujan Function
• Ramanujan g- and G-Functions
• Ramanujan-Petersson Conjecture
• Ramanujan Psi Sum
• Ramanujan's Hypergeometric Identity
• Ramanujan's Hypothesis
• Ramanujan's Identity
• Ramanujan's Integral
• Ramanujan's Interpolation Formula
• Ramanujan's Master Theorem
• Ramanujan's Square Equation