"Protection in Programming-Language Translations" Martin Abadi Report #154, April 17, 1998. 21 pages. We discuss abstractions for protection and the correctness of their implementations. Relying on the concept of full abstraction, we consider two examples: (1) the translation of Java classes to an intermediate bytecode language, and (2) in the setting of the pi calculus, the implementation of private channels in terms of cryptographic operations.