案例库 · 软件与 IT · 技术决策 · 1977–1978
这条还没译成中文，下面是英文原文。
RSA let anyone encrypt to you without sharing a secret first.
Rivest, Shamir and Adleman made the encrypting key public and the decrypting key private, so two strangers could trade secrets with no courier and no prior key.
Massachusetts Institute of Technology
那一手
Before public-key cryptography, secure communication had a built-in trap: two parties who had never met had to first share a secret key, which itself needed a secure channel. Couriers, trusted phone calls and key tables were the expensive, leaky ways to do it.
Rivest, Shamir and Adleman's 1978 paper showed an encryption method with the property that publicly revealing an encryption key does not reveal the corresponding decryption key. A message is encoded as a number M raised to a public power e and reduced modulo a public product n of two large primes, and only the matching secret power d recovers it.
That one trick solved both problems at once. Couriers were no longer needed to transmit keys, and a message could be signed with the private key so anyone could verify it with the public key, giving unforgeable, non-repudiable signatures for electronic mail and funds transfer. Security rests on the difficulty of factoring the published modulus.
为什么管用
- Making the encryption key public removes the need to share a secret first.
- Factoring the modulus is hard, so publishing n does not expose the private key.
- The same math gives both confidentiality and signatures, so one scheme covered both uses.
- Its patent and the MIT paper turned public-key cryptography into a productizable standard.
可以搬走什么
The key-distribution chicken-and-egg dissolves once the encryption operation is public and only the inverse of it stays secret.
后来呢
RSA became the most widely deployed public-key scheme, securing web traffic, email and electronic payments for decades, and it made public-key cryptography the foundation of digital signatures and the public-key infrastructure. It also earned its authors the Turing Award in 2002.
资料来源
- A Method for Obtaining Digital Signatures and Public-Key Cryptosystems
- Cryptographic communications system and method (U.S. Patent 4,405,829)
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