Merkle-Hellman is an asymmetric-key cryptosystem, meaning that for communication, two keys are required: a public key and a private key.

* An asymmetric-key cryptosystem is published by Whitfield Diffie and Martin Hellman who disclose the Diffie – Hellman key exchange method of public-key agreement for public-key cryptography.

No asymmetric-key algorithms with this property are known ; elliptic curve cryptography comes the closest with an effective security of roughly half its key length.

The result was a potentially excellent cryptosystem.

In cryptography, Kerckhoffs's principle ( also called Kerckhoffs's Desiderata, Kerckhoffs's assumption, axiom, or law ) was stated by Auguste Kerckhoffs in the 19th century: A cryptosystem should be secure even if everything about the system, except the key, is public knowledge.

The Merkle – Hellman knapsack cryptosystem was one of the earliest public key cryptosystems invented by Ralph Merkle and Martin Hellman in 1978.

In 1979, Rabin invented the Rabin cryptosystem, the first asymmetric cryptosystem whose security was proved equivalent to the intractability of integer factorization.

The Rabin cryptosystem was the first asymmetric cryptosystem where recovering the entire plaintext from the ciphertext could be proven to be as hard as factoring.

At first the cryptosystem sometimes failed to decrypt a message back to the original message even though the message was encrypted correctly.

Even though the system sometimes failed to decrypt, the developers considered it a public key cryptosystem and thereby based their security claims on the assumption that this system was a public key cryptosystem.

Phil Zimmermann's PGP cryptosystem and its distribution on the Internet in 1991 was the first major ' individual level ' challenge to controls on export of cryptography.

The underlying cryptosystem is IND-CPA ( and thus semantically secure under chosen plaintext attack ) if the adversary cannot determine which of the two messages was chosen by the oracle, with probability significantly greater than ( the success rate of random guessing ).

It was designed to be a manual cryptosystem calculated with an ordinary deck of playing cards.

Hidden Fields Equations ( HFE ) is a public key cryptosystem which was introduced at Eurocrypt in 1996 and proposed by Jacques Patarin following the idea of the Matsumoto and Imai system.

In 1979, Michael O. Rabin published a related cryptosystem that is provably secure, at least as long as the factorization of the public key remains difficult-it remains an assumption that RSA also enjoys this security.

In 1985, Elgamal published a paper titled A Public key Cryptosystem and A Signature Scheme based on discrete Logarithms in which he proposed the design of the ElGamal discrete log cryptosystem and of the ElGamal signature scheme.

These names were used by Ron Rivest in the 1978 Communications of the ACM article presenting the RSA cryptosystem, and in A Method for Obtaining Digital Signatures and Public-Key Cryptosystems published April 4, 1977, revised September 1, 1977 as technical Memo LCS / TM82.

In 2008, Bernstein, Lange and Peters described a practical attack on the original McEliece cryptosystem, based on finding low-weight code words using an algorithm published by Jacques Stern in 1989.

In cryptography, Merkle's Puzzles is an early construction for a public-key cryptosystem, a protocol devised by Ralph Merkle in 1974 and published in 1978.

Note that any published ( or otherwise accessible ) random data table is unsuitable for cryptographic purposes since the accessibility of the numbers makes them effectively predictable, and hence their effect on a cryptosystem is also predictable.

The ElGamal cryptosystem, invented by Taher ElGamal.

Most are used in hybrid cryptosystems for reasons of efficiency-in such a cryptosystem, a shared secret key (" session key ") is generated by one party, and this much briefer session key is then encrypted by each recipient's public key.

The Paillier cryptosystem, named after and invented by Pascal Paillier in 1999, is a probabilistic asymmetric algorithm for public key cryptography.

In cryptography, a timing attack is a side channel attack in which the attacker attempts to compromise a cryptosystem by analyzing the time taken to execute cryptographic algorithms.

Attempts to break a cryptosystem by deceiving or coercing people with legitimate access are not typically called side-channel attacks: see social engineering and rubber-hose cryptanalysis.

In all cases, the underlying principle is that physical effects caused by the operation of a cryptosystem ( on the side ) can provide useful extra information about secrets in the system, for example, the cryptographic key, partial state information, full or partial plaintexts and so forth.

In cryptography, the McEliece cryptosystem is an asymmetric encryption algorithm developed in 1978 by Robert McEliece.

Instead, cryptosystem engineers must ensure that devices ' power variations do not reveal information usable by adversaries.

The notion of security of a cryptosystem is meaningful only with respect to particular attacks ( usually presumed to be carried out by particular sorts of adversaries ).

It has been largely superseded by the Miller – Rabin primality test, but has great historical importance in showing the practical feasibility of the RSA cryptosystem.

The Kushilevitz and Ostrovsky protocol is based on the Goldwasser – Micali cryptosystem while the protocol by Lipmaa is based on the Damgård – Jurik cryptosystem.

Developed by Ronald Cramer and Victor Shoup in 1998, it is an extension of the Elgamal cryptosystem.

Kleptographic attacks can be constructed as a cryptotrojan that infects a cryptosystem and opens a backdoor for the attacker, or can be implemented by the manufacturer of a cryptosystem.

Knapsack problems appear in real-world decision-making processes in a wide variety of fields, such as finding the least wasteful way to cut raw materials, selection of capital investments and financial portfolios, selection of assets for asset-backed securitization, and generating keys for the Merkle – Hellman knapsack cryptosystem.

* Merkle – Hellman knapsack cryptosystem

He co-invented the Merkle – Hellman knapsack cryptosystem, Merkle – Damgård construction, and invented Merkle trees.

* Merkle – Hellman knapsack cryptosystem

In cryptography, a cryptosystem is semantically secure if an adversary who knows the encryption algorithm and is in possession of a ciphertext is unable to determine any information about the plaintext.

* Victor Shoup, who with Ronald Cramer developed the Cramer – Shoup cryptosystem

It is normally presented as a game, where the cryptosystem is considered secure if no adversary can win the game with significantly greater probability than an adversary who must guess randomly.

If each entry is encrypted using a public-key cryptosystem, anyone can add to the database, and only the distinguished " receiver " who has the secret key can decrypt the database entries.