permutation cipher

Two-letter group instead of password (Charles Wheatstone)

Multi-letter replacement password

hill password

Virginia password

Shift cipher

Jimmy king Zum

Morse code

ROT 13

affine cipher

Atbash password

Transposition cipher

sickle

Grid cipher

VIC password (a complicated manual password, which was used by at least one Soviet spy in the early 1950s and was very safe at that time).

Stream cipher

LFSR stream cipher

EIGamal password

RSA password

An attack on traditional cryptography

frequency analysis

Coincidence index

Classical cryptography

Before modern times, cryptography only considered the confidentiality of information: how to transform understandable information into incomprehensible information, and make people with secret information reply in reverse, but interceptors or eavesdroppers who lacked secret information could not interpret it. In recent decades, this field has expanded to include various technologies such as identity authentication (or authentication), information integrity check, digital signature, interactive proof, secure multi-party computing and so on.

Liu Tao of the Zhou Dynasty in ancient China also recorded the application of cryptography. Among them, Yin Fu and Yin Shu recorded that Zhou Wuwang asked Jiang Ziya about the way to communicate with Tai Gong during the election campaign: Tai Gong said, "Tai Gong and General have Yin Fu, and everything is equal to eight. There are signs of defeating the enemy, one foot longer. Pojun captured the general and was nine inches long. The symbol of this city is eight inches long. However, the enemy reported that it was seven inches long. The symbol of police perseverance is six inches long. Please use the symbol of grain benefiting soldiers, five inches long. The symbol of the defeated army is four inches long. The symbol of failure and death is three inches long. All the envoys who act on their behalf stay behind. If they hear anything, they will be punished. The eight-character person is the secret of the Lord, so the yin communicates with words and does not show the skill of knowing each other. Although the enemy is wise, you must know it. "

King featuring asked squire, "... symbol is not clear; Far apart, the words are impassable. What can you do? "

Taigong said, "When you are worried about something sinister, you should use books instead of symbols. The Lord will leave the book and ask the Lord in it. All the books are closed and left, and one person will know in three rounds. Those who leave again are divided into three books. If you know three things and know one thing, you will get one point if you say three things, and you will take part without knowing it. It's called a dirty book. Although the enemy is wise, you must know it. " Yin character is an eight-length symbol, which is used to represent different information and instructions. It can be regarded as an alternative method in cryptography (en:substitution), which transforms information into symbols that the enemy cannot understand. As for the yin book, the shift method is adopted, and the book is divided into three parts, which are delivered by three people. Only by recombining the three books can we get the recovered data.

Besides being used in military affairs, in the 4th century AD, the Brahmin scholar en:Vatsyayana mentioned in The Sutra of Desire 4 that information was encrypted by substitution method. Item 45 in the book is a secret letter (en:mlecchita-vikalpa) to help women hide their relationship with their loved ones. One way is to exchange letters at random. If it is applied to the Roman alphabet, the following table can be obtained: A B C D E F G H I J K L M Z Y X W V U T S R Q P O N Cryptography generated by classical encryption method is easy to reveal statistical information about plaintext, which is actually easy to be cracked from a modern point of view. An Arab, en:al-Kindi, mentioned that if you want to crack encrypted information, you can count the frequency of each letter in an article at least one page long, count the frequency of each symbol in an encrypted letter, and then exchange them with each other. This is the predecessor of frequency analysis, and almost all such passwords have been cracked immediately since then. However, classical cryptography has not disappeared, and it often appears in riddles (see en:cryptogram). This analysis method is not only used to crack passwords, but also commonly used in archaeology. This decryption method was used in deciphering ancient Egyptian hieroglyphics (en: hieroglyphics). Standard organization

Federal Information Processing Standards Publishing Program (managed by NIST, which produces standards in many fields to guide the operation of the US federal government; Many FIPS bars are related to cryptography.

ANSI standardization process (many standards are produced in many fields; Some related to cryptography, in progress)

ISO standardization process (produces many standards in many fields; Some related to cryptography, in progress)

IEEE standardization process (produces many standards in many fields; Some related to cryptography, in progress)

IETF standardization process (producing many standards in many fields (called RFC); Some related to cryptography, in progress)

See encryption standard.

Encrypted organization

NSA internal evaluation/selection (of course, it is extensive, and there is no public information about the process or results of internal use; The National Security Agency is accused of assisting NIST to perform its encryption duties)

GCHQ internal evaluation/selection (of course, it is extensive, and there is no open process or result for GCHQ to use; A department of GCHQ is responsible for developing and recommending encryption standards for the British government)

DSD is part of ECHELON, a SIGINT organization in Australia.

Communications Security Agency (CSE)-Canadian Intelligence Agency.

The result of hard work

DES selection (NBS selection process, ending at 1976)

The mature part of the race project (sponsored by the European Union and ended in the mid-1980s)

AES competition ("interruption" sponsored by NIST; End at 200 1)

NESSIE project (EU-sponsored evaluation/selection plan; End of 2002)

CRYPTREC program (evaluation/recommendation project sponsored by the Japanese government; Draft recommendations published in 2003)

Internet engineering task force (technical organization responsible for Internet standards-consultation series: in progress)

CrypTool project (e-learning program in English and German; Free software; Detailed educational tools on cryptography and cryptanalysis)

Encrypted hash function (message digest algorithm, MD algorithm)

Encrypted hash function

Message authentication code

Keyed hash message verification code

Nisi chooses MAC.

HMAC (selected by Nishi MACISO/FIPS IEC 9797- 1 and IETF RFC)

TTMAC is also called dual-track MAC(nessie selection MAC；; Leuven Belgium; Debis ag (Germany)

UMAC (Nixi select MAC Intel, Renault, IBM, Technion and. UCal Davis)

MD5 (one of a series of message digest algorithms, proposed by Professor Ron Rivest of MIT; 128 bit abstract)

Sha- 1 (160 bit abstract is developed by NSA and is one of FIPS standards; The first released version was found to be defective and was replaced by this version; NIST/ National Security Agency released several variants with longer "abstracts"; Recommended by CRYPTREC (limited))

SHA-256 (NESSIE series message digest algorithm, 180-2, one of FIPS standards, with a digest length of 256 bits).

SHA-384 (Nissl message digest algorithm, one of FIPS standards, 180-2, the digest length is 384 bits; CRYPTREC suggested)

SHA-5 12 (NESSIE message digest algorithm, one of FIPS standards, 180-2, the digest length is 5 12 bits; CRYPTREC suggested)

RIPEMD- 160 (developed for RIPE project in Europe, 160 abstract; Recommended by CRYPTREC (limited))

Tiger (rose anderson et al.)

Snefru

Whirlpool (Loch Ness monster chooses hash function, Scopus Tecnologia S.A (Brazil) & ampK.U Leuven (Belgium))

Public/private key encryption algorithm (also known as asymmetric key algorithm)

ACE-KEM (NESSIE chooses asymmetric encryption scheme; IBM Zurich research)

ACE encryption

Chor- Rivest

Diffie-Hellman (key agreement; Recommended by CRYPTREC)

Discrete logarithm

ECC (Elliptic Curve Encryption Algorithm) (Discrete Logarithmic Variant)

PSEC-KEM (Nishi chooses asymmetric encryption scheme; NTT (Japan); CRYPTREC suggests using SEC 1 parameter only in DEM construction).

Elliptic curve comprehensive encryption system; Certicom company)

ECIES-KEM

ECDH (elliptic curve Diffie-Hellman key protocol; Recommended by CRYPTREC)

EPOC

Merkle-Hellman (knapsack scheme)

Mcellis

influence

RSA (factorization)

RSA-KEM (Nishi chooses asymmetric encryption scheme; ISO/IEC 18033-2 draft)

RSA-OAEP (recommended by Cryptrec)

Rabin Cryptosystem (Factorization)

Rabin -SAEP

HIME

XTR

Public/private key signature algorithm

DSA(zh: digital signature; Zh-tw: digital signature algorithm) (from NSA, Zh: digital signature; Zh-tw: Part of Digital Signature Standard (DSS): recommended by CRYPTREC)

Elliptic curve DSA (NESSIE chooses digital signature scheme; Certicom company); CRYPTREC suggests ANSI X9.62, SEC 1).

Schnorr signature

RSA signature

RSA-PSS (NESSIE chooses digital signature scheme; RSA lab); CRYPTREC suggested)

Rsassa-pkcs1v1.5 (suggested by cryptrec)

Signed by Nieberg-Roupell

MQV protocol

Gennaro-Halevi-Rabin signature scheme

Cramer-Shoup signature scheme

One-time signature

Lamport signature scheme

Bos-Chaum signature scheme

An undeniable signature

Chaum-van Antwerpen signature scheme

Failed to stop signing

Ong-Schnorr-Shamir signature scheme

Bi-rational permutation scheme

design

Design -D

Design -R

Direct anonymous proof

NTRUSign is a public key encryption algorithm for mobile devices. The key is short, but it can also achieve the encryption effect of high key ECC.

SFLASH (NESSIE chooses a digital signature scheme (especially for smart card applications and similar applications); Schlumberger (France))

quartz

Secret key algorithm (also known as symmetric key algorithm)

Stream cipher

A5/ 1, A5/2 (encryption standard specified in GSM mobile phone standard)

BMGL

chameleon

FISH (Siemens)

World War II' Fish' Code

Geheimfernschreiber (the mechanical one-time password of Siemens AG was called sturgeon by Blackley Manor during World War II).

Schlusselzusatz (Lorenz's mechanical one-time secret password during World War II was called [[tunny]] by Blackley Manor.

spiral

ISAAC (used as a pseudo-random number generator)

Leviathan (password)

Lili-128

Mug1(recommended by cryptrec)

Multi-s 01(recommended by cryptrec)

One secret at a time (werner and Mao Bonne, who were patented in the mid-1920s; An extreme stream cipher)

Panama

Dog fish (rose anderson's improvement of fish)

RC4 (ARCFOUR) (one of the series of Professor Ron Rivest at MIT; CRYPTREC is recommended (limited to 128-bit keys).

Ciphersaber (RC4 variant with 10 byte random iv, easy to implement)

Navy Seals

snow

sober

SOBER-t 16

SOBER-t32

wake up

Block cipher

Block cipher operation mode

Product cipher

Feistel cipher (block cipher design mode proposed by Horst Feistel)

Advanced encryption standard (packet length is 128 bits; AES NIST anthology, FIPS197,2001-by Joan Damon and Vincent Riemann; A selection of Loch Ness monsters; Recommended by CRYPTREC)

Anubis (128 bit block)

BEAR (proposed by rose anderson) is a block cipher constructed by stream cipher and hash function.

Blowfish (packet length is 128 bits; Bruce schneier waits)

Camellia (packet length is 128 bits; Ntt&; Mitsubishi electric); Recommended by CRYPTREC)

CAST- 128 (CAST5) (64-bit block; One of a series of algorithms by Carlisle Adams and Stafford Tavares, who insist (in fact, they are firm) that the name is not because of their initials.

CAST-256 (CAST6) (128 bit packet length; One of AES competitors, CAST- 128' s successor)

CIPHERUNICORN-A (packet length is 128 bits; Recommended by CRYPTREC)

CIPHERUNICORN-E (64-bit block; Recommended by CRYPTREC (limited))

Cmea, the password used in American mobile phones, was found to have weaknesses.

CS-Cipher (64-bit packet length)

DESzh: number; Zh-tw: Digital Encryption Standard (64-bit packet length; FIPS 46-3， 1976)

Deal-AES candidate algorithm evolved from DES

DES-X is a variant of DES, which increases the key length.

Fair alloy

GDES is a derivative of DES, which aims to improve the encryption speed.

Grand Cru (128-bit packet length)

HieroCrypt-3 (packet length 128 bits; Recommended by CRYPTREC))

Hierocrypt-L 1 (64-bit packet length; Recommended by CRYPTREC (limited))

International Data Encryption Algorithm (idea) (64-bit packet length-James Messi &; X lai)

Iraqi block cipher (IBC)

KASUMI (64-bit packet length; Based on MISTY 1, used for the next generation of W-CDMA mobile phone security)

KHAZAD (64-bit module designed by Barretto and Rijmen)

Khufu and Ha Fula (64-bit block cipher)

LOKI89/9 1 (64-bit block cipher)

Loki97 (cipher with block length of 128 bits, AES candidate)

Lucifer (by Tuchman et al. of IBM, Early1970s; Modified by NSA/NBS and released as DES)

Magenta (AES candidate)

Mars (AES final work, author Don Coppersmith and others)

MISTY 1 (Nishi selects 64-bit blocks; Mitsubishi electric (Japan); Recommended by CRYPTREC (limited))

MISTY2 (packet length is 128 bits: mitsubishi electric (Japan))

Nimbus (64-bit packet)

Noekeon (packet length is 128 bits)

NUSH (variable packet length (64-256 bits))

Q (packet length is 128 bits)

RC2 64-bit packet with variable key length.

RC6 (variable packet length; AES finalist, Ron Rivest et al.)

RC5 (Ron Rivest)

More secure (variable packet length)

SC2000 (packet length is 128 bits; Recommended by CRYPTREC)

Serpent (packet length is 128 bits; AES finalists rose anderson, Eli Beaham, Lars Knudsen)

SHACAL- 1 (256-bit block)

SHACAL-2 (256-bit block cipher; Nishi Selected Gemplus (France))

Shark (grandfather of Rijndael/AES, designed by Damon and Rijmen)

Square (the father of Rijndael/AES, designed by Damon and Rijmen)

3 way (Joan Damon's 96-bit block)

TEA (small encryption algorithm) (by David Wheeler &; Roger Needham)

Triple DES(Walter tuch man, the leader of Lucifer design team-not all triple use of DES increases security, Tuchman did it; CRYPTREC (limited, only used in FIPS publication 46-3) is recommended.

Twofish (packet length is 128 bits; AES Final Works by Bruce Schneier et al.)

XTEA (David Wheeler & Roger Needham)

Multi-table instead of cipher machine password

Enigma (German wheel cipher machine in World War II-there are many variants, most of which have huge user networks)

Purple (the highest level cipher machine in Japanese diplomacy in World War II; Japanese navy design)

SIGABA (World War II American cipher machine, designed by William Friedman and Frank Rolet. )

TypeX (world war ii British cipher machine)

Mixed code/password combination

JN-25 (advanced password of Japanese navy in World War II; There are many variations)

Naval Cypher 3 (30 advanced password of the Royal Navy in 1930s and World War II)

Visual password

Secret password (USA)

Electronic key management system of EKMS national security agency

FNBDT NSA encrypted narrowband voice standard

Fortezza encryption based on PC card format portable encryption token

KW-26 ROMULUS telex encryption machine (1960s- 1980s)

Voice encryption of KY-57 VINSON tactical radio station

SINCGARS code-controlled frequency hopping tactical radio station

STE encrypted telephone

STU-III's old encrypted phone

Storms prevent leaks

1 product

Although frequency analysis is an effective technique, encryption is usually useful. Cracking messages without using frequency analysis requires knowing what encryption method is used, which leads to espionage, bribery, theft or betrayal. It was not until19th century that scholars realized that encryption algorithm was not rational or practical protection. In fact, appropriate encryption mechanisms (including encryption and decryption) should remain secure, even if the enemy knows which algorithm to use. For a good encryption method, the confidentiality of the key should be enough to ensure the confidentiality of the data. This principle was first put forward by Auguste Kerckhoffs, and it is called Kerckhoff principle. Claude elwood Shannon, the originator of information theory, reiterated: "The enemy knows the system."

The emergence of a large number of open academic research is a modern thing, which originated from the National Bureau of Standards, NBS；; The National Institute of Standards and Technology (NIST), now known as the National Institute of Standards and Technology, has formulated the Digital Encryption Standard (DES), which is the pioneering paper put forward by Diffie and Hellman, and published RSA publicly. Since then, cryptography has become an important tool for communication, computer network and computer security. The foundation of many modern cryptographic techniques depends on the difficulty of specific basic calculation problems, such as factorization or discrete logarithm. Many cryptographic techniques can be proved to be secure as long as a specific calculation problem cannot be effectively solved. Except for one famous exception: one-time pad (OTP), this proof is accidental rather than decisive, but it is the best way available at present.

Designers of cryptographic algorithms and systems should not only pay attention to the history of cryptography, but also consider its future development. For example, increasing the processing speed of computers will increase the speed of violent attacks. The potential impact of quantum computing has always been the focus of some cryptographers.

Cryptography in the early 20th century essentially considered language patterns. From then on, the center of gravity shifts, number theory. Cryptography is also a branch of engineering, but it is different because it must face intelligent and malicious opponents, while most other projects only need to deal with harmless natural forces. Studying the relationship between cryptography and quantum physics is also a research hotspot.

Modern cryptography can be roughly divided into several fields. Symmetric key encryption means that the sender and the receiver have the same key. Before 1976, it was the only public encryption method.

Modern research mainly focuses on block cipher and stream cipher and their applications. In a sense, block cipher is the modernization of Aberdeen multi-character encryption method. Block cipher takes a plaintext block and a key, and outputs ciphertext blocks with the same size. Because information is usually longer than a single block, there are various ways to weave consecutive blocks together. DES and AES are block cipher standards approved by the US federal government (AES will replace DES). Although it will be abolished from the standard, DES is still very popular (the 3DES variant is still quite safe) and is used in many applications, from automatic trading machines to e-mail to remote access. Many other block ciphers have been invented and released, with different quality and applications, and many of them have been cracked.

Compared with block encryption, stream cipher combines any length of key material with plaintext bit by bit or character by character, which is somewhat similar to one encryption at a time. When encrypting, the output stream depends on the internal state. In some stream ciphers, the change of state is controlled by the key. RC4 is a famous stream cipher.

The cryptographic hash function (sometimes called message digest function, hash function or hash function) does not necessarily use a key, but it is related to many important cryptographic algorithms. It outputs the input data (usually the whole document) as a short fixed-length hash value. This process is one-way, the reverse operation is difficult to complete, and the probability of collision (two different inputs produce the same hash value) is very small.

A message authentication code (MAC) is very similar to an encrypted hash function except that the receiver uses a secret key to authenticate the hash value.