密码学简史：时间密语

​ 注：机翻，未校。

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A brief history of cryptography: Sending secret messages throughout time

Stemming from the Greek words for “hidden writing,” cryptography is the practice of encrypting transmitted information so that it can only be interpreted by the intended recipient. Since the days of antiquity, the practice of sending secret messages has been common across almost all major civilizations. In modern times, cryptography has become a critical lynchpin of cybersecurity. From securing everyday personal messages and the authentication of digital signatures to protecting payment information for online shopping and even guarding top-secret government data and communications—cryptography makes digital privacy possible.
密码学源于希腊语中的 “隐藏文字”，是一种对传输的信息进行加密的做法，使其只能由预期的接收者解释。自古代以来，发送秘密信息的做法在几乎所有主要文明中都很常见。在现代，密码学已成为网络安全的关键。从保护日常个人信息和数字签名的身份验证，到保护在线购物的支付信息，甚至保护绝密的政府数据和通信，加密技术使数字隐私成为可能。

While the practice dates back thousands of years, the use of cryptography and the broader field of cryptanalysis are still considered relatively young, having made tremendous advancements in only the last 100 years. Coinciding with the invention of modern computing in the 19th century, the dawn of the digital age also heralded the birth of modern cryptography. As a critical means of establishing digital trust, mathematicians, computer scientists and cryptographers began developing modern cryptographic techniques and cryptosystems to protect critical user data from hackers, cybercriminals, and prying eyes.
虽然这种做法可以追溯到几千年前，但密码学的使用和更广泛的密码分析领域仍然被认为是相对年轻的，仅在过去 100 年中就取得了巨大的进步。与 19 世纪现代计算的发明相吻合，数字时代的到来也预示着现代密码学的诞生。作为建立数字信任的关键手段，数学家、计算机科学家和密码学家开始开发现代加密技术和密码系统，以保护关键用户数据免受黑客、网络犯罪分子和窥探者的侵害。

Most cryptosystems begin with an unencrypted message known as plaintext, which is then encrypted into an indecipherable code known as ciphertext using one or more encryption keys. This ciphertext is then transmitted to a recipient. If the ciphertext is intercepted and the encryption algorithm is strong, the ciphertext will be useless to any unauthorized eavesdroppers because they won’t be able to break the code. The intended recipient, however, will easily be able to decipher the text, assuming they have the correct decryption key.
大多数密码系统从称为明文的未加密消息开始，然后使用一个或多个加密密钥将其加密成称为密文的不可破译代码。然后，此密文被传输给接收者。如果密文被截获并且加密算法强大，那么密文对于任何未经授权的窃听者都将毫无用处，因为他们将无法破解代码。但是，假设预期的接收者拥有正确的解密密钥，则很容易破译文本。

In this article, we’ll look back at the history and evolution of cryptography.
在本文中，我们将回顾密码学的历史和演变。

Ancient cryptography 古代密码学

1900 BC: One of the first implementations of cryptography was found in the use of non-standard hieroglyphs carved into the wall of a tomb from the Old Kingdom of Egypt.
公元前 1900 年：最早的密码学实现之一是使用雕刻在埃及古王国墓墙上的非标准象形文字。

1500 BC: Clay tablets found in Mesopotamia contained enciphered writing believed to be secret recipes for ceramic glazes—what might be considered to be trade secrets in today’s parlance.
公元前 1500 年：在美索不达米亚发现的泥板上含有加密文字，据信是陶瓷釉料的秘密配方 —— 在今天的说法中可能被认为是商业秘密。

650 BC: Ancient Spartans used an early transposition cipher to scramble the order of the letters in their military communications. The process works by writing a message on a piece of leather wrapped around a hexagonal staff of wood known as a scytale. When the strip is wound around a correctly sized scytale, the letters line up to form a coherent message; however, when the strip is unwound, the message is reduced to ciphertext. In the scytale system, the specific size of the scytale can be thought of as a private key.
公元前 650 年：古代斯巴达人使用早期的换位密码来扰乱他们军事通信中字母的顺序。该过程的工作原理是在一块皮革上写下一条信息，该皮革包裹在称为镰刀的六角形木杖上。当条带缠绕在正确大小的镰刀上时，字母排成一行形成一个连贯的信息；但是，当条带展开时，消息会缩减为密文。在 scytale 系统中，scytale 的具体大小可以看作是私钥。

100-44 BC: To share secure communications within the Roman army, Julius Caesar is credited for using what has come to be called the Caesar Cipher, a substitution cipher wherein each letter of the plaintext is replaced by a different letter determined by moving a set number of letters either forward or backward within the Latin alphabet. In this symmetric key cryptosystem, the specific steps and direction of the letter transposition is the private key.
公元前 100-44 年：为了在罗马军队中共享安全通信，凯撒大帝因使用后来被称为凯撒密码的东西而受到赞誉，这是一种替代密码，其中明文的每个字母都被不同的字母替换，这些字母是通过在拉丁字母中向前或向后移动一定数量的字母来确定的。在这种对称密钥密码系统中，字母转置的具体步骤和方向就是私钥。

Medieval cryptography 中世纪密码学

800: Arab mathematician Al-Kindi invented the frequency analysis technique for cipher breaking, representing one of the most monumental breakthroughs in cryptanalysis. Frequency analysis uses linguistic data—such as the frequency of certain letters or letter pairings, parts of speech and sentence construction—to reverse engineer private decryption keys. Frequency analysis techniques can be used to expedite brute-force attacks in which codebreakers attempt to methodically decrypt encoded messages by systematically applying potential keys in hopes of eventually finding the correct one. Monoalphabetic substitution ciphers that use only one alphabet are particularly susceptible to frequency analysis, especially if the private key is short and weak. Al-Kandi’s writings also covered cryptanalysis techniques for polyalphabetic ciphers, which replace plaintext with ciphertext from multiple alphabets for an added layer of security far less vulnerable to frequency analysis.
800 年：阿拉伯数学家 Al-Kindi 发明了用于密码破解的频率分析技术，代表了密码分析领域最具有纪念意义的突破之一。频率分析使用语言数据（例如某些字母或字母对的频率、词性和句子结构）对私有解密密钥进行逆向工程。频率分析技术可用于加速暴力攻击，在这种攻击中，密码破译者试图通过系统地应用潜在密钥来有条不紊地解密编码消息，以期最终找到正确的密钥。仅使用一个字母表的单字母替换密码特别容易受到频率分析的影响，尤其是在私钥短且较弱的情况下。Al-Kandi 的著作还涵盖了多字母密码的密码分析技术，该技术用来自多个字母的密文代替明文，以增加一层安全层，大大降低对频率分析的影响。

1467: Considered the father of modern cryptography, Leon Battista Alberti’s work most clearly explored the use of ciphers incorporating multiple alphabets, known as polyphonic cryptosystems, as the middle age’s strongest form of encryption.
1467 年：被认为是现代密码学之父的莱昂・巴蒂斯塔・阿尔贝蒂（Leon Battista Alberti）的工作最清楚地探索了包含多个字母的密码的使用，称为复调密码系统，作为中世纪最强大的加密形式。

1500: Although actually published by Giovan Battista Bellaso, the Vigenère Cipher was misattributed to French cryptologist Blaise de Vigenère and is considered the landmark polyphonic cipher of the 16th century. While Vigenère did not invent the Vigenère Cipher, he did create a stronger autokey cipher in 1586.
1500 年：虽然实际上由乔万・巴蒂斯塔・贝拉索（Giovan Battista Bellaso）出版，但维吉内尔密码被误认为是法国密码学家布莱斯・德・维吉内尔（Blaise de Vigenère）的功臣，被认为是 16 世纪具有里程碑意义的复调密码。虽然 Vigenère 没有发明 Vigenère 密码，但他确实在 1586 年创造了更强大的自动密钥密码。

Modern cryptography 现代密码学

1913: The outbreak of World War I at the beginning of the 20th century saw a steep increase in both cryptology for military communications, as well as cryptanalysis for codebreaking. The success of English cryptologists in deciphering German telegram codes led to pivotal victories for the Royal Navy.
1913 年：20 世纪初第一次世界大战爆发，军事通信的密码学以及密码破译的密码分析都急剧增加。英国密码学家在破译德国电报代码方面的成功为皇家海军带来了关键的胜利。

1917: American Edward Hebern created the first cryptography rotor machine by combining electrical circuitry with mechanical typewriter parts to automatically scramble messages. Users could type a plaintext message into a standard typewriter keyboard and the machine would automatically create a substitution cipher, replacing each letter with a randomized new letter to output ciphertext. The ciphertext could in turn be decoded by manually reversing the circuit rotor and then typing the ciphertext back into the Hebern Rotor Machine, producing the original plaintext message.
1917 年：美国人爱德华・赫伯恩（Edward Hebern）通过将电路与机械打字机部件相结合，创造了第一台密码转子机，以自动加扰消息。用户可以在标准打字机键盘上输入明文消息，机器将自动创建一个替换密码，用随机的新字母替换每个字母以输出密文。反过来，可以通过手动反转电路转子来解码密文，然后将密文输入回 Hebern 转子机，从而产生原始的明文消息。

1918: In the aftermath of war, German cryptologist Arthur Scherbius developed the Enigma Machine, an advanced version of Hebern’s rotor machine, which also used rotor circuits to both encode plaintext and decode ciphertext. Used heavily by the Germans before and during WWII, the Enigma Machine was considered suitable for the highest level of top-secret cryptography. However, like Hebern’s Rotor Machine, decoding a message encrypted with the Enigma Machine required the advanced sharing of machine calibration settings and private keys that were susceptible to espionage and eventually led to the Enigma’s downfall.
1918 年：战后，德国密码学家亚瑟・谢尔比乌斯 （Arthur Scherbius） 开发了 Enigma Machine，这是 Hebern 转子机的高级版本，该机还使用转子电路来编码明文和解码密文。在二战前和二战期间被德国人大量使用，Enigma Machine 被认为适用于最高级别的绝密密码学。然而，就像 Hebern 的 Rotor Machine 一样，解码使用 Enigma Machine 加密的消息需要高级共享机器校准设置和私钥，这些设置和私钥容易受到间谍活动的影响，并最终导致 Enigma 的垮台。

1939-45: At the outbreak of World War II, Polish codebreakers fled Poland and joined many notable and famous British mathematicians—including the father of modern computing, Alan Turing—to crack the German Enigma cryptosystem, a critical breakthrough for the Allied Forces. Turing’s work specifically established much of the foundational theory for algorithmic computations.
1939-45 年：第二次世界大战爆发时，波兰密码破译者逃离波兰，与许多著名的英国数学家（包括现代计算之父艾伦・图灵）一起破解德国的 Enigma 密码系统，这是盟军的一项重大突破。图灵的工作专门建立了算法计算的大部分基础理论。

1975: Researchers working on block ciphers at IBM developed the Data Encryption Standard (DES)—the first cryptosystem certified by the National Institute for Standards and Technology (then known as the National Bureau of Standards) for use by the US Government. While the DES was strong enough to stymie even the strongest computers of the 1970s, its short key length makes it insecure for modern applications, but its architecture was and is highly influential in the advancement of cryptography.
1975 年：IBM 从事分组密码工作的研究人员开发了数据加密标准 （DES），这是第一个由美国国家标准与技术研究院（当时称为美国国家标准局）认证的密码系统，供美国政府使用。虽然 DES 足够强大，甚至可以阻止 1970 年代最强大的计算机，但其较短的密钥长度使其对现代应用程序不安全，但它的架构过去和现在对密码学的发展非常有影响力。

1976: Researchers Whitfield Hellman and Martin Diffie introduced the Diffie-Hellman key exchange method for securely sharing cryptographic keys. This enabled a new form of encryption called asymmetric key algorithms. These types of algorithms, also known as public key cryptography, offer an even higher level of privacy by no longer relying on a shared private key. In public key cryptosystems, each user has their own private secret key which works in tandem with a shared public for added security.
1976 年：研究人员 Whitfield Hellman 和 Martin Diffie 引入了 Diffie-Hellman 密钥交换方法，用于安全共享加密密钥。这启用了一种称为非对称密钥算法的新加密形式。这些类型的算法，也称为公钥加密，通过不再依赖共享私钥来提供更高级别的隐私。在公钥密码系统中，每个用户都有自己的私钥，该私钥与共享的公共密钥协同工作以增加安全性。

1977: Ron Rivest, Adi Shamir and Leonard Adleman introduce the RSA public key cryptosystem, one of the oldest encryption techniques for secure data transmission still in use today. RSA public keys are created by multiplying large prime numbers, which are prohibitively difficult for even the most powerful computers to factor without prior knowledge of the private key used to create the public key.
1977 年：Ron Rivest、Adi Shamir 和 Leonard Adleman 引入了 RSA 公钥加密系统，这是迄今为止仍在使用的最古老的安全数据传输加密技术之一。RSA 公钥是通过将大素数相乘来创建的，即使是最强大的计算机，如果没有事先了解用于创建公钥的私钥，也很难对数进行分解。

2001: Responding to advancements in computing power, the DES was replaced by the more robust Advanced Encryption Standard (AES) encryption algorithm. Similar to the DES, the AES is also a symmetric cryptosystem, however, it uses a much longer encryption key that cannot be cracked by modern hardware.
2001 年：为了应对计算能力的进步，DES 被更强大的高级加密标准 （AES） 加密算法所取代。与 DES 类似，AES 也是一个对称密码系统，但是，它使用更长的加密密钥，现代硬件无法破解。

Quantum cryptography, post-quantum cryptography and the future of encryption 量子密码学、后量子密码学和加密技术的未来

The field of cryptography continues to evolve to keep pace with advancing technology and increasingly more sophisticated cyberattacks. Quantum cryptography (also known as quantum encryption) refers to the applied science of securely encrypting and transmitting data based on the naturally occurring and immutable laws of quantum mechanics for use in cybersecurity. While still in its early stages, quantum encryption has the potential to be far more secure than previous types of cryptographic algorithms, and, theoretically, even unhackable.
密码学领域不断发展，以跟上技术进步和日益复杂的网络攻击的步伐。量子密码学（也称为量子加密）是指基于量子力学的自然发生和不变定律，用于网络安全的安全加密和传输数据的应用科学。虽然量子加密仍处于早期阶段，但它有可能比以前类型的加密算法更安全，而且从理论上讲，甚至是不可破解的。

Not to be confused with quantum cryptography which relies on the natural laws of physics to produce secure cryptosystems, post-quantum cryptographic (PQC) algorithms use different types of mathematical cryptography to create quantum computer-proof encryption.

According to the National Institute of Standards and Technology (NIST) (link resides outside ibm.com), the goal of post-quantum cryptography (also called quantum-resistant or quantum-safe) is to “develop cryptographic systems that are secure against both quantum and classical computers, and can interoperate with existing communications protocols and networks.”
不要与量子密码学混淆，量子密码学依赖于自然物理定律来产生安全的密码系统，后量子密码学 （PQC） 算法使用不同类型的数学密码学来创建量子计算机证明加密。 根据美国国家标准与技术研究院（NIST）（链接位于 ibm.com 以外），后量子密码学（也称为抗量子或量子安全）的目标是 “开发对量子和经典计算机都安全的加密系统，并且可以与现有的通信协议和网络进行互操作。

Learn how IBM cryptography solutions help businesses guard critical data 了解 IBM 加密解决方案如何帮助企业保护关键数据

IBM cryptography solutions combine technologies, consulting, systems integration and managed security services to help ensure crypto agility, quantum-safety and solid governance and risk compliance. From symmetric to asymmetric cryptography, to hash functions and beyond, ensure data and mainframe security with end-to-end encryption tailor-made to meet your business needs.
IBM 加密解决方案将技术、咨询、系统集成和托管安全服务相结合，帮助确保加密敏捷性、量子安全性以及可靠的治理和风险合规性。从对称加密到非对称加密，再到哈希函数等，通过量身定制的端到端加密功能，确保数据和主机的安全性，以满足您的业务需求。

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via:

• A brief history of cryptography: Sending secret messages throughout time - IBM Blog Security January By Josh Schneider 5, 2024

  https://www.ibm.com/blog/cryptography-history/