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Cryptography维吉尼亚密码维吉尼亚密码用重复关键词决定逐字母移位，相比固定移位形成多表替换；周期性仍会泄露统计规律，属于历史教学算法。
The Vigenère cipher uses a repeating keyword to choose letter shifts, producing polyalphabetic substitution. Its periodic structure leaks statistical patterns and is insecure for modern use.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 仿射密码将字母编号映射为 ax+b 模字母表大小。为保证可逆，a 必须与模数互素；它的线性结构无法提供现代密码安全性。
An affine cipher maps alphabet indices to ax+b modulo the alphabet size. The multiplier must be coprime to that size for reversibility, but the linear structure is not cryptographically secure.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ Atbash 将字母表的顺序反转，例如 A 对应 Z、B 对应 Y。它没有有效的秘密密钥，仅能作为字符映射和历史密码示例。
Atbash reverses an alphabet, pairing A with Z and B with Y in the Latin alphabet. It has no effective secret key and serves only as a historical substitution example.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 栅栏密码把字符沿多条轨道往返排列再按轨读取，改变字符位置而非字符本身；这种可预测换位不能抵抗现代密码分析。
The rail fence cipher writes characters along a zigzag across rails and reads them rail by rail. It permutes positions rather than values and cannot resist modern cryptanalysis.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 频率分析比较密文符号或符号组的出现频数与已知语言统计，常用于研究历史替换密码；现代安全密码应消除这类直接对应。
Frequency analysis compares ciphertext symbol frequencies with known language statistics. It is useful against historical substitution ciphers, while modern secure ciphers avoid such direct correlations.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 重合指数估计随机抽取的两个符号相同的概率，可帮助分析历史多表密码的周期和语言分布；短样本的估计波动很大。
The index of coincidence estimates the probability that two sampled symbols match. It can help analyze historical polyalphabetic ciphers, but estimates from short samples vary substantially.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ Kasiski 检验通过重复密文片段的间距寻找重复密钥的可能周期。间距因子的统计提示需要进一步验证，不能单独确定密钥。
Kasiski examination studies distances between repeated ciphertext fragments to suggest periods of repeating keys. Common distance factors provide clues, not a complete determination of the key.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ Feistel 网络把分组分为两部分，通过轮函数与交换构建可逆变换；轮函数本身不必可逆，安全性依赖具体设计和轮数。
A Feistel network splits a block into halves and combines round functions with swaps to obtain an invertible transform. Round functions need not be invertible; security depends on the design.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 代换置换网络交替执行非线性代换和线性混合，使输入影响逐轮扩散到输出。组件存在并不保证安全，还需足够轮数和密码分析。
A substitution–permutation network alternates nonlinear substitution and linear mixing to spread input influence across a block. Its security still depends on round counts and cryptanalytic resistance.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 雪崩效应描述输入改变少量比特时输出出现广泛变化的现象。单个样例约一半位改变并不是算法安全性的充分证明。
The avalanche effect describes widespread output changes after a small input change. Observing about half the bits change in a single example is not sufficient evidence of cryptographic security.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 混淆使密钥和密文之间的关系复杂，扩散将明文统计影响分散到多个密文位置。两者是密码设计原则，而不是完整安全证明。
Confusion complicates relationships between keys and ciphertext, while diffusion spreads plaintext statistics over many output positions. These are design principles rather than complete security proofs.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 工作模式规定怎样用固定长度分组密码处理长消息。不同模式对随机数、填充、并行性和认证有不同要求，不能任意互换。
A block cipher mode specifies how a fixed-block cipher processes longer messages. Modes differ in nonce, padding, parallelism and authentication requirements and are not interchangeable.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ ECB 独立加密每个分组，同样的明文分组产生同样的密文，因此会泄露重复结构；一般不适合加密有结构的完整消息。
ECB encrypts blocks independently, so identical plaintext blocks produce identical ciphertext blocks under one key. This reveals repeated structure and makes it unsuitable for most messages.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ CBC 在加密前把当前明文与前一密文异或，第一块使用初始化向量。它本身不提供认证，填充错误处理不当可能造成预言机攻击。
CBC XORs each plaintext block with the preceding ciphertext block, starting with an initialization vector. It does not authenticate messages, and unsafe padding errors can create oracle attacks.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 计数器模式加密依次变化的计数块生成密钥流，再与明文异或。同一密钥下绝不能重复计数序列；该模式本身也不验证完整性。
Counter mode encrypts a sequence of counters to form a keystream that is XORed with plaintext. Counter sequences must never repeat under one key, and the mode alone provides no integrity.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ GCM 将计数器加密与有限域认证结合，保护密文及可选附加数据。相同密钥下重复随机数会严重破坏保密性和完整性。
GCM combines counter-mode encryption with finite-field authentication for ciphertext and optional associated data. Repeating a nonce under the same key can destroy confidentiality and integrity.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 附加数据由认证加密算法保护其完整性，但不进行加密，例如协议头和版本字段。接收方必须使用同样的数据完成标签验证。
Associated data is authenticated but not encrypted by an authenticated-encryption scheme, such as a protocol header. The receiver must supply the same data when verifying the authentication tag.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 认证标签是由密钥及受保护数据计算的短值，用于检测未经授权的修改。标签长度、验证失败处理和密钥管理都会影响安全性。
An authentication tag is a short value computed from a secret key and protected data to detect unauthorized changes. Tag length, failure handling and key management all affect security.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ Nonce 是在指定密钥和协议范围内只使用一次的值。具体算法可能要求唯一、随机或不可预测，不能把这些不同条件视为同义。
A cryptographic nonce is a value used once within a specified key or protocol scope. An algorithm may require uniqueness, randomness or unpredictability, and these requirements are not equivalent.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 盐值是与口令派生输入结合的公开数据，用于减少相同口令产生相同结果和预计算攻击的收益。盐不需要保密，也不能替代强口令。
A salt is public data combined with a password-derivation input to reduce shared outputs and the value of precomputation attacks. It need not be secret and cannot compensate for weak passwords alone.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 密钥是选择密码变换的参数，可能为对称秘密、公钥或私钥。密钥的生成、保存、用途隔离和撤销属于系统安全的组成部分。
A cryptographic key selects a transformation and may be a symmetric secret, public key or private key. Generation, storage, purpose separation and revocation are integral to system security.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 密码学哈希把任意长度输入映射到固定长度摘要，并追求原像、第二原像和碰撞抗性。普通哈希表散列函数不一定具有这些性质。
A cryptographic hash maps arbitrary-length input to a fixed-length digest while seeking preimage, second-preimage and collision resistance. Ordinary hash-table functions need not provide these properties.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ HMAC 使用密钥和哈希函数的内外两层结构生成消息认证码。它提供完整性和来源认证，但不会对消息进行加密。
HMAC combines a secret key with inner and outer applications of a hash function to produce a message authentication code. It authenticates data but does not encrypt the message.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ 消息认证码由共享秘密和消息计算，允许持有密钥的双方检测修改。因为双方都能生成有效码，它不提供公钥签名意义的不可否认性。
A MAC is computed from a shared secret and a message so key holders can detect alteration. Since both parties can generate valid codes, it does not provide public-signature nonrepudiation.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ SHA-3 是基于 Keccak 海绵结构的哈希标准族。它与 SHA-2 的内部结构不同，包含多种摘要长度以及相关的可扩展输出函数。
SHA-3 is a family of standardized hashes based on the Keccak sponge construction. Its internal structure differs from SHA-2 and supports several digest sizes and related extensible-output functions.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ SHA-1 输出 160 位摘要，已存在实用碰撞攻击。依赖碰撞抗性的签名和证书等新系统不应继续选择它作为安全哈希。
SHA-1 produces a 160-bit digest and has practical collision attacks. New systems relying on collision resistance, including signatures and certificates, should not select it as a secure hash.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ MD5 输出 128 位摘要，其碰撞抗性已被破坏。它有时出现在遗留校验中，但不能作为抵抗恶意篡改的完整性或签名依据。
MD5 produces a 128-bit digest and has broken collision resistance. It may appear in legacy checksums but must not be treated as a secure basis for adversarial integrity or signatures.
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View content license ↗ 可扩展输出函数在吸收消息后可按需输出不同长度的字节序列。输出越长并不意味着安全强度可以无限增长，仍受底层结构限制。
An extendable-output function absorbs a message and emits a requested number of output bytes. Increasing the output length does not increase security without bound; the construction limits its strength.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ PBKDF2 结合口令、盐、迭代次数和伪随机函数派生密钥。迭代用于增加猜测成本，参数必须按当前硬件和应用要求设置。
PBKDF2 derives key material from a password, salt, iteration count and pseudorandom function. Iterations raise guessing cost, and parameters must reflect current hardware and application requirements.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
View content license ↗ scrypt 是增加内存成本的口令派生算法，参数共同决定时间和空间需求。资源限制过低会降低抗猜测能力，过高则可能造成服务耗尽。
Scrypt is a memory-hard password derivation algorithm whose parameters determine time and memory demand. Low settings weaken guessing resistance, while excessive settings can exhaust service resources.
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SciAtlas original bilingual definition · Edited2026-10-04 · CC BY-SA 4.0. Further-reading links provide context; the definition is original and does not assert that the linked page was retrieved or checked.For concept reference; consult the original standards for authoritative requirements.
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