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| Section | Weight | Objectives |
|---|---|---|
| Cryptography Fundamentals | 20% | - Core goals: confidentiality, integrity, authentication, non-repudiation - Historical evolution and modern applications - Basic terminology: plaintext, ciphertext, algorithm, key |
| Symmetric Encryption | 25% | - Principles and operation - Key generation, distribution, and management challenges - Algorithms: AES, DES, 3DES, Blowfish - Block vs stream ciphers, modes of operation (ECB, CBC, OFB, CFB) |
| Asymmetric Encryption & Public Key Infrastructure | 25% | - Certificate lifecycle: creation, validation, revocation - Digital signatures: purpose and process - Algorithms: RSA, ECC, Diffie-Hellman - PKI components: certificates, CAs, trust models - Principles: public/private key pairs |
| Hash Functions & Data Integrity | 15% | - Uses: integrity checks, password storage, message authentication - Algorithms: SHA-1, SHA-256, SHA-3, MD5 - Properties: collision resistance, one-way function - HMAC construction and application |
| Key Management & Secure Protocols | 10% | - Key generation, storage, exchange, and destruction - Cryptographic attacks: brute force, birthday, man-in-the-middle - Secure protocols: TLS/SSL, IPsec, SSH, PGP |
| Implementation & Best Practices | 5% | - Standards and compliance - Common mistakes and vulnerabilities - Selecting appropriate algorithms and key sizes |
>> Introduction-to-Cryptography試験勉強書 <<
研究により、学習への関心を刺激することが最善の解決策であることがわかっています。したがって、Introduction-to-Cryptography準備ガイドの焦点は、Introduction-to-Cryptography試験の準備方法を変更することにより、厳格で無駄なメモリモードを改革することです。 Introduction-to-Cryptography実践教材のソフトバージョンは、知識と最新テクノロジーを組み合わせて学習力を大幅に刺激します。楽しい学習シーンと鮮明な説明をシミュレートすることにより、ユーザーは資格のあるIntroduction-to-Cryptography試験に合格する自信が大きくなります。
質問 # 25
(Two people want to communicate through secure email. The person creating the email wants to ensure only their friend can decrypt the email. Which key should the person creating the email use to encrypt the message?)
正解：A
解説：
To ensure confidentiality so that only the intended recipient can decrypt an email, the sender must encrypt in a way that only the recipient can reverse. In public key cryptography, that means encrypting with the recipient's public key. The recipient is the only party who should possess the matching private key, so only they can decrypt the ciphertext. This pattern is fundamental to PKI-based secure email systems such as S/MIME and OpenPGP: the sender looks up or is provided the recipient's certificate/public key, encrypts the message (often by encrypting a randomly generated symmetric session key with the recipient's public key), and the recipient uses their private key to recover the session key and decrypt the content. Encrypting with the sender' s private key would not provide confidentiality; it resembles signing because anyone with the sender's public key could "decrypt" it. Encrypting with a private key of the recipient is also incorrect because private keys are not shared and should never leave the recipient's control. Therefore, the correct key to encrypt the message so only the friend can decrypt it is the recipient's public key.
質問 # 26
(Which cipher uses shifting letters of the alphabet for encryption?)
正解：C
解説：
The Caesar cipher is the classic substitution cipher that encrypts by shifting letters of the alphabet by a fixed number of positions (e.g., shift by 3: A#D, B#E, etc.). It is a monoalphabetic cipher because a single shift value is applied uniformly across the entire message, making it simple and vulnerable to frequency analysis and brute force (only 25 meaningful shifts in the Latin alphabet). Vigenere also involves shifting, but it uses a repeating keyword to vary the shift per character (polyalphabetic), whereas the question's phrasing typically points to the fundamental "shift cipher," which is Caesar. SHA-1 is a cryptographic hash function, not a cipher. Bifid is a fractionation cipher combining Polybius square coordinates and transposition, not a direct shifting method. Therefore, the cipher that uses shifting letters of the alphabet for encryption is the Caesar cipher.
質問 # 27
(How can auditing enhance an organization ' s cryptographic practices?)
正解：C
解説：
Auditing improves cryptographic practice by systematically evaluating whether cryptographic controls are correctly selected, implemented, configured, and maintained. Through audits, an organization can discover weak algorithms (e.g., deprecated hashes), improper key lengths, unsafe modes (e.g., unauthenticated CBC), missing integrity controls, poor certificate validation, and operational problems such as key reuse, weak randomness sources, inadequate rotation, or overly permissive access to key material. Audits also assess compliance with internal policy and external standards, ensuring crypto is used consistently across systems and that exceptions are documented and risk-managed. Importantly, auditing does not guarantee that incidents will never happen; it reduces risk by finding gaps before attackers do. It also does not eliminate the need for updates-audits often reveal that policies must evolve as threats and best practices change. Employee training can be recommended as an outcome of auditing, but audits do not automatically ensure training. Thus, the most accurate benefit is that auditing identifies weaknesses and drives corrective action, strengthening cryptographic posture over time.
質問 # 28
(What is the RC4 encryption key size when utilizing WPA with Temporal Key Integrity Protocol (TKIP)?)
正解：C
解説：
WPA with TKIP was designed as an interim improvement over WEP while still using the RC4 stream cipher for compatibility with legacy hardware. TKIP addresses WEP's major weaknesses by introducing per-packet key mixing, a message integrity mechanism ("Michael"), and replay protection.
In TKIP, the encryption key used with RC4 is 128 bits. Practically, TKIP derives a per-packet RC4 key from a 128-bit temporal key (TK), the transmitter's MAC address, and a sequence counter (TKIP Sequence Counter, TSC) to avoid the simple IV reuse patterns that made WEP easy to break. Even with these improvements, TKIP has known weaknesses and is deprecated in favor of WPA2/WPA3 using AES-based CCMP/GCMP. But strictly for the question asked, TKIP's RC4 keying material is based on a 128-bit key size, not 40/56-bit legacy sizes and not 256-bit.
質問 # 29
(Which mechanism implemented in WPA-Enterprise guards against bit-flipping exploits?)
正解：A
解説：
Bit-flipping exploits target encryption modes or protocols that do not provide strong integrity, allowing attackers to modify ciphertext so that predictable changes occur in plaintext after decryption. To defend against this, protocols add an integrity mechanism that detects tampering. In WPA (including enterprise deployments), TKIP introduced a Message Integrity Check (MIC) called "Michael." The MIC is computed over the frame contents (with additional fields) and verified by the receiver; if an attacker flips bits in transit, the MIC verification fails, and the frame is rejected. While AES (used by WPA2's CCMP) also provides integrity via authenticated encryption, the option presented that directly names the tamper-detection mechanism associated with guarding against bit-flipping is MIC. A pre-shared key is an authentication/keying method (and not enterprise-mode anyway), and a "global encryption key" would be the opposite of what you want-global/static keys worsen security. Therefore, the intended mechanism that mitigates bit-flipping by detecting unauthorized modifications is the Message Integrity Check.
質問 # 30
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