Cryptography and its Terminologies
Cryptography is one of the most important topics in computer networks and cybersecurity. It is the science of securing communication by converting data into a form that cannot be easily understood by unauthorized people. In the modern digital era, cryptography plays a critical role in ensuring confidentiality, integrity, authenticity, and non-repudiation of information. In this post, we will discuss cryptography concepts, terminologies, and practice important MCQs with answers that are frequently asked in competitive exams such as UGC NET, GATE, SSC, Banking, and IT certifications.
🔐 What is Cryptography?
Cryptography is the process of protecting information by transforming it into an unreadable format. Only authorized parties who have the key can access the original data. In simple terms, cryptography ensures that sensitive information remains hidden from hackers, cyber attackers, and unauthorized users.
Core Objectives of Cryptography
- Confidentiality: Protecting information from unauthorized access.
- Integrity: Ensuring that data is not altered during transmission.
- Authentication: Verifying the identity of the sender/receiver.
- Non-repudiation: Ensuring that the sender cannot deny sending the message.
📖 Cryptography Terminologies
To understand cryptography better, let us look at some of the common terms used:
- Plaintext: The original readable message or data.
- Ciphertext: The encrypted version of the plaintext.
- Encryption: Process of converting plaintext into ciphertext.
- Decryption: Process of converting ciphertext back into plaintext.
- Key: A secret code used in encryption and decryption.
- Symmetric Key Cryptography: Uses the same key for both encryption and decryption.
- Asymmetric Key Cryptography: Uses a pair of keys (public key & private key).
- Digital Signature: A cryptographic technique used for authentication and non-repudiation.
🧑💻 Applications of Cryptography
Cryptography is widely used in our daily life. Some common applications include:
- Online banking transactions
- Securing emails and instant messages
- Protecting sensitive files with encryption
- Digital signatures for authenticity
- Cryptocurrencies like Bitcoin and Ethereum
- SSL/TLS certificates for secure websites
📌 Cryptography MCQs with Answers
Below are some important multiple-choice questions (MCQs) related to cryptography and its terminologies. These questions are exam-oriented and help in quick revision.
Cryptography and its Terminologies
(Cryptanalysis, Cryptography, etc.)
Cryptography Q&A
Q1 What is substitution ciphers? / प्रतिस्थापन सिफर क्या है?
Answer: (B) Letters of the plaintext messages are replaced with other letters during the encryption. / एन्क्रिप्शन के दौरान प्लेनटेक्स्ट संदेशों के अक्षरों को अन्य अक्षरों से बदल दिया जाता है।
Q2 If 20 people need to communicate using symmetric-key cryptography, ____ symmetric keys are needed. / यदि 20 लोगों को सममित-कुंजी क्रिप्टोग्राफी का उपयोग करके संवाद करने की आवश्यकता है, ____ सममित कुंजियों की आवश्यकता है।
Answer: (A) 190
Q3 An important application of cryptography used in computerized commercial and financial transaction. / कम्प्यूटरीकृत वाणिज्यिक और वित्तीय लेनदेन में प्रयुक्त क्रिप्टोग्राफी का एक महत्वपूर्ण अनुप्रयोग।
Answer: (C) Digital signature / डिजिटल सिग्नेचर
Q4 The data to be encrypted at the sender site is called ____ and the data to be decrypted at the receiver end is called ____. / प्रेषक साइट पर एन्क्रिप्ट किए जाने वाले डेटा को ____ कहा जाता है और रिसीवर के अंत में डिक्रिप्ट किए जाने वाले डेटा को ____ कहा जाता है।
Answer: (C) plain text, cipher text / सादा टेक्स्ट, सिफर टेक्स्ट
Q5 In digital signature, the private key is used for ____ and the public key for ____. / डिजिटल सिग्नेचर में प्राइवेट कुंजी का प्रयोग ____ के लिए और पब्लिक key का ____ के लिए प्रयोग किया जाता है।
Answer: (A) encryption, decryption / एन्क्रिप्शन, डिक्रिप्शन
Q6 Encryption/decryption provides a network with ____. / एन्क्रिप्शन/डिक्रिप्शन एक नेटवर्क प्रदान करता है ____।
Answer: (D) non-repudiation / गैर परित्याग
Q7 If you want to secure a message (sending/receiving) use ____. / यदि आप किसी संदेश को सुरक्षित करना चाहते हैं (भेजना/प्राप्त करना) तो ____ का उपयोग करें।
Answer: (B) encryption key / एन्क्रिप्शन कुंजी
Q8 The altering of data so that it is not usable unless the changes are undone is ____. / डेटा में फेरबदल करना ताकि यह तब तक प्रयोग करने योग्य न हो जब तक कि परिवर्तन पूर्ववत न हो जाए ____।
Answer: (C) encryption / एन्क्रिप्शन
Q9 Cipher text / सिफर टेक्स्ट है
Answer: (A) an encryption form / एन्क्रिप्शन फॉर्म
Q10 The scrambling of code is known as / कोड की स्क्रैम्बलिंग को जाना जाता है
Answer: (A) encryption / एन्क्रिप्शन
Q11 Digital signature cannot provide ____ for the message. / डिजिटल हस्ताक्षर संदेश के लिए ____ प्रदान नहीं कर सकता है।
Answer: (A) Authentication
Q12 In digital signature schemes, ____ is used for ____, whereas ____ is used for ____. / डिजिटल हस्ताक्षर स्कीम में, ____ का उपयोग ____ के लिए किया जाता है जबकि ____ का उपयोग ____ के लिए किया जाता है।
Answer: (C) DES, Encryption, DES, Decryption
Q13 Encryption is primarily used to provide ____ security service. / एन्क्रिप्शन मुख्य रूप से सुरक्षा सेवा प्रदान करने के लिए उपयोग किया जाता है।
Answer: (A) Access Control / एक्सेस कंट्रोल
Q14 Which one of the following is true for asymmetric-key cryptography? / असममित-कुंजी क्रिप्टोग्राफी के लिए निम्नलिखित में से कौन सा सत्य है?
Answer: (C) Both private key and public key is kept by the receiver / निजी कुंजी और पब्लिक कुंजी दोनों ही रिसीवर द्वारा रखी जाती है
Q15 Decryption and Encryption of data are responsibilities of ____. / डेटा का डिक्रिप्शन और एन्क्रिप्शन ____ जिम्मेदारी है।
Answer: (C) Presentation Layer / प्रेजेंटेशन लेयर
📊 Symmetric vs Asymmetric Key Cryptography
One of the most frequently asked questions in exams is the difference between symmetric and asymmetric cryptography. Here is a quick comparison:
- Symmetric: Same key for encryption and decryption, faster, suitable for bulk data.
- Asymmetric: Different keys (public/private), slower but more secure, widely used in digital signatures and certificates.
📝 Conclusion
Cryptography is the backbone of modern network security. Whether it is securing messages, online banking, or protecting personal data, cryptography ensures a safe digital environment. By understanding its terminologies and practicing MCQs, students and professionals can prepare well for competitive exams as well as enhance their knowledge in cybersecurity.
❓ FAQs on Cryptography
Q1. What is the main purpose of cryptography?
Cryptography is used to secure communication by ensuring confidentiality, integrity, authentication, and non-repudiation of data.
Q2. What is the difference between encryption and decryption?
Encryption converts plaintext into ciphertext, while decryption converts ciphertext back into plaintext.
Q3. Which layer of the OSI model is responsible for encryption/decryption?
The Presentation Layer of the OSI model is responsible for encryption and decryption of data.
Q4. What is the role of digital signatures in cryptography?
Digital signatures ensure authenticity and non-repudiation in online transactions and secure communications.