Cryptography is the study of secure communications techniques that allow only the sender and intended recipient of a message to view its contents. The term is derived from the Greek word *kryptos,* which means hidden. It is closely associated to encryption, which is the act of scrambling ordinary text into what’s known as ciphertext and then back again upon arrival. In addition, cryptography also covers the obfuscation of information in images using techniques such as microdots or merging

When transmitting electronic data, the most common use of cryptography is to encrypt and decrypt email and other plain-text messages. The simplest method uses the symmetric or “secret key” system. Here, data is encrypted using a secret key, and then both the encoded message and secret key are sent to the recipient for decryption. The problem? If the message is intercepted, a third party has everything they need to decrypt and read the message. To address this issue, cryptologists devised the asymmetric or “public key” system. In this case, every user has two keys: one public and one private. Senders request the public key of their intended recipient, encrypt the message and send it along. When the message arrives, only the recipient’s private key will decode it — meaning theft is of no use without the corresponding private key.

**Authentication/Digital Signatures:**

Authentication is any process through which one proves and verifies certain information. Sometimes one may want to verify the origin of a document, the identity of the sender, the time and date a document was sent and/or signed, the identity of a computer or user, and so on. A digital signature is a cryptographic means through which many of these may be verified. The digital signature of a document is a piece of information based on both the document and the signer’s private key. It is typically created through the use of a hash function and a private signing function (algorithms that create encypyted characters containing specific information about a document and its private keys).

**Time Stamping:**

Time stamping is a technique that can certify that a certain electronic document or communication existed or was delivered at a certain time. Time stamping uses an encryption model called a blind signature scheme. Blind signature schemes allow the sender to get a message receipted by another party without revealing any information about the message to the other party.

Time stamping is very similar to sending a registered letter through the U.S. mail, but provides an additional level of proof. It can prove that a recipient received a specific document. Possible applications include patent applications, copyright archives, and contracts. Time stamping is a critical application that will help make the transition to electronic legal documents possible.

**Electronic Money:**

The definition of electronic money (also called electronic cash or digital cash) is a term that is still evolving. It includes transactions carried out electronically with a net transfer of funds from one party to another, which may be either debit or credit and can be either anonymous or identified. There are both hardware and software implementations.

Anonymous applications do not reveal the identity of the customer and are based on blind signature schemes. Identified spending schemes reveal the identity of the customer and are based on more general forms of signature schemes. Anonymous schemes are the electronic analog of cash, while identified schemes are the electronic analog of a debit or credit card. There are also some hybrid approaches where payments can be anonymous with respect to the merchant but not the bank ;or anonymous to everyone, but traceable (a sequence of purchases can be related, but not linked directly to the spender’s identity).

Encryption is used in electronic money schemes to protect conventional transaction data like account numbers and transaction amounts, digital signatures can replace handwritten signatures or a credit-card authorizations, and public-key encryption can provide confidentiality. There are several systems that cover this range of applications, from transactions mimicking conventional paper transactions with values of several dollars and up, to various micropayment schemes that batch extremely low cost transactions into amounts that will bear the overhead of encryption and clearing the bank.

**Encryption/Decryption in email:**

Email encryption is a method of securing the content of emails from anyone outside of the email conversation looking to obtain a participant’s information. In its encrypted form, an email is no longer readable by a human. Only with your private email key can your emails be unlocked and decrypted back into the original message.

Email encryption works by employing something called public key cryptography. Each person with an email address has a pair of keys associated with that email address, and these keys are required in order to encrypt or decrypt an email. One of the keys is known as a “public key”, and is stored on a keyserver where it is tied to your name and email address and can be accessed by anyone. The other key is your private key, which is not shared publicly with anyone.

When an email is sent, it is encrypted by a computer using the public key and the contents of the email are turned into a complex, indecipherable scramble that is very difficult to crack. This public key cannot be used to decrypt the sent message, only to encrypt it. Only the person with the proper corresponding private key has the ability to decrypt the email and read its contents.

There are various types of email encryption, but some of the most common encryption protocols are:

**OpenPGP**— a type of PGP encryption that utilizes a decentralized, distributed trust model and integrates well with modern web email clients**S/MIME**— a type of encryption that is built into most Apple devices and utilizes a centralized authority to pick the encryption algorithm and key size

Email encryption services can be used to provide encryption in a few separate but related areas:

- The connection between email providers can be encrypted, preventing outside attackers from finding a way to intercept any incoming or outgoing emails as they travel between servers
- The content of the email can be encrypted, ensuring that even if an email is intercepted by an attacker, the contents of the email will still be entirely unreadable
- Old or archived emails that are already stored within your email client should also be encrypted to prevent attackers from potentially gaining access to emails that aren’t currently in transit between servers

**Encryption in WhatsApp:**

WhatsApp uses the ‘signal’ protocol for encryption, which uses a combination of asymmetric and symmetric key cryptographic algorithms. The symmetric key algorithms ensure confidentiality and integrity whereas the asymmetric key cryptographic algorithms help in achieving the other security goals namely authentication and non-repudiation. In symmetric key cryptography a single key is used for encryption of the data as well as decryption. In asymmetric key cryptography there would be two separate keys. The data which is encrypted using the public key of a user can only be decrypted using the private key of that user and vice versa.

Whatsapp uses the Curve25519 based algorithm. The history of Curve25519 is worth noting as it was introduced after the concerns over allegations that certain parameters of the previously prevalent P-256 NIST standards have been manipulated by NSA for easier snooping. Elliptic Curve Diffie Hellman algorithm is a mathematical algorithm which helps two communicating entities to agree up on a shared secret without actually sending the actual keys to each other.

**Encryption in Instagram:**

Your interaction with Instagram is likely an encrypted communication. When your phone requests data with instagram it will use SSL/TLS over port 443 to encrypt requests from Instagram servers and will send you data over the same encrypted data stream.

This prevents malicious parties from eavesdropping on the conversation between you and instagram.

## Sim card Authentication:

**Authentication** To decide whether or not the SIM may access the network, the SIM needs to be authenticated. A random number is generated by the operator, and is sent to the mobile device. Together with the secret key Ki, this random number runs through the A3 algorithm (it is this Ki that recently has been compromised). The output of this calculation is sent back to the operator, where the output is compared with the calculation that the operator has executed himself (the operator possesses the secret keys for all SIM cards the operator has distributed).

**Encryption** This part is the part that has been cracked. In short, the operator generates a random number (again), and sends it to the mobile phone. Together with the secret key Ki, this random number runs through the A8 algorithm, and generates a session key KC. This KC is used, in combination with the A5 algorithm to encrypt/decrypt the data.

## FAQs

### Where cryptography is used in real life? ›

Encryption is used in **electronic money schemes to protect conventional transaction data like account numbers and transaction amounts**, digital signatures can replace handwritten signatures or a credit-card authorizations, and public-key encryption can provide confidentiality.

**What are the applications of cryptography? ›**

The most obvious use of cryptography, and the one that all of us use frequently, is encrypting communications between us and another system. This is most commonly used for communicating between a client program and a server. Examples are a web browser and web server, or email client and email server.

**What is cryptography why it is important in day to day life? ›**

Cryptography is **used to secure all transmitted information in our IoT-connected world, to authenticate people and devices, and devices to other devices**. If all of the cryptographic engines/functions stopped working for a day, modern life as we know it would stop.

**Is the one of application of cryptography? ›**

Used in a variety of fields in the real world, cryptography uses encryption to hide information in a coded language that does not let adversaries (malicious third parties) access it anyhow. Simply put, cryptography prevents unauthorized access to information and keeps data secure and safe.

**What is cryptography in computer class 8? ›**

In computer science, cryptography refers to secure information and communication techniques derived from mathematical concepts and a set of rule-based calculations called algorithms, to transform messages in ways that are hard to decipher.

**What are some of the first applications of cryptography? ›**

The first known evidence of the use of cryptography (in some form) was found in **an inscription carved around 1900 BC, in the main chamber of the tomb of the nobleman Khnumhotep II, in Egypt**. The scribe used some unusual hieroglyphic symbols here and there in place of more ordinary ones.

**What is an example of cryptology? ›**

A particular suite of algorithms and protocols for encryption, decryption, and key generation. Examples: **Cramer-Shoup cryptosystem, Rabin cryptosystem, Benaloh cryptosystem, RSA cryptosystem**.

**How do you write a cryptography application? ›**

- Prerequisites.
- Create a Windows Forms application.
- Declare global objects.
- Create an asymmetric key.
- Encrypt a file.
- Decrypt a file.
- Export a public key.
- Import a public key.

**What is the application of cryptography in cyber security? ›**

Cryptography **ensures the integrity of data using hashing algorithms and message digests**. By providing codes and digital keys to ensure that what is received is genuine and from the intended sender, the receiver is assured that the data received has not been tampered with during transmission.

**What are types of cryptography? ›**

Cryptography can be broken down into three different types: **Secret Key Cryptography**. Public Key Cryptography. Hash Functions.

### What is the role of cryptography in modern society? ›

used for secure communication. In the modern world, cryptography is **a very important tool for protecting information in computer systems**. With the invention of the World Wide Web or Internet, computer systems are highly interconnected and accessible from any part of the world.

**Which tool is used in cryptography? ›**

**OpenSSL**. OpenSSL is another powerful tool for cryptography. It can be used in different scenarios such as generating keys for different cryptosystems (although the keys can be generated directly with Java) and working with SSL requests.

**What is called cryptography? ›**

Cryptography is **the study of secure communications techniques that allow only the sender and intended recipient of a message to view its contents**. The term is derived from the Greek word kryptos, which means hidden.

**What are the 3 main types of cryptographic algorithms? ›**

**There are three general classes of NIST-approved cryptographic algorithms, which are defined by the number or types of cryptographic keys that are used with each.**

- Hash functions.
- Symmetric-key algorithms.
- Asymmetric-key algorithms.
- Hash Functions.
- Symmetric-Key Algorithms for Encryption and Decryption.

**What are the 4 principles of cryptography? ›**

**Data Confidentiality, Data Integrity, Authentication and Non-repudiation** are core principles of modern-day cryptography.

**Where is cryptography applied? ›**

Cryptography uses mathematical functions to transform data and prevent it from being read or tampered with by unauthorized parties. **Nearly every computing and communications device** uses cryptographic technologies to protect the confidentiality and integrity of information that is communicated and/or stored.

**What are the two types of encryption applications? ›**

There are two types of encryption in widespread use today: **symmetric and asymmetric encryption**. The name derives from whether or not the same key is used for encryption and decryption.

**What is a key in cryptography example? ›**

In cryptography, an encryption key is **a variable value that is applied using an algorithm to a string or block of unencrypted text to produce encrypted text or to decrypt encrypted text**. The length of the key is a factor in considering how difficult it will be to decrypt the text in a given message.

**What are 2 examples of early cryptography? ›**

**A brief history of encryption (and cryptography)**

- Circa 600 BC: The ancient Spartans used a scytale device to send secret messages during battle.
- Circa 60 BC: Julius Caesar invents a substitution cypher that shifts characters by three places: A becomes D, B becomes E, etc.

**What are the 2 main types of cryptographic algorithms? ›**

Encryption Algorithms

Cryptography is broadly classified into two categories: **Symmetric key Cryptography and Asymmetric key Cryptography** (popularly known as public key cryptography).

### How does a cryptography work? ›

Cryptography is a form of securing digital data and messages often using special keys that only the sender and recipient have access to. Cryptography **uses mathematical systems and algorithms to encrypt and decrypt data**. Symmetrical cryptography uses the same key for both encryption and decryption.

**Why is learning cryptography important? ›**

Cryptography is an important aspect of cybersecurity because **it helps keep information secure**. The use of encryption is one way to keep data safe. This entails converting readable data into unreadable data that can only be viewed with the use of an encryption key.

**What is the main goal of cryptography? ›**

Cryptography is the science of using mathematics to **encrypt and decrypt data**. Cryptography enables you to store sensitive information or transmit it across insecure networks (like the Internet) so that it cannot be read by anyone except the intended recipient.

**Who invented cryptography? ›**

**Claude Shannon**. Claude E. Shannon is considered by many to be the father of mathematical cryptography. Shannon worked for several years at Bell Labs, and during his time there, he produced an article entitled "A mathematical theory of cryptography".

**What is cryptology simple language? ›**

cryptology, science concerned with data communication and storage in secure and usually secret form.

**How many types of key in cryptography are there? ›**

Firstly, and most importantly, there are **two primary types** of cryptographic keys: symmetric and asymmetric. The latter always come in mathematically-related pairs consisting of a private key and a public key.

**What are the two branches of cryptography? ›**

Cryptography is a subbranch of **cryptology.** **The other branch is called cryptanalysis**. Cryptography refers to the science of writing secrets with the aim of obscuring the message's meaning. The art and science of breaking cryptosystems are referred to as Cryptanalysis.

**What is the best cryptography method? ›**

AES. **The Advanced Encryption Standard (AES)** is the algorithm trusted as the standard by the U.S. Government and numerous organizations. Although it is highly efficient in 128-bit form, AES also uses keys of 192 and 256 bits for heavy-duty encryption purposes.

**What are the main components of cryptography? ›**

Most practical cryptographic systems combine two elements: **A process or algorithm which is a set of rules that specify the mathematical steps needed to encipher or decipher data.** **A cryptographic key (a string of numbers or characters), or keys**.

**What are the properties of cryptography? ›**

The cryptographic properties of Boolean functions consist of the following: **high degree, balancedness, correlation immunity and r-resilience, high nonlinearity, algebraic immunity**, etc.

### How and where is cryptology used commonly? ›

Core concepts related to information security (data confidentiality, data integrity, authentication, and non-repudiation) are also central to cryptography. Practical applications of cryptography include **electronic commerce, chip-based payment cards, digital currencies, computer passwords, and military communications**.

**Is WhatsApp an example of cryptography? ›**

That's because **the encryption and decryption of messages sent and received on WhatsApp occurs entirely on your device**. Before a message ever leaves your device, it's secured with a cryptographic lock, and only the recipient has the keys. In addition, the keys change with every single message that's sent.

**How does cryptography applied this time? ›**

Modern cryptography uses sophisticated mathematical equations (algorithms) and secret keys to encrypt and decrypt data. Today, cryptography is used **to provide secrecy and integrity to our data, and both authentication and anonymity to our communications**.

**Is cryptography still used? ›**

**Symmetric cryptography is widely used to keep data confidential**. It can be very useful for keeping a local hard drive private, for instance; since the same user is generally encrypting and decrypting the protected data, sharing the secret key is not an issue.

**What is the role of cryptography? ›**

Cryptography includes a set of techniques for scrambling or disguising data so that it is available only to someone who can restore the data to its original form. In current computer systems, cryptography **provides a strong, economical basis for keeping data secret and for verifying data integrity**.

**How cryptography plays its role in communication? ›**

Cryptography **ensures the integrity of data using hashing algorithms and message digests**. By providing codes and digital keys to ensure that what is received is genuine and from the intended sender, the receiver is assured that the data received has not been tampered with during transmission.

**Which type of function is used in cryptography? ›**

**Hash functions** are mathematical functions that transform or "map" a given set of data into a bit string of fixed size, also known as the "hash value." Hash functions are used in cryptography and have variable levels of complexity and difficulty.

**Is VPN a cryptography? ›**

The simple answer is **yes, a VPN is encrypted**. As we explain in our guide to VPNs, a VPN, or a virtual private network, is an encrypted tunnel that connects your computer to a network, typically a public network.

**Does Gmail use cryptography? ›**

Learn more about encryption

S/MIME is a long standing protocol which allows encrypted and signed messages to be sent using standard mail delivery SMTP. **It uses public key cryptography** to: Encrypt the message on send and decrypt the message on receipt with a suitable private key to keep message content private.