Cryptography is a fundamental discipline in information security, used to protect data from unauthorized access, guaranteeing the confidentiality, integrity and authenticity of information. Here are some common concepts and techniques in basic cryptography: ## <br>Fundamental Concepts In the fundamental concepts we find 3 groups 1. **plain text and cipher text** 2. **Ciphers and Algorithms** 3. **Cryptographic Keys** In the Common Techniques we can find the following categories: ### <br>1. Symmetric Encryption: + Algorithms: AES (Advanced Encryption Standard), DES (Data Encryption Standard), 3DES. + Characteristics: High speed and efficiency. Requires the key to be kept secret between the communicating parties. ### <br>2. Asymmetric Cryptography: + Algorithms: RSA, ECC (Elliptic Curve Cryptography). + Characteristics: Uses public and private key pairs. Slower than symmetric cryptography, but solves the problem of secure key distribution. ### <br>3. Hashing: + Algorithms: SHA-256, MD5 (not recommended due to vulnerabilities). + Characteristics: Generates a fixed size value from an input of any size. Used to guarantee data integrity. Hash functions are unidirectional and cannot be reversed. ### <br>4. Digital Signatures: + Process: Combines asymmetric cryptography and hashing to authenticate the origin and integrity of a message. + Use: Confirms that the message was sent by a legitimate sender and has not been altered. ### <br>5. Digital Certificates: + Definition: Electronic documents that use digital signatures to link a public key to an identity. + Use: Secure distribution of public keys, verification of online identities, authentication of websites and systems. ## <br>Common applications ### <br>1. Secure communications: + Protocols: SSL/TLS for HTTPS connections, VPNs (Virtual Private Networks). + Use: Protects the transmission of sensitive data on the Internet. ### <br>2. Secure Storage: + Examples: Disk and file encryption, cloud storage systems. + Use: Protects stored data from unauthorized access. ### <br>3. Authentication and Access Control: + Techniques: 2FA (Two-Factor Authentication), identity and access management (IAM) systems. + Use: Ensures that only authorized users access sensitive systems and data. Cryptography is an essential tool for protecting information in a variety of contexts, from personal communications to corporate and government systems. The choice of encryption algorithm and techniques depends on the specific security and performance needs of each application.