Cryptography Beginners Guide with openSSL

Explore why encryption protects data by transforming plain text into cipher text using a secret key and encryption algorithm, and distinguish symmetric and asymmetric keys for secure sharing.

Generate a random 64-bit key using OpenSSL to match the block size. Brute-force complexity grows with key length, so use 128-bit keys or larger.

Explore key space, illustrated with a four-bit key and its 16 possible values. See how the correct key reveals the original plaintext, while an incorrect key does not.

Explore cipher algorithms, including block and stream ciphers, handling plain text and a secret key for encryption and decryption, with examples like des and aes.

Explore how substitution and transposition underlie cipher operations, with reversible mappings using a key, a two-bit substitution example, and a glimpse of 64- and 128-bit block ciphers.

Explore how a two-bit block cipher performs substitution on binary digits, converting plain text to binary and showing four input values (00,01,10,11) with 24 possible keys for ciphertext permutations.

Encrypt a secret text file with a symmetric key using OpenSSL in ECB mode, display binary output, and decrypt with the same key and initialization vector; future lessons cover AES.

Decrypt the deciphered input with OpenSSL enc using ECB and D option, producing 60 output with keys and an initialization vector, revealing the plaintext: 'hi there, the message is secret'.

Recaps steps to encrypt and decrypt a file by generating two keys, one primary and one initialization vector, then encrypting with a block cipher in ECB mode using openssl.

The lecture demonstrates an OpenSSL speed test on DES, compares ECB and CBC modes, and shows encryption speeds of tens of megabytes per second for 16-byte blocks and 64-byte chunks.

Discover how hash functions secure authentication and integrity across blockchain, databases, passwords, and digital signatures. Learn how input maps to output and configure sha-256 with OpenSSL.

Explore how a hash function takes any length input and outputs a 128-bit value, 32 hexadecimal characters, as an irreversible one-way message digest that can digest text, images, or video.

Explain how a 128-bit hash yields 2^128 outputs and why modern hashes like SHA-256 are used for integrity checks. Learn to hash files and compare values to verify downloads.

Understand how hash functions verify integrity by showing that any modification yields a different hash value, with irreversible hashes that detect tampering in transmitted files.

Explore how hash functions secure authentication and integrity by hashing text and encrypting the hash with a symmetric key using des via OpenSSL, including the initialization vector.

Hash the message and encrypt the hash with a symmetric key, attach it to the original message for transmission so the recipient can verify integrity by decrypting and comparing.

Discover how hashes secure passwords, the role of salting, and how linux stores hashes in /etc/shadow using sha-512 for authentication.

Learn to hash mp3 and image files with SHA-256 using OpenSSL, inspect available ciphers, and compare a 256-bit digest to MD5.

Conduct a hash speed test with open SSL, measuring hashes per second on 16-byte and 64-byte inputs, showing about a million hashes per second and GPUs enabling hundreds of millions.

Explore the rise of public key cryptography, from diffie-hellman to RSA, and how private and public keys enable encryption, authentication, and shared keys via open ssl.

Generate your first private key using OpenSSL, explore how public and private keys form a pair, their roles in encryption, decryption, authentication, and digital signatures.

Learn how private keys sign messages with an encrypted hash, a digital signature, and how recipients verify origin by hashing the message and decrypting the signature with a public key.

Explore how public key cryptography enables encryption, decryption, digital signing, and key exchange to secure symmetric session keys between a browser and a web server with OpenSSL certificates.

Explore how public key cryptography enables key exchange and server authentication in https, using private keys, certificates, and digital signatures to secure the session.

The lecture explains how a digital certificate verifies a server's identity by hashing the server's public key and identity, then encrypting the hash with the certificate authority's private key.

Discover how browsers verify a server's certificate by decrypting the signature with certificate authority public keys, checking the hash and timestamp, and obtaining the server's public key.

Learn to generate a private key and create a certificate signing request with OpenSSL, including subject details and options for a real certificate authority or a self-signed certificate.

Learn to self-sign a certificate without a certificate authority by using your private key and a certificate signing request (CSR) to produce an x.509 certificate with OpenSSL.