Signing, Encrypting, Encoding

AES (Advanced Encryption Standard)

Type: Symmetric Encryption

Alice and Bob use a shared secret to exchange encrypted messages.

Use Cases:

• Secure communication

OpenSSL::Cipher.new("AES-256-CBC")

RSA (Rivest–Shamir–Adleman)

Type: Asymmetric Encryption

Alice uses Bob's public key to encrypt the message, Bob decrypts the message using his private key. Bob uses his private key to sign the message, Alice uses Bob's public key to verify the signature.

Use Cases:

• Digital signatures / data integrity
• Secure communication

OpenSSL::PKey::RSA

HMAC (Hash-based Message Authentication Code)

Type: Signing / Symmetric cryptography

Use Cases:

• Digital signatures / data integrity

OpenSSL::HMAC.hexdigest("sha256", key, data)

ECDSA (Elliptic Curve Digital Signature Algorithm)

Type: Signing / Asymmetric cryptography

Use Cases:

• Digital signatures / data integrity

OpenSSL::PKey::EC.new("prime256v1")

Base64

Type: Encoding

Use Cases:

• Data serialization
• URL-safe encoding

Base64.encode64(data)
Base64.urlsafe_encode64(data)

JWT (JSON Web Tokens)

Type: Authentication

JWT consists of data in JSON format, split into 3 parts using a dot:

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiaWF0IjoxNTE2MjM5MDIyfQ.SflKxwRJSMeKKF2QT4fwpMeJf36POk6yJV_adQssw5c

1st and 2nd parts are a Base64-encoded header and a payload, the 3rd part is a signature over this data. JWT can use both symmetric and asymmetric cryptography for signatures.

Use Cases:

• Stateful authentication
• Data integrity

JWK (JSON Web Key)

Type: Standartized Cryptographic Key Representation

Use Cases:

• Key exchange
• Managing cryptographic keys