What are the three main security goals that cryptography can provide?

Confidentiality (secrecy), Data Authenticity/Integrity, and User Authentication.

These form the foundation of the "crypto puzzle":

1. Confidentiality (Geheimhaltung)

• Keeping information secret from unauthorized parties
• Achieved through encryption (symmetric or asymmetric)
• Algorithms: 3DES, AES, etc. (in various modes)

2. Data Authenticity / Integrity

• Ensuring data hasn't been tampered with and comes from the claimed sender
• Integrity is a subset of authenticity
• Achieved through MACs (Message Authentication Codes) or digital signatures
• Symmetric: MAC/HMAC (e.g., HMAC with SHA-3)
• Asymmetric: Digital signatures (RSA, ECC, EdDSA, etc.)

3. User Authentication (Benutzerauthentizität)

• Verifying the identity of a person or system
• Also called "instant authentication"

Important distinctions:

• Integrity is a subset of authenticity (you can have integrity without full authenticity)
• Non-repudiation (Verbindlichkeit = non-deniability) is integrated into data authenticity
• Encryption alone does NOT provide authenticity — a common and dangerous misconception