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Cryptography & Public Key Infrastructure

Secure systems design principles and cryptographic implementations for distributed networks

Understanding PKI

Public Key Infrastructure (PKI) forms the backbone of secure digital communication. It combines cryptographic techniques, policies, and physical infrastructure to enable:

  • Authentication of identities
  • Data encryption
  • Non-repudiation through digital signatures
  • Secure key management lifecycle

Asymmetric Cryptography

Uses key pairs - public keys for encryption/verification and private keys for decryption/signing.

openssl genrsa -out private.pem 2048
openssl rsa -in private.pem -pubout > public.pem

Digital Certificates

Verify the association between a public key and an entity identified by a subject name.

CN=mydomain.com
O=My Organization
OU=IT Department
L=City
ST=State
C=Country

PKI Architecture

CA ICA Entity 1 Entity 2

The diagram illustrates a typical PKI hierarchy with:

  • Trusted Root Certificate Authority
  • Intermediate CAs for better security
  • End entities (clients/servers)
  • Secure chain of trust validation

Key Pair Generator

2048-bit key 
-----BEGIN PRIVATE KEY-----
MIIEvQIBADANBgkqhkiG9w0BAQEFAASCBKcwggSjAgEAAoIBAQC5v21Z7B6Y2KjJ
...
-----END PRIVATE KEY-----

Advanced Cryptographic Concepts

Quantum-Resistant Algorithms

Next-gen cryptographic solutions designed to withstand Shor's algorithm attacks:

  • Lattice-based cryptography
  • Hash-based signatures (LM-OTS)
  • Multivariate quadratic systems
  • Error-correcting code-based schemes

Zero-Knowledge Proofs

Protocols that allow one party to prove to another that a statement is true without revealing any additional information.

zk-SNARKs
zk-STARKs
ZK-PCS