Asymmetric keys

Asymmetric keys

Asymmetric keys (a.k.a public key cryptography) involves a pair of keys for encryption and decryption—a public key and a private key. The public key is shared openly for encrypting messages, while the private key is kept secret for decryption. This method is foundational for secure communications over the internet, enabling confidentiality, authentication, and non-repudiation.

  • Asymmetric keys use a pair of keys: a public key for encryption and a private key for decryption.
  • Suitable for secure data transmission over unsecured channels.
  • Requires more computational resources, making it slower for large data volumes.
  • Enables digital signatures, verifying both the message’s integrity and the sender’s identity.
  • Key management is simpler since only the private key needs to be kept secret; the public key can be widely distributed.
flowchart LR
    A[Public Key] -->|Encrypts Data| B[Encrypted Data]
    B -->|Decrypts with Private Key| C[Decrypted Data]

Pros and Cons

Advantages Disadvantages
Secure communication over unsecured channels. Higher computational requirements than symmetric keys.
Enables digital signatures for authenticity and integrity. Slower for encrypting large data volumes.
Simplifies key distribution since only the public key needs to be shared. Complexity in implementation and key management.

Common Algorithms

  • RSA (Rivest-Shamir-Adleman): Utilizes the difficulty of factoring large integers.
  • ECC (Elliptic Curve Cryptography): Provides security with smaller keys for efficiency.
  • Diffie-Hellman: Facilitates secure key exchange over unsecure channels.
  • DSA (Digital Signature Algorithm): Used for digital signatures, ensuring authenticity and integrity.

Key Management

Asymmetric key management involves securely generating, storing, and sharing the keys between parties. Key management practices include:

  • Key Generation: Securely creating a public-private key pair using a cryptographically secure random number generator.
  • Key Storage: Safely storing the private key to prevent unauthorized access or tampering.
  • Key Distribution: Securely sharing the public key between parties using secure channels or key exchange protocols.
  • Key Rotation: Periodically updating the key pair to mitigate the impact of a compromised key.1
  • Key Revocation: Disabling a compromised key to prevent further use and replacing it with a new key.
  • Access Control: Limiting key access to authorized individuals only.
  • Audit and Compliance: Regularly reviewing key usage and access to ensure compliance with security policies.

  1. Key Rotation with asymmetric keys can be challenging due to the need to update the public key across all entities that rely on it. However, it is essential to mitigate the impact of a compromised private key and maintain secure communication. ↩︎