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API Reference
Symmetric Encryption

Symmetric Encryption

Symmetric encryption algorithms, focusing on authenticated encryption (AEAD) modes.

Authenticated Encryption (AEAD)

Provides both confidentiality AND authenticity. Always use these for encryption.

AES-GCM ⭐ Recommended

Advanced Encryption Standard with Galois/Counter Mode

  • Industry standard authenticated encryption
  • Hardware accelerated (AES-NI, ARM Crypto)
  • Fast parallel encryption/decryption
  • 128, 192, or 256-bit keys

Use AES-GCM for:

  • File encryption (with careful nonce management)
  • Network protocol encryption (TLS, IPsec)
  • Database encryption
  • Any scenario requiring both encryption and authentication

ChaCha20-Poly1305

Modern authenticated encryption alternative

  • Excellent for systems without AES hardware acceleration
  • Constant-time (resistant to timing attacks)
  • 256-bit keys only
  • Used in TLS 1.3, WireGuard, Signal

XChaCha20-Poly1305

Extended nonce variant of ChaCha20-Poly1305

  • 24-byte nonce with negligible collision risk
  • Safe to use random nonces
  • Ideal for file encryption and at-rest data
  • No counter tracking required

AES-CCM

Counter with CBC-MAC mode

  • Used in Wi-Fi (WPA2/WPA3 CCMP-128), Bluetooth, Zigbee, and TLS
  • Two-pass mode (slower than GCM)
  • Requires pre-specified data lengths
  • Variable nonce size (7-13 bytes)

AES-EAX

EAX authenticated encryption mode

  • Simple, well-analysed construction
  • Built from CTR mode + CMAC
  • Flexible nonce length (any size)
  • Good choice when GCM hardware unavailable

Low-Level Primitives

Warning: These are building blocks. Use AEAD modes above instead.

AES, ChaCha20, Twofish, and other block/stream ciphers are available as raw primitives, but you should almost always use the AEAD modes above.

  • Twofish - AES finalist block cipher (128-bit block, 128/192/256-bit keys)

Legacy Modes (Require Separate MAC)

Warning: These modes don’t provide authentication. Prefer AEAD modes like GCM, ChaCha20-Poly1305, XChaCha20-Poly1305, EAX, or CCM instead.

Don’t use ECB mode; it’s insecure and not recommended.

Quick Comparison

Mode/CipherAuthenticationParallelHardware AccelRecommended
AES-GCM✅ Yes✅ Yes✅ Yes⭐ Primary choice
ChaCha20-Poly1305✅ Yes✅ Yes❌ NoSoftware systems
XChaCha20-Poly1305✅ Yes✅ Yes❌ NoRandom nonces
AES-CCM✅ YesLimited✅ YesWi-Fi, Bluetooth, TLS
AES-EAX✅ YesPartial✅ YesSimple AEAD
AES-CBC❌ No❌ No✅ YesLegacy only
AES-CTR❌ No✅ Yes✅ YesWith HMAC only

Choosing an Algorithm

For New Systems

  1. AES-GCM (primary recommendation)

    • Hardware acceleration available on target platform
    • Need maximum performance
    • Industry standard compliance required

  2. ChaCha20-Poly1305 (alternative)

    • No AES hardware acceleration
    • Mobile/embedded platforms
    • Constant-time implementation preferred

For Legacy Systems

  • Upgrading from AES-CBC: Migrate to AES-GCM
  • Upgrading from AES-CTR+HMAC: Migrate to AES-GCM
  • Cannot change: Add HMAC authentication if not present

Security Best Practices

  1. Always use authenticated encryption (AES-GCM, ChaCha20-Poly1305, XChaCha20-Poly1305, EAX, CCM)
  2. Never reuse IVs with the same key
  3. Generate random IVs using AutoSeededRandomPool
  4. Use 256-bit keys for new systems (future-proof)
  5. Verify authentication tags - failed verification = tampered data
  6. Store IVs with ciphertext (IVs don’t need to be secret)
  7. Use SecByteBlock for keys (auto-zeroing memory)

Performance Notes

On modern x86 with AES-NI, AES-GCM is typically about 2× faster than CCM/EAX, and ChaCha20-Poly1305 is competitive when AES-NI isn’t available.

Hardware Acceleration Detection 

#include <cryptopp/aes.h>
#include <iostream>

void checkHardwareSupport() {
    using namespace CryptoPP;

    std::cout << "AES Provider: "
              << AES::Encryption().AlgorithmProvider()
              << std::endl;

    // Output examples:
    // "AESNI"      - Intel/AMD x86-64 with AES-NI
    // "ARMv8"      - ARM with Crypto Extensions
    // "POWER8"     - IBM POWER8+ with AES
    // "C++"        - Software implementation
}

See Also