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Security Fundamentals & Crypto · Advanced

ChaCha20-Poly1305

AEAD algorithm combining the ChaCha20 stream cipher with the Poly1305 authenticator, standardized in RFC 8439.

Definition

ChaCha20-Poly1305 uses a 256-bit key and is fast in software on devices without AES hardware acceleration. It is supported in TLS 1.3, SSH, and is the cipher used by WireGuard. It provides confidentiality and integrity in one construction.

Example

Mobile browsers often negotiate TLS_CHACHA20_POLY1305_SHA256 for speed on ARM processors.

Exam tip

Know it as the modern alternative to AES-GCM, especially for mobile and WireGuard.

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