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ChaCha20-Poly1305

ChaCha20-Poly1305 encrypts data with a defined symmetric construction.

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Quick Facts

Compact metadata for implementation and discovery.

Category
Cryptography
Difficulty
Intermediate
Family
Authenticated Encryption
Tier
Core
Status
Verified
Review
Source Checked
Sources
1
Formulas
0
Relationships
1
Code example
Ready
Visualization
Ready
Aliases
ChaCha20-Poly1305 AEAD

Overview

ChaCha20-Poly1305 is a cryptographic method that protects confidentiality, authenticity, or integrity with a defined primitive or protocol step. It should be used only as part of a well-defined protocol with correct parameters and key handling.

Core Concepts

key materialsecurity parameterverification ruleverification

Quick facts

Complexity

Runtime and memory behavior at a glance.

Best

O(n)

Average

O(n)

Worst

O(n)

Space

O(1)

When to Use

  • Use ChaCha20-Poly1305 only when the protocol calls for this specific primitive or construction.
  • Use it when a vetted implementation is available and parameter handling can be enforced.

When Not to Use

  • Avoid custom protocol combinations around this primitive.
  • Avoid when nonce, key, padding, or parameter requirements cannot be enforced.

What It Does

  • Computes authenticated encryption within Authenticated Encryption workloads (O(n) time, O(1) space).
  • Works by It should be used only as part of a well-defined protocol with correct parameters and key handling.
  • Maintains key invariants across key material, security parameter, verification rule.

Use Cases

  • Secure communication
  • Authentication
  • Key management

Inputs

  • Message or secret
  • Key material
  • Nonce, salt, or public parameters

Outputs

  • Ciphertext, tag, key, signature, or proof
  • Verification result

Pseudocode

  1. 1.Validate keys, nonces, and required parameters
  2. 2.Apply the primitive's block, group, hash, or verification operation
  3. 3.Combine intermediate values according to the construction
  4. 4.Return the ciphertext, tag, key, signature, proof, or verification result

Canonical Example

Input
message = 'pay 10', key material = provided, nonce or public parameters = provided
Output
protected value or verification result
Explanation
ChaCha20-Poly1305 applies its defined cryptographic operation without inventing extra protocol steps.

Implementation Notes

  • Use vetted implementations for low-level primitives.
  • Validate parameter lengths, nonce handling, and authentication failure behavior explicitly.

Common Pitfalls

  • Reusing nonces, salts, or ephemeral values can break security assumptions.
  • Treating a primitive as a full protocol invites key-management and authentication mistakes.

Interactive Mechanism Walkthrough

Graph Frontier & Edge Relaxation

Show messages, keys, nonces, and verification values moving through the cryptographic construction.

ChaCha20-Poly1305 mechanism walkthrough step 1 of 4suvwxt
Step 1 of 4: Validate keys, nonces, and required parameters
crypto

Notes

ChaCha20-Poly1305 operates in O(n) time and O(1) space within the Authenticated Encryption family. Often compared with ChaCha20 and HMAC.

Sources (1)

What each reference supports for this entry.

RFC 8439

Documentation

Defines ChaCha20, Poly1305, and the combined AEAD construction relevant to ChaCha20-Poly1305.

Open source

Explore Next

Good next jumps from the relationship graph, ranked for useful discovery.

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Conceptual neighborChaCha20

Cryptography · Core

ChaCha20-Poly1305 and ChaCha20 address nearby cryptography problems but make different implementation tradeoffs.

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Relationships

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Conceptual neighborChaCha20

ChaCha20-Poly1305 and ChaCha20 address nearby cryptography problems but make different implementation tradeoffs.

Related Algorithms

ChaCha20HMACAES-GCMAESSHA-256

Tags

CryptographySecurityStream CipherMessage Authentication