> For the complete documentation index, see [llms.txt](https://0xn3va.gitbook.io/application-security-handbook/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://0xn3va.gitbook.io/application-security-handbook/web-application/cryptography.md).

# Cryptography

## Overview

This section contains recommendations for implementing and using functionality related to cryptographic operations.

{% hint style="warning" %}
Main rule of cryptography is do **not** invent your own cryptography. It can definitely be hacked.
{% endhint %}

## General practices

| Scenario              | Algorithm (base)                      | Algorithm (advanced)                     |
| --------------------- | ------------------------------------- | ---------------------------------------- |
| Key exchange          | Diffie-Hellman key exchange, 2048 bit | ECDH Curve25519                          |
| Message integrity     | HMAC-SHA2, 256 bit                    | HMAC-SHA2, 512 bit                       |
| Message hash          | SHA2, 256 bit                         | SHA2, 512 bit                            |
| Asymmetric encryption | RSA, 2048 bit, SHA-256                | ECC Curve25519 or RSA, 3072 bit, SHA-256 |
| Symmetric encryption  | AES, 128 bit, GCM                     | AES, 256 bit, GCM                        |
| Key exchange          | Argon2 or PBKDF2                      | Argon2 or PBKDF2                         |


---

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