Android开发中能否使用Adiantum加密？求实现方法及相关指引

Great question—Adiantum was explicitly designed to solve exactly the problem you’re facing: slow AES performance on low-end Android devices without hardware acceleration. Let’s clear up your key questions and give you actionable guidance:

Can Adiantum be used in app-level development? #

Absolutely. While Google initially rolled out Adiantum for system-level full-disk encryption (FDE) on low-end devices, there’s no restriction preventing you from integrating it into your Android app. It’s a general-purpose encryption algorithm optimized for software performance, making it perfect for app use cases like encrypting user data, cached files, or sensitive app assets.

Implementation Guidance for Android Apps #

Here’s how to get started with Adiantum in your app:

1. Pick a Supported Cryptography Library #

Adiantum isn’t directly exposed in the Android Framework’s javax.crypto package, so you’ll need to use a third-party library that includes its implementation. Two reliable options:

• BoringSSL: Google’s own open-source crypto library (used in Android itself). It has a complete Adiantum implementation.
• Libsodium: A user-friendly, secure crypto library that wraps Adiantum (via its crypto_secretstream_xchacha20poly1305 primitive, which aligns closely with Adiantum’s design).

2. Core Implementation Steps #

Adiantum is a stream cipher with authenticated encryption (similar to ChaCha20-Poly1305, but optimized for disk encryption). Here’s a high-level breakdown of the workflow:

• Generate a Secure Key: Adiantum uses a 256-bit (32-byte) key. Store this key securely using Android’s Keystore System to avoid hardcoding or exposing it in memory.
• Generate a Unique Nonce: Adiantum requires a 128-bit (16-byte) nonce. Critical rule: never reuse the same nonce with the same key—this breaks the encryption’s security. Generate a new nonce for every encryption operation (you can store the nonce alongside the ciphertext, as it doesn’t need to be secret).
• Encrypt/Decrypt with Authentication: Use the library’s Adiantum functions to encrypt your data, which will also generate a 16-byte Poly1305 authentication tag. When decrypting, verify this tag first to ensure the data hasn’t been tampered with.

3. Example Code Snippet (BoringSSL) #

If you’re using BoringSSL, here’s a simplified code outline to illustrate the flow:

#include <openssl/adiantum.h>
#include <openssl/rand.h>

// Generate a 256-bit Adiantum key
uint8_t adiantum_key[32];
if (!RAND_bytes(adiantum_key, sizeof(adiantum_key))) {
    // Handle key generation failure
    return;
}

// Generate a unique 128-bit nonce
uint8_t nonce[16];
if (!RAND_bytes(nonce, sizeof(nonce))) {
    // Handle nonce generation failure
    return;
}

// Sample plaintext data
uint8_t plaintext[] = "Sensitive user data";
size_t plaintext_len = sizeof(plaintext) - 1;

// Encrypt: ciphertext will match plaintext length, plus a 16-byte tag
uint8_t ciphertext[plaintext_len];
uint8_t auth_tag[16];
Adiantum_encrypt(ciphertext, auth_tag, plaintext, plaintext_len, nonce, adiantum_key);

// Decrypt & verify authenticity
uint8_t decrypted_data[plaintext_len];
if (!Adiantum_decrypt(decrypted_data, ciphertext, plaintext_len, auth_tag, nonce, adiantum_key)) {
    // Authentication failed: data may be corrupted or tampered with
    // Handle error (e.g., alert user, discard invalid data)
    return;
}

4. Key Considerations #

• Performance Testing: While Adiantum is far faster than software-based AES on low-end CPUs (like Cortex-A7), always test on your target devices to confirm it meets your app’s performance needs.
• Compatibility: Since you’re using a third-party library, you won’t hit Android version restrictions—your implementation will work on older devices as long as you bundle the library correctly.
• Documentation: For deep algorithm details, refer to Google’s official Adiantum technical paper. For library-specific implementation docs, check the BoringSSL or Libsodium source code comments and official guides.

Final Takeaway #

Adiantum is absolutely viable for app-level development, and it’s the perfect drop-in replacement for AES when targeting low-end Android devices without hardware acceleration. By using a trusted crypto library and following secure key/nonce practices, you can integrate it smoothly into your app to improve user experience on those devices.

内容的提问来源于stack exchange，提问作者Tejas Pandya