Building secure applications demands precision and safety. Rust’s memory management and performance characteristics provide a strong foundation for cryptographic tasks. I’ve found that combining these language features with well-designed libraries creates robust security solutions. Let’s examine eight practical cryptographic techniques implemented in Rust.

Cryptographically secure random generation forms the bedrock of security systems. Predictable values create vulnerabilities. Rust’s rand_core crate offers access to system-level entropy. Consider this key generation example:

use rand_core::{OsRng, RngCore};

fn generate_encryption_key() -> [u8; 32] {
    let mut key = [0u8; 32];
    OsRng.fill_bytes(&mut key);
    key
}

The OsRng struct taps into your operating system’s entropy source, producing values suitable for cryptographic operations. I always verify generation quality using statistical test suites before deployment.

Authenticated encryption protects both confidentiality and integrity. AES-GCM remains my preferred choice for many applications. Here’s how I implement it:

use aes_gcm::{
    aead::{Aead, KeyInit, OsRng},
    Aes256Gcm, Nonce
};

fn encrypt_data(key: &[u8], data: &[u8]) -> Vec<u8> {
    let cipher = Aes256Gcm::new_from_slice(key).expect("Valid key length");
    let nonce = Nonce::from_slice(b"unique_nonce_96bit");
    cipher.encrypt(nonce, data).expect("Encryption failure")
}

Notice the explicit handling of potential failures. In production systems, I rotate nonces frequently and monitor encryption success rates.

Digital signatures verify message authenticity. Ed25519 provides strong security with efficient performance. Here’s my signing pattern:

use ed25519_dalek::{SigningKey, Verifier, Signature};
use rand_core::OsRng;

let signing_key = SigningKey::generate(&mut OsRng);
let message = b"Critical system update";
let signature: Signature = signing_key.sign(message);

// Verification
assert!(signing_key.verify(message, &signature).is_ok());

For distributed systems, I serialize keys using serde and implement key rotation schedules. Signature failures trigger immediate security audits.

Password hashing requires specialized algorithms. Argon2 resists GPU cracking by design. My implementation includes configurable parameters:

use argon2::{
    password_hash::{PasswordHash, PasswordHasher, SaltString},
    Argon2, Params
};

let password = b"user_password_123";
let salt = SaltString::generate(&mut OsRng);
let custom_params = Params::new(15000, 2, 1, None).unwrap();
let argon2 = Argon2::new(argon2::Algorithm::Argon2id, argon2::Version::V0x13, custom_params);
let hash = argon2.hash_password(password, &salt).unwrap().to_string();

I adjust memory costs based on server resources and enforce minimum password requirements. Storage includes algorithm parameters for future verification.

Key derivation expands secrets safely. HKDF prevents key reuse vulnerabilities. Here’s my approach for deriving multiple keys:

use hkdf::Hkdf;
use sha2::Sha256;

fn derive_keys(master_key: &[u8]) -> ([u8; 32], [u8; 32]) {
    let hk = Hkdf::<Sha256>::new(None, master_key);
    let mut enc_key = [0u8; 32];
    let mut auth_key = [0u8; 32];
    hk.expand(b"encryption_context", &mut enc_key).unwrap();
    hk.expand(b"authentication_context", &mut auth_key).unwrap();
    (enc_key, auth_key)
}

Clear context strings prevent accidental overlap. I derive separate keys for each cryptographic purpose within a system.

Secure memory handling prevents secret leakage. Zeroization ensures sensitive data doesn’t persist:

use zeroize::Zeroize;

struct EncryptionKey([u8; 32]);

impl EncryptionKey {
    fn new() -> Self {
        let mut key = [0u8; 32];
        OsRng.fill_bytes(&mut key);
        Self(key)
    }
}

impl Drop for EncryptionKey {
    fn drop(&mut self) {
        self.0.zeroize()
    }
}

This pattern protects against core dumps and memory inspection attacks. I combine it with mlock for additional protection.

Constant-time operations defeat timing attacks. Cryptographic comparisons require careful implementation:

use subtle::ConstantTimeEq;

fn verify_mac(a: &[u8], b: &[u8]) -> bool {
    if a.len() != b.len() {
        return false;
    }
    bool::from(a.ct_eq(b))
}

I use this for HMAC verification and signature checks. The subtle crate’s operations compile to branch-free assembly.

Certificate validation avoids legacy vulnerabilities. Rustls provides a pure-Rust TLS implementation:

use rustls::{OwnedTrustAnchor, RootCertStore};
use webpki_roots::TLS_SERVER_ROOTS;

fn build_tls_config() -> rustls::ClientConfig {
    let mut root_store = RootCertStore::empty();
    for anchor in TLS_SERVER_ROOTS.iter() {
        root_store.add(&OwnedTrustAnchor::from_subject_spki_name_constraints(
            anchor.subject,
            anchor.spki,
            anchor.name_constraints,
        )).unwrap();
    }
    rustls::ClientConfig::builder()
        .with_safe_defaults()
        .with_root_certificates(root_store)
        .with_no_client_auth()
}

This approach eliminates OpenSSL dependencies. I pin certificates for critical services and implement revocation checks.

Rust’s type system prevents common cryptographic mistakes. The compiler enforces proper key sizes, handles lifetimes for sensitive data, and prevents buffer overflows. Through trait implementations, libraries guarantee correct algorithm usage. I’ve found that these compile-time checks significantly reduce runtime vulnerabilities compared to other languages. Cryptographic security requires constant vigilance, but Rust provides the tools to build with confidence.