Cryptographic Failures in Axum with Cockroachdb

When building a service in Axum that persists data in Cockroachdb, cryptographic failures typically arise from how application code handles encryption before data reaches the database, and how it manages keys and connections. Cockroachdb natively supports TLS for transport encryption and offers application-level features such as column-level encryption, but it does not automatically encrypt data at rest in a way that relieves the application from key management responsibilities.

A common pattern is to serialize a domain model to JSON and store it in a JSONB column. If the application inserts sensitive fields (e.g., ssn, credit_card_last4, or session tokens) without encrypting them, these values are stored in clear text. Even with Cockroachdb’s TLS, an attacker who compromises a client or an intermediary network component can observe traffic if the server certificate validation is not enforced in the Axum client. Additionally, logs, metrics, or error messages emitted by Axum handlers may inadvertently include raw database values, leading to data exposure in observability pipelines.

Another vulnerability occurs when encryption keys are derived or stored alongside application code or configuration files that are version-controlled or accessible to unauthorized processes. In a containerized deployment, environment variables injected into the Pod may be readable by co-located containers or via debug endpoints. If the Axum application uses a static key for encryption without key rotation, a single leaked key exposes all records. This violates principles such as those in the OWASP API Top 10 — Data Protection, and can map to findings like those reported by middleBrick under Data Exposure and Encryption checks.

SSR and improper connection handling can also amplify cryptographic failures. For example, if an Axum middleware reuses database connections without enforcing per-request TLS settings, or if it accidentally allows non-TLS connections to Cockroachdb in a mixed-environment setup, traffic may traverse unencrypted channels. MiddleBrick scans detect such misconfigurations under its Encryption and Data Exposure checks, highlighting whether traffic is properly encrypted and whether sensitive data appears in outputs that could be intercepted or logged.

To mitigate cryptographic failures, handle encryption in Axum before data reaches Cockroachdb, and enforce strict connection policies. Below is a concise, realistic example using rustls for TLS and aws-kms for envelope encryption. The pattern ensures that sensitive fields are encrypted as application objects, never stored as plaintext in the database.

// Cargo.toml dependencies
// [dependencies]
// axum = "0.6"
// serde = { version = "1.0", features = ["derive"] }
// tokio = { version = "1", features = ["full"] }
// sqlx = { version = "0.7", features = ["postgres", "runtime-tokio", "uuid", "json"] }
// aws-sdk-kms = "0.24"
// tower-http = { version = "0.5", features = ["cors"] }

use axum::{routing::post, Router};
use serde::{Deserialize, Serialize};
use sqlx::postgres::PgPoolOptions;
use std::net::SocketAddr;
use aws_sdk_kms::Client as KmsClient;
use aws_config::meta::region::RegionProviderChain;

#[derive(Debug, Serialize, Deserialize, sqlx::FromRow)]
struct UserRecord {
    id: uuid::Uuid,
    // Encrypted fields are stored as base64-encoded ciphertext
    ssn_ciphertext: String,
    ssn_iv: String,
}

async fn store_user(
    pool: sqlx::PgPool,
    kms: KmsClient,
    payload: UserPayload,
) -> Result> {
    // Envelope encryption: generate data key, encrypt payload, store ciphertext + IV
    let resp = kms.generate_data_key()
        .key_id("alias/app-sensitive")
        .send()
        .await?;
    let plaintext_key = resp.plaintext_key.unwrap();
    let encrypted_key = resp.ciphertext_blob.unwrap();

    // Use AES-GCM via a safe crate in real code; here we abstract with a placeholder
    let (ciphertext, iv) = encrypt_aes_gcm(&payload.ssn, &plaintext_key)?;

    sqlx::query!(
        r#"
        INSERT INTO user_records (id, ssn_ciphertext, ssn_iv, encrypted_key)
        VALUES ($1, $2, $3, $4)
        "#,
        uuid::Uuid::new_v4(),
        base64::encode(ciphertext),
        base64::encode(iv),
        base64::encode(encrypted_key)
    )
    .execute(&pool)
    .await?;

    Ok("stored".to_string())
}

#[tokio::main]
async fn main() -> Result<(), Box> {
    // Enforce TLS when connecting to Cockroachdb
    let database_url = std::env::var("DATABASE_URL")?;
    let pool = PgPoolOptions::new()
        .connect(&format!("{}?sslmode=verify-full", database_url))
        .await?;

    // Initialize KMS client with region and assume role if needed
    let region_provider = RegionProviderChain::default_provider().or_else("us-east-1");
    let config = aws_config::from_env().region(region_provider).load().await;
    let kms = KmsClient::new(&config);

    let app = Router::new()
        .route("/users", post(|pool, kms| async move {
            // handler using pool and kms
        }));

    let addr = SocketAddr::from(([127, 0, 0, 1], 3000));
    axum::Server::bind(&addr)
        .serve(app.into_make_service())
        .await?;

    Ok(())
}

fn encrypt_aes_gcm(data: &str, key: &[u8]) -> Result<(Vec, Vec), Box> {
    // Placeholder: implement with aes-gcm crate in production
    Ok((vec![0; 32], vec![0; 12]))
}

Key points:

• Use sslmode=verify-full in the connection string to enforce certificate validation and prevent man-in-the-middle attacks.
• Perform envelope encryption: generate a data key from KMS, encrypt the sensitive field, store the ciphertext and IV in the database, and protect the data key with KMS.
• Avoid logging raw values; ensure Axum’s error handlers do not serialize database fields into responses or logs.
• Rotate KMS keys and data keys periodically; middleBrick’s Encryption and Data Exposure checks can help verify that encryption is applied consistently.

These steps align with compliance expectations such as PCI-DSS and SOC 2, and they address findings that middleBrick may surface under its Encryption, Data Exposure, and Unsafe Consumption checks when scanning APIs backed by Cockroachdb.