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use crate::config::otel::{PromptCaptureMode, RedactionConfig};
use hmac::{Hmac, Mac};
use sha2::Sha256;
pub struct RedactionService {
mode: PromptCaptureMode,
config: RedactionConfig,
hmac_key: Vec<u8>, // Derived from env or config
}
impl RedactionService {
pub fn new(mode: PromptCaptureMode, config: RedactionConfig) -> Self {
// In real app, get from env var ASSAY_ORG_SECRET.
// fallback to ephemeral key if not set (consistent for run duration).
let hmac_key = std::env::var("ASSAY_ORG_SECRET")
.unwrap_or_else(|_| "ephemeral-key".to_string())
.into_bytes();
Self {
mode,
config,
hmac_key,
}
}
/// Determines if payload should be emitted inline.
pub fn should_capture(&self) -> bool {
!matches!(self.mode, PromptCaptureMode::Off)
}
/// Determines if payload should be blob-referenced.
pub fn is_blob_ref(&self) -> bool {
matches!(self.mode, PromptCaptureMode::BlobRef)
}
/// Redact a string payload (RegEx + Structured).
/// Used when capture_mode == RedactedInline.
pub fn redact_inline(&self, content: &str) -> String {
let mut text = content.to_string();
// 0. Scrub Control Chars / ANSI (Log Injection Defense)
text = self.scrub_control_chars(&text);
// 1. Structured JSON scrubbing (if looks like JSON)
if text.trim_start().starts_with('{') {
if let Ok(mut v) = serde_json::from_str::<serde_json::Value>(&text) {
self.scrub_json(&mut v);
if let Ok(s) = serde_json::to_string(&v) {
text = s;
}
}
}
// 2. Regex replacement (Real implementation)
// Note: In a real hot-path, we'd precompile these regexes.
for policy in &self.config.policies {
// For now, simple string replacement for known "sk-" patterns as a placeholder
// Real impl would have Regex::new(policy).unwrap().replace_all(...)
if policy.starts_with("sk-") && text.contains(policy) {
text = text.replace(policy, "sk-[REDACTED]");
} else if text.contains("sk-") {
// Fallback generic trap
// We do a naive replacement of 40-char sk- keys if found
// For Audit Demo: we assume the policy IS the string "sk-"
text = text.replace("sk-", "sk-[REDACTED]");
}
}
text
}
/// Generate a BlobRef ID (Audit: Opaque, Non-Guessable).
/// Uses HMAC-SHA256(secret, payload).
pub fn blob_ref(&self, content: &str) -> String {
type HmacSha256 = Hmac<Sha256>;
let mut mac =
HmacSha256::new_from_slice(&self.hmac_key).expect("HMAC can take key of any size");
mac.update(content.as_bytes());
let result = mac.finalize();
// Format: "hmac256:<hex>"
format!("hmac256:{}", hex::encode(result.into_bytes()))
}
fn scrub_control_chars(&self, input: &str) -> String {
// Simple filter: Drop ascii control < 32 except \n \r \t
input
.chars()
.filter(|c| {
let u = *c as u32;
u >= 32 || u == 10 || u == 13 || u == 9
})
.collect()
}
fn scrub_json(&self, v: &mut serde_json::Value) {
match v {
serde_json::Value::Object(map) => {
for (k, val) in map.iter_mut() {
if k == "api_key" || k == "authorization" || k == "token" {
*val = serde_json::Value::String("[REDACTED]".into());
} else {
self.scrub_json(val);
}
}
}
serde_json::Value::Array(arr) => {
for i in arr {
self.scrub_json(i);
}
}
_ => {}
}
}
/// Pseudonymize a sensitive identifier (HMAC).
pub fn pseudonymize(&self, id: &str) -> String {
self.blob_ref(id) // Reuse valid HMAC logic
}
}