Fix VoicePrint service-layer correctness bugs P1-1, P1-7, P2-2 (FRE-5002)

P1-1: Replace non-deterministic Math.random() with buffer-variance score
P1-7: Fix findSimilar result ordering by using Map instead of index zip
P2-2: Replace weak hashes with SHA-256 for both embedding and audio

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/api/src/services/voiceprint/voiceprint.service.ts

@@ -1,9 +1,9 @@
+import { createHash } from 'crypto';
 import { prisma, VoiceEnrollment, VoiceAnalysis } from '@shieldai/db';
 import {
   voicePrintEnv,
   AnalysisJobStatus,
   DetectionType,
-  ConfidenceLevel,
   audioPreprocessingConfig,
   voicePrintFeatureFlags,
 } from './voiceprint.config';
@@ -189,20 +189,19 @@ export class VoiceEnrollmentService {
     const enrollments = await prisma.voiceEnrollment.findMany({
       where: { id: { in: enrollmentIds } },
     });
+    const enrollmentMap = new Map(enrollments.map((e) => [e.id, e]));
 
-    return results.map((r, i) => ({
-      enrollment: enrollments[i],
-      similarity: r.similarity,
-    }));
+    return results
+      .map((r) => ({
+        enrollment: enrollmentMap.get(r.id),
+        similarity: r.similarity,
+      }))
+      .filter((r): r is { enrollment: VoiceEnrollment; similarity: number } => r.enrollment !== undefined);
   }
 
   private computeEmbeddingHash(embedding: number[]): string {
-    let hash = 0;
-    for (let i = 0; i < embedding.length; i++) {
-      hash = ((hash << 5) - hash) + embedding[i];
-      hash |= 0;
-    }
-    return `vp_${Math.abs(hash).toString(16)}_${embedding.length}`;
+    const content = embedding.map((v) => v.toFixed(6)).join(',');
+    return `vp_${createHash('sha256').update(content).digest('hex').slice(0, 16)}_${embedding.length}`;
   }
 }
 
@@ -287,13 +286,7 @@ export class AnalysisService {
   }
 
   private computeAudioHash(buffer: Buffer): string {
-    let hash = 0;
-    const sampleSize = Math.min(buffer.length, 1024);
-    for (let i = 0; i < sampleSize; i += 8) {
-      hash = ((hash << 5) - hash) + buffer.readUInt8(i);
-      hash |= 0;
-    }
-    return `audio_${Math.abs(hash).toString(16)}`;
+    return `audio_${createHash('sha256').update(buffer).digest('hex').slice(0, 16)}`;
   }
 }
 
@@ -462,13 +455,22 @@ export class EmbeddingService {
           embedding.length
       ) || 0;
 
+    // Deterministic buffer variance as alternative to Math.random()
+    const mean = meanAmplitude * 255;
+    let variance = 0;
+    for (let i = 0; i < buffer.length; i++) {
+      variance += (buffer[i] - mean) ** 2;
+    }
+    variance /= buffer.length;
+    const varianceScore = Math.min(1.0, variance / 16384);
+
     // Combine features into confidence score
     const amplitudeScore = Math.abs(meanAmplitude - 0.5) * 2;
     const embeddingScore = 1.0 - Math.min(1.0, embeddingStdDev * 2);
 
     return Math.min(
       1.0,
-      amplitudeScore * 0.3 + embeddingScore * 0.4 + Math.random() * 0.3
+      amplitudeScore * 0.3 + embeddingScore * 0.4 + varianceScore * 0.3
     );
   }