Update SWIFT PII detection (#37)

* Update SWIFT PII detection
* Fix bank codes

Author: steven10a

src/__tests__/unit/checks/pii.test.ts

@@ -224,19 +224,54 @@ describe('pii guardrail', () => {
     expect(result.info?.checked_text).toBe('cvv=<CVV>');
   });
 
-  it('detects BIC/SWIFT codes', async () => {
+  it('detects BIC/SWIFT codes with explicit prefixes', async () => {
     const config = PIIConfig.parse({
       entities: [PIIEntity.BIC_SWIFT],
       block: false,
     });
-    const text = 'Transfer to BIC DEXXDEXX tomorrow.';
+    const text = 'Transfer to BIC DEUTDEFF500 tomorrow.';
 
     const result = await pii({}, text, config);
 
-    expect((result.info?.detected_entities as Record<string, string[]>)?.BIC_SWIFT).toEqual(['DEXXDEXX']);
+    expect((result.info?.detected_entities as Record<string, string[]>)?.BIC_SWIFT).toEqual([
+      'DEUTDEFF500',
+    ]);
     expect(result.info?.checked_text).toBe('Transfer to BIC <BIC_SWIFT> tomorrow.');
   });
 
+  it('detects BIC/SWIFT codes from known bank prefixes', async () => {
+    const config = PIIConfig.parse({
+      entities: [PIIEntity.BIC_SWIFT],
+      block: false,
+    });
+    const text = 'Send funds to CHASUS33 by Friday.';
+
+    const result = await pii({}, text, config);
+
+    expect((result.info?.detected_entities as Record<string, string[]>)?.BIC_SWIFT).toEqual(['CHASUS33']);
+    expect(result.info?.checked_text).toBe('Send funds to <BIC_SWIFT> by Friday.');
+  });
+
+  it('does not flag common words as BIC/SWIFT codes', async () => {
+    const config = PIIConfig.parse({
+      entities: [PIIEntity.BIC_SWIFT],
+      block: false,
+    });
+    const texts = [
+      'The CUSTOMER ordered a product.',
+      'We will REGISTER your account.',
+      'Please CONSIDER this option.',
+      'The DOCUMENT is ready.',
+      'This is ABSTRACT art.',
+    ];
+
+    for (const text of texts) {
+      const result = await pii({}, text, config);
+      expect((result.info?.detected_entities as Record<string, string[]>)?.BIC_SWIFT).toBeUndefined();
+      expect(result.info?.pii_detected).toBe(false);
+    }
+  });
+
   it('detects precise street addresses as location', async () => {
     const config = PIIConfig.parse({
       entities: [PIIEntity.LOCATION],

src/checks/pii.ts

@@ -205,6 +205,88 @@ interface PiiDetectionResult {
   spans: ReplacementSpan[];
 }
 
+const BIC_CONTEXT_PREFIX_PATTERN = [
+  '(?:[sS][wW][iI][fF][tT])',
+  '(?:[bB][iI][cC])',
+  '(?:[bB][aA][nN][kK][\\s-]?[cC][oO][dD][eE])',
+  '(?:[sS][wW][iI][fF][tT][\\s-]?[cC][oO][dD][eE])',
+  '(?:[bB][iI][cC][\\s-]?[cC][oO][dD][eE])',
+].join('|');
+
+const BIC_WITH_CONTEXT_REGEX = new RegExp(
+  `(?:${BIC_CONTEXT_PREFIX_PATTERN})[:\\s=]+([A-Z]{4}[A-Z]{2}[A-Z0-9]{2}(?:[A-Z0-9]{3})?)\\b`,
+  'g'
+);
+
+const KNOWN_BIC_PREFIXES = [
+  'DEUT',
+  'CHAS',
+  'BARC',
+  'HSBC',
+  'BNPA',
+  'CITI',
+  'WELL',
+  'BOFA',
+  'JPMC',
+  'GSCC',
+  'MSNY',
+  'COBA',
+  'DRSD',
+  'BYLA',
+  'MALA',
+  'HYVE',
+  'WFBI',
+  'USBC',
+  'LOYD',
+  'MIDL',
+  'NWBK',
+  'RBOS',
+  'CRLY',
+  'SOGE',
+  'AGRI',
+  'UBSW',
+  'CRES',
+  'SANB',
+  'BBVA',
+  'UNCR',
+  'BCIT',
+  'INGB',
+  'ABNA',
+  'RABO',
+  'ROYA',
+  'TDOM',
+  'BNSC',
+  'ANZB',
+  'NATA',
+  'WPAC',
+  'CTBA',
+  'BKCH',
+  'MHCB',
+  'BOTK',
+  'ICBK',
+  'ABOC',
+  'PCBC',
+  'HSBC',
+  'SCBL',
+  'DBSS',
+  'OCBC',
+  'UOVB',
+  'CZNB',
+  'SHBK',
+  'KOEX',
+  'HVBK',
+  'NACF',
+  'IBKO',
+  'KODB',
+  'HNBN',
+  'CITI',
+];
+
+const KNOWN_BIC_REGEX = new RegExp(
+  `\\b(?:${KNOWN_BIC_PREFIXES.join('|')})[A-Z]{2}[A-Z0-9]{2}(?:[A-Z0-9]{3})?\\b`,
+  'g'
+);
+
 /**
  * Default regex patterns for PII entity types.
  */
@@ -245,7 +327,10 @@ const DEFAULT_PII_PATTERNS: Record<PIIEntity, PatternDefinition[]> = {
       group: 1,
     },
   ],
-  [PIIEntity.BIC_SWIFT]: [{ regex: /\b[A-Z]{4}[A-Z]{2}[A-Z0-9]{2}(?:[A-Z0-9]{3})?\b/g }],
+  [PIIEntity.BIC_SWIFT]: [
+    { regex: BIC_WITH_CONTEXT_REGEX, group: 1 },
+    { regex: KNOWN_BIC_REGEX },
+  ],
 
   // USA
   [PIIEntity.US_BANK_NUMBER]: [{ regex: /\b\d{8,17}\b/g }],