fix: correct checksum for Taiwan ID numbers

koblas · Dec 4, 2023 · e1aae3a · e1aae3a
1 parent a860a9a
commit e1aae3a
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Showing 4 changed files with 52 additions and 20 deletions.
diff --git a/src/tw/natid.spec.ts b/src/tw/natid.spec.ts
@@ -8,10 +8,10 @@ describe('tw/natid', () => {
     expect(result).toEqual('00501503');
   });
 
-  it('validate:A200501503', () => {
-    const result = validate('A200501503');
+  it('validate:A200501505', () => {
+    const result = validate('A200501505');
 
-    expect(result.isValid && result.compact).toEqual('A200501503');
+    expect(result.isValid && result.compact).toEqual('A200501505');
   });
 
   it('validate:12345', () => {
@@ -25,4 +25,17 @@ describe('tw/natid', () => {
 
     expect(result.error).toBeInstanceOf(InvalidComponent);
   });
+
+  test.each(['A200501503', 'A800501509', 'A800501509'])('not-valid:', value => {
+    const result = validate(value);
+    expect(result.isValid).toEqual(false);
+  });
+
+  test.each(['A800000014', 'A123456789', 'A100501503', 'A200501505'])(
+    'valid:',
+    value => {
+      const result = validate(value);
+      expect(result.isValid).toEqual(true);
+    },
+  );
 });
diff --git a/src/tw/natid.ts b/src/tw/natid.ts
@@ -72,7 +72,7 @@ const impl = {
     if (!strings.isalpha(issuer)) {
       return { isValid: false, error: new exceptions.InvalidComponent() };
     }
-    if (!['1', '2'].includes(gender)) {
+    if (!/[1-28-9]/.test(gender)) {
       return { isValid: false, error: new exceptions.InvalidComponent() };
     }
     if (!strings.isdigits(code)) {
@@ -82,11 +82,15 @@ const impl = {
       return { isValid: false, error: new exceptions.InvalidComponent() };
     }
 
-    const sum = weightedSum(value, {
-      weights: [1, 9, 8, 7, 6, 5, 4, 3, 2, 1],
-      alphabet: ALPHABET,
-      modulus: 10,
-    });
+    const leading = ALPHABET.indexOf(issuer) - 10;
+    const sum =
+      weightedSum(`${gender}${code}${check}`, {
+        weights: [8, 7, 6, 5, 4, 3, 2, 1, 1],
+        alphabet: ALPHABET,
+        modulus: 10,
+      }) +
+      Math.floor(leading / 10 + 1) +
+      leading * 9;
     if (sum % 10 !== 0) {
       return { isValid: false, error: new exceptions.InvalidChecksum() };
     }

diff --git a/src/tw/ui.spec.ts b/src/tw/ui.spec.ts
@@ -12,14 +12,14 @@ describe('tw/ui', () => {
     expect(result).toEqual('00501503');
   });
 
-  it('validate:A800501509', () => {
-    const result = validate('A800501509');
+  it('validate:AB00501503', () => {
+    const result = validate('AB00501503');
 
-    expect(result.isValid && result.compact).toEqual('A800501509');
+    expect(result.isValid && result.compact).toEqual('AB00501503');
   });
 
-  it('validate:A800501508', () => {
-    const result = validate('A800501508');
+  it('validate:AD00501509', () => {
+    const result = validate('AD00501509');
 
     expect(result.error).toBeInstanceOf(InvalidChecksum);
   });
@@ -35,4 +35,15 @@ describe('tw/ui', () => {
 
     expect(result.error).toBeInstanceOf(InvalidComponent);
   });
+
+  // additional tests
+  test.each(['A200501503', 'A800501509', 'CC00151113'])('not-valid:', value => {
+    const result = validate(value);
+    expect(result.isValid).toEqual(false);
+  });
+
+  test.each(['AB12345677', 'CC00151114', 'AB00501503'])('valid:', value => {
+    const result = validate(value);
+    expect(result.isValid).toEqual(true);
+  });
 });
diff --git a/src/tw/ui.ts b/src/tw/ui.ts
@@ -74,7 +74,7 @@ const impl = {
     if (!strings.isalpha(issuer)) {
       return { isValid: false, error: new exceptions.InvalidComponent() };
     }
-    if (!['A', 'B', 'C', 'D', '8', '9'].includes(gender)) {
+    if (!/[A-D]/.test(gender)) {
       return { isValid: false, error: new exceptions.InvalidComponent() };
     }
     if (!strings.isdigits(code)) {
@@ -84,11 +84,15 @@ const impl = {
       return { isValid: false, error: new exceptions.InvalidComponent() };
     }
 
-    const sum = weightedSum(value, {
-      weights: [1, 9, 8, 7, 6, 5, 4, 3, 2, 1],
-      alphabet: ALPHABET,
-      modulus: 10,
-    });
+    const leading = ALPHABET.indexOf(issuer) - 10;
+    const sum =
+      weightedSum(`${gender}${code}${check}`, {
+        weights: [8, 7, 6, 5, 4, 3, 2, 1, 1],
+        alphabet: ALPHABET,
+        modulus: 10,
+      }) +
+      Math.floor(leading / 10 + 1) +
+      leading * 9;
     if (sum % 10 !== 0) {
       return { isValid: false, error: new exceptions.InvalidChecksum() };
     }