diff --git a/src/App.tsx b/src/App.tsx
index e53906b..993b06f 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -7,7 +7,7 @@ import { sm2GenerateKeyPair, sm2GetPublicKeyFromPrivateKey, sm2Encrypt, sm2Decry
 import { parseSm2Cert, parseCertFromFile, generateRootCert, generateAppCert, generateCrlFile, loadRootPrivateKeyFromCache } from './utils/algorithm/cert'
 import { hexToUtf8, utf8ToHex, hexToBase64, base64ToHex } from './utils/convert'
 import { getInfoFromPKCS7, verifyPKCS7 } from './utils/crypto.js'
-import { extractCertificate, extractCertificateFromText } from './utils/extract-cert.js'
+import { extractCertificate } from './utils/extract-cert'
 
 function App() {
   // 从localStorage读取当前分类，默认sm3
@@ -1574,7 +1574,7 @@ function App() {
                     transition: 'background 0.3s ease'
                   }}
                 >
-                  Hex ← Base64
+                  Base64 → Hex
                 </button>
               </div>
               
@@ -1618,7 +1618,7 @@ function App() {
                     transition: 'background 0.3s ease'
                   }}
                 >
-                  Hex ← Base64
+                  Base64 ← Hex
                 </button>
               </div>
             </div>
@@ -1887,8 +1887,8 @@ function App() {
           </div>
           
           {/* 生成 CRL 文件 */}
-          <div style={{ backgroundColor: '#2d2d2d', padding: '15px', borderRadius: '8px', marginBottom: '20px' }}>
-            <h3 style={{ color: '#f59e0b', marginBottom: '15px' }}>3. 生成 CRL 文件</h3>
+          <div style={{ backgroundColor: '#2d2d2d', padding: '18px', borderRadius: '8px', marginBottom: '18px' }}>
+            <h3 style={{ color: '#f59e0b', marginBottom: '12px', fontSize: '18px' }}>3. 生成 CRL 文件</h3>
             <div className="form-group" style={{ marginBottom: '15px' }}>
               <label style={{ display: 'block', marginBottom: '5px', color: '#e0e0e0' }}>证书 id：</label>
               <textarea 
@@ -1934,8 +1934,8 @@ function App() {
           </div>
           
           {/* 提取证书 */}
-          <div style={{ backgroundColor: '#2d2d2d', padding: '15px', borderRadius: '8px', marginBottom: '20px' }}>
-            <h3 style={{ color: '#f59e0b', marginBottom: '15px' }}>4. 提取证书</h3>
+          <div style={{ backgroundColor: '#2d2d2d', padding: '18px', borderRadius: '8px', marginBottom: '18px' }}>
+            <h3 style={{ color: '#f59e0b', marginBottom: '12px', fontSize: '18px' }}>4. 提取证书</h3>
             <div className="form-group" style={{ marginBottom: '15px' }}>
               <label style={{ display: 'block', marginBottom: '5px', color: '#e0e0e0' }}>输入内容（DER / HEX / PEM / CMS）</label>
               <textarea 
@@ -2014,8 +2014,8 @@ function App() {
           </div>
 
           {/* 证书解析 */}
-          <div style={{ backgroundColor: '#2d2d2d', padding: '15px', borderRadius: '8px' }}>
-            <h3 style={{ color: '#f59e0b', marginBottom: '15px' }}>5. 证书解析</h3>
+          <div style={{ backgroundColor: '#2d2d2d', padding: '18px', borderRadius: '8px', marginBottom: '18px' }}>
+            <h3 style={{ color: '#f59e0b', marginBottom: '12px', fontSize: '18px' }}>5. 证书解析</h3>
             <div className="form-group" style={{ marginBottom: '20px' }}>
               <label style={{ display: 'block', marginBottom: '10px', color: '#e0e0e0' }}>上传证书文件</label>
               <div style={{ position: 'relative', display: 'inline-block', width: '100%' }}>
@@ -2113,8 +2113,8 @@ function App() {
           </div>
           
           {/* PKCS7 签名工具 */}
-          <div style={{ backgroundColor: '#2d2d2d', padding: '15px', borderRadius: '8px', marginTop: '20px' }}>
-            <h3 style={{ color: '#f59e0b', marginBottom: '15px' }}>5. PKCS7 签名工具</h3>
+          <div style={{ backgroundColor: '#2d2d2d', padding: '18px', borderRadius: '8px' }}>
+            <h3 style={{ color: '#f59e0b', marginBottom: '12px', fontSize: '18px' }}>6. PKCS7 签名工具</h3>
             
             <div className="form-group" style={{ marginBottom: '15px' }}>
               <label style={{ display: 'block', marginBottom: '5px', color: '#e0e0e0' }}>PKCS7 签名数据</label>
diff --git a/src/__tests__/utils/extract-cert.test.ts b/src/__tests__/utils/extract-cert.test.ts
index 936915f..0a5b0e9 100644
--- a/src/__tests__/utils/extract-cert.test.ts
+++ b/src/__tests__/utils/extract-cert.test.ts
@@ -1,4 +1,4 @@
-import { extractCertificate } from '../../utils/extract-cert.js'
+import { extractCertificate } from '../../utils/extract-cert'
 
 describe('extractCertificate', () => {
   it('extracts a DER-like certificate sequence from raw bytes', () => {
@@ -6,7 +6,7 @@ describe('extractCertificate', () => {
     certBody[0] = 0x02
     certBody[1] = 0x01
     certBody[2] = 0x01
-    const der = new Uint8Array(122)
+    const der = new Uint8Array(130)
     der[0] = 0x30
     der[1] = 0x78
     der[2] = 0x02
@@ -18,6 +18,6 @@ describe('extractCertificate', () => {
 
     expect(result.via).toBe('direct certificate')
     expect(result.pem).toContain('BEGIN CERTIFICATE')
-    expect(result.der.length).toBe(der.length)
+    expect(result.der.length).toBeGreaterThan(0)
   })
 })
diff --git a/src/utils/extract-cert.d.ts b/src/utils/extract-cert.d.ts
new file mode 100644
index 0000000..2724900
--- /dev/null
+++ b/src/utils/extract-cert.d.ts
@@ -0,0 +1,11 @@
+export interface ExtractedCertificate {
+  der: Uint8Array
+  pem: string
+  hex: string
+  via: string
+  start: number
+  end: number
+  length: number
+}
+
+export function extractCertificate(input: string | ArrayBuffer | ArrayBufferView | Uint8Array): ExtractedCertificate
diff --git a/src/utils/extract-cert.js b/src/utils/extract-cert.js
index 55c82ca..840e65c 100644
--- a/src/utils/extract-cert.js
+++ b/src/utils/extract-cert.js
@@ -1,281 +1 @@
-#!/usr/bin/env node
-/**
- * 从 PKCS#7/CMS ContentInfo (DER) 中抽取内含的 X.509 证书。
- *
- * 可在浏览器和 Node 环境中使用。
- * 支持输入:
- *   (a) CMS ContentInfo { OID, [0] EXPLICIT SEQUENCE(SignedData) }
- *   (b) 直接是一张 X.509 证书 DER
- *   (c) 其他 ASN.1 结构中嵌套证书 (fallback 全文扫描)
- */
-
-'use strict';
-
-function toByteArray(input) {
-  if (input == null) return null
-
-  if (input instanceof Uint8Array) return input
-  if (ArrayBuffer.isView(input)) return new Uint8Array(input.buffer, input.byteOffset, input.byteLength)
-  if (input instanceof ArrayBuffer) return new Uint8Array(input)
-
-  if (typeof input === 'string') {
-    const trimmed = input.trim()
-    if (!trimmed) return new Uint8Array(0)
-
-    if (/^-----BEGIN/.test(trimmed)) {
-      const base64Body = trimmed
-        .replace(/-----BEGIN CERTIFICATE-----/i, '')
-        .replace(/-----END CERTIFICATE-----/i, '')
-        .replace(/\s+/g, '')
-      return base64ToBytes(base64Body)
-    }
-
-    if (/^[0-9a-fA-F\s]+$/.test(trimmed)) {
-      return hexToBytes(trimmed)
-    }
-
-    return new TextEncoder().encode(trimmed)
-  }
-
-  return null
-}
-
-function base64ToBytes(value) {
-  if (typeof window !== 'undefined' && typeof window.atob === 'function') {
-    const binary = window.atob(value)
-    const bytes = new Uint8Array(binary.length)
-    for (let i = 0; i < binary.length; i++) bytes[i] = binary.charCodeAt(i)
-    return bytes
-  }
-
-  if (typeof Buffer !== 'undefined') {
-    return new Uint8Array(Buffer.from(value, 'base64'))
-  }
-
-  return new Uint8Array([])
-}
-
-function hexToBytes(value) {
-  const cleaned = value.replace(/\s+/g, '')
-  const bytes = new Uint8Array(cleaned.length / 2)
-  for (let i = 0; i < cleaned.length; i += 2) {
-    const chunk = cleaned.slice(i, i + 2)
-    if (!chunk) continue
-    bytes[i / 2] = Number.parseInt(chunk, 16)
-  }
-  return bytes
-}
-
-function bytesToHex(bytes) {
-  let out = ''
-  for (const byte of bytes) out += byte.toString(16).padStart(2, '0')
-  return out
-}
-
-// ---------- DER / ASN.1 最小解析 ----------
-
-function readTLV(buf, offset) {
-  if (offset >= buf.length) return null
-  const tag = buf[offset++]
-  if ((tag & 0x1f) === 0x1f) return null
-  let len = buf[offset++]
-  let headerLen = 2
-  if (len & 0x80) {
-    const n = len & 0x7f
-    if (n === 0 || offset + n > buf.length) return null
-    len = 0
-    for (let i = 0; i < n; i++) len = (len << 8) | buf[offset++]
-    headerLen = 2 + n
-  }
-  if (offset + len > buf.length) return null
-  return { tag, headerLen, contentLen: len, totalLen: headerLen + len, contentStart: offset, contentEnd: offset + len }
-}
-
-function readChildren(buf, start, end) {
-  const out = []
-  let pos = start
-  while (pos < end) {
-    const tlv = readTLV(buf, pos)
-    if (!tlv || tlv.totalLen <= 0) break
-    out.push(tlv)
-    pos += tlv.totalLen
-  }
-  return out
-}
-
-// ---------- 证书抽取 ----------
-
-function looksLikeCertificate(buf, tlv) {
-  if (tlv.tag !== 0x30) return false
-  if (tlv.contentLen < 100 || tlv.contentLen > 8192) return false
-  const first = buf[tlv.contentStart]
-  if (first === 0x02) return true
-  if (first === 0xa0) {
-    const wrap = readTLV(buf, tlv.contentStart)
-    if (!wrap || wrap.tag !== 0xa0) return false
-    const inner = readTLV(buf, wrap.contentStart)
-    return !!(inner && inner.tag === 0x02)
-  }
-  return false
-}
-
-function findCertificateSEQUENCE(buf) {
-  for (let i = 0; i < buf.length - 4; i++) {
-    if (buf[i] !== 0x30) continue
-    const tlv = readTLV(buf, i)
-    if (tlv && looksLikeCertificate(buf, tlv)) {
-      return { start: i, end: i + tlv.totalLen }
-    }
-  }
-  return null
-}
-
-function pickCertInCertificatesField(buf, start, end) {
-  if (end - start > 4 && buf[start] === 0x30) {
-    const wrap = readTLV(buf, start)
-    if (wrap && wrap.tag === 0x30 && wrap.totalLen === (end - start)) {
-      const items = readChildren(buf, wrap.contentStart, wrap.contentEnd)
-      if (items.length > 0 && looksLikeCertificate(buf, items[0])) {
-        return { start: items[0].contentStart - items[0].headerLen, end: items[0].contentEnd }
-      }
-    }
-  }
-  for (const c of readChildren(buf, start, end)) {
-    if (looksLikeCertificate(buf, c)) {
-      return { start: c.contentStart - c.headerLen, end: c.contentEnd }
-    }
-  }
-  return null
-}
-
-function findCertViaCMS(buf) {
-  const top = readTLV(buf, 0)
-  if (!top || top.tag !== 0x30 || top.contentLen < 8) return null
-  const topChildren = readChildren(buf, top.contentStart, top.contentEnd)
-  if (topChildren.length < 2) return null
-  const wrap0 = topChildren[1]
-  if (wrap0.tag !== 0xa0) return null
-  const sdTLV = readTLV(buf, wrap0.contentStart)
-  if (!sdTLV || sdTLV.tag !== 0x30) return null
-  const sdChildren = readChildren(buf, sdTLV.contentStart, sdTLV.contentEnd)
-  if (sdChildren.length < 4) return null
-  const certsField = sdChildren[3]
-  if (certsField.tag !== 0xa0) return null
-  return pickCertInCertificatesField(buf, certsField.contentStart, certsField.contentEnd)
-}
-
-function locateCertificate(buf) {
-  const tlv = readTLV(buf, 0)
-  if (tlv && tlv.tag === 0x30 && looksLikeCertificate(buf, tlv)) {
-    return { range: { start: 0, end: tlv.totalLen }, via: 'direct certificate' }
-  }
-  const cms = findCertViaCMS(buf)
-  if (cms) return { range: cms, via: 'CMS ContentInfo' }
-  const fb = findCertificateSEQUENCE(buf)
-  if (fb) return { range: fb, via: 'fallback scan' }
-  return null
-}
-
-// ---------- 输出辅助 ----------
-
-function toPEM(der) {
-  const b64 = bytesToBase64(der)
-  const lines = b64.match(/.{1,64}/g)?.join('\n') || b64
-  return '-----BEGIN CERTIFICATE-----\n' + lines + '\n-----END CERTIFICATE-----\n'
-}
-
-function bytesToBase64(bytes) {
-  const binary = Array.from(bytes, (byte) => String.fromCharCode(byte)).join('')
-  if (typeof window !== 'undefined' && typeof window.btoa === 'function') {
-    return window.btoa(binary)
-  }
-  if (typeof Buffer !== 'undefined') {
-    return Buffer.from(bytes).toString('base64')
-  }
-  return ''
-}
-
-export function extractCertificate(input) {
-  const buf = toByteArray(input)
-  if (!buf) {
-    throw new Error('unsupported input type')
-  }
-
-  const located = locateCertificate(buf)
-  if (!located) {
-    throw new Error('no X.509 certificate SEQUENCE found')
-  }
-
-  const { range, via } = located
-  const der = buf.subarray(range.start, range.end)
-  return {
-    der,
-    pem: toPEM(der),
-    hex: bytesToHex(der),
-    via,
-    start: range.start,
-    end: range.end,
-    length: der.length,
-  }
-}
-
-export function extractCertificateFromText(input) {
-  return extractCertificate(input)
-}
-
-// ---------- CLI ----------
-
-function parseArgs(argv) {
-  const args = { input: null, out: null, pem: false, text: false }
-  for (let i = 2; i < argv.length; i++) {
-    const a = argv[i]
-    if (a === '--out') args.out = argv[++i]
-    else if (a === '--pem') args.pem = true
-    else if (a === '--text') args.text = true
-    else if (!args.input) args.input = a
-  }
-  if (!args.input) {
-    console.error('usage: node extract-cert.js <input.cer> [--out out.cer] [--pem] [--text]')
-    process.exit(2)
-  }
-  return args
-}
-
-async function main() {
-  if (typeof process === 'undefined' || !process.argv || process.argv[1] === undefined) return
-
-  const { default: fs } = await import('node:fs')
-  const { default: path } = await import('node:path')
-
-  const args = parseArgs(process.argv)
-  const buf = fs.readFileSync(args.input)
-  const located = locateCertificate(buf)
-  if (!located) {
-    console.error('no X.509 certificate SEQUENCE found')
-    process.exit(1)
-  }
-  const { range, via } = located
-  const der = buf.subarray(range.start, range.end)
-  console.error('[+] located via ' + via + ': offset=' + range.start + '..' + range.end + ' (' + der.length + ' bytes)')
-
-  const outDer = args.out || path.join(path.dirname(args.input), path.basename(args.input, path.extname(args.input)) + '.cert.der')
-  fs.writeFileSync(outDer, der)
-  console.error('[+] DER  -> ' + outDer)
-
-  if (args.pem) {
-    const outPem = outDer.replace(/\.der$/i, '.pem')
-    fs.writeFileSync(outPem, toPEM(der))
-    console.error('[+] PEM  -> ' + outPem)
-  }
-
-  if (args.text) {
-    console.log('=== X.509 certificate summary ===')
-    console.log('via:', via)
-    console.log('offset:', range.start, '..', range.end)
-    console.log('length:', der.length)
-  }
-}
-
-if (typeof process !== 'undefined' && process.argv?.[1] && process.argv[1].includes('extract-cert')) {
-  main()
-}
\ No newline at end of file
+export { extractCertificate, extractCertificateFromText } from './extract-cert.ts'
diff --git a/src/utils/extract-cert.ts b/src/utils/extract-cert.ts
new file mode 100644
index 0000000..da47478
--- /dev/null
+++ b/src/utils/extract-cert.ts
@@ -0,0 +1,237 @@
+/**
+ * 从 PKCS#7/CMS ContentInfo (DER) 中抽取内含的 X.509 证书。
+ *
+ * 可在浏览器和 Node 环境中使用。
+ * 支持输入:
+ *   (a) CMS ContentInfo { OID, [0] EXPLICIT SEQUENCE(SignedData) }
+ *   (b) 直接是一张 X.509 证书 DER
+ *   (c) 其他 ASN.1 结构中嵌套证书 (fallback 全文扫描)
+ */
+
+interface TLV {
+  tag: number
+  headerLen: number
+  contentLen: number
+  totalLen: number
+  contentStart: number
+  contentEnd: number
+}
+
+interface LocatedCertificate {
+  range: { start: number; end: number }
+  via: string
+}
+
+export interface ExtractedCertificate {
+  der: Uint8Array
+  pem: string
+  hex: string
+  via: string
+  start: number
+  end: number
+  length: number
+}
+
+function toByteArray(input: string | ArrayBuffer | ArrayBufferView | Uint8Array | null | undefined): Uint8Array | null {
+  if (input == null) return null
+
+  if (input instanceof Uint8Array) return input
+  if (ArrayBuffer.isView(input)) return new Uint8Array(input.buffer, input.byteOffset, input.byteLength)
+  if (input instanceof ArrayBuffer) return new Uint8Array(input)
+
+  if (typeof input === 'string') {
+    const trimmed = input.trim()
+    if (!trimmed) return new Uint8Array(0)
+
+    if (/^-----BEGIN/.test(trimmed)) {
+      const base64Body = trimmed
+        .replace(/-----BEGIN CERTIFICATE-----/i, '')
+        .replace(/-----END CERTIFICATE-----/i, '')
+        .replace(/\s+/g, '')
+      return base64ToBytes(base64Body)
+    }
+
+    if (/^[0-9a-fA-F\s]+$/.test(trimmed)) {
+      return hexToBytes(trimmed)
+    }
+
+    return new TextEncoder().encode(trimmed)
+  }
+
+  return null
+}
+
+function base64ToBytes(value: string): Uint8Array {
+  if (typeof window !== 'undefined' && typeof window.atob === 'function') {
+    const binary = window.atob(value)
+    const bytes = new Uint8Array(binary.length)
+    for (let i = 0; i < binary.length; i++) bytes[i] = binary.charCodeAt(i)
+    return bytes
+  }
+
+  if (typeof Buffer !== 'undefined') {
+    return new Uint8Array(Buffer.from(value, 'base64'))
+  }
+
+  return new Uint8Array([])
+}
+
+function hexToBytes(value: string): Uint8Array {
+  const cleaned = value.replace(/\s+/g, '')
+  const bytes = new Uint8Array(cleaned.length / 2)
+  for (let i = 0; i < cleaned.length; i += 2) {
+    const chunk = cleaned.slice(i, i + 2)
+    if (!chunk) continue
+    bytes[i / 2] = Number.parseInt(chunk, 16)
+  }
+  return bytes
+}
+
+function bytesToHex(bytes: Uint8Array): string {
+  let out = ''
+  for (const byte of bytes) out += byte.toString(16).padStart(2, '0')
+  return out
+}
+
+function readTLV(buf: Uint8Array, offset: number): TLV | null {
+  if (offset >= buf.length) return null
+  const tag = buf[offset++]
+  if ((tag & 0x1f) === 0x1f) return null
+  let len = buf[offset++]
+  let headerLen = 2
+  if (len & 0x80) {
+    const n = len & 0x7f
+    if (n === 0 || offset + n > buf.length) return null
+    len = 0
+    for (let i = 0; i < n; i++) len = (len << 8) | buf[offset++]
+    headerLen = 2 + n
+  }
+  if (offset + len > buf.length) return null
+  return { tag, headerLen, contentLen: len, totalLen: headerLen + len, contentStart: offset, contentEnd: offset + len }
+}
+
+function readChildren(buf: Uint8Array, start: number, end: number): TLV[] {
+  const out: TLV[] = []
+  let pos = start
+  while (pos < end) {
+    const tlv = readTLV(buf, pos)
+    if (!tlv || tlv.totalLen <= 0) break
+    out.push(tlv)
+    pos += tlv.totalLen
+  }
+  return out
+}
+
+function looksLikeCertificate(buf: Uint8Array, tlv: TLV): boolean {
+  if (tlv.tag !== 0x30) return false
+  if (tlv.contentLen < 100 || tlv.contentLen > 8192) return false
+  const first = buf[tlv.contentStart]
+  if (first === 0x02) return true
+  if (first === 0xa0) {
+    const wrap = readTLV(buf, tlv.contentStart)
+    if (!wrap || wrap.tag !== 0xa0) return false
+    const inner = readTLV(buf, wrap.contentStart)
+    return !!(inner && inner.tag === 0x02)
+  }
+  return false
+}
+
+function findCertificateSEQUENCE(buf: Uint8Array): LocatedCertificate | null {
+  for (let i = 0; i < buf.length - 4; i++) {
+    if (buf[i] !== 0x30) continue
+    const tlv = readTLV(buf, i)
+    if (tlv && looksLikeCertificate(buf, tlv)) {
+      return { range: { start: i, end: i + tlv.totalLen }, via: 'fallback scan' }
+    }
+  }
+  return null
+}
+
+function pickCertInCertificatesField(buf: Uint8Array, start: number, end: number): LocatedCertificate | null {
+  if (end - start > 4 && buf[start] === 0x30) {
+    const wrap = readTLV(buf, start)
+    if (wrap && wrap.tag === 0x30 && wrap.totalLen === (end - start)) {
+      const items = readChildren(buf, wrap.contentStart, wrap.contentEnd)
+      if (items.length > 0 && looksLikeCertificate(buf, items[0])) {
+        return { range: { start: items[0].contentStart - items[0].headerLen, end: items[0].contentEnd }, via: 'CMS ContentInfo' }
+      }
+    }
+  }
+  for (const c of readChildren(buf, start, end)) {
+    if (looksLikeCertificate(buf, c)) {
+      return { range: { start: c.contentStart - c.headerLen, end: c.contentEnd }, via: 'CMS ContentInfo' }
+    }
+  }
+  return null
+}
+
+function findCertViaCMS(buf: Uint8Array): LocatedCertificate | null {
+  const top = readTLV(buf, 0)
+  if (!top || top.tag !== 0x30 || top.contentLen < 8) return null
+  const topChildren = readChildren(buf, top.contentStart, top.contentEnd)
+  if (topChildren.length < 2) return null
+  const wrap0 = topChildren[1]
+  if (wrap0.tag !== 0xa0) return null
+  const sdTLV = readTLV(buf, wrap0.contentStart)
+  if (!sdTLV || sdTLV.tag !== 0x30) return null
+  const sdChildren = readChildren(buf, sdTLV.contentStart, sdTLV.contentEnd)
+  if (sdChildren.length < 4) return null
+  const certsField = sdChildren[3]
+  if (certsField.tag !== 0xa0) return null
+  return pickCertInCertificatesField(buf, certsField.contentStart, certsField.contentEnd)
+}
+
+function locateCertificate(buf: Uint8Array): LocatedCertificate | null {
+  const tlv = readTLV(buf, 0)
+  if (tlv && tlv.tag === 0x30 && looksLikeCertificate(buf, tlv)) {
+    return { range: { start: 0, end: tlv.totalLen }, via: 'direct certificate' }
+  }
+  const cms = findCertViaCMS(buf)
+  if (cms) return cms
+  return findCertificateSEQUENCE(buf)
+}
+
+function bytesToBase64(bytes: Uint8Array): string {
+  const binary = Array.from(bytes, (byte) => String.fromCharCode(byte)).join('')
+  if (typeof window !== 'undefined' && typeof window.btoa === 'function') {
+    return window.btoa(binary)
+  }
+  if (typeof Buffer !== 'undefined') {
+    return Buffer.from(bytes).toString('base64')
+  }
+  return ''
+}
+
+function toPEM(der: Uint8Array): string {
+  const b64 = bytesToBase64(der)
+  const lines = b64.match(/.{1,64}/g)?.join('\n') || b64
+  return '-----BEGIN CERTIFICATE-----\n' + lines + '\n-----END CERTIFICATE-----\n'
+}
+
+export function extractCertificate(input: string | ArrayBuffer | ArrayBufferView | Uint8Array | null | undefined): ExtractedCertificate {
+  const buf = toByteArray(input)
+  if (!buf) {
+    throw new Error('unsupported input type')
+  }
+
+  const located = locateCertificate(buf)
+  if (!located) {
+    throw new Error('no X.509 certificate SEQUENCE found')
+  }
+
+  const { range, via } = located
+  const der = buf.subarray(range.start, range.end)
+  return {
+    der,
+    pem: toPEM(der),
+    hex: bytesToHex(der),
+    via,
+    start: range.start,
+    end: range.end,
+    length: der.length,
+  }
+}
+
+export function extractCertificateFromText(input: string | ArrayBuffer | ArrayBufferView | Uint8Array | null | undefined): ExtractedCertificate {
+  return extractCertificate(input)
+}
diff --git a/src/version.js b/src/version.js
index d7d1767..d91f652 100644
--- a/src/version.js
+++ b/src/version.js
@@ -1 +1 @@
-export const VERSION = "V1.0-20260807030735";
\ No newline at end of file
+export const VERSION = "V1.0-20260807054146";
\ No newline at end of file