springboot 实现pdf签名

Spring Boot 可以使用 iText 库来实现 PDF 签名。以下是添加数字签名的基本步骤：

1. 导入 iText 和 BC 签名库的 Maven 依赖。

<dependency>
    <groupId>com.itextpdf</groupId>
    <artifactId>itextpdf</artifactId>
    <version>5.5.13</version>
</dependency>
<dependency>
    <groupId>org.bouncycastle</groupId>
    <artifactId>bcprov-jdk15on</artifactId>
    <version>1.61</version>
</dependency>

2. 配置密钥库和证书。

KeyStore ks = KeyStore.getInstance("PKCS12");
ks.load(new FileInputStream("path/to/keystore.p12"), "keystorePassword".toCharArray());
String alias = (String) ks.aliases().nextElement();
PrivateKey privateKey = (PrivateKey) ks.getKey(alias, "keyPassword".toCharArray());
Certificate[] chain = ks.getCertificateChain(alias);

3. 创建 PdfReader 对象并打开文档。

PdfReader reader = new PdfReader("path/to/pdf");
PdfStamper stamper = PdfStamper.createSignature(reader, outputStream, '\0');
PdfSignatureAppearance appearance = stamper.getSignatureAppearance();

4. 设置签名外观。

appearance.setReason("Reason for signing");
appearance.setLocation("Location of signing");
appearance.setCertificationLevel(PdfSignatureAppearance.CERTIFIED_FORM_FILLING_AND_ANNOTATIONS);
appearance.setVisibleSignature(new Rectangle(36, 748, 144, 780), 1, "signature");

5. 创建数字签名。

ExternalSignature es = new PrivateKeySignature(privateKey, "SHA-256", "BC");
ExternalDigest digest = new BouncyCastleDigest();
MakeSignature.signDetached(appearance, digest, es, chain, null, null, null, 0, MakeSignature.CryptoStandard.CMS);

6. 关闭文档和输出流。

stamper.close();
outputStream.close();

以上步骤仅作为示例，具体实现可能因为证书类型、签名算法等不同而有所区别。