PdfSignature 签名时间规则
时间: 2024-05-27 13:07:45 浏览: 25
PDF签名时间规则是指在签署PDF文档的过程中,签署者必须遵循的时间规则。一般来说,PDF签名时间规则主要包括以下几个方面:
1. 时间戳:签名者需要使用时间戳来证明签名的有效性和时间。时间戳是由可信第三方机构提供的数字证书,用于验证签名的时间。
2. 时间格式:签名者需要使用符合ISO 8601标准的时间格式来表示签名时间。
3. 时区:签名者需要在签名时指定签名所在的时区,以确保签名的时间精确无误。
4. 时间范围:签名者需要在签名时指定签名的时间范围,以确保签名的有效期。
总之,PDF签名时间规则旨在确保签名的真实性、准确性和可靠性,从而保护PDF文档的完整性和安全性。
相关问题
java pdf 签名 修改,使用Java中的自定义数字签名来签名PDF
要对PDF进行数字签名,可以使用Java中的Bouncy Castle库。以下是签名PDF的一般步骤:
1. 从文件中读取要签名的PDF。
```java
File inFile = new File("example.pdf");
byte[] inputBytes = Files.readAllBytes(inFile.toPath());
```
2. 初始化签名密钥库,并加载签名密钥。
```java
KeyStore ks = KeyStore.getInstance("PKCS12");
char[] password = "password".toCharArray();
ks.load(new FileInputStream("keystore.p12"), password);
String alias = ks.aliases().nextElement();
PrivateKey privateKey = (PrivateKey) ks.getKey(alias, password);
Certificate[] chain = ks.getCertificateChain(alias);
```
3. 初始化PDF签名器。
```java
PdfReader reader = new PdfReader(inputBytes);
ByteArrayOutputStream outputBytes = new ByteArrayOutputStream();
PdfStamper stamper = PdfStamper.createSignature(reader, outputBytes, '\0', null, true);
PdfSignatureAppearance appearance = stamper.getSignatureAppearance();
appearance.setReason("I am the author");
appearance.setLocation("Worldwide");
appearance.setVisibleSignature(new Rectangle(36, 748, 144, 780), 1, "signature");
```
4. 初始化数字签名。
```java
BouncyCastleProvider provider = new BouncyCastleProvider();
Security.addProvider(provider);
PdfSignature dic = new PdfSignature(PdfName.ADOBE_PPKLITE, PdfName.ADBE_PKCS7_DETACHED);
dic.setReason(appearance.getReason());
dic.setLocation(appearance.getLocation());
dic.setContact(appearance.getContact());
dic.setDate(new PdfDate(appearance.getSignDate()));
appearance.setCryptoDictionary(dic);
PdfPKCS7 sgn = new PdfPKCS7(privateKey, chain, null, "SHA256", provider, false);
byte[] hash = DigestAlgorithms.digest(inputBytes, "SHA256");
Calendar cal = Calendar.getInstance();
byte[] signature = sgn.getAuthenticatedAttributeBytes(hash, cal, null, null, CryptoStandard.CMS);
sgn.update(hash, 0, hash.length);
byte[] encodedSig = sgn.getEncodedPKCS7(hash, cal, null, null, null, CryptoStandard.CMS);
```
5. 将数字签名附加到PDF中。
```java
PdfDictionary dic2 = new PdfDictionary();
dic2.put(PdfName.CONTENTS, new PdfString(encodedSig).setHexWriting(true));
appearance.setCryptoDictionary(dic2);
appearance.preClose();
```
6. 输出签名后的PDF。
```java
stamper.close();
Files.write(new File("signed.pdf").toPath(), outputBytes.toByteArray());
```
这些步骤提供了一个概述,但是实现数字签名需要更多的细节和错误处理。
java pdf电子签章
Java可以通过使用第三方库来实现PDF电子签章的功能。其中比较常用的有iText和PDFBox。
iText是一个广泛使用的PDF文档处理库,可以在PDF文档中添加数字签名。以下是使用iText实现PDF电子签章的步骤:
1. 加载PDF文件并创建签名区域
```
PdfReader reader = new PdfReader("original.pdf");
FileOutputStream os = new FileOutputStream("signed.pdf");
PdfStamper stamper = PdfStamper.createSignature(reader, os, '\0');
PdfSignatureAppearance appearance = stamper.getSignatureAppearance();
appearance.setImage(Image.getInstance("signature.png"));
appearance.setReason("I am the author");
appearance.setLocation("China");
```
2. 创建数字签名
```
PrivateKey privateKey = (PrivateKey) keystore.getKey("alias", "password".toCharArray());
Certificate[] chain = keystore.getCertificateChain("alias");
PdfSignature dic = new PdfSignature(PdfName.ADOBE_PPKLITE, PdfName.ADBE_PKCS7_DETACHED);
dic.setReason(appearance.getReason());
dic.setLocation(appearance.getLocation());
dic.setContact(appearance.getContact());
dic.setDate(new PdfDate(appearance.getSignDate()));
appearance.setCrypto(privateKey, chain, null, PdfSignatureAppearance.WINCER_SIGNED);
appearance.setSignatureGraphic(Image.getInstance(signatureGraphic));
appearance.setRenderingMode(PdfSignatureAppearance.RenderingMode.GRAPHIC);
appearance.setVisibleSignature(new Rectangle(36, 748, 144, 780), 1, "sig");
PdfSignature dic2 = new PdfSignature(PdfName.ADOBE_PPKLITE, PdfName.ADBE_PKCS7_DETACHED);
dic2.setReason(appearance.getReason());
dic2.setLocation(appearance.getLocation());
dic2.setContact(appearance.getContact());
dic2.setDate(new PdfDate(appearance.getSignDate()));
PdfSignatureAppearance appearance2 = PdfStamper.createSignature(reader, null, '\0');
appearance2.setVisibleSignature(new Rectangle(36, 748, 144, 780), 1, "sig");
appearance2.setCrypto(privateKey, chain, null, PdfSignatureAppearance.WINCER_SIGNED);
PdfSignature dic3 = new PdfSignature(PdfName.ADOBE_PPKLITE, PdfName.ADBE_PKCS7_DETACHED);
dic3.setReason(appearance.getReason());
dic3.setLocation(appearance.getLocation());
dic3.setContact(appearance.getContact());
dic3.setDate(new PdfDate(appearance.getSignDate()));
appearance2.setSignatureGraphic(Image.getInstance(signatureGraphic));
appearance2.setRenderingMode(PdfSignatureAppearance.RenderingMode.GRAPHIC);
PdfDictionary dic4 = new PdfDictionary();
dic4.put(PdfName.CONTENTS, new PdfString("test".getBytes()));
```
3. 签名并保存PDF文件
```
PdfSignature dic5 = new PdfSignature(PdfName.ADOBE_PPKLITE, PdfName.ADBE_PKCS7_DETACHED);
dic5.setReason(appearance.getReason());
dic5.setLocation(appearance.getLocation());
dic5.setContact(appearance.getContact());
dic5.setDate(new PdfDate(appearance.getSignDate()));
appearance4.setCrypto(privateKey, chain, null, PdfSignatureAppearance.WINCER_SIGNED);
appearance4.setSignatureGraphic(Image.getInstance(signatureGraphic));
appearance4.setRenderingMode(PdfSignatureAppearance.RenderingMode.GRAPHIC);
PdfDictionary dic6 = new PdfDictionary();
dic6.put(PdfName.CONTENTS, new PdfString("test".getBytes()));
PdfDictionary dic7 = new PdfDictionary();
dic7.put(PdfName.CONTENTS, new PdfString("test".getBytes()));
```
以上就是使用iText实现PDF电子签章的基本步骤。值得注意的是,签章的过程中需要使用数字证书,确保签章的真实性和合法性。
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