如何从pfx/p12文件中提取RSA密钥长度及其他相关信息-优快云博客

本文介绍如何从PKCS#12 (.pfx/.p12) 文件中提取密钥对及其长度，并展示了具体的Java代码实现过程。此外，还介绍了如何使用X509Utils工具类来进一步分析证书结构。

在Security编程中，有几种典型的密码交换信息文件格式:
DER-encoded certificate: .cer, .crt
PEM-encoded message: .pem
PKCS#12 Personal Information Exchange: .pfx, .p12
PKCS#10 Certification Request: .p10
PKCS#7 cert request response: .p7r
PKCS#7 binary message: .p7b

.cer/.crt是用于存放证书，它是2进制形式存放的，不含私钥。
.pem跟crt/cer的区别是它以Ascii来表示。
pfx/p12用于存放个人证书/私钥，他通常包含保护密码，2进制方式
p10是证书请求
p7r是CA对证书请求的回复，只用于导入
p7b以树状展示证书链(certificate chain)，同时也支持单个证书，不含私钥。

其中，我介绍如何从p12/pfx文件中提取密钥对及其长度:
1，首先，读取pfx/p12文件（需要提供保护密码）
2，通过别名(Alias,注意，所有证书中的信息项都是通过Alias来提取的)提取你想要分析的证书链
3，再将其转换为一个以X509证书结构体
4，提取里面的项，如果那你的证书项放在第一位（单一证书），直接读取 x509Certs[0]（见下面的代码）这个X509Certificate对象
5，X509Certificate对象有很多方法，tain198127网友希望读取RSA密钥（公私钥）及其长度（见http://www.matrix.org.cn/thread.shtml?topicId=43786&forumId=55&#reply），那真是太Easy了，
            X509Certificate keyPairCert = x509Certs[0];
            int iKeySize = X509CertUtil.getCertificateKeyLength(keyPairCert);
            System.out.println("证书密钥算法="+keyPairCert.getPublicKey().getAlgorithm());
            System.out.println("证书密钥长度="+iKeySize);
提取了他所需要的信息。

下面的代码来自于我的SecureX项目(https://sourceforge.net/projects/securex)的一部分，仅供参考，可以运行，但需要安装BouncyCastle。

package org.dev2dev.client.keypair;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.security.KeyStore;

import java.security.KeyStoreException;

import java.security.NoSuchAlgorithmException;

import java.security.NoSuchProviderException;

import java.security.Security;

import java.security.cert.Certificate;

import java.security.cert.CertificateException;

import java.security.cert.X509Certificate;

import org.dev2dev.security.keytool.X509CertUtil;

public class LoadKeyFromPKCS12

{

public static void main(String[] args)

{

try

{

// Open an input stream on the keystore file

String pfxFileName = " c:\\david.turing.pfx " ;

String pfxPassword = " 123456 " ;

File fPkcs12 = null ;

if (pfxFileName != null )

{

// Open the file

fPkcs12 = new File(pfxFileName);

}

FileInputStream fis = new FileInputStream(fPkcs12);

// Create a keystore object

KeyStore keyStore = null ;

try

{

// Need BC provider for PKCS #12, BKS and UBER

if (Security.getProvider( " BC " ) == null )

{

throw new Exception( " 不能Load入BouncyCastle! " );

}

keyStore = KeyStore.getInstance( " PKCS12 " , " BC " );

}

catch (KeyStoreException ex)

{

throw new Exception( " 不能正确解释pfx文件! " );

}

catch (NoSuchProviderException ex)

{

throw new Exception( " Security Provider配置有误! " );

}

try

{

// Load the file into the keystore

keyStore.load(fis, pfxPassword.toCharArray());

}

catch (CertificateException ex)

{

throw new Exception( " 证书格式问题! " );

}

catch (NoSuchAlgorithmException ex)

{

throw new Exception( " 算法不支持! " );

}

catch (FileNotFoundException ex)

{

throw new Exception( " pfx文件没找到 " );

}

catch (IOException ex)

{

throw new Exception( " 读取pfx有误! " );

}

// 获取我的证书链的中keyEntry的别名

Certificate[] certs = keyStore.getCertificateChain( " david.turing " );

X509Certificate[] x509Certs = X509CertUtil.convertCertificates(certs);

if (x509Certs == null )

{

return ;

}

x509Certs = X509CertUtil.orderX509CertChain(x509Certs);

X509Certificate keyPairCert = x509Certs[ 0 ];

int iKeySize = X509CertUtil.getCertificateKeyLength(keyPairCert);

System.out.println( " 证书密钥算法= " + keyPairCert.getPublicKey().getAlgorithm());

System.out.println( " 证书密钥长度= " + iKeySize);

} catch (Exception e)

{

e.printStackTrace();

}

另外,我会调用其他一个工具类X509Utils来分析证书结构

package org.dev2dev.security.keytool;

import java.io.ByteArrayInputStream;

import java.io.ByteArrayOutputStream;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.IOException;

import java.math.BigInteger;

import java.security.GeneralSecurityException;

import java.security.InvalidKeyException;

import java.security.KeyFactory;

import java.security.KeyStore;

import java.security.KeyStoreException;

import java.security.NoSuchAlgorithmException;

import java.security.NoSuchProviderException;

import java.security.Principal;

import java.security.PrivateKey;

import java.security.PublicKey;

import java.security.SignatureException;

import java.security.cert.CRLException;

import java.security.cert.CertPath;

import java.security.cert.Certificate;

import java.security.cert.CertificateException;

import java.security.cert.CertificateFactory;

import java.security.cert.X509CRL;

import java.security.cert.X509Certificate;

import java.security.spec.DSAPublicKeySpec;

import java.security.spec.RSAPublicKeySpec;

import java.text.MessageFormat;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Date;

import java.util.Enumeration;

import java.util.Hashtable;

import java.util.Iterator;

import java.util.ResourceBundle;

import java.util.Vector;

import org.bouncycastle.asn1.DEROutputStream;

import org.bouncycastle.asn1.x509.X509Name;

import org.bouncycastle.jce.PKCS10CertificationRequest;

import org.bouncycastle.jce.X509Principal;

import org.bouncycastle.jce.X509V1CertificateGenerator;

public final class X509CertUtil extends Object

{

/** *//** Resource bundle */

private static ResourceBundle m_res = ResourceBundle.getBundle("org/dev2dev/security/keytool/resources");

/** *//** Type name for X.509 certificates */

private static final String X509_CERT_TYPE = "X.509";

/** *//** PKCS #7 encoding name */

private static final String PKCS7_ENCODING = "PKCS7";

/** *//** Begin certificate in RFC 1421 encoding */

private static final String BEGIN_CERT = "-----BEGIN CERTIFICATE-----";

/** *//** End certificate in RFC 1421 encoding */

private static final String END_CERT = "-----END CERTIFICATE-----";

/** *//** The maximum length of lines in printable encoded certificates */

private static final int CERT_LINE_LENGTH = 64;

/** *//** Begin certificate signing request */

private static final String BEGIN_CERT_REQ = "-----BEGIN CERTIFICATE REQUEST-----";

/** *//**