RSA

 

公钥长度读写

 

 

读取长度：

this.length = DerInputStream.getLength(i & 0xFF, paramInputStream);

 

static int getLength(int paramInt, InputStream paramInputStream)
  throws IOException
{
  int j = paramInt;    int i;
  if ((j & 0x80) == 0) {
    i = j;
  } else {
    j &= 127;



    if (j == 0)
      return -1;
    if ((j < 0) || (j > 4)) {
      throw new IOException("DerInputStream.getLength(): lengthTag=" + j + ", " + ((j < 0) ? "incorrect DER encoding." : "too big."));

    }

    for (i = 0; j > 0; --j) {
      i <<= 8;
      i += (0xFF & paramInputStream.read());
    }
  }
  return i;
}

 

写入长度：

public void putLength(int paramInt)
  throws IOException
{
  if (paramInt < 128) {
    write((byte)paramInt);
  }
  else if (paramInt < 256) {
    write(-127);
    write((byte)paramInt);
  }
  else if (paramInt < 65536) {
    write(-126);
    write((byte)(paramInt >> 8));
    write((byte)paramInt);
  }
  else if (paramInt < 16777216) {
    write(-125);
    write((byte)(paramInt >> 16));
    write((byte)(paramInt >> 8));
    write((byte)paramInt);
  }
  else {
    write(-124);
    write((byte)(paramInt >> 24));
    write((byte)(paramInt >> 16));
    write((byte)(paramInt >> 8));
    write((byte)paramInt);
  }
}

 

Java PKCS8EncodedKeySpec & X509EncodedKeySpec

 EncodedKeySpec

java.security.spec.EncodedKeySpec

 

PKCS8EncodedKeySpec

私钥的ASN.1编码（规范），编码按照PKCS#8标准：

 

PrivateKeyInfo ::= SEQUENCE {
  version Version,
  privateKeyAlgorithm PrivateKeyAlgorithmIdentifier,
  privateKey PrivateKey,
  attributes [0] IMPLICIT Attributes OPTIONAL }

Version ::= INTEGER

PrivateKeyAlgorithmIdentifier ::= AlgorithmIdentifier

PrivateKey ::= OCTET STRING

Attributes ::= SET OF Attribute

 

 

X509EncodedKeySpec

公钥的ASN.1编码（规范），编码按照X.509标准：

 

SubjectPublicKeyInfo ::= SEQUENCE {
  algorithm AlgorithmIdentifier,
  subjectPublicKey BIT STRING }

 

 

String privateKey = "MIIBVAIBADANBgkqhkiG9w0BAQEFAASCAT4wggE6AgEAAkEApTHMs+zR16SE0v3npoVbMGo70xX5tJ7HF23SvM2rARkJNtRs4xZRQpWQ1JBZnGna9HcVQsrRAORqYhhTrZ9rMQIDAQABAkAFNrlYrasZErJGQEEiIWP9lwHCvZchLTB4j+TahIV+2iLTiLa21QOqQFmpBqw/uqmHsJGtqtHIXdtgCrGtoLVhAiEA4zpbZ52vkCskvZ2eJ34n6dTsiybZLIMYIdp21kd6mpECIQC6HJ2f0R6BwL/ORYhF6tA1YeXZEKyAuTgDkwgmGN/WoQIgPsXrZHeafbB9iOiXPX/LlPyekF6eFn7s1sVcmRvMEhECIBnJDS2vU4K2qdxyVccaGW7L+YRxgvTytIgKPv7IQ3sBAiEAh3XrxyuR3nJhFD5pPcRLmnst9Ag6WQuthc/SgkKJlXk=";
String publicKey = "MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBAKUxzLPs0dekhNL956aFWzBqO9MV+bSexxdt0rzNqwEZCTbUbOMWUUKVkNSQWZxp2vR3FULK0QDkamIYU62fazECAwEAAQ==";

byte[] privateKeyEncoded = Base64.base64ToByteArray(privateKey);
byte[] publicKeyEncoded = Base64.base64ToByteArray(publicKey);

 

// 加密
PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(privateKeyEncoded);
KeyFactory keyFactory = null;
try {
    keyFactory = KeyFactory.getInstance("RSA");
} catch (NoSuchAlgorithmException e) {
    Assert.fail("no such algorithm: " + e.getMessage());
}

PrivateKey privateKey = null;
try {
    privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
} catch (InvalidKeySpecException e) {
    Assert.fail("invalid key spec: " + e.getMessage());
}
System.out.println("private key: " + Base64.byteArrayToBase64(((Key) privateKey).getEncoded()));

 

// 解密
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(publicKeyEncoded);
try {
    keyFactory = KeyFactory.getInstance("RSA");
} catch (NoSuchAlgorithmException e) {
    Assert.fail("no such algorithm: " + e.getMessage());
}
PublicKey publicKey = null;
try {
    publicKey = keyFactory.generatePublic(x509KeySpec);
} catch (InvalidKeySpecException e) {
    Assert.fail("invalid key spec: " + e.getMessage());
}
System.out.println("public key: " + Base64.byteArrayToBase64(((Key) publicKey).getEncoded()));

 

完整代码

/**
 * private key: MIIBVAIBADANBgkqhkiG9w0BAQEFAASCAT4wggE6AgEAAkEApTHMs+zR16SE0v3npoVbMGo70xX5tJ7HF23SvM2rARkJNtRs4xZRQpWQ1JBZnGna9HcVQsrRAORqYhhTrZ9rMQIDAQABAkAFNrlYrasZErJGQEEiIWP9lwHCvZchLTB4j+TahIV+2iLTiLa21QOqQFmpBqw/uqmHsJGtqtHIXdtgCrGtoLVhAiEA4zpbZ52vkCskvZ2eJ34n6dTsiybZLIMYIdp21kd6mpECIQC6HJ2f0R6BwL/ORYhF6tA1YeXZEKyAuTgDkwgmGN/WoQIgPsXrZHeafbB9iOiXPX/LlPyekF6eFn7s1sVcmRvMEhECIBnJDS2vU4K2qdxyVccaGW7L+YRxgvTytIgKPv7IQ3sBAiEAh3XrxyuR3nJhFD5pPcRLmnst9Ag6WQuthc/SgkKJlXk=
 * public key: MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBAKUxzLPs0dekhNL956aFWzBqO9MV+bSexxdt0rzNqwEZCTbUbOMWUUKVkNSQWZxp2vR3FULK0QDkamIYU62fazECAwEAAQ==
 */
@Test
public void test11() {
    String privateKey = "MIIBVAIBADANBgkqhkiG9w0BAQEFAASCAT4wggE6AgEAAkEApTHMs+zR16SE0v3npoVbMGo70xX5tJ7HF23SvM2rARkJNtRs4xZRQpWQ1JBZnGna9HcVQsrRAORqYhhTrZ9rMQIDAQABAkAFNrlYrasZErJGQEEiIWP9lwHCvZchLTB4j+TahIV+2iLTiLa21QOqQFmpBqw/uqmHsJGtqtHIXdtgCrGtoLVhAiEA4zpbZ52vkCskvZ2eJ34n6dTsiybZLIMYIdp21kd6mpECIQC6HJ2f0R6BwL/ORYhF6tA1YeXZEKyAuTgDkwgmGN/WoQIgPsXrZHeafbB9iOiXPX/LlPyekF6eFn7s1sVcmRvMEhECIBnJDS2vU4K2qdxyVccaGW7L+YRxgvTytIgKPv7IQ3sBAiEAh3XrxyuR3nJhFD5pPcRLmnst9Ag6WQuthc/SgkKJlXk=";
    String publicKey = "MFwwDQYJKoZIhvcNAQEBBQADSwAwSAJBAKUxzLPs0dekhNL956aFWzBqO9MV+bSexxdt0rzNqwEZCTbUbOMWUUKVkNSQWZxp2vR3FULK0QDkamIYU62fazECAwEAAQ==";

    byte[] privateKeyEncoded = Base64.base64ToByteArray(privateKey);
    byte[] publicKeyEncoded = Base64.base64ToByteArray(publicKey);

    String message = "13120983870";
    System.out.println(message);

    encryptAndDecrypt(message, privateKeyEncoded, publicKeyEncoded);
}

 

private void encryptAndDecrypt(String message, byte[] privateKeyEncoded, byte[] publicKeyEncoded) {
    // 加密
    PKCS8EncodedKeySpec pkcs8KeySpec = new PKCS8EncodedKeySpec(privateKeyEncoded);
    KeyFactory keyFactory = null;
    try {
        keyFactory = KeyFactory.getInstance("RSA");
    } catch (NoSuchAlgorithmException e) {
        Assert.fail("no such algorithm: " + e.getMessage());
    }

    PrivateKey privateKey = null;
    try {
        privateKey = keyFactory.generatePrivate(pkcs8KeySpec);
    } catch (InvalidKeySpecException e) {
        Assert.fail("invalid key spec: " + e.getMessage());
    }
    System.out.println("private key: " + Base64.byteArrayToBase64(((Key) privateKey).getEncoded()));

    Cipher cipher = null;
    try {
        cipher = Cipher.getInstance(keyFactory.getAlgorithm());
    } catch (NoSuchAlgorithmException e) {
        Assert.fail("no such algorithm: " + e.getMessage());
    } catch (NoSuchPaddingException e) {
        Assert.fail("no such padding: " + e.getMessage());
    }
    try {
        cipher.init(Cipher.ENCRYPT_MODE, privateKey);
    } catch (InvalidKeyException e) {
        Assert.fail("invalid key: " + e.getMessage());
    }

    byte[] encryption = null;
    try {
        encryption = cipher.doFinal(message.getBytes());
    } catch (IllegalBlockSizeException e) {
        Assert.fail("illegal block size: " + e.getMessage());
    } catch (BadPaddingException e) {
        Assert.fail("bad padding: " + e.getMessage());
    }
    System.out.println("encryption: " + Base64.byteArrayToBase64(encryption));

    // 解密
    X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(publicKeyEncoded);
    try {
        keyFactory = KeyFactory.getInstance("RSA");
    } catch (NoSuchAlgorithmException e) {
        Assert.fail("no such algorithm: " + e.getMessage());
    }
    PublicKey publicKey = null;
    try {
        publicKey = keyFactory.generatePublic(x509KeySpec);
    } catch (InvalidKeySpecException e) {
        Assert.fail("invalid key spec: " + e.getMessage());
    }
    System.out.println("public key: " + Base64.byteArrayToBase64(((Key) publicKey).getEncoded()));
    try {
        cipher = Cipher.getInstance(keyFactory.getAlgorithm());
    } catch (NoSuchAlgorithmException e) {
        Assert.fail("no such algorithm: " + e.getMessage());
    } catch (NoSuchPaddingException e) {
        Assert.fail("no such padding: " + e.getMessage());
    }
    try {
        cipher.init(Cipher.DECRYPT_MODE, publicKey);
    } catch (InvalidKeyException e) {
        Assert.fail("invalid key: " + e.getMessage());
    }

    byte[] decryption = null;
    try {
        decryption = cipher.doFinal(encryption);
    } catch (IllegalBlockSizeException e) {
        Assert.fail("illegal block size: " + e.getMessage());
    } catch (BadPaddingException e) {
        Assert.fail("bad padding: " + e.getMessage());
    }
    System.out.println("decryption: " + new String(decryption) + ", base64:" + Base64.byteArrayToBase64(decryption));
}