Mar 15, 2009
[Tiger] RSA 暗号の鍵を DB に格納する方法
RSA 暗号の公開鍵を DB に格納しようと苦心惨憺したときのメモ。 以下のサイトが非常に参考になった。多謝。
- Java Cryptgraphy
- http://tokyo.cool.ne.jp/hharuki/java/81crypt.html
- @//メモ - JavaSE RSA暗号
- http://hondou.homedns.org/pukiwiki/index.php?cmd=read&page=JavaSE%20RSA%B0%C5%B9%E6
コード
ここではテストのためファイルから公開鍵、秘密鍵を取得している。
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import javax.crypto.Cipher;
import javax.crypto.CipherOutputStream;
import javax.mail.internet.MimeUtility;
...
public void test() throws Exception {
String data = "hogehogehogehoge";
// 公開鍵の読み込み
ByteArrayOutputStream baos = new ByteArrayOutputStream();
InputStream is = null;
try {
is = new FileInputStream(new File("./mykey.x509"));
int ch = 0;
while ((ch = is.read()) >= 0) {
baos.write(ch);
}
} finally {
if(is != null) {
is.close();
}
}
// 暗号化。
byte[] encrypted = this.encrypt(data.getBytes(), baos.toByteArray());
System.out.println("" + new String(encrypted));
// 秘密鍵の読み込み
baos = new ByteArrayOutputStream();
try {
is = new FileInputStream(new File("./mykey.pkcs8"));
ch = 0;
while ((ch = is.read()) >= 0) {
baos.write(ch);
}
} finally {
if(is != null) {
is.close();
}
}
// 復号化。
byte[] decrypted = this.decrypt(encrypted, baos.toByteArray());
System.out.println("" + new String(decrypted));
}
public byte[] encrypt(final byte[] text, final byte[] publicKey)
throws Exception {
PublicKey key = KeyFactory.getInstance("RSA").generatePublic(
new X509EncodedKeySpec(this.decodeBase64(publicKey)));
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, key);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
CipherOutputStream cos = new CipherOutputStream(baos, cipher);
cos.write(text);
cos.close();
return baos.toByteArray();
}
public byte[] decrypt(final byte[] text, final byte[] privateKey)
throws Exception {
PrivateKey key = KeyFactory.getInstance("RSA").generatePrivate(
new PKCS8EncodedKeySpec(this.decodeBase64(privateKey)));
ByteArrayOutputStream baos = new ByteArrayOutputStream();
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, key);
CipherOutputStream cos = new CipherOutputStream(baos, cipher);
cos.write(text);
cos.close();
return baos.toByteArray();
}
protected byte[] decodeBase64(final byte[] text) throws MessagingException,
IOException {
InputStream is = MimeUtility.decode(new ByteArrayInputStream(text), "base64");
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int ch = 0;
while ((ch = is.read()) >= 0) {
baos.write(ch);
}
return baos.toByteArray();
}
鍵の作成
下記で作成した mykey.x509, mykey.pkcs8 がそれぞれ公開鍵、秘密鍵になる。
$ openssl genrsa -des 1024 > ./mykey.pem Generating RSA private key, 1024 bit long modulus ...............++++++ ............++++++ e is 65537 (0x10001) Enter pass phrase: Verifying - Enter pass phrase: $ openssl pkcs8 -topk8 -in ./mykey.pem -out ./mykey.pkcs8 -nocrypt Enter pass phrase for ./mykey.pem: $ openssl rsa -in ./mykey.pem -pubout -out ./mykey.x509 Enter pass phrase for ./mykey.pem: writing RSA key $ cp ./mykey.pkcs8 ./mykey.pkcs8.original $ vi ./mykey.pkcs8 $ diff ./mykey.pkcs8.original ./mykey.pkcs8 1d0 < -----BEGIN PRIVATE KEY----- 16d14 < -----END PRIVATE KEY----- $ cp ./mykey.x509 ./mykey.x509.original $ vi ./mykey.x509 $ diff ./mykey.x509.original ./mykey.x509 1d0 < -----BEGIN PUBLIC KEY----- 6d4 < -----END PUBLIC KEY----- $
