> For the complete documentation index, see [llms.txt](https://docs.payments.thalescloud.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.payments.thalescloud.io/xpay-enablement/ja/api-rifarensu/sekyuriti/pkcs.md).

# PKCS

### 暗号化フォーマット <a href="#pkcs7-encryption-format" id="pkcs7-encryption-format"></a>

PKCS#7 メッセージ形式は RFC 2315/5652 で定義されています。

使用されるコンテンツ暗号化アルゴリズムは「AES256/CBC/PKCS7Padding」です。

鍵暗号化アルゴリズムは、TSP の構成によって 'RSAES-PKCS1-v1\_5' (RSA/NONE/PKCS1Padding) または 'RSA/NONE/OAEPWithSHA256AndMGF1Padding'（MGF1 が SHA-256 を使用）であり、プロジェクト開始時に共有された暗号化証明書を使用します。

暗号化結果は JSON メッセージで送信できるように base64 でエンコードされます。

#### 証明書交換

1. 顧客は RSA 2048 ビットまたは RSA 4096 ビットの鍵ペアを作成します。
2. 顧客はその RSA 鍵から証明書署名要求（CSR）を生成します。
3. 顧客は PEM 形式の CSR を Thales のプロジェクトチームに送信します。

#### コードサンプル

以下は BouncyCastle ライブラリを使用して PKCS#7 データの暗号化/復号化を扱う JAVA のコードサンプルです。

```java
package com.gemalto.test.pkcs7;

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Security;
import java.util.Collection;

import org.bouncycastle.cms.CMSAlgorithm;
import org.bouncycastle.cms.CMSEnvelopedData;
import org.bouncycastle.cms.CMSEnvelopedDataGenerator;
import org.bouncycastle.cms.CMSProcessableByteArray;
import org.bouncycastle.cms.KeyTransRecipientInformation;
import org.bouncycastle.cms.RecipientInformation;
import org.bouncycastle.cms.bc.BcCMSContentEncryptorBuilder;
import org.bouncycastle.cms.jcajce.JceKeyTransEnvelopedRecipient;
import org.bouncycastle.cms.jcajce.JceKeyTransRecipientInfoGenerator;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.operator.OutputEncryptor;
import org.bouncycastle.util.encoders.Base64;

public class MainPKCS7 {

	private static final String DATA_TO_ENCRYPT = "{\"fpan\":\"4974013055554646\",\"exp\":\"0316\",\"cvv\":\"123\"}";

	private static BouncyCastleProvider bcProvider;
	private static PrivateKey privKey;
	private static PublicKey pubKey;

	static {
		try {
			KeyPairGenerator kpg = KeyPairGenerator.getInstance("RSA");
			kpg.initialize(2048);
			KeyPair kp = kpg.generateKeyPair();
			privKey = kp.getPrivate();
			pubKey = kp.getPublic();
			bcProvider = new BouncyCastleProvider();
			Security.addProvider(bcProvider);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	public static void main(String[] args) throws Exception {
		

		// 暗号化
		byte[] encData = encryptPKCS7(DATA_TO_ENCRYPT.getBytes());
		System.out.println("Encrypted data = " + Base64.toBase64String(encData));

		// 復号化
		byte[] result = decryptPKCS7(encData);
		System.out.println("Decrypted data = " + new String(result));

	}

	private static byte[] encryptPKCS7(byte[] plainData) throws Exception {
		// ジェネレータを設定する
		CMSEnvelopedDataGenerator gen = new CMSEnvelopedDataGenerator();
		gen.addRecipientInfoGenerator(new JceKeyTransRecipientInfoGenerator(new byte[] { 0x01 }, pubKey)
				.setProvider(bcProvider));
		// enveloped-data オブジェクトを作成する
		CMSProcessableByteArray data = new CMSProcessableByteArray(plainData);
		BcCMSContentEncryptorBuilder builder = new BcCMSContentEncryptorBuilder(CMSAlgorithm.AES256_CBC);
		OutputEncryptor oe = builder.build();
		CMSEnvelopedData enveloped = gen.generate(data, oe);

		return enveloped.getEncoded();
	}

	private static byte[] decryptPKCS7(byte[] encryptedData) throws Exception {
		CMSEnvelopedData enveloped = new CMSEnvelopedData(encryptedData);
		Collection<RecipientInformation> recip = enveloped.getRecipientInfos().getRecipients();
		KeyTransRecipientInformation rinfo = (KeyTransRecipientInformation) recip.iterator().next();
		byte[] contents = rinfo.getContent(new JceKeyTransEnvelopedRecipient(privKey).setProvider(bcProvider));
		return (contents);
	}

}
```


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