fix rsa block

CHANGELOG.md

@@ -17,6 +17,7 @@
 * 【core  】     增强EnumConvert判断能力（issue#I17082@Gitee）
 * 【all   】     log、template、tokenizer使用SPI机制代替硬编码
 * 【poi   】     Word07Writer增加addPicture
+* 【crypto】     RSA算法中，BlockSize长度策略调整（issue#721@Github）
 
 ### Bug修复
 

hutool-crypto/src/main/java/cn/hutool/crypto/asymmetric/AsymmetricCrypto.java

@@ -1,20 +1,19 @@
 package cn.hutool.crypto.asymmetric;
 
-import java.io.IOException;
-import java.security.Key;
-import java.security.PrivateKey;
-import java.security.PublicKey;
-
-import javax.crypto.BadPaddingException;
-import javax.crypto.Cipher;
-import javax.crypto.IllegalBlockSizeException;
-
 import cn.hutool.core.codec.Base64;
 import cn.hutool.core.io.FastByteArrayOutputStream;
 import cn.hutool.crypto.CryptoException;
 import cn.hutool.crypto.SecureUtil;
 import cn.hutool.crypto.symmetric.SymmetricAlgorithm;
 
+import javax.crypto.BadPaddingException;
+import javax.crypto.Cipher;
+import javax.crypto.IllegalBlockSizeException;
+import java.io.IOException;
+import java.security.Key;
+import java.security.PrivateKey;
+import java.security.PublicKey;
+
 /**
  * 非对称加密算法
  * 
@@ -196,12 +195,19 @@ public class AsymmetricCrypto extends AbstractAsymmetricCrypto<AsymmetricCrypto>
 	@Override
 	public byte[] encrypt(byte[] data, KeyType keyType) {
 		final Key key = getKeyByType(keyType);
-		final int maxBlockSize = this.encryptBlockSize < 0 ? data.length : this.encryptBlockSize;
-
 		lock.lock();
 		try {
 			cipher.init(Cipher.ENCRYPT_MODE, key);
-			return doFinal(data, maxBlockSize);
+
+			if(this.encryptBlockSize < 0){
+				// 在引入BC库情况下，自动获取块大小
+				final int blockSize = this.cipher.getBlockSize();
+				if(blockSize > 0){
+					this.encryptBlockSize = blockSize;
+				}
+			}
+
+			return doFinal(data, this.encryptBlockSize < 0 ? data.length : this.encryptBlockSize);
 		} catch (Exception e) {
 			throw new CryptoException(e);
 		} finally {
@@ -220,12 +226,19 @@ public class AsymmetricCrypto extends AbstractAsymmetricCrypto<AsymmetricCrypto>
 	@Override
 	public byte[] decrypt(byte[] data, KeyType keyType) {
 		final Key key = getKeyByType(keyType);
-		final int maxBlockSize = this.decryptBlockSize < 0 ? data.length : this.decryptBlockSize;
-
 		lock.lock();
 		try {
 			cipher.init(Cipher.DECRYPT_MODE, key);
-			return doFinal(data, maxBlockSize);
+
+			if(this.decryptBlockSize < 0){
+				// 在引入BC库情况下，自动获取块大小
+				final int blockSize = this.cipher.getBlockSize();
+				if(blockSize > 0){
+					this.decryptBlockSize = blockSize;
+				}
+			}
+
+			return doFinal(data, this.decryptBlockSize < 0 ? data.length : this.decryptBlockSize);
 		} catch (Exception e) {
 			throw new CryptoException(e);
 		} finally {

hutool-crypto/src/main/java/cn/hutool/crypto/asymmetric/RSA.java

@@ -11,6 +11,7 @@ import java.security.spec.RSAPublicKeySpec;
 
 import cn.hutool.core.util.CharsetUtil;
 import cn.hutool.crypto.CryptoException;
+import cn.hutool.crypto.GlobalBouncyCastleProvider;
 import cn.hutool.crypto.SecureUtil;
 
 /**
@@ -186,7 +187,8 @@ public class RSA extends AsymmetricCrypto {
 
 	@Override
 	public byte[] encrypt(byte[] data, KeyType keyType) {
-		if (this.encryptBlockSize < 0) {
+		// 在非使用BC库情况下，blockSize使用默认的算法
+		if (this.encryptBlockSize < 0 && null == GlobalBouncyCastleProvider.INSTANCE.getProvider()) {
 			// 加密数据长度 <= 模长-11
 			this.encryptBlockSize = ((RSAKey) getKeyByType(keyType)).getModulus().bitLength() / 8 - 11;
 		}
@@ -195,7 +197,8 @@ public class RSA extends AsymmetricCrypto {
 
 	@Override
 	public byte[] decrypt(byte[] bytes, KeyType keyType) {
-		if (this.decryptBlockSize < 0) {
+		// 在非使用BC库情况下，blockSize使用默认的算法
+		if (this.decryptBlockSize < 0 && null == GlobalBouncyCastleProvider.INSTANCE.getProvider()) {
 			// 加密数据长度 <= 模长-11
 			this.decryptBlockSize = ((RSAKey) getKeyByType(keyType)).getModulus().bitLength() / 8;
 		}