公钥RSA解密

此为RSA解密的方法

public static byte[] decrypt(byte[] encryptedBytes, PrivateKey privateKey, int keyLength, int reserveSize, String cipherAlgorithm) throws Exception {
		int keyByteSize = keyLength / 8;
		int decryptBlockSize = keyByteSize - reserveSize;
		int nBlock = encryptedBytes.length / keyByteSize;
		ByteArrayOutputStream outbuf = null;
		try {
			Cipher cipher = Cipher.getInstance(cipherAlgorithm);
			cipher.init(Cipher.DECRYPT_MODE, privateKey);

			outbuf = new ByteArrayOutputStream(nBlock * decryptBlockSize);
			for (int offset = 0; offset < encryptedBytes.length; offset += keyByteSize) {
				int inputLen = encryptedBytes.length - offset;
				if (inputLen > keyByteSize) {
					inputLen = keyByteSize;
				}
				byte[] decryptedBlock = cipher.doFinal(encryptedBytes, offset, inputLen);
				outbuf.write(decryptedBlock);
			}
			outbuf.flush();
			return outbuf.toByteArray();
		} catch (Exception e) {
			throw new Exception("DEENCRYPT ERROR:", e);
		} finally {
			try{
				if(outbuf != null){
					outbuf.close();
				}
			}catch (Exception e){
				outbuf = null;
				throw new Exception("CLOSE ByteArrayOutputStream ERROR:", e);
			}
		}
	}

去调用这个方法：

byte[] b = decrypt(Base64.decodeBase64(encrypt_random_key), privateKey, 2048, 11, "RSA/None/PKCS1Padding");
				String encrypt_key = new String(b,"utf-8");

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