1.关于RSA算法的原理解析参考：http://www.ruanyifeng.com/blog/2013/06/rsa_algorithm_part_one.html
2.RSA密钥长度、明文长度和密文长度参考：https://blog.csdn.net/liuhuabai100/article/details/7585879
3.以下示例代码可以将密钥Base64转码之后保存到文本文件内，也可以从文本文件中读取密钥。
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 | public class RSAGenerator { /** * 算法 */ private String ALGORITHM_RSA = "RSA"; private String DEFAULT_ENCODING = "UTF-8"; public static final String KEY_TYPE_PUBLIC = "PUBLIC"; public static final String KEY_TYPE_PRIVATE = "PRIVATE"; /** * 公钥 */ private RSAPublicKey publicKey; private String publicKeyStr; /** * 私钥 */ private RSAPrivateKey privateKey; private String privateKeyStr; /** * 用于加解密 */ private Cipher cipher; /** * 明文块的长度 它必须小于密文块的长度 - 11 */ private int originLength = 128; /** * 密文块的长度 */ private int encrytLength = 256; /** * 生成密钥对 * @return */ public RSAGenerator generateKeyPair() { try { // RSA加密算法 KeyPairGenerator keyPairGenerator = KeyPairGenerator .getInstance(ALGORITHM_RSA); // 创建密钥对，长度采用2048 keyPairGenerator.initialize(2048); KeyPair keyPair = keyPairGenerator.generateKeyPair(); // 分别得到公钥和私钥 publicKey = (RSAPublicKey) keyPair.getPublic(); privateKey = (RSAPrivateKey) keyPair.getPrivate(); // 使用 Base64编码 publicKeyStr = Base64Util.encode(publicKey.getEncoded()); privateKeyStr = Base64Util.encode(privateKey.getEncoded()); //将BASE64编码的结果保存到文件内 String classPath = this.getClass().getClassLoader().getResource("").toString(); String prefix = classPath.substring(classPath.indexOf(":") + 1); String publicFilePath = prefix+"public.txt"; File publicFile= new File(publicFilePath); saveBase64KeyToFile(publicFile, publicKeyStr); String privateFilePath = prefix+"private.txt"; File privateFile= new File(privateFilePath); saveBase64KeyToFile(privateFile, privateKeyStr); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } return this; } /** * 用公钥加密 * @param content * @return 加密后的16进制字符串 */ public String encryptByPublic(String content) { String encode = ""; try { cipher = Cipher.getInstance(ALGORITHM_RSA); cipher.init(Cipher.ENCRYPT_MODE, publicKey); // 该密钥能够加密的最大字节长度 int splitLength = publicKey.getModulus().bitLength() / 8 - 11; byte[][] arrays = splitBytes(content.getBytes(), splitLength); // 加密 StringBuffer buffer = new StringBuffer(); for (byte[] array : arrays) { buffer.append(bytesToHexString(cipher.doFinal(array))); } encode = buffer.toString(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (NoSuchPaddingException e) { e.printStackTrace(); } catch (InvalidKeyException e) { e.printStackTrace(); } catch (IllegalBlockSizeException e) { e.printStackTrace(); } catch (BadPaddingException e) { e.printStackTrace(); } return encode; } /** * 用私钥加密 * * @param content * @return 加密后的16进制字符串 */ public String encryptByPrivate(String content) { try { Cipher cipher = Cipher.getInstance(ALGORITHM_RSA); cipher.init(Cipher.ENCRYPT_MODE, privateKey); // 该密钥能够加密的最大字节长度 int splitLength = ((RSAPrivateKey) privateKey).getModulus() .bitLength() / 8 - 11; byte[][] arrays = splitBytes(content.getBytes(), splitLength); StringBuffer stringBuffer = new StringBuffer(); for (byte[] array : arrays) { stringBuffer.append(bytesToHexString(cipher.doFinal(array))); } return stringBuffer.toString(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (NoSuchPaddingException e) { e.printStackTrace(); } catch (InvalidKeyException e) { e.printStackTrace(); } catch (BadPaddingException e) { e.printStackTrace(); } catch (IllegalBlockSizeException e) { e.printStackTrace(); } return null; } /** * 用私钥解密 * @param content * @return 解密后的原文 */ public String decryptByPrivate(String content) { String decode = ""; try { cipher = Cipher.getInstance(ALGORITHM_RSA); cipher.init(Cipher.DECRYPT_MODE, privateKey); // 该密钥能够加密的最大字节长度 int splitLength = privateKey.getModulus().bitLength() / 8; byte[] contentBytes = hexStringToBytes(content); byte[][] arrays = splitBytes(contentBytes, splitLength); StringBuffer stringBuffer = new StringBuffer(); for (byte[] array : arrays) { stringBuffer.append(new String(cipher.doFinal(array))); } decode = stringBuffer.toString(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (NoSuchPaddingException e) { e.printStackTrace(); } catch (InvalidKeyException e) { e.printStackTrace(); } catch (IllegalBlockSizeException e) { e.printStackTrace(); } catch (BadPaddingException e) { e.printStackTrace(); } return decode; } /** * 用私钥解密 * * @param content * @return 解密后的原文 */ public String decryptByPublic(String content) { String decode = ""; try { cipher = Cipher.getInstance(ALGORITHM_RSA); cipher.init(Cipher.DECRYPT_MODE, publicKey); // 该密钥能够加密的最大字节长度 int splitLength = publicKey.getModulus().bitLength() / 8; byte[] contentBytes = hexStringToBytes(content); byte[][] arrays = splitBytes(contentBytes, splitLength); StringBuffer stringBuffer = new StringBuffer(); for (byte[] array : arrays) { stringBuffer.append(new String(cipher.doFinal(array))); } decode = stringBuffer.toString(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (NoSuchPaddingException e) { e.printStackTrace(); } catch (InvalidKeyException e) { e.printStackTrace(); } catch (IllegalBlockSizeException e) { e.printStackTrace(); } catch (BadPaddingException e) { e.printStackTrace(); } return decode; } /** * 根据限定的每组字节长度，将字节数组分组 * @param bytes 等待分组的字节组 * @param splitLength 每组长度 * @return 分组后的字节组 */ public static byte[][] splitBytes(byte[] bytes, int splitLength) { // bytes与splitLength的余数 int remainder = bytes.length % splitLength; // 数据拆分后的组数，余数不为0时加1 int quotient = remainder > 0 ? bytes.length / splitLength + 1 : bytes.length / splitLength; byte[][] arrays = new byte[quotient][]; byte[] array = null; for (int i = 0; i < quotient; i++) { // 如果是最后一组（quotient-1）,同时余数不等于0，就将最后一组设置为remainder的长度 if (i == quotient - 1 && remainder != 0) { array = new byte[remainder]; System.arraycopy(bytes, i * splitLength, array, 0, remainder); } else { array = new byte[splitLength]; System.arraycopy(bytes, i * splitLength, array, 0, splitLength); } arrays[i] = array; } return arrays; } /** * 将字节数组转换成16进制字符串 * @param bytes 即将转换的数据 * @return 16进制字符串 */ public static String bytesToHexString(byte[] bytes) { StringBuffer sb = new StringBuffer(bytes.length); String temp = null; for (int i = 0; i < bytes.length; i++) { temp = Integer.toHexString(0xFF & bytes[i]); if (temp.length() < 2) { sb.append(0); } sb.append(temp); } return sb.toString(); } /** * 将16进制字符串转换成字节数组 * * @param hex * 16进制字符串 * @return byte[] */ public static byte[] hexStringToBytes(String hex) { int len = (hex.length() / 2); hex = hex.toUpperCase(); byte[] result = new byte[len]; char[] chars = hex.toCharArray(); for (int i = 0; i < len; i++) { int pos = i * 2; result[i] = (byte) (toByte(chars[pos]) << 4 | toByte(chars[pos + 1])); } return result; } /** * 将char转换为byte * * @param c * char * @return byte */ private static byte toByte(char c) { return (byte) "0123456789ABCDEF".indexOf(c); } /** * 保存公钥到文件 * * @param file * @return */ public boolean savePublicKey(File file) { return saveKeyToFile(publicKey, file); } /** * 保存私钥到文件 * * @param file * @return */ public boolean savePrivateKey(File file) { return saveKeyToFile(privateKey, file); } /** * 保存密钥到文件 * @param key 密钥 * @param file 文件 * @return */ private boolean saveKeyToFile(Key key, File file) { boolean result = false; FileOutputStream fos = null; try { fos = new FileOutputStream(file); ObjectOutputStream oos = new ObjectOutputStream(fos); // 公钥默认使用的是X.509编码，私钥默认采用的是PKCS #8编码 byte[] encode = key.getEncoded(); // 注意，此处采用writeObject方法，读取时也要采用readObject方法 oos.writeObject(encode); oos.close(); result = true; } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { fos.close(); } catch (IOException e) { e.printStackTrace(); } } return result; } private boolean saveBase64KeyToFile(File file, String key) { boolean result = false; FileOutputStream fos = null; try { fos = new FileOutputStream(file); fos.write(key.getBytes()); fos.close(); result = true; } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } finally { try { fos.close(); } catch (IOException e) { e.printStackTrace(); } } return result; } /** * 从BASE64文件中读取KEY值 * @param fileName * @param keyType */ public void getKeyFromBase64File(String fileName,String keyType) { try { InputStream inputStream = this.getClass().getClassLoader().getResource(fileName).openStream(); ByteArrayOutputStream outStream = new ByteArrayOutputStream(); byte[] subByte = new byte[1024]; int len = 0; while((len=inputStream.read(subByte))>0) { outStream.write(subByte,0,len); } inputStream.close(); outStream.close(); String base64Key = new String(outStream.toByteArray(), DEFAULT_ENCODING); byte[] keybyte = Base64Util.decode(base64Key); // 默认编码 KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM_RSA); if (KEY_TYPE_PUBLIC.equals(keyType)) { X509EncodedKeySpec x509eks = new X509EncodedKeySpec(keybyte); publicKey = (RSAPublicKey) keyFactory.generatePublic(x509eks); System.out.println(publicKey.getAlgorithm()); } else { PKCS8EncodedKeySpec pkcs8eks = new PKCS8EncodedKeySpec(keybyte); privateKey = (RSAPrivateKey) keyFactory .generatePrivate(pkcs8eks); } } catch (IOException e) { e.printStackTrace(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (InvalidKeySpecException e) { e.printStackTrace(); } } /** * 从文件中得到公钥 * * @param file */ public void getPublicKey(File file) { getKey(file, KEY_TYPE_PUBLIC); } /** * 从文件中得到私钥 * * @param file */ public void getPrivateKey(File file) { getKey(file, KEY_TYPE_PRIVATE); } /** * 从文件中得到密钥 * * @param file * @param keyType */ private void getKey(File file, String keyType) { FileInputStream fis = null; try { fis = new FileInputStream(file); ObjectInputStream ois = new ObjectInputStream(fis); byte[] keybyte = (byte[]) ois.readObject(); // 关闭资源 ois.close(); // 默认编码 KeyFactory keyFactory = KeyFactory.getInstance(ALGORITHM_RSA); if (KEY_TYPE_PUBLIC.equals(keyType)) { X509EncodedKeySpec x509eks = new X509EncodedKeySpec(keybyte); publicKey = (RSAPublicKey) keyFactory.generatePublic(x509eks); System.out.println(publicKey.getAlgorithm()); } else { PKCS8EncodedKeySpec pkcs8eks = new PKCS8EncodedKeySpec(keybyte); privateKey = (RSAPrivateKey) keyFactory .generatePrivate(pkcs8eks); } } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (InvalidKeySpecException e) { e.printStackTrace(); } finally { try { fis.close(); } catch (IOException e) { e.printStackTrace(); } } }} |
代码中涉及到的Base64Util如下：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 | public class Base64Util{ private static final char S_BASE64CHAR[] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' }; private static final byte S_DECODETABLE[]; static { S_DECODETABLE = new byte[128]; for (int i = 0; i < S_DECODETABLE.length; i++) S_DECODETABLE[i] = 127; for (int i = 0; i < S_BASE64CHAR.length; i++) S_DECODETABLE[S_BASE64CHAR[i]] = (byte) i; } /** * * @param ibuf * @param obuf * @param wp * @return */ private static int decode0(char ibuf[], byte obuf[], int wp) { int outlen = 3; if (ibuf[3] == '=') outlen = 2; if (ibuf[2] == '=') outlen = 1; int b0 = S_DECODETABLE[ibuf[0]]; int b1 = S_DECODETABLE[ibuf[1]]; int b2 = S_DECODETABLE[ibuf[2]]; int b3 = S_DECODETABLE[ibuf[3]]; switch (outlen) { case 1: // '\001' obuf[wp] = (byte) (b0 << 2 & 252 | b1 >> 4 & 3); return 1; case 2: // '\002' obuf[wp++] = (byte) (b0 << 2 & 252 | b1 >> 4 & 3); obuf[wp] = (byte) (b1 << 4 & 240 | b2 >> 2 & 15); return 2; case 3: // '\003' obuf[wp++] = (byte) (b0 << 2 & 252 | b1 >> 4 & 3); obuf[wp++] = (byte) (b1 << 4 & 240 | b2 >> 2 & 15); obuf[wp] = (byte) (b2 << 6 & 192 | b3 & 63); return 3; } throw new RuntimeException("Internal error"); } /** * * @param data * @param off * @param len * @return */ public static byte[] decode(char data[], int off, int len) { char ibuf[] = new char[4]; int ibufcount = 0; byte obuf[] = new byte[(len / 4) * 3 + 3]; int obufcount = 0; for (int i = off; i < off + len; i++) { char ch = data[i]; if (ch != '=' && (ch >= S_DECODETABLE.length || S_DECODETABLE[ch] == 127)) continue; ibuf[ibufcount++] = ch; if (ibufcount == ibuf.length) { ibufcount = 0; obufcount += decode0(ibuf, obuf, obufcount); } } if (obufcount == obuf.length) { return obuf; } else { byte ret[] = new byte[obufcount]; System.arraycopy(obuf, 0, ret, 0, obufcount); return ret; } } /** * * @param data * @return */ public static byte[] decode(String data) { char ibuf[] = new char[4]; int ibufcount = 0; byte obuf[] = new byte[(data.length() / 4) * 3 + 3]; int obufcount = 0; for (int i = 0; i < data.length(); i++) { char ch = data.charAt(i); if (ch != '=' && (ch >= S_DECODETABLE.length || S_DECODETABLE[ch] == 127)) continue; ibuf[ibufcount++] = ch; if (ibufcount == ibuf.length) { ibufcount = 0; obufcount += decode0(ibuf, obuf, obufcount); } } if (obufcount == obuf.length) { return obuf; } else { byte ret[] = new byte[obufcount]; System.arraycopy(obuf, 0, ret, 0, obufcount); return ret; } } /** * * @param data * @param off * @param len * @param ostream * @throws IOException */ public static void decode(char data[], int off, int len, OutputStream ostream) throws IOException { char ibuf[] = new char[4]; int ibufcount = 0; byte obuf[] = new byte[3]; for (int i = off; i < off + len; i++) { char ch = data[i]; if (ch != '=' && (ch >= S_DECODETABLE.length || S_DECODETABLE[ch] == 127)) continue; ibuf[ibufcount++] = ch; if (ibufcount == ibuf.length) { ibufcount = 0; int obufcount = decode0(ibuf, obuf, 0); ostream.write(obuf, 0, obufcount); } } } /** * * @param data * @param ostream * @throws IOException */ public static void decode(String data, OutputStream ostream) throws IOException { char ibuf[] = new char[4]; int ibufcount = 0; byte obuf[] = new byte[3]; for (int i = 0; i < data.length(); i++) { char ch = data.charAt(i); if (ch != '=' && (ch >= S_DECODETABLE.length || S_DECODETABLE[ch] == 127)) continue; ibuf[ibufcount++] = ch; if (ibufcount == ibuf.length) { ibufcount = 0; int obufcount = decode0(ibuf, obuf, 0); ostream.write(obuf, 0, obufcount); } } } /** * * @param data * @return */ public static String encode(byte data[]) { return encode(data, 0, data.length); } /** * * @param data * @param off * @param len * @return */ public static String encode(byte data[], int off, int len) { if (len <= 0) return ""; char out[] = new char[(len / 3) * 4 + 4]; int rindex = off; int windex = 0; int rest; for (rest = len - off; rest >= 3; rest -= 3) { int i = ((data[rindex] & 255) << 16) + ((data[rindex + 1] & 255) << 8) + (data[rindex + 2] & 255); out[windex++] = S_BASE64CHAR[i >> 18]; out[windex++] = S_BASE64CHAR[i >> 12 & 63]; out[windex++] = S_BASE64CHAR[i >> 6 & 63]; out[windex++] = S_BASE64CHAR[i & 63]; rindex += 3; } if (rest == 1) { int i = data[rindex] & 255; out[windex++] = S_BASE64CHAR[i >> 2]; out[windex++] = S_BASE64CHAR[i << 4 & 63]; out[windex++] = '='; out[windex++] = '='; } else if (rest == 2) { int i = ((data[rindex] & 255) << 8) + (data[rindex + 1] & 255); out[windex++] = S_BASE64CHAR[i >> 10]; out[windex++] = S_BASE64CHAR[i >> 4 & 63]; out[windex++] = S_BASE64CHAR[i << 2 & 63]; out[windex++] = '='; } return new String(out, 0, windex); } /** * * @param data * @param off * @param len * @param ostream * @throws IOException */ public static void encode(byte data[], int off, int len, OutputStream ostream) throws IOException { if (len <= 0) return; byte out[] = new byte[4]; int rindex = off; int rest; for (rest = len - off; rest >= 3; rest -= 3) { int i = ((data[rindex] & 255) << 16) + ((data[rindex + 1] & 255) << 8) + (data[rindex + 2] & 255); out[0] = (byte) S_BASE64CHAR[i >> 18]; out[1] = (byte) S_BASE64CHAR[i >> 12 & 63]; out[2] = (byte) S_BASE64CHAR[i >> 6 & 63]; out[3] = (byte) S_BASE64CHAR[i & 63]; ostream.write(out, 0, 4); rindex += 3; } if (rest == 1) { int i = data[rindex] & 255; out[0] = (byte) S_BASE64CHAR[i >> 2]; out[1] = (byte) S_BASE64CHAR[i << 4 & 63]; out[2] = 61; out[3] = 61; ostream.write(out, 0, 4); } else if (rest == 2) { int i = ((data[rindex] & 255) << 8) + (data[rindex + 1] & 255); out[0] = (byte) S_BASE64CHAR[i >> 10]; out[1] = (byte) S_BASE64CHAR[i >> 4 & 63]; out[2] = (byte) S_BASE64CHAR[i << 2 & 63]; out[3] = 61; ostream.write(out, 0, 4); } } /** * * @param data * @param off * @param len * @param writer * @throws IOException */ public static void encode(byte data[], int off, int len, Writer writer) throws IOException { if (len <= 0) return; char out[] = new char[4]; int rindex = off; int rest = len - off; int output = 0; do { if (rest < 3) break; int i = ((data[rindex] & 255) << 16) + ((data[rindex + 1] & 255) << 8) + (data[rindex + 2] & 255); out[0] = S_BASE64CHAR[i >> 18]; out[1] = S_BASE64CHAR[i >> 12 & 63]; out[2] = S_BASE64CHAR[i >> 6 & 63]; out[3] = S_BASE64CHAR[i & 63]; writer.write(out, 0, 4); rindex += 3; rest -= 3; if ((output += 4) % 76 == 0) writer.write("\n"); } while (true); if (rest == 1) { int i = data[rindex] & 255; out[0] = S_BASE64CHAR[i >> 2]; out[1] = S_BASE64CHAR[i << 4 & 63]; out[2] = '='; out[3] = '='; writer.write(out, 0, 4); } else if (rest == 2) { int i = ((data[rindex] & 255) << 8) + (data[rindex + 1] & 255); out[0] = S_BASE64CHAR[i >> 10]; out[1] = S_BASE64CHAR[i >> 4 & 63]; out[2] = S_BASE64CHAR[i << 2 & 63]; out[3] = '='; writer.write(out, 0, 4); } } } |
测试类：
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 | public class RSATest { @Test public void test() { RSAGenerator rsaGenerator = new RSAGenerator().generateKeyPair(); String str="数表的质数又称素数。指整数在一个大于1的自然数中，除了1和此整数自身外，没法被其他自然数整除的数"; String encode = rsaGenerator.encryptByPublic(str); System.out.println(encode); System.out.println(rsaGenerator.decryptByPrivate(encode)); System.out.println("用私钥加密公钥解密"); String encrypt = rsaGenerator.encryptByPrivate(str); System.out.println(encrypt); System.out.println(rsaGenerator.decryptByPublic(encrypt)); } @Test public void readKeyFromBase64File(){ //从BASE64文件中读取KEY值 RSAGenerator rsaGenerator = new RSAGenerator(); rsaGenerator.getKeyFromBase64File("private.txt", RSAGenerator.KEY_TYPE_PRIVATE); rsaGenerator.getKeyFromBase64File("public.txt", RSAGenerator.KEY_TYPE_PUBLIC); String str="数表的质数又称素数。指整数在一个大于1的自然数中，除了1和此整数自身外，没法被其他自然数整除的数"; String encode = rsaGenerator.encryptByPublic(str); System.out.println(encode); System.out.println(rsaGenerator.decryptByPrivate(encode)); }} |
以上代码大部分都是参考自网络，感谢网友的分享
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