RSAPadding.java 16.3 KB
Newer Older
D
duke 已提交
1
/*
2
 * Copyright (c) 2003, 2013 Oracle and/or its affiliates. All rights reserved.
D
duke 已提交
3 4 5 6
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
7
 * published by the Free Software Foundation.  Oracle designates this
D
duke 已提交
8
 * particular file as subject to the "Classpath" exception as provided
9
 * by Oracle in the LICENSE file that accompanied this code.
D
duke 已提交
10 11 12 13 14 15 16 17 18 19 20
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
21 22 23
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
D
duke 已提交
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
 */

package sun.security.rsa;

import java.math.BigInteger;
import java.util.*;

import java.security.*;
import java.security.interfaces.*;
import java.security.spec.*;

import javax.crypto.BadPaddingException;
import javax.crypto.spec.PSource;
import javax.crypto.spec.OAEPParameterSpec;

import sun.security.jca.JCAUtil;

/**
 * RSA padding and unpadding.
 *
 * Format of PKCS#1 v1.5 padding is:
 *   0x00 | BT | PS...PS | 0x00 | data...data
 * where BT is the blocktype (1 or 2). The length of the entire string
 * must be the same as the size of the modulus (i.e. 128 byte for a 1024 bit
 * key). Per spec, the padding string must be at least 8 bytes long. That
 * leaves up to (length of key in bytes) - 11 bytes for the data.
 *
 * OAEP padding is a bit more complicated and has a number of options.
 * We support:
 *   . arbitrary hash functions ('Hash' in the specification), MessageDigest
 *     implementation must be available
 *   . MGF1 as the mask generation function
 *   . the empty string as the default value for label L and whatever
 *     specified in javax.crypto.spec.OAEPParameterSpec
 *
 * Note: RSA keys should be at least 512 bits long
 *
 * @since   1.5
 * @author  Andreas Sterbenz
 */
public final class RSAPadding {

    // NOTE: the constants below are embedded in the JCE RSACipher class
    // file. Do not change without coordinating the update

    // PKCS#1 v1.5 padding, blocktype 1 (signing)
    public final static int PAD_BLOCKTYPE_1    = 1;
    // PKCS#1 v1.5 padding, blocktype 2 (encryption)
    public final static int PAD_BLOCKTYPE_2    = 2;
    // nopadding. Does not do anything, but allows simpler RSACipher code
    public final static int PAD_NONE           = 3;
    // PKCS#1 v2.1 OAEP padding
    public final static int PAD_OAEP_MGF1 = 4;

    // type, one of PAD_*
    private final int type;

    // size of the padded block (i.e. size of the modulus)
    private final int paddedSize;

    // PRNG used to generate padding bytes (PAD_BLOCKTYPE_2, PAD_OAEP_MGF1)
    private SecureRandom random;

    // maximum size of the data
    private final int maxDataSize;

    // OAEP: main messagedigest
    private MessageDigest md;

    // OAEP: message digest for MGF1
    private MessageDigest mgfMd;

    // OAEP: value of digest of data (user-supplied or zero-length) using md
    private byte[] lHash;

    /**
     * Get a RSAPadding instance of the specified type.
     * Keys used with this padding must be paddedSize bytes long.
     */
    public static RSAPadding getInstance(int type, int paddedSize)
            throws InvalidKeyException, InvalidAlgorithmParameterException {
        return new RSAPadding(type, paddedSize, null, null);
    }

    /**
     * Get a RSAPadding instance of the specified type.
     * Keys used with this padding must be paddedSize bytes long.
     */
    public static RSAPadding getInstance(int type, int paddedSize,
            SecureRandom random) throws InvalidKeyException,
            InvalidAlgorithmParameterException {
        return new RSAPadding(type, paddedSize, random, null);
    }

    /**
     * Get a RSAPadding instance of the specified type, which must be
     * OAEP. Keys used with this padding must be paddedSize bytes long.
     */
    public static RSAPadding getInstance(int type, int paddedSize,
            SecureRandom random, OAEPParameterSpec spec)
        throws InvalidKeyException, InvalidAlgorithmParameterException {
        return new RSAPadding(type, paddedSize, random, spec);
    }

    // internal constructor
    private RSAPadding(int type, int paddedSize, SecureRandom random,
            OAEPParameterSpec spec) throws InvalidKeyException,
            InvalidAlgorithmParameterException {
        this.type = type;
        this.paddedSize = paddedSize;
        this.random = random;
        if (paddedSize < 64) {
            // sanity check, already verified in RSASignature/RSACipher
            throw new InvalidKeyException("Padded size must be at least 64");
        }
        switch (type) {
        case PAD_BLOCKTYPE_1:
        case PAD_BLOCKTYPE_2:
            maxDataSize = paddedSize - 11;
            break;
        case PAD_NONE:
            maxDataSize = paddedSize;
            break;
        case PAD_OAEP_MGF1:
            String mdName = "SHA-1";
            String mgfMdName = "SHA-1";
            byte[] digestInput = null;
            try {
                if (spec != null) {
                    mdName = spec.getDigestAlgorithm();
                    String mgfName = spec.getMGFAlgorithm();
                    if (!mgfName.equalsIgnoreCase("MGF1")) {
                        throw new InvalidAlgorithmParameterException
                            ("Unsupported MGF algo: " + mgfName);
                    }
                    mgfMdName = ((MGF1ParameterSpec)spec.getMGFParameters()).getDigestAlgorithm();
                    PSource pSrc = spec.getPSource();
                    String pSrcAlgo = pSrc.getAlgorithm();
                    if (!pSrcAlgo.equalsIgnoreCase("PSpecified")) {
                        throw new InvalidAlgorithmParameterException
                            ("Unsupported pSource algo: " + pSrcAlgo);
                    }
                    digestInput = ((PSource.PSpecified) pSrc).getValue();
                }
                md = MessageDigest.getInstance(mdName);
                mgfMd = MessageDigest.getInstance(mgfMdName);
            } catch (NoSuchAlgorithmException e) {
                throw new InvalidKeyException
                        ("Digest " + mdName + " not available", e);
            }
            lHash = getInitialHash(md, digestInput);
            int digestLen = lHash.length;
            maxDataSize = paddedSize - 2 - 2 * digestLen;
            if (maxDataSize <= 0) {
                throw new InvalidKeyException
                        ("Key is too short for encryption using OAEPPadding" +
                         " with " + mdName + " and MGF1" + mgfMdName);
            }
            break;
        default:
            throw new InvalidKeyException("Invalid padding: " + type);
        }
    }

    // cache of hashes of zero length data
    private static final Map<String,byte[]> emptyHashes =
        Collections.synchronizedMap(new HashMap<String,byte[]>());

    /**
     * Return the value of the digest using the specified message digest
     * <code>md</code> and the digest input <code>digestInput</code>.
     * if <code>digestInput</code> is null or 0-length, zero length
     * is used to generate the initial digest.
     * Note: the md object must be in reset state
     */
    private static byte[] getInitialHash(MessageDigest md,
        byte[] digestInput) {
        byte[] result = null;
        if ((digestInput == null) || (digestInput.length == 0)) {
            String digestName = md.getAlgorithm();
            result = emptyHashes.get(digestName);
            if (result == null) {
                result = md.digest();
                emptyHashes.put(digestName, result);
            }
        } else {
            result = md.digest(digestInput);
        }
        return result;
    }

    /**
     * Return the maximum size of the plaintext data that can be processed using
     * this object.
     */
    public int getMaxDataSize() {
        return maxDataSize;
    }

    /**
     * Pad the data and return the padded block.
     */
    public byte[] pad(byte[] data, int ofs, int len)
            throws BadPaddingException {
        return pad(RSACore.convert(data, ofs, len));
    }

    /**
     * Pad the data and return the padded block.
     */
    public byte[] pad(byte[] data) throws BadPaddingException {
        if (data.length > maxDataSize) {
            throw new BadPaddingException("Data must be shorter than "
                + (maxDataSize + 1) + " bytes");
        }
        switch (type) {
        case PAD_NONE:
            return data;
        case PAD_BLOCKTYPE_1:
        case PAD_BLOCKTYPE_2:
            return padV15(data);
        case PAD_OAEP_MGF1:
            return padOAEP(data);
        default:
            throw new AssertionError();
        }
    }

    /**
     * Unpad the padded block and return the data.
     */
    public byte[] unpad(byte[] padded, int ofs, int len)
            throws BadPaddingException {
        return unpad(RSACore.convert(padded, ofs, len));
    }

    /**
     * Unpad the padded block and return the data.
     */
    public byte[] unpad(byte[] padded) throws BadPaddingException {
        if (padded.length != paddedSize) {
            throw new BadPaddingException("Padded length must be " + paddedSize);
        }
        switch (type) {
        case PAD_NONE:
            return padded;
        case PAD_BLOCKTYPE_1:
        case PAD_BLOCKTYPE_2:
            return unpadV15(padded);
        case PAD_OAEP_MGF1:
            return unpadOAEP(padded);
        default:
            throw new AssertionError();
        }
    }

    /**
     * PKCS#1 v1.5 padding (blocktype 1 and 2).
     */
    private byte[] padV15(byte[] data) throws BadPaddingException {
        byte[] padded = new byte[paddedSize];
        System.arraycopy(data, 0, padded, paddedSize - data.length, data.length);
        int psSize = paddedSize - 3 - data.length;
        int k = 0;
        padded[k++] = 0;
        padded[k++] = (byte)type;
        if (type == PAD_BLOCKTYPE_1) {
            // blocktype 1: all padding bytes are 0xff
            while (psSize-- > 0) {
                padded[k++] = (byte)0xff;
            }
        } else {
            // blocktype 2: padding bytes are random non-zero bytes
            if (random == null) {
                random = JCAUtil.getSecureRandom();
            }
            // generate non-zero padding bytes
            // use a buffer to reduce calls to SecureRandom
            byte[] r = new byte[64];
            int i = -1;
            while (psSize-- > 0) {
                int b;
                do {
                    if (i < 0) {
                        random.nextBytes(r);
                        i = r.length - 1;
                    }
                    b = r[i--] & 0xff;
                } while (b == 0);
                padded[k++] = (byte)b;
            }
        }
        return padded;
    }

    /**
     * PKCS#1 v1.5 unpadding (blocktype 1 and 2).
     */
    private byte[] unpadV15(byte[] padded) throws BadPaddingException {
        int k = 0;
        if (padded[k++] != 0) {
            throw new BadPaddingException("Data must start with zero");
        }
        if (padded[k++] != type) {
            throw new BadPaddingException("Blocktype mismatch: " + padded[1]);
        }
        while (true) {
            int b = padded[k++] & 0xff;
            if (b == 0) {
                break;
            }
            if (k == padded.length) {
                throw new BadPaddingException("Padding string not terminated");
            }
            if ((type == PAD_BLOCKTYPE_1) && (b != 0xff)) {
                throw new BadPaddingException("Padding byte not 0xff: " + b);
            }
        }
        int n = padded.length - k;
        if (n > maxDataSize) {
            throw new BadPaddingException("Padding string too short");
        }
        byte[] data = new byte[n];
        System.arraycopy(padded, padded.length - n, data, 0, n);
        return data;
    }

    /**
     * PKCS#1 v2.0 OAEP padding (MGF1).
     * Paragraph references refer to PKCS#1 v2.1 (June 14, 2002)
     */
    private byte[] padOAEP(byte[] M) throws BadPaddingException {
        if (random == null) {
            random = JCAUtil.getSecureRandom();
        }
        int hLen = lHash.length;

        // 2.d: generate a random octet string seed of length hLen
        // if necessary
        byte[] seed = new byte[hLen];
        random.nextBytes(seed);

        // buffer for encoded message EM
        byte[] EM = new byte[paddedSize];

        // start and length of seed (as index into EM)
        int seedStart = 1;
        int seedLen = hLen;

        // copy seed into EM
        System.arraycopy(seed, 0, EM, seedStart, seedLen);

        // start and length of data block DB in EM
        // we place it inside of EM to reduce copying
        int dbStart = hLen + 1;
        int dbLen = EM.length - dbStart;

        // start of message M in EM
        int mStart = paddedSize - M.length;

        // build DB
        // 2.b: Concatenate lHash, PS, a single octet with hexadecimal value
        // 0x01, and the message M to form a data block DB of length
        // k - hLen -1 octets as DB = lHash || PS || 0x01 || M
        // (note that PS is all zeros)
        System.arraycopy(lHash, 0, EM, dbStart, hLen);
        EM[mStart - 1] = 1;
        System.arraycopy(M, 0, EM, mStart, M.length);

        // produce maskedDB
        mgf1(EM, seedStart, seedLen, EM, dbStart, dbLen);

        // produce maskSeed
        mgf1(EM, dbStart, dbLen, EM, seedStart, seedLen);

        return EM;
    }

    /**
     * PKCS#1 v2.1 OAEP unpadding (MGF1).
     */
    private byte[] unpadOAEP(byte[] padded) throws BadPaddingException {
        byte[] EM = padded;
        int hLen = lHash.length;

        if (EM[0] != 0) {
            throw new BadPaddingException("Data must start with zero");
        }

        int seedStart = 1;
        int seedLen = hLen;

        int dbStart = hLen + 1;
        int dbLen = EM.length - dbStart;

        mgf1(EM, dbStart, dbLen, EM, seedStart, seedLen);
        mgf1(EM, seedStart, seedLen, EM, dbStart, dbLen);

        // verify lHash == lHash'
        for (int i = 0; i < hLen; i++) {
            if (lHash[i] != EM[dbStart + i]) {
                throw new BadPaddingException("lHash mismatch");
            }
        }

        // skip over padding (0x00 bytes)
        int i = dbStart + hLen;
        while (EM[i] == 0) {
            i++;
            if (i >= EM.length) {
                throw new BadPaddingException("Padding string not terminated");
            }
        }

        if (EM[i++] != 1) {
            throw new BadPaddingException
                ("Padding string not terminated by 0x01 byte");
        }

        int mLen = EM.length - i;
        byte[] m = new byte[mLen];
        System.arraycopy(EM, i, m, 0, mLen);

        return m;
    }

    /**
     * Compute MGF1 using mgfMD as the message digest.
     * Note that we combine MGF1 with the XOR operation to reduce data
     * copying.
     *
     * We generate maskLen bytes of MGF1 from the seed and XOR it into
     * out[] starting at outOfs;
     */
    private void mgf1(byte[] seed, int seedOfs, int seedLen,
            byte[] out, int outOfs, int maskLen)  throws BadPaddingException {
        byte[] C = new byte[4]; // 32 bit counter
461
        byte[] digest = new byte[mgfMd.getDigestLength()];
D
duke 已提交
462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483
        while (maskLen > 0) {
            mgfMd.update(seed, seedOfs, seedLen);
            mgfMd.update(C);
            try {
                mgfMd.digest(digest, 0, digest.length);
            } catch (DigestException e) {
                // should never happen
                throw new BadPaddingException(e.toString());
            }
            for (int i = 0; (i < digest.length) && (maskLen > 0); maskLen--) {
                out[outOfs++] ^= digest[i++];
            }
            if (maskLen > 0) {
                // increment counter
                for (int i = C.length - 1; (++C[i] == 0) && (i > 0); i--) {
                    // empty
                }
            }
        }
    }

}