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Diffstat (limited to 'libjava/classpath/gnu/java/security/sig/rsa/EMSA_PKCS1_V1_5.java')
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diff --git a/libjava/classpath/gnu/java/security/sig/rsa/EMSA_PKCS1_V1_5.java b/libjava/classpath/gnu/java/security/sig/rsa/EMSA_PKCS1_V1_5.java new file mode 100644 index 000000000..3cddab4aa --- /dev/null +++ b/libjava/classpath/gnu/java/security/sig/rsa/EMSA_PKCS1_V1_5.java @@ -0,0 +1,243 @@ +/* EMSA_PKCS1_V1_5.java -- + Copyright (C) 2003, 2006 Free Software Foundation, Inc. + +This file is a part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2 of the License, or (at +your option) any later version. + +GNU Classpath 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 for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; if not, write to the Free Software +Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 +USA + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package gnu.java.security.sig.rsa; + +import gnu.java.security.Registry; +import gnu.java.security.hash.HashFactory; +import gnu.java.security.hash.IMessageDigest; + +import java.io.ByteArrayOutputStream; + +/** + * An implementation of the EMSA-PKCS1-V1.5 encoding scheme. + * <p> + * EMSA-PKCS1-V1.5 is parameterised by the choice of hash function Hash and + * hLen which denotes the length in octets of the hash function output. + * <p> + * References: + * <ol> + * <li><a href="http://www.ietf.org/rfc/rfc3447.txt">Public-Key Cryptography + * Standards (PKCS) #1:</a><br> + * RSA Cryptography Specifications Version 2.1.<br> + * Jakob Jonsson and Burt Kaliski.</li> + * </ol> + */ +public class EMSA_PKCS1_V1_5 + implements Cloneable +{ + /* Notes. + 1. For the six hash functions mentioned in Appendix B.1, the DER encoding + T of the DigestInfo value is equal to the following: + + MD2: (0x)30 20 30 0c 06 08 2a 86 48 86 f7 0d 02 02 05 00 04 10 || H + MD5: (0x)30 20 30 0c 06 08 2a 86 48 86 f7 0d 02 05 05 00 04 10 || H + SHA-1: (0x)30 21 30 09 06 05 2b 0e 03 02 1a 05 00 04 14 || H + SHA-256: (0x)30 31 30 0d 06 09 60 86 48 01 65 03 04 02 01 05 00 04 20 || H + SHA-384: (0x)30 41 30 0d 06 09 60 86 48 01 65 03 04 02 02 05 00 04 30 || H + SHA-512: (0x)30 51 30 0d 06 09 60 86 48 01 65 03 04 02 03 05 00 04 40 || H + */ + private static final byte[] MD2_PREFIX = { + (byte) 0x30, (byte) 0x20, (byte) 0x30, (byte) 0x0c, (byte) 0x06, + (byte) 0x08, (byte) 0x2a, (byte) 0x86, (byte) 0x48, (byte) 0x86, + (byte) 0xf7, (byte) 0x0d, (byte) 0x02, (byte) 0x02, (byte) 0x05, + (byte) 0x00, (byte) 0x04, (byte) 0x10 + }; + + private static final byte[] MD5_PREFIX = { + (byte) 0x30, (byte) 0x20, (byte) 0x30, (byte) 0x0c, (byte) 0x06, + (byte) 0x08, (byte) 0x2a, (byte) 0x86, (byte) 0x48, (byte) 0x86, + (byte) 0xf7, (byte) 0x0d, (byte) 0x02, (byte) 0x05, (byte) 0x05, + (byte) 0x00, (byte) 0x04, (byte) 0x10 + }; + + private static final byte[] SHA160_PREFIX = { + (byte) 0x30, (byte) 0x21, (byte) 0x30, (byte) 0x09, (byte) 0x06, + (byte) 0x05, (byte) 0x2b, (byte) 0x0e, (byte) 0x03, (byte) 0x02, + (byte) 0x1a, (byte) 0x05, (byte) 0x00, (byte) 0x04, (byte) 0x14 + }; + + private static final byte[] SHA256_PREFIX = { + (byte) 0x30, (byte) 0x31, (byte) 0x30, (byte) 0x0d, (byte) 0x06, + (byte) 0x09, (byte) 0x60, (byte) 0x86, (byte) 0x48, (byte) 0x01, + (byte) 0x65, (byte) 0x03, (byte) 0x04, (byte) 0x02, (byte) 0x01, + (byte) 0x05, (byte) 0x00, (byte) 0x04, (byte) 0x20 + }; + + private static final byte[] SHA384_PREFIX = { + (byte) 0x30, (byte) 0x41, (byte) 0x30, (byte) 0x0d, (byte) 0x06, + (byte) 0x09, (byte) 0x60, (byte) 0x86, (byte) 0x48, (byte) 0x01, + (byte) 0x65, (byte) 0x03, (byte) 0x04, (byte) 0x02, (byte) 0x02, + (byte) 0x05, (byte) 0x00, (byte) 0x04, (byte) 0x30 + }; + + private static final byte[] SHA512_PREFIX = { + (byte) 0x30, (byte) 0x51, (byte) 0x30, (byte) 0x0d, (byte) 0x06, + (byte) 0x09, (byte) 0x60, (byte) 0x86, (byte) 0x48, (byte) 0x01, + (byte) 0x65, (byte) 0x03, (byte) 0x04, (byte) 0x02, (byte) 0x03, + (byte) 0x05, (byte) 0x00, (byte) 0x04, (byte) 0x40 + }; + + /** The underlying hash function to use with this instance. */ + private IMessageDigest hash; + + /** The output size of the hash function in octets. */ + private int hLen; // TODO: field not used!!! investigate + + /** The DER part of DigestInfo not containing the hash value itself. */ + private byte[] prefix; + + /** + * Trivial private constructor to enforce use through Factory method. + * + * @param hash the message digest instance to use with this scheme instance. + */ + private EMSA_PKCS1_V1_5(final IMessageDigest hash) + { + super(); + + this.hash = hash; + hLen = hash.hashSize(); + final String name = hash.name(); + if (name.equals(Registry.MD2_HASH)) + prefix = MD2_PREFIX; + else if (name.equals(Registry.MD5_HASH)) + prefix = MD5_PREFIX; + else if (name.equals(Registry.SHA160_HASH)) + prefix = SHA160_PREFIX; + else if (name.equals(Registry.SHA256_HASH)) + prefix = SHA256_PREFIX; + else if (name.equals(Registry.SHA384_HASH)) + prefix = SHA384_PREFIX; + else if (name.equals(Registry.SHA512_HASH)) + prefix = SHA512_PREFIX; + else + throw new UnsupportedOperationException(); // should not happen + } + + /** + * Returns an instance of this object given a designated name of a hash + * function. + * + * @param mdName the canonical name of a hash function. + * @return an instance of this object configured for use with the designated + * options. + * @throws UnsupportedOperationException if the hash function is not + * implemented or does not have an ID listed in RFC-3447. + */ + public static final EMSA_PKCS1_V1_5 getInstance(final String mdName) + { + final IMessageDigest hash = HashFactory.getInstance(mdName); + final String name = hash.name(); + if (! (name.equals(Registry.MD2_HASH) + || name.equals(Registry.MD5_HASH) + || name.equals(Registry.SHA160_HASH) + || name.equals(Registry.SHA256_HASH) + || name.equals(Registry.SHA384_HASH) + || name.equals(Registry.SHA512_HASH))) + throw new UnsupportedOperationException("hash with no OID: " + name); + + return new EMSA_PKCS1_V1_5(hash); + } + + public Object clone() + { + return getInstance(hash.name()); + } + + /** + * Frames the hash of a message, along with an ID of the hash function in + * a DER sequence according to the specifications of EMSA-PKCS1-V1.5 as + * described in RFC-3447 (see class documentation). + * + * @param mHash the byte sequence resulting from applying the message digest + * algorithm Hash to the message <i>M</i>. + * @param emLen intended length in octets of the encoded message, at least + * <code>tLen + 11</code>, where <code>tLen</code> is the octet length of the + * DER encoding <code>T</code> of a certain value computed during the + * encoding operation. + * @return encoded message, an octet string of length <code>emLen</code>. + * @throws IllegalArgumentException if the message is too long, or if the + * intended encoded message length is too short. + */ + public byte[] encode(final byte[] mHash, final int emLen) + { + // 1. Apply the hash function to the message M to produce a hash value + // H: H = Hash(M). + // If the hash function outputs "message too long," output "message + // too long" and stop. + // 2. Encode the algorithm ID for the hash function and the hash value + // into an ASN.1 value of type DigestInfo (see Appendix A.2.4) with + // the Distinguished Encoding Rules (DER), where the type DigestInfo + // has the syntax + // DigestInfo ::= SEQUENCE { + // digestAlgorithm AlgorithmIdentifier, + // digest OCTET STRING + // } + // The first field identifies the hash function and the second contains + // the hash value. Let T be the DER encoding of the DigestInfo value + // (see the notes below) and let tLen be the length in octets of T. + final ByteArrayOutputStream baos = new ByteArrayOutputStream(); + baos.write(prefix, 0, prefix.length); + baos.write(mHash, 0, mHash.length); + final byte[] T = baos.toByteArray(); + final int tLen = T.length; + // 3. If emLen < tLen + 11, output "intended encoded message length too + // short" and stop. + if (emLen < tLen + 11) + throw new IllegalArgumentException("emLen too short"); + // 4. Generate an octet string PS consisting of emLen - tLen - 3 octets + // with hexadecimal value 0xff. The length of PS will be at least 8 + // octets. + final byte[] PS = new byte[emLen - tLen - 3]; + for (int i = 0; i < PS.length; i++) + PS[i] = (byte) 0xFF; + // 5. Concatenate PS, the DER encoding T, and other padding to form the + // encoded message EM as: EM = 0x00 || 0x01 || PS || 0x00 || T. + baos.reset(); + baos.write(0x00); + baos.write(0x01); + baos.write(PS, 0, PS.length); + baos.write(0x00); + baos.write(T, 0, tLen); + final byte[] result = baos.toByteArray(); + baos.reset(); + // 6. Output EM. + return result; + } +} |