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Diffstat (limited to 'libjava/classpath/gnu/javax/crypto/key/srp6/SRP6KeyAgreement.java')
| -rw-r--r-- | libjava/classpath/gnu/javax/crypto/key/srp6/SRP6KeyAgreement.java | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/libjava/classpath/gnu/javax/crypto/key/srp6/SRP6KeyAgreement.java b/libjava/classpath/gnu/javax/crypto/key/srp6/SRP6KeyAgreement.java new file mode 100644 index 000000000..d3d27b381 --- /dev/null +++ b/libjava/classpath/gnu/javax/crypto/key/srp6/SRP6KeyAgreement.java @@ -0,0 +1,141 @@ +/* SRP6KeyAgreement.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.javax.crypto.key.srp6; + +import gnu.java.security.Registry; +import gnu.java.security.hash.IMessageDigest; +import gnu.java.security.util.Util; + +import gnu.javax.crypto.key.BaseKeyAgreementParty; +import gnu.javax.crypto.key.KeyAgreementException; +import gnu.javax.crypto.sasl.srp.SRP; + +import java.math.BigInteger; + +/** + * The Secure Remote Password (SRP) key agreement protocol, also known as SRP-6, + * is designed by Thomas J. Wu (see references). The protocol, and its elements + * are described as follows: + * <pre> + * N A large safe prime (N = 2q+1, where q is prime) + * All arithmetic is done modulo N. + * g A generator modulo N + * s User's salt + * I Username + * p Cleartext Password + * H() One-way hash function + * ˆ (Modular) Exponentiation + * u Random scrambling parameter + * a,b Secret ephemeral values + * A,B Public ephemeral values + * x Private key (derived from p and s) + * v Password verifier + * + * The host stores passwords using the following formula: + * x = H(s | H(I ":" p)) (s is chosen randomly) + * v = gˆx (computes password verifier) + * + * The host then keeps {I, s, v} in its password database. + * + * The authentication protocol itself goes as follows: + * User -> Host: I, A = gˆa (identifies self, a = random number) + * Host -> User: s, B = 3v + gˆb (sends salt, b = random number) + * + * Both: u = H(A, B) + * + * User: x = H(s, p) (user enters password) + * User: S = (B - 3gˆx) ˆ (a + ux) (computes session key) + * User: K = H(S) + * + * Host: S = (Avˆu) ˆ b (computes session key) + * Host: K = H(S) + * </pre> + * <p> + * Reference: + * <ol> + * <li><a href="http://srp.stanford.edu/design.html">SRP Protocol Design</a><br> + * Thomas J. Wu.</li> + * </ol> + */ +public abstract class SRP6KeyAgreement + extends BaseKeyAgreementParty +{ + public static final String SOURCE_OF_RANDOMNESS = "gnu.crypto.srp6.ka.prng"; + public static final String SHARED_MODULUS = "gnu.crypto.srp6.ka.N"; + public static final String GENERATOR = "gnu.crypto.srp6.ka.g"; + public static final String HASH_FUNCTION = "gnu.crypto.srp6.ka.H"; + public static final String USER_IDENTITY = "gnu.crypto.srp6.ka.I"; + public static final String USER_PASSWORD = "gnu.crypto.srp6.ka.p"; + public static final String HOST_PASSWORD_DB = "gnu.crypto.srp6.ka.password.db"; + protected static final BigInteger THREE = BigInteger.valueOf(3L); + protected SRP srp; + protected BigInteger N; + protected BigInteger g; + /** The shared secret key. */ + protected BigInteger K; + + protected SRP6KeyAgreement() + { + super(Registry.SRP6_KA); + } + + protected byte[] engineSharedSecret() throws KeyAgreementException + { + return Util.trim(K); + } + + protected void engineReset() + { + srp = null; + N = null; + g = null; + K = null; + } + + protected BigInteger uValue(final BigInteger A, final BigInteger B) + { + final IMessageDigest hash = srp.newDigest(); + byte[] b; + b = Util.trim(A); + hash.update(b, 0, b.length); + b = Util.trim(B); + hash.update(b, 0, b.length); + return new BigInteger(1, hash.digest()); + } +} |