diff options
author | David Hook <dgh@cryptoworkshop.com> | 2013-05-31 11:07:45 +0400 |
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committer | David Hook <dgh@cryptoworkshop.com> | 2013-05-31 11:07:45 +0400 |
commit | 2b976f5364cfdbc37d3086019d93483c983eb80b (patch) | |
tree | cb846af3fd1d43f9c2562a1fb2d06b997ad8f229 /core/src/main/java/org/bouncycastle/crypto/signers/GOST3410Signer.java | |
parent | 5f714bd92fbd780d22406f4bc3681be005f6f04a (diff) |
initial reshuffle
Diffstat (limited to 'core/src/main/java/org/bouncycastle/crypto/signers/GOST3410Signer.java')
-rw-r--r-- | core/src/main/java/org/bouncycastle/crypto/signers/GOST3410Signer.java | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/core/src/main/java/org/bouncycastle/crypto/signers/GOST3410Signer.java b/core/src/main/java/org/bouncycastle/crypto/signers/GOST3410Signer.java new file mode 100644 index 00000000..9fcc41b9 --- /dev/null +++ b/core/src/main/java/org/bouncycastle/crypto/signers/GOST3410Signer.java @@ -0,0 +1,127 @@ +package org.bouncycastle.crypto.signers; + +import org.bouncycastle.crypto.CipherParameters; +import org.bouncycastle.crypto.DSA; +import org.bouncycastle.crypto.params.*; + +import java.security.SecureRandom; +import java.math.BigInteger; + +/** + * GOST R 34.10-94 Signature Algorithm + */ +public class GOST3410Signer + implements DSA +{ + GOST3410KeyParameters key; + + SecureRandom random; + + public void init( + boolean forSigning, + CipherParameters param) + { + if (forSigning) + { + if (param instanceof ParametersWithRandom) + { + ParametersWithRandom rParam = (ParametersWithRandom)param; + + this.random = rParam.getRandom(); + this.key = (GOST3410PrivateKeyParameters)rParam.getParameters(); + } + else + { + this.random = new SecureRandom(); + this.key = (GOST3410PrivateKeyParameters)param; + } + } + else + { + this.key = (GOST3410PublicKeyParameters)param; + } + } + + /** + * generate a signature for the given message using the key we were + * initialised with. For conventional GOST3410 the message should be a GOST3411 + * hash of the message of interest. + * + * @param message the message that will be verified later. + */ + public BigInteger[] generateSignature( + byte[] message) + { + byte[] mRev = new byte[message.length]; // conversion is little-endian + for (int i = 0; i != mRev.length; i++) + { + mRev[i] = message[mRev.length - 1 - i]; + } + + BigInteger m = new BigInteger(1, mRev); + GOST3410Parameters params = key.getParameters(); + BigInteger k; + + do + { + k = new BigInteger(params.getQ().bitLength(), random); + } + while (k.compareTo(params.getQ()) >= 0); + + BigInteger r = params.getA().modPow(k, params.getP()).mod(params.getQ()); + + BigInteger s = k.multiply(m). + add(((GOST3410PrivateKeyParameters)key).getX().multiply(r)). + mod(params.getQ()); + + BigInteger[] res = new BigInteger[2]; + + res[0] = r; + res[1] = s; + + return res; + } + + /** + * return true if the value r and s represent a GOST3410 signature for + * the passed in message for standard GOST3410 the message should be a + * GOST3411 hash of the real message to be verified. + */ + public boolean verifySignature( + byte[] message, + BigInteger r, + BigInteger s) + { + byte[] mRev = new byte[message.length]; // conversion is little-endian + for (int i = 0; i != mRev.length; i++) + { + mRev[i] = message[mRev.length - 1 - i]; + } + + BigInteger m = new BigInteger(1, mRev); + GOST3410Parameters params = key.getParameters(); + BigInteger zero = BigInteger.valueOf(0); + + if (zero.compareTo(r) >= 0 || params.getQ().compareTo(r) <= 0) + { + return false; + } + + if (zero.compareTo(s) >= 0 || params.getQ().compareTo(s) <= 0) + { + return false; + } + + BigInteger v = m.modPow(params.getQ().subtract(new BigInteger("2")),params.getQ()); + + BigInteger z1 = s.multiply(v).mod(params.getQ()); + BigInteger z2 = (params.getQ().subtract(r)).multiply(v).mod(params.getQ()); + + z1 = params.getA().modPow(z1, params.getP()); + z2 = ((GOST3410PublicKeyParameters)key).getY().modPow(z2, params.getP()); + + BigInteger u = z1.multiply(z2).mod(params.getP()).mod(params.getQ()); + + return u.equals(r); + } +} |