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/agreement/ECDHCBasicAgreement.java | |
parent | 5f714bd92fbd780d22406f4bc3681be005f6f04a (diff) |
initial reshuffle
Diffstat (limited to 'core/src/main/java/org/bouncycastle/crypto/agreement/ECDHCBasicAgreement.java')
-rw-r--r-- | core/src/main/java/org/bouncycastle/crypto/agreement/ECDHCBasicAgreement.java | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/core/src/main/java/org/bouncycastle/crypto/agreement/ECDHCBasicAgreement.java b/core/src/main/java/org/bouncycastle/crypto/agreement/ECDHCBasicAgreement.java new file mode 100644 index 00000000..12b84052 --- /dev/null +++ b/core/src/main/java/org/bouncycastle/crypto/agreement/ECDHCBasicAgreement.java @@ -0,0 +1,58 @@ +package org.bouncycastle.crypto.agreement; + +import java.math.BigInteger; + +import org.bouncycastle.crypto.BasicAgreement; +import org.bouncycastle.crypto.CipherParameters; +import org.bouncycastle.crypto.params.ECDomainParameters; +import org.bouncycastle.crypto.params.ECPrivateKeyParameters; +import org.bouncycastle.crypto.params.ECPublicKeyParameters; +import org.bouncycastle.math.ec.ECPoint; + +/** + * P1363 7.2.2 ECSVDP-DHC + * + * ECSVDP-DHC is Elliptic Curve Secret Value Derivation Primitive, + * Diffie-Hellman version with cofactor multiplication. It is based on + * the work of [DH76], [Mil86], [Kob87], [LMQ98] and [Kal98a]. This + * primitive derives a shared secret value from one party's private key + * and another party's public key, where both have the same set of EC + * domain parameters. If two parties correctly execute this primitive, + * they will produce the same output. This primitive can be invoked by a + * scheme to derive a shared secret key; specifically, it may be used + * with the schemes ECKAS-DH1 and DL/ECKAS-DH2. It does not assume the + * validity of the input public key (see also Section 7.2.1). + * <p> + * Note: As stated P1363 compatibility mode with ECDH can be preset, and + * in this case the implementation doesn't have a ECDH compatibility mode + * (if you want that just use ECDHBasicAgreement and note they both implement + * BasicAgreement!). + */ +public class ECDHCBasicAgreement + implements BasicAgreement +{ + ECPrivateKeyParameters key; + + public void init( + CipherParameters key) + { + this.key = (ECPrivateKeyParameters)key; + } + + public int getFieldSize() + { + return (key.getParameters().getCurve().getFieldSize() + 7) / 8; + } + + public BigInteger calculateAgreement( + CipherParameters pubKey) + { + ECPublicKeyParameters pub = (ECPublicKeyParameters)pubKey; + ECDomainParameters params = pub.getParameters(); + ECPoint P = pub.getQ().multiply(params.getH().multiply(key.getD())); + + // if (p.isInfinity()) throw new RuntimeException("Invalid public key"); + + return P.getX().toBigInteger(); + } +} |