diff options
Diffstat (limited to 'src/cz/crcs/ectester/common/util/ECUtil.java')
| -rw-r--r-- | src/cz/crcs/ectester/common/util/ECUtil.java | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/src/cz/crcs/ectester/common/util/ECUtil.java b/src/cz/crcs/ectester/common/util/ECUtil.java index e29bfdd..511f93f 100644 --- a/src/cz/crcs/ectester/common/util/ECUtil.java +++ b/src/cz/crcs/ectester/common/util/ECUtil.java @@ -7,9 +7,11 @@ import org.bouncycastle.asn1.ASN1Integer; import org.bouncycastle.asn1.ASN1StreamParser; import org.bouncycastle.asn1.DERSequence; import org.bouncycastle.asn1.DERSequenceParser; +import org.bouncycastle.crypto.digests.SHA1Digest; import java.io.IOException; import java.math.BigInteger; +import java.nio.charset.StandardCharsets; import java.security.KeyPair; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; @@ -190,6 +192,27 @@ public class ECUtil { } } + public static byte[] semiRandomKey(EC_Curve curve) { + int bytes = (curve.getBits() + 7) / 8; + byte[] result = new byte[bytes]; + SHA1Digest digest = new SHA1Digest(); + byte[] curveName = curve.getId().getBytes(StandardCharsets.US_ASCII); + digest.update(curveName, 0, curveName.length); + int written = 0; + while (written < bytes) { + byte[] dig = new byte[digest.getDigestSize()]; + digest.doFinal(dig, 0); + int toWrite = digest.getDigestSize() > bytes - written ? bytes - written : digest.getDigestSize(); + System.arraycopy(dig, 0, result, written, toWrite); + written += toWrite; + digest.update(dig, 0, dig.length); + } + BigInteger priv = new BigInteger(1, result); + BigInteger order = new BigInteger(1, curve.getParam(EC_Consts.PARAMETER_R)[0]); + priv = priv.mod(order); + return toByteArray(priv, curve.getBits()); + } + private static ECPoint toPoint(EC_Params params) { return new ECPoint( new BigInteger(1, params.getParam(EC_Consts.PARAMETER_W)[0]), |