package org.bouncycastle.openpgp;
import java.io.IOException;
import java.security.SecureRandom;
import org.bouncycastle.asn1.ASN1InputStream;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.ASN1Integer;
import org.bouncycastle.bcpg.HashAlgorithmTags;
import org.bouncycastle.bcpg.MPInteger;
import org.bouncycastle.bcpg.PublicKeyAlgorithmTags;
import org.bouncycastle.bcpg.SymmetricKeyAlgorithmTags;
/**
* Basic utility class
*/
public class PGPUtil
implements HashAlgorithmTags
{
static MPInteger[] dsaSigToMpi(
byte[] encoding)
throws PGPException
{
ASN1InputStream aIn = new ASN1InputStream(encoding);
ASN1Integer i1;
ASN1Integer i2;
try
{
ASN1Sequence s = (ASN1Sequence)aIn.readObject();
i1 = (ASN1Integer)s.getObjectAt(0);
i2 = (ASN1Integer)s.getObjectAt(1);
}
catch (IOException e)
{
throw new PGPException("exception encoding signature", e);
}
MPInteger[] values = new MPInteger[2];
values[0] = new MPInteger(i1.getValue());
values[1] = new MPInteger(i2.getValue());
return values;
}
static String getDigestName(
int hashAlgorithm)
throws PGPException
{
switch (hashAlgorithm)
{
case HashAlgorithmTags.SHA1:
return "SHA1";
case HashAlgorithmTags.MD2:
return "MD2";
case HashAlgorithmTags.MD5:
return "MD5";
case HashAlgorithmTags.RIPEMD160:
return "RIPEMD160";
case HashAlgorithmTags.SHA256:
return "SHA256";
case HashAlgorithmTags.SHA384:
return "SHA384";
case HashAlgorithmTags.SHA512:
return "SHA512";
case HashAlgorithmTags.SHA224:
return "SHA224";
default:
throw new PGPException("unknown hash algorithm tag in getDigestName: " + hashAlgorithm);
}
}
static String getSignatureName(
int keyAlgorithm,
int hashAlgorithm)
throws PGPException
{
String encAlg;
switch (keyAlgorithm)
{
case PublicKeyAlgorithmTags.RSA_GENERAL:
case PublicKeyAlgorithmTags.RSA_SIGN:
encAlg = "RSA";
break;
case PublicKeyAlgorithmTags.DSA:
encAlg = "DSA";
break;
case PublicKeyAlgorithmTags.ELGAMAL_ENCRYPT: // in some malformed cases.
case PublicKeyAlgorithmTags.ELGAMAL_GENERAL:
encAlg = "ElGamal";
break;
default:
throw new PGPException("unknown algorithm tag in signature:" + keyAlgorithm);
}
return getDigestName(hashAlgorithm) + "with" + encAlg;
}
public static byte[] makeRandomKey(
int algorithm,
SecureRandom random)
throws PGPException
{
int keySize = 0;
switch (algorithm)
{
case SymmetricKeyAlgorithmTags.TRIPLE_DES:
keySize = 192;
break;
case SymmetricKeyAlgorithmTags.IDEA:
keySize = 128;
break;
case SymmetricKeyAlgorithmTags.CAST5:
keySize = 128;
break;
case SymmetricKeyAlgorithmTags.BLOWFISH:
keySize = 128;
break;
case SymmetricKeyAlgorithmTags.SAFER:
keySize = 128;
break;
case SymmetricKeyAlgorithmTags.DES:
keySize = 64;
break;
case SymmetricKeyAlgorithmTags.AES_128:
keySize = 128;
break;
case SymmetricKeyAlgorithmTags.AES_192:
keySize = 192;
break;
case SymmetricKeyAlgorithmTags.AES_256:
keySize = 256;
break;
case SymmetricKeyAlgorithmTags.TWOFISH:
keySize = 256;
break;
default:
throw new PGPException("unknown symmetric algorithm: " + algorithm);
}
byte[] keyBytes = new byte[(keySize + 7) / 8];
random.nextBytes(keyBytes);
return keyBytes;
}
}