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diff --git a/botan/src/pubkey/dl_group/dl_group.h b/botan/src/pubkey/dl_group/dl_group.h
new file mode 100644
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+++ b/botan/src/pubkey/dl_group/dl_group.h
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+/*
+* Discrete Logarithm Group
+* (C) 1999-2008 Jack Lloyd
+*
+* Distributed under the terms of the Botan license
+*/
+
+#ifndef BOTAN_DL_PARAM_H__
+#define BOTAN_DL_PARAM_H__
+
+#include <botan/bigint.h>
+#include <botan/data_src.h>
+
+namespace Botan {
+
+/**
+* This class represents discrete logarithm groups. It holds a prime p,
+* a prime q = (p-1)/2 and g = x^((p-1)/q) mod p.
+*/
+class BOTAN_DLL DL_Group
+   {
+   public:
+      /**
+      * Get the prime p.
+      * @return the prime p
+      */
+      const BigInt& get_p() const;
+
+      /**
+      * Get the prime q.
+      * @return the prime q
+      */
+      const BigInt& get_q() const;
+
+      /**
+      * Get the base g.
+      * @return the base g
+      */
+      const BigInt& get_g() const;
+
+      /**
+      * The DL group encoding format variants.
+      */
+      enum Format {
+         ANSI_X9_42,
+         ANSI_X9_57,
+         PKCS_3,
+
+         DSA_PARAMETERS = ANSI_X9_57,
+         DH_PARAMETERS = ANSI_X9_42,
+         X942_DH_PARAMETERS = ANSI_X9_42,
+         PKCS3_DH_PARAMETERS = PKCS_3
+      };
+
+      /**
+      * Determine the prime creation for DL groups.
+      */
+      enum PrimeType { Strong, Prime_Subgroup, DSA_Kosherizer };
+
+      /**
+      * Perform validity checks on the group.
+      * @param rng the rng to use
+      * @param strong whether to perform stronger by lengthier tests
+      * @return true if the object is consistent, false otherwise
+      */
+      bool verify_group(RandomNumberGenerator& rng, bool strong) const;
+
+      /**
+      * Encode this group into a string using PEM encoding.
+      * @param format the encoding format
+      * @return the string holding the PEM encoded group
+      */
+      std::string PEM_encode(Format format) const;
+
+      /**
+      * Encode this group into a string using DER encoding.
+      * @param format the encoding format
+      * @return the string holding the DER encoded group
+      */
+      SecureVector<byte> DER_encode(Format format) const;
+
+      /**
+      * Decode a DER/BER encoded group into this instance.
+      * @param src a DataSource providing the encoded group
+      * @param format the format of the encoded group
+      */
+      void BER_decode(DataSource& src, Format format);
+
+      /**
+      * Decode a PEM encoded group into this instance.
+      * @param src a DataSource providing the encoded group
+      */
+      void PEM_decode(DataSource& src);
+
+      /**
+      * Construct a DL group with uninitialized internal value.
+      * Use this constructor is you wish to set the groups values
+      * from a DER or PEM encoded group.
+      */
+      DL_Group();
+
+      /**
+      * Construct a DL group that is registered in the configuration.
+      * @param name the name that is configured in the global configuration
+      * for the desired group. If no configuration file is specified,
+      * the default values from the file policy.cpp will be used. For instance,
+      * use "modp/ietf/768" as name.
+      */
+      DL_Group(const std::string& name);
+
+      /**
+      * Create a new group randomly.
+      * @param rng the random number generator to use
+      * @param type specifies how the creation of primes p and q shall
+      * be performed. If type=Strong, then p will be determined as a
+      * safe prime, and q will be chosen as (p-1)/2. If
+      * type=Prime_Subgroup and qbits = 0, then the size of q will be
+      * determined according to the estimated difficulty of the DL
+      * problem. If type=DSA_Kosherizer, DSA primes will be created.
+      * @param pbits the number of bits of p
+      * @param qbits the number of bits of q. Leave it as 0 to have
+      * the value determined according to pbits.
+      */
+      DL_Group(RandomNumberGenerator& rng, PrimeType type,
+               u32bit pbits, u32bit qbits = 0);
+
+      /**
+      * Create a DSA group with a given seed.
+      * @param rng the random number generator to use
+      * @param seed the seed to use to create the random primes
+      * @param pbits the desired bit size of the prime p
+      * @param qbits the desired bit size of the prime q.
+      */
+      DL_Group(RandomNumberGenerator& rng, const MemoryRegion<byte>& seed,
+               u32bit pbits = 1024, u32bit qbits = 0);
+
+      /**
+      * Create a DL group. The prime q will be determined according to p.
+      * @param p the prime p
+      * @param g the base g
+      */
+      DL_Group(const BigInt& p, const BigInt& g);
+
+      /**
+      * Create a DL group.
+      * @param p the prime p
+      * @param q the prime q
+      * @param g the base g
+      */
+      DL_Group(const BigInt& p, const BigInt& q, const BigInt& g);
+   private:
+      static BigInt make_dsa_generator(const BigInt&, const BigInt&);
+
+      void init_check() const;
+      void initialize(const BigInt&, const BigInt&, const BigInt&);
+      bool initialized;
+      BigInt p, q, g;
+   };
+
+}
+
+#endif