text: /*
   * Copyright 2007-2016 The OpenSSL Project Authors. All Rights Reserved.
   *
   * Licensed under the OpenSSL license (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.openssl.org/source/license.html
   */
  
  #include <openssl/dsa.h>
  #include "internal/refcount.h"
  
  struct dsa_st {
      /*
       * This first variable is used to pick up errors where a DSA is passed
       * instead of of a EVP_PKEY
       */
      int pad;
      int32_t version;
      BIGNUM *p;
      BIGNUM *q;                  /* == 20 */
      BIGNUM *g;
      BIGNUM *pub_key;            /* y public key */
      BIGNUM *priv_key;           /* x private key */
      int flags;
      /* Normally used to cache montgomery values */
      BN_MONT_CTX *method_mont_p;
      CRYPTO_REF_COUNT references;
      CRYPTO_EX_DATA ex_data;
      const DSA_METHOD *meth;
      /* functional reference if 'meth' is ENGINE-provided */
      ENGINE *engine;
      CRYPTO_RWLOCK *lock;
  };
  
  struct DSA_SIG_st {
      BIGNUM *r;
      BIGNUM *s;
  };
  
  struct dsa_method {
      char *name;
      DSA_SIG *(*dsa_do_sign) (const unsigned char *dgst, int dlen, DSA *dsa);
      int (*dsa_sign_setup) (DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
                             BIGNUM **rp);
      int (*dsa_do_verify) (const unsigned char *dgst, int dgst_len,
                            DSA_SIG *sig, DSA *dsa);
      int (*dsa_mod_exp) (DSA *dsa, BIGNUM *rr, const BIGNUM *a1,
                          const BIGNUM *p1, const BIGNUM *a2, const BIGNUM *p2,
                          const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont);
      /* Can be null */
      int (*bn_mod_exp) (DSA *dsa, BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
                         const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
      int (*init) (DSA *dsa);
      int (*finish) (DSA *dsa);
      int flags;
      void *app_data;
      /* If this is non-NULL, it is used to generate DSA parameters */
      int (*dsa_paramgen) (DSA *dsa, int bits,
                           const unsigned char *seed, int seed_len,
                           int *counter_ret, unsigned long *h_ret,
                           BN_GENCB *cb);
      /* If this is non-NULL, it is used to generate DSA keys */
      int (*dsa_keygen) (DSA *dsa);
  };
  
  int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
                           const EVP_MD *evpmd, const unsigned char *seed_in,
                           size_t seed_len, unsigned char *seed_out,
                           int *counter_ret, unsigned long *h_ret,
                           BN_GENCB *cb);
  
  int dsa_builtin_paramgen2(DSA *ret, size_t L, size_t N,
                            const EVP_MD *evpmd, const unsigned char *seed_in,
                            size_t seed_len, int idx, unsigned char *seed_out,
                            int *counter_ret, unsigned long *h_ret,
                            BN_GENCB *cb);
  