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(gcrypt.info.gz) Basic functions

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 11.2 Basic functions
 ====================
 
 To work with MPIs, storage must be allocated and released for the
 numbers.  This can be done with one of these functions:
 
  -- Function: gcry_mpi_t gcry_mpi_new (unsigned int NBITS)
      Allocate a new MPI object, initialize it to 0 and initially
      allocate enough memory for a number of at least NBITS.  This
      pre-allocation is only a small performance issue and not actually
      necessary because Libgcrypt automatically re-allocates the
      required memory.
 
  -- Function: gcry_mpi_t gcry_mpi_snew (unsigned int NBITS)
      This is identical to `gcry_mpi_new' but allocates the MPI in the so
      called "secure memory" which in turn will take care that all
      derived values will also be stored in this "secure memory".  Use
      this for highly confidential data like private key parameters.
 
  -- Function: gcry_mpi_t gcry_mpi_copy (const gcry_mpi_t A)
      Create a new MPI as the exact copy of A.
 
  -- Function: void gcry_mpi_release (gcry_mpi_t A)
      Release the MPI A and free all associated resources.  Passing
      `NULL' is allowed and ignored.  When a MPI stored in the "secure
      memory" is released, that memory gets wiped out immediately.
 
 The simplest operations are used to assign a new value to an MPI:
 
  -- Function: gcry_mpi_t gcry_mpi_set (gcry_mpi_t W, const gcry_mpi_t U)
      Assign the value of U to W and return W.  If `NULL' is passed for
      W, a new MPI is allocated, set to the value of U and returned.
 
  -- Function: gcry_mpi_t gcry_mpi_set_ui (gcry_mpi_t W, unsigned long U)
      Assign the value of U to W and return W.  If `NULL' is passed for
      W, a new MPI is allocated, set to the value of U and returned.
      This function takes an `unsigned int' as type for U and thus it is
      only possible to set W to small values (usually up to the word
      size of the CPU).
 
  -- Function: void gcry_mpi_swap (gcry_mpi_t A, gcry_mpi_t B)
      Swap the values of A and B.
 
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