BN_num_bits man page on IRIX

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     /xlv3/openssl/0.9.7e-sgipl1/work/0.9.7e-sgipl1/openssl-
     0.9.7e/doc/crypto

     Page 1					    (printed 10/20/05)

     BN_num_bytes(3)	    1/Jul/2004 (0.9.7e)	       BN_num_bytes(3)

     NAME
	  BN_num_bits, BN_num_bytes, BN_num_bits_word - get BIGNUM
	  size

     SYNOPSIS
	   #include <openssl/bn.h>

	   int BN_num_bytes(const BIGNUM *a);

	   int BN_num_bits(const BIGNUM *a);

	   int BN_num_bits_word(BN_ULONG w);

     DESCRIPTION
	  BN_num_bytes() returns the size of a BIGNUM in bytes.

	  BN_num_bits_word() returns the number of significant bits in
	  a word.  If we take 0x00000432 as an example, it returns 11,
	  not 16, not 32.  Basically, except for a zero, it returns
	  floor(log2(w))+1.

	  BN_num_bits() returns the number of significant bits in a
	  BIGNUM, following the same principle as BN_num_bits_word().

	  BN_num_bytes() is a macro.

     RETURN VALUES
	  The size.

     NOTES
	  Some have tried using BN_num_bits() on individual numbers in
	  RSA keys, DH keys and DSA keys, and found that they don't
	  always come up with the number of bits they expected
	  (something like 512, 1024, 2048, ...).  This is because
	  generating a number with some specific number of bits
	  doesn't always set the highest bits, thereby making the
	  number of significant bits a little lower.  If you want to
	  know the "key size" of such a key, either use functions like
	  RSA_size(), DH_size() and DSA_size(), or use BN_num_bytes()
	  and multiply with 8 (although there's no real guarantee that
	  will match the "key size", just a lot more probability).

     SEE ALSO
	  bn(3), DH_size(3), DSA_size(3), RSA_size(3)

     HISTORY
	  BN_num_bytes(), BN_num_bits() and BN_num_bits_word() are
	  available in all versions of SSLeay and OpenSSL.

     Page 1					    (printed 10/20/05)

     BN_num_bytes(3)	    1/Jul/2004 (0.9.7e)	       BN_num_bytes(3)

     Page 2					    (printed 10/20/05)

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