[openssl.org #1099] Problem with keysize operations

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[openssl.org #1099] Problem with keysize operations

Rich Salz via RT

Brad Hards wrote:
> I'm trying to determine the length (in bits) for my DSA and DH keys.  I'm
> happily using RSA_size() for RSA keys, and I assumed that DSA_size and
> DH_size would do equivalent operations (based on the man page for
> BN_size_bits, which states 'If you want to know the "key size" of such a
key,
> either use functions like RSA_size(), DH_size() and DSA_size()'..

yep, that's a bug.

>
> However the man page for DSA_size says that it returns the size of the
> signature (which for me is always 48 bytes or 384 bits, irrespective of the
> key parameters)
>
> Is there a way to determine the keylength for DSA keys and DH keys?

in case of a EVP_PKEY object EVP_PKEY_bits, otherwise
BN_num_bits(dsa->p). But as the "NOTES" section in the BN_num_bits
manpage already says this isn't really a satisfying solution, it
would be better to have functions like
        size_t DSA_signature_size(const DSA *);
        size_t DSA_pkey_size(const DSA *);
for this ... just a thought.
You should send a bug report to [hidden email].

Nils
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