Thank you very much for the answer.
Le 30/11/2012 12:54, Dr. Stephen Henson a écrit :
On Fri, Nov 30, 2012, Michel wrote:
Before trying to use it, I was misleaded by the documentation (and
the example) of the EVP_PKEY_sign() call at :
http://www.openssl.org/docs/crypto/EVP_PKEY_sign.html
I'll add a clarification to the manual page.
What is not yet clear to me is :
if the input is a previously calculated digest, what is the use of
the EVP_PKEY_CTX_set_signature_md() call in the example ?
The main reason is that some algorithms (currently only RSA) need to know the
message digest algorithm to prepare the signature.
The value can also be used as a sanity check to see the digest length is
correct (though not all algorithms currently do this).
Steve.
--
Dr Stephen N. Henson. OpenSSL project core developer.
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