I remembered encountering this problem before. And although I don't remember all the details now, the basic idea is that openssl will only allocate enough memory for the "significant" bits of the signature. So if your signature has the first byte of 0x00, it will not store that byte. And if you want consistent signature length (64 in your case), you have to manually pad it with zeros. You have to go back to the comments in the function header to get the details. But I'm pretty positive that is the case.
________________________________________ From: owner-openssl-us...@openssl.org [owner-openssl-us...@openssl.org] on behalf of redpath [redp...@us.ibm.com] Sent: Tuesday, September 17, 2013 2:48 PM To: openssl-users@openssl.org Subject: Re: Concerning the ECDSA_sig size I am glad someone is asking this question. I sign the same data with same private key and sometimes the signature is 63 and sometimes it is 64 but overall the verification works for each anyhow. -- View this message in context: http://openssl.6102.n7.nabble.com/Concerning-the-ECDSA-sig-size-tp46553p46559.html Sent from the OpenSSL - User mailing list archive at Nabble.com. ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager majordomo@openssl.org______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager majord...@openssl.org
