title: HMAC-SHA1 with OpenSSL/Request to Amazon S3 signature
body: <p>I am writing a program to upload file to Amazon S3 in C with libCurl and OpenSSL. To send a request to amazon I have to sign it - with  HMAC-SHA1 <a href="http://docs.amazonwebservices.com/fws/latest/DeveloperGuide/index.html?SummaryOfAuthentication.html" rel="nofollow">here amazon doc</a> that explain it. Help, please, can it be done with openSSL, and if U know advise how? Or I need to use some other libs?</p>