Thanks for the information. We were thinking about having the client send up a hash over the entire file any time it attempted to start or resume an upload, and if the computed checksum didn't match the original, just force the client to start over from the beginning.
Would this work? -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of David Schwartz Sent: Wednesday, May 30, 2007 8:01 PM To: openssl-users@openssl.org Subject: RE: Saving (and restoring) cipher context One huge problem with many encryption modes is that if the plaintext changes at all, the ciphertext may become completely incomprehensible across the resume point because the context will not be the same. So you will probably need some resynch mechanism. You actually have an interesting problem. If the client does the encryption, it's not too complicated. But if you want the added flexibility of allowing the server to totally control the encryption algorithm, it gets trickier. You can have the server able to request SHA1 checksums over arbitrary byte ranges, allowing the resynchronization to be totally controlled by the server. But there's still the issue of how the server should do it. DS ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager [EMAIL PROTECTED] ______________________________________________________________________ OpenSSL Project http://www.openssl.org User Support Mailing List openssl-users@openssl.org Automated List Manager [EMAIL PROTECTED]
