Re: add hash signature as part of the stream on which this hash is based on
My guess is that if you could write a hash working the way you say, it would be vulnerable to all sorts of cryptographic attacks: give up! I have indeed given up and found other ways to incorporate the hash while verifying the stream integrity. __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
Re: add hash signature as part of the stream on which this hash is based on
On 10/27/2012 06:30 PM, Michael Zintakis wrote: Maybe a bit daft of me to ask this, but is it possible to calculate a hash on a stream of bytes where the resulting hash is considered to be part of that stream? In other words, lets assume that I have a stream which is, say, 64 bytes long in total, consisting of 48 bytes of payload, plus 16-byte for the hash and that hash has been calculated based on the *entire* stream (payload+hash) of 64 bytes. Would that be possible to produce with openssl or is this a bit of a chicken-and-egg scenario? Thanks! __ By its nature, a hash completely changes if just a bit of the original content is modified, that also includes appending anything to it. Any change will make the difference unpredictable. My guess is that if you could write a hash working the way you say, it would be vulnerable to all sorts of cryptographic attacks: give up! __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
Re: add hash signature as part of the stream on which this hash is based on
On Mon, Nov 19, 2012 at 9:24 AM, lists li...@rustichelli.net wrote: By its nature, a hash completely changes if just a bit of the original content is modified By design, a cryptographic hash function (on average) changes half the output bits when a single bit in the input is inverted. __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
RE: add hash signature as part of the stream on which this hash is based on
Isn't that a little like the guy who committed suicide, cut himself up in little pieces, and flushed himself down the toilet? Some checksums are computed such that the checksum is part of the message, and if all if well, the checksum of the entire message including the appended sum is 0 or 0x or some such, but the original checksum I think is always computed on what came before it. The bi-sync CRC-16 (boy, am I dating myself!) was computed that way IIRC. Charles -Original Message- From: owner-openssl-us...@openssl.org [mailto:owner-openssl-us...@openssl.org] On Behalf Of Michael Zintakis Sent: Saturday, October 27, 2012 9:31 AM To: openssl-users@openssl.org Subject: add hash signature as part of the stream on which this hash is based on Maybe a bit daft of me to ask this, but is it possible to calculate a hash on a stream of bytes where the resulting hash is considered to be part of that stream? In other words, lets assume that I have a stream which is, say, 64 bytes long in total, consisting of 48 bytes of payload, plus 16-byte for the hash and that hash has been calculated based on the *entire* stream (payload+hash) of 64 bytes. Would that be possible to produce with openssl or is this a bit of a chicken-and-egg scenario? Thanks! __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org __ OpenSSL Project http://www.openssl.org User Support Mailing Listopenssl-users@openssl.org Automated List Manager majord...@openssl.org
