Re: Avoid recipient-compatibility SHA1

2020-11-18 Thread Neal H. Walfield
Hi Stefan, A chosen-prefix collision attack works as follows: an attacker chooses two message prefixes, and then uses near collisions blocks (in the SHA-1 is a Shambles paper they needed about 10 such 512-bit blocks) to align the internal state of the two hashes. Since SHA-1 is a streaming

Re: Avoid recipient-compatibility SHA1

2020-11-18 Thread Phil Pennock via Gnupg-users
On 2020-11-17 at 22:18 -0700, Mark wrote: > Not to ask a stupid question but how can you tell which algorithm your > keys are using and if using SHA1 update them to a more secure one? I have a better answer than my previous one, because the very next mailing-list I read has a post today from the

Re: Avoid recipient-compatibility SHA1

2020-11-18 Thread Phil Pennock via Gnupg-users
On 2020-11-17 at 22:18 -0700, Mark wrote: > Not to ask a stupid question but how can you tell which algorithm your > keys are using and if using SHA1 update them to a more secure one? With GnuPG, `gpg --list-packets` shows a lot of fine detail, but unless you're familiar with the standards it can

Re: GPG Encryption/Decryption Failing

2020-11-18 Thread Sirisha Gopigiri via Gnupg-users
Hi Thank you for the reply and we have looked into the documentation. But after debugging a little we found that we are running into this issue only if we use gpg 2.2.4 version. We tested the same code with gpg 1.4.20 version and it seems to work fine. I mean we ran the test cases for the code

Re: Avoid recipient-compatibility SHA1

2020-11-18 Thread Ernst G Giessmann via Gnupg-users
Am 2020-11-18 um 14:30 schrieb Stefan Claas: On Tue, Nov 17, 2020 at 11:11 PM Ernst G Giessmann via Gnupg-users wrote: The answer to the second question is: A SHA-1 collision of two documents D1 and D2 means that the hash values Hash(D1) and Hash(D2) are equal, which in turn means that

Re: Avoid recipient-compatibility SHA1

2020-11-18 Thread Stefan Claas via Gnupg-users
On Wed, Nov 18, 2020 at 2:30 PM Stefan Claas wrote: > > On Tue, Nov 17, 2020 at 11:11 PM Ernst G Giessmann via Gnupg-users > wrote: > > > > The answer to the second question is: > > > > A SHA-1 collision of two documents D1 and D2 means that the hash values > > Hash(D1) and Hash(D2) are equal,

Re: Avoid recipient-compatibility SHA1

2020-11-18 Thread Stefan Claas via Gnupg-users
On Tue, Nov 17, 2020 at 11:11 PM Ernst G Giessmann via Gnupg-users wrote: > > The answer to the second question is: > > A SHA-1 collision of two documents D1 and D2 means that the hash values > Hash(D1) and Hash(D2) are equal, which in turn means that (regardless > who signs) any signature of D1

Re: Avoid recipient-compatibility SHA1

2020-11-18 Thread Stefan Claas via Gnupg-users
Thank you for your reply, much appreciated! I will however ask also Ernst here again the same question one more time again, as an illustrative example. Regards Stefan On Mon, Nov 2, 2020 at 3:25 PM Phil Pennock via Gnupg-users wrote: > > On 2020-11-02 at 13:49 +0100, Werner Koch via Gnupg-users