Azure VPN Phase-1 Negotiation using the wrong methods
For SHA1 in IpSec, it's either 2^160 possible values that the key can have (if the attacker has the key, he can generate HMACs for all received messages, ie. give you as much garbage as he wants), or 2^96 possible values for the hash itself (if the attacker manages to get that, just one block can be changed). hash - HMAC-SHA1 vs HMAC-SHA256 - Cryptography Stack … As for the output size, that may be a factor especially if you're sending hashes over a network. However, it's also acceptable to truncate the output of the HMAC to a certain length. So really, choosing between SHA1 and SHA256 doesn't make a huge difference. Might as well stick with SHA1. $\endgroup$ – user3100783 Apr 4 '14 at 1:05 SSL encryption, SHA-1 and SHA-2 - Stack Overflow First of all, neither SHA-1 nor anything related to SHA-2 is an "encryption" algorithm. They are hash functions. In SSL, hash functions are used mostly for integrity, not confidentiality, through the HMAC construction. A hash function takes an input of arbitrary length, and produces an output with a fixed length, which is a kind of "digest" of the input data; the operation is meant not to be
Jun 26, 2020 · HMAC-SHA2-256-128; HMAC-SHA2-512-256; HMAC-SHA1-96; Cloud VPN's proposal presents these HMAC algorithms in the order shown. Cloud VPN accepts any proposal that contains one or more of these algorithms, in any order. Documentation for your on-premises VPN gateway might use a slightly different name for the algorithm.
As for the output size, that may be a factor especially if you're sending hashes over a network. However, it's also acceptable to truncate the output of the HMAC to a certain length. So really, choosing between SHA1 and SHA256 doesn't make a huge difference. Might as well stick with SHA1. $\endgroup$ – user3100783 Apr 4 '14 at 1:05
Microsoft security advisory: Deprecation of SHA-1 hashing
SHA-1 to SHA-2: The future of SSL and enterprise Application security expert Michael Cobb explains what the transition from SHA-1 to SHA-2 means for SSL security and the future of enterprise application security. consider changing sha2-truncbug to "no" in /etc/ipsec.conf Sep 19, 2019 auth SHA256 or SHA512 - OpenVPN Support Forum Jan 15, 2017