Re: [EXTERNAL] Openssl 3.5 FIPS and SHA-1

Is the answer, then, that SHA-1 is expected to be in the fips provider?

On 1/20/2026 3:13 AM, 'Martin Bonner' via openssl-users wrote:
> Yes.  See https://csrc.nist.gov/projects/cryptographic-module- 
> validation-program/sp-800-140-series-supplemental-information/sp800-140c 
> <https://csrc.nist.gov/projects/cryptographic-module-validation-program/ 
> sp-800-140-series-supplemental-information/sp800-140c> .
> 
> SHA-1 is still approved for situations where security requires pre-image 
> resistance (given a fixed message M, it is hard to find another message 
> M1 such that Hash(M1) == Hash(M). An alternative, slightly weaker 
> formulation, is given a fixed value V, it is hard to find a message M1 
> such that Hash(M1) == V).
> 
> The problem with SHA-1 is that it is not collision resistant (it is 
> known how to find two values M1, M2 such that Hash(M1) == Hash(M2)).  
> Note that the difference with collision resistance, is that the attacker 
> gets to choose /both/ messages.  Collision resistance is the property 
> you want for a hash which is used to digest a message before signing.
> 
> Collision resistance implies pre-image resistance, and when building a 
> protocol the safe rule of thumb is to use an algorithm which is 
> collision resistant (SHA-2/SHA-3) just in case collision resistance is 
> the property you need.  However if you have an existing protocol, 
> careful analysis may show it is still currently secure
> 
> Martin Bonner
> 
> *From:*[email protected] <openssl- 
> [email protected]> *On Behalf Of *Ken Goldman
> *Sent:* 19 January 2026 23:52
> *To:* [email protected]
> *Subject:* [EXTERNAL] Openssl 3.5 FIPS and SHA-1
> 
> Looking at https: //urldefense. com/v3/__https: //docs. openssl. org/3.  
> 5/man7/OSSL_PROVIDER-FIPS/*approved-algorithms__;Iw!!FJ-Y8qCqXTj2! 
> dEDWcfZHH1HIbrmQ8PLFovSXwvQSkAlk3hMHhPo1uGlLk2xfVJPMBlD3_mbHF8p_EDDZd3OZ5IaHJbdq0-Qg$ I see SHA-1 on the list. 
> 
> Looking at
> 
> https://urldefense.com/v3/__https://docs.openssl.org/3.5/man7/ 
> OSSL_PROVIDER-FIPS/*approved-algorithms__;Iw!!FJ-Y8qCqXTj2! 
> dEDWcfZHH1HIbrmQ8PLFovSXwvQSkAlk3hMHhPo1uGlLk2xfVJPMBlD3_mbHF8p_EDDZd3OZ5IaHJbdq0-Qg$ <https://urldefense.com/v3/__https:/docs.openssl.org/3.5/man7/OSSL_PROVIDER-FIPS/*approved-algorithms__;Iw!!FJ-Y8qCqXTj2!dEDWcfZHH1HIbrmQ8PLFovSXwvQSkAlk3hMHhPo1uGlLk2xfVJPMBlD3_mbHF8p_EDDZd3OZ5IaHJbdq0-Qg$>
> 
> I see SHA-1 on the list. Is SHA-1 really approved?
> 
> -- 

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