Re: [jose] Towards a More Secure JOSE Standard

[Justin Richer <[e-mail]>]

If the problem is substituting “alg: RS256” with “alg: HS256” or the like, how is that any different from substituting “mode: ps” with “mode: sa”? There have been some reasonable arguments for removing the algorithm selection from the JOSE package, but this proposal doesn’t do that. Instead, it simply defines *new* headers for algorithm selection. Ergo, unless I’m missing a key point here, this is just kicking things down the road a little bit.

 — Justin

> On Mar 29, 2017, at 11:19 AM, Paragon Initiative Enterprises Security Team <[e-mail]> wrote:
> 
> Hello,
> 
> We've outlined some suggestions to make a JOSE replacement/upgrade more secure. Our suggestions are outlined at https://gist.github.com/paragonie-scott/c88290347c2589b0cd38d8bb6ac27c03 <https://gist.github.com/paragonie-scott/c88290347c2589b0cd38d8bb6ac27c03>, but I have mirrored them below.
> 
> Changes to JOSE that will prevent insecurity
> 
>  <https://gist.github.com/paragonie-scott/c88290347c2589b0cd38d8bb6ac27c03#deletions>Deletions
> 
>  <https://gist.github.com/paragonie-scott/c88290347c2589b0cd38d8bb6ac27c03#jws-and-jwe>JWS and JWE
> 
>  <https://gist.github.com/paragonie-scott/c88290347c2589b0cd38d8bb6ac27c03#drop-the-alg-header>Drop the alg header
> 
> Neither JOSE users nor JOSE library designers should be required to understand cryptography primitives. At a lower level, this can lead to badly implemented primitives <http://www.cryptofails.com/post/70059600123/saltstack-rsa-e-d-1>. On a higher level, this can lead to reasoning by lego <http://www.cryptofails.com/post/121201011592/reasoning-by-lego-the-wrong-way-to-think-about>.
> 
> For all the reasons outlined here <https://paragonie.com/blog/2017/03/jwt-json-web-tokens-is-bad-standard-that-everyone-should-avoid> and here <https://storify.com/jcuid/thomas-h-ptacek-don-t-use-json-web-tokens>, the alg header (and algorithm agility in its entirety) should be considered harmful.
> 
>  <https://gist.github.com/paragonie-scott/c88290347c2589b0cd38d8bb6ac27c03#jwe>JWE
> 
>  <https://gist.github.com/paragonie-scott/c88290347c2589b0cd38d8bb6ac27c03#drop-the-enc-header>Drop the enc header
> 
> For the same reason we're dropping the alg header, we should drop the enc header.
> 
>  <https://gist.github.com/paragonie-scott/c88290347c2589b0cd38d8bb6ac27c03#consider-dropping-the-zip-header>Consider dropping the zip header
> 
> As we've seen with CRIME <https://en.wikipedia.org/wiki/CRIME> and BREACH <http://breachattack.com/>, as well as this error oracle attack against iMessage <https://blog.cryptographyengineering.com/2016/03/21/attack-of-week-apple-imessage/>, compression can introduce side-channels that totally undermine confidentiality.
> 
> This one is less of a hard-and-fast requirement to make JOSE secure, but I still strongly recommend it.
> 
>  <https://gist.github.com/paragonie-scott/c88290347c2589b0cd38d8bb6ac27c03#additions>Additions
> 
>  <https://gist.github.com/paragonie-scott/c88290347c2589b0cd38d8bb6ac27c03#jws-and-jwe-1>JWS and JWE
> 
>  <https://gist.github.com/paragonie-scott/c88290347c2589b0cd38d8bb6ac27c03#new-header-ver-version>New header: ver (version)
> 
> Instead of letting library developers and users mix-and-match cryptography algorithms, the only choice they should be given is, "Which version are we using?" Versions can look like this:
> 
> Version 1:
> HMAC-SHA256 for shared-key authentication
> AES-128-CBC + HMAC-SHA256 in Encrypt-then-MAC mode for shared-key encryption
> RSA-OAEP with MGF1-SHA256 and e=65537 + AES-128-CBC in KEM+DEM for public-key encryption, min. key size: 2048-bit
> RSASSA-PSS with MGF1-SHA256 and e=65537 for public-key digital signatures, min. key size: 2048-bit
> Version 2:
> HMAC-SHA256 for shared-key authentication
> AES-256-GCM for shared-key encryption
> ECDH over secp256r1 (NIST P-256) + AES-256-GCM for public-key encryption
> Libraries must verify that the point is on the curve
> ECDSA over secp256r1 (NIST P-256), adhering to RFC 6979 (deterministic ECDSA), for public-key digital signatures
> Version 3:
> HMAC-SHA512-256 for shared-key authentication
> As per NaCl, this is HMAC-SHA-512 truncated to 256 bits, not HMAC-SHA-512/256.
> Xsalsa20poly1305 for shared-key encryption
> X25519 + Xsalsa20poly1305 for public-key encryption
> Ed25519 for public-key digital signatures
> Libraries that support version 3 SHOULD NOT support version 1.
> 
>  <https://gist.github.com/paragonie-scott/c88290347c2589b0cd38d8bb6ac27c03#new-header-mode>New header: mode
> 
> Only four options (case-insensitive):
> 
> se = Shared-key Encryption
> sa = Shared-key Authentication
> pe = Public-key Encryption
> ps = Public-key digital Signatures
>  
> ​Kind regards,
> 
> Security Team
> Paragon Initiative Enterprises <https://paragonie.com/security>_______________________________________________
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