spec VS paseto-spec

https://github.com/fernet/spec/blob/master/Spec.md

It's just a simple format specification using standard crypto primitives.

> AES in CBC mode with a 128-bit key for encryption; using PKCS7 padding.

> HMAC using SHA256 for authentication.

So, you are using an implementation of Fernet spec, which describe a specific token format. So, you basically need to implement the same spec in Go. You may have a look at https://github.com/fernet/fernet-go

I googled the fernet specification for you: https://github.com/fernet/spec/blob/master/Spec.md

Another signcryption scheme as described in the article is also implemented by the libsodium author as an extension:

https://github.com/jedisct1/libsodium-signcryption

It's unclear from the article if this is the same algorithm age uses.

Signcryption schemes are also a good candidate algorithm for replacing JWTs and PASETO as they suffer from no algorithm confusion, and don't need what PASETO calls "Algorithm Lucidity" and serve both plaintext authentication, authenticated encryption, sender receiver verification, and shared key generation that can be used for unlimited encrypted streaming, for example with libsodium's crypto_secretstream API.

https://doc.libsodium.org/secret-key_cryptography/secretstre...

https://github.com/paseto-standard/paseto-spec/blob/master/d...

The rationale for V3/V4 may be of particular interest for this forum.

Whether you're curious or skeptical, we believe in transparency, so the detailed rationale for these exact changes in V3/V4 is available here.