tests/e2e: Add s390x encrypted image test

[stevenhorsman]

In 1a76163 I had to skip the encrypted image test on s390x as the test image only supports amd64 and the kata CI's multi-arch image has a decryption key that is 44 bytes and our code rejects it as it only works with 32 byte keys.

We should try and switch to a multi-arch image, and/or understand the 32-byte key restriction.

[stevenhorsman]

@mkulke - do you understand why we have the 32-byte restriction, when we don't have that in the Kata CI? I think Chris Porter is working on creating some standardised regenerated test images, but until then re-using the kata ones might be helpful?

[mkulke]

@mkulke - do you understand why we have the 32-byte restriction, when we don't have that in the Kata CI? I think Chris Porter is working on creating some standardised regenerated test images, but until then re-using the kata ones might be helpful?

that's just what ocicrypt-rs expectes, afaik. We use aes 256 as symmetric key. so no idea why a 44 byte key would work, maybe it's just truncated?

[stevenhorsman]

that's just what ocicrypt-rs expectes, afaik. We use aes 256 as symmetric key. so no idea why a 44 byte key would work, maybe it's just truncated?

Interesting. I'll give that a try and see if it works (once we have a stable s390x test back!)