@vincent There was a problem with image property of dotmakeup actor. The url attribute of Image is set to null:
"image": { "type": "Image", "mediaType": "image/jpeg", "url": null },I changed my validator to be more lenient, but such representation doesn't feel right. I think it would be better to not add image at all if url is not known.
After fixing this issue I was able to resolve actor. Then I sent a Follow activity and dotmakeup sent Accept activity back to me. However, my server failed to verify the HTTP signature.
I'm not 100% sure but it looks like keyId parameter is incorrect, its value is https://kilogram.makeup/users/instagram (actor ID) when it should be https://kilogram.makeup/users/instagram#main-key (key ID).