# Cosign Generic Predicate Specification `Cosign` supports working with [In-Toto Attestations](https://github.com/in-toto/attestation) using the predicate model. Several well-known predicates are supported natively, but `cosign` also supports a simple, generic, format for data that doesn't fit well into other types. The format for this is defined as follows: `data`: Raw data to place in the attestation. This is a base64-encoded string of bytes. `timestamp`: The timestamp the attestation was generated at in the RFC3339 format in the UTC timezone. Here is an example attestation containing a data file containing `foo`: ```json { "_type": "https://in-toto.io/Statement/v0.1", "predicateType": "https://cosign.sigstore.dev/attestation/v1", "subject": [ { "name": "us.gcr.io/dlorenc-vmtest2/demo", "digest": { "sha256": "124e1fdee94fe5c5f902bc94da2d6e2fea243934c74e76c2368acdc8d3ac7155" } } ], "predicate": { "Data": "foo\n", "Timestamp": "2021-08-11T14:51:09Z" } } ```