File formats

This section describes the bytes Bifröst writes and the signed evidence it exports. It is for people building readers, checking interoperability, or examining test fixtures. For configuration and day-to-day use, start with the audit log or session recording guides instead.

Find your format

Artifact	What it contains	Read next
.baudit, .beaudit	Signed audit segments; the latter encrypts private event fields.	Native audit format and audit vectors
.bcast, .becast	Signed recordings; the latter encrypts event groups.	Native recording format and recording vectors
Exported .cast	Signed, readable asciicast v3, reconstructed from a recording.	Standalone Cast

Start with shared container rules if you need to parse or produce native bytes. They define framing, CBOR, compression, encryption, and commit boundaries. The audit and recording pages then define their different map keys and signature/hash chains. A signed .cast is a verified export, not another native container.

Before trusting a file

A valid signature alone does not identify a trusted producer. Obtain the expected producer ID independently of the file. To detect a missing suffix of an audit history, also preserve an expected chain tip independently. An encrypted recording can pass outer verification without a private key; that does not verify its decrypted Cast content.

The operational audit workflow and recording export workflow explain how to verify and handle artifacts without implementing a decoder.