attestix (R)

Offline verifier for the verifiable credentials and UCAN delegation chains issued by the Attestix Python core - no Python runtime needed. Built for compliance, research and biostatistics users who live in R and need to check AI-agent compliance credentials.

It verifies:

• W3C Verifiable Credentials signed with Ed25519 (RFC 8032).
• did:key Ed25519 identifiers (multibase base58btc + 0xed01 multicodec).
• UCAN delegation chains (EdDSA JWTs) including capability attenuation.

Every check is validated against the shared cross-language conformance vectors (inst/testdata/vectors.json), the same oracle used by the Go, Rust, Java and JS ports. The vectors are generated from the real attestix 0.4.0 crypto.

The canonical form is JCS-style, not strict RFC 8785

This is the single most error-prone part of any port, so it is worth stating up front. The Attestix canonical form is a practical subset of JCS that diverges from strict RFC 8785 in two load-bearing ways:

1. NFC Unicode normalization is applied to every string value and every object key. RFC 8785 explicitly does not normalize; Attestix does.
2. Whole-number floats collapse to integers (1.0 -> 1); non-whole floats use Python's repr. Signed payloads should avoid non-trivial floats (the vectors use only integers and 1.5, on which all ports agree).

Otherwise: keys sorted by Unicode code point, ","/":" separators with no whitespace, raw UTF-8 output (no \uXXXX escapes), large integers preserved exactly. The full spec is in the parent repo at spec/verify/v1/README.md and the bundle wire format is published at https://attestix.io/spec/bundle/v1.

Install

# system dependency: libsodium (e.g. `apt-get install libsodium-dev`)

# from GitHub:
# install.packages("remotes")
remotes::install_github("VibeTensor/attestix-r")

# once on CRAN (submission pending):
# install.packages("attestix")

Verify a credential (10 lines)

library(attestix)

# vc is the credential JSON (string, raw bytes, or a parsed value tree).
vc <- readChar("credential.json", file.info("credential.json")$size)

res <- atx_verify_credential(vc)            # issuer key auto-resolved from did:key
res$signature_valid                          # Ed25519 over JCS-canonical bytes
res$not_expired                              # now < expirationDate (tz-aware)
res$not_revoked                              # credentialStatus.revoked is falsy
res$verify                                   # TRUE only if all three hold

# canonical bytes, did:key decode, and delegation chains are first-class too:
atx_decode_did_key("did:key:z6Mko5TBPGKHkCxSgmf3aC6p6SGj2auwCfRmBydXJFEwL4ev")

Public API

Function	Purpose
atx_verify_credential(vc, public_key, now)	Verify a W3C VC (signature + expiry + revocation).
atx_canonicalize(obj)	JCS-style canonical UTF-8 bytes (the oracle).
atx_decode_did_key(did)	Decode an Ed25519 did:key to the raw 32-byte key.
atx_verify_delegation_chain(chain, public_key)	Verify a UCAN chain + attenuation.
atx_ed25519_verify(message, signature, public_key)	Raw Ed25519 verify.

Conformance

# from the package source:
devtools::test()        # runs tests/testthat against inst/testdata/vectors.json

The CI workflow runs R CMD check --as-cran plus the vector suite on ubuntu-latest across two R versions. The vectors are vendored verbatim from the parent repo's spec/verify/v1/vectors.json.

Relationship to the parent project

This is one of several language ports of the Attestix offline verifier. The authoritative implementation and the issuing side live in the Python core at VibeTensor/attestix. Project home: attestix.io.

License

Apache-2.0.