Package {attestix}

attestix: Offline verifier for Attestix credentials and delegations

Description

The attestix package verifies, fully offline, the verifiable credentials and UCAN delegation chains issued by the Attestix Python core (https://github.com/VibeTensor/attestix). No Python runtime is needed.

Details

Key entry points:

• atx_verify_credential - verify a W3C VC (Ed25519 signature + expiry + revocation).

• atx_canonicalize - the JCS-style canonical form (NOT strict RFC 8785; it additionally NFC-normalizes).

• atx_decode_did_key - decode an Ed25519 did:key to its raw 32-byte public key.

• atx_verify_delegation_chain - verify a UCAN delegation chain (per-link EdDSA + capability attenuation).

The canonical form is the load-bearing detail: see the spec at https://attestix.io/spec/bundle/v1 and the conformance vectors vendored under inst/testdata/vectors.json.

Author(s)

Maintainer: Pavan Kumar Dubasi info@vibetensor.com

Authors:

• Pavan Kumar Dubasi info@vibetensor.com

Other contributors:

• VibeTensor [copyright holder, funder]

See Also

Useful links:

• https://github.com/VibeTensor/attestix-r

• https://attestix.io

• Report bugs at https://github.com/VibeTensor/attestix-r/issues

Fields excluded from the W3C VC signature (MUTABLE_FIELDS).

Description

Fields excluded from the W3C VC signature (MUTABLE_FIELDS).

Usage

.ATX_MUTABLE_FIELDS

Ed25519 multicodec prefix (0xed 0x01) for ed25519-pub.

Description

Ed25519 multicodec prefix (0xed 0x01) for ed25519-pub.

Usage

.ED25519_MULTICODEC_PREFIX

base64url decode (accepts padded or unpadded input)

Description

VC proofValue is base64url with padding; JWT compact segments are base64url without padding. This decoder accepts both by re-padding as needed, then delegating to openssl::base64_decode after translating the URL alphabet (-_) to the standard alphabet (+/).

Usage

atx_b64url_decode(s)

Arguments

Value

A raw vector.

base64url encode WITH padding (matches Python base64.urlsafe_b64encode).

Description

base64url encode WITH padding (matches Python base64.urlsafe_b64encode).

Usage

atx_b64url_encode(bytes)

Arguments

Value

A length-1 base64url string (padded).

Decode a base58btc string to raw bytes.

Description

Decode a base58btc string to raw bytes.

Usage

atx_base58_decode(s)

Arguments

Value

A raw vector.

Encode raw bytes to a base58btc string.

Description

Encode raw bytes to a base58btc string.

Usage

atx_base58_encode(bytes)

Arguments

Value

A length-1 character string.

Attestix JCS-style canonical JSON

Description

Reproduces attestix/auth/crypto.py::canonicalize_json byte-for-byte.

Usage

atx_canonicalize(obj)

Arguments

Details

This is JCS-style, NOT strict RFC 8785. The two load-bearing divergences from RFC 8785 are:

1. NFC Unicode normalization is applied to every string value and every object key (RFC 8785 does not normalize).

2. Whole-number floats collapse to integers (1.0 -> 1); non-whole floats use Python's repr (the vectors only use integers and 1.5, on which every port agrees).

Keys are sorted by Unicode code point, separators are "," and ":" with no whitespace, output is raw UTF-8 (no \uXXXX escapes), and large integers (> 2^53) are preserved exactly.

Value

A raw vector of the canonical UTF-8 bytes.

Examples

bytes <- atx_canonicalize('{"b":2,"a":1}')
rawToChar(bytes) # {"a":1,"b":2}

Decode an Ed25519 did:key to its raw 32-byte public key

Description

Reproduces attestix/auth/crypto.py::did_key_to_public_key: strip the did:key:z prefix, base58btc-decode the multibase payload, assert the first two bytes are the 0xed 0x01 multicodec prefix, and return the remaining 32 raw bytes.

Usage

atx_decode_did_key(did)

Arguments

Value

A raw vector of length 32 (the Ed25519 public key).

Examples

did <- "did:key:z6Mko5TBPGKHkCxSgmf3aC6p6SGj2auwCfRmBydXJFEwL4ev"
length(atx_decode_did_key(did)) # 32

Return the multibase fragment portion of a did:key

Description

The verification method is <did>#<multibase> where <multibase> is the z... portion of the did:key. This returns that fragment with a leading #.

Usage

atx_did_key_fragment(did)

Arguments

Value

The #z... fragment.

Verify an Ed25519 (RFC 8032) signature

Description

Thin wrapper over sodium::sig_verify (libsodium). Returns a logical rather than signalling, so callers can fold it into a structured result.

Usage

atx_ed25519_verify(message, signature, public_key)

Arguments

Value

TRUE if the signature is valid, else FALSE.

Examples

## Not run: 
atx_ed25519_verify(msg, sig, pubkey)

## End(Not run)

Hex string -> raw vector.

Description

Hex string -> raw vector.

Usage

atx_hex_to_raw(h)

Arguments

Value

A raw vector.

Minimal, deterministic JSON parser for canonicalisation

Description

jsonlite is excellent but its number handling is ambiguous for our needs: we must tell a big integer (9007199254740993, which must be emitted bare with no precision loss) apart from a JSON string, and we must know whether a numeric token was written 1.0 (whole -> int) or 1.5 (non-whole). This hand-written recursive-descent parser preserves every number token as a tagged raw lexeme so the canonicaliser can apply the exact Attestix number rules.

Usage

atx_json_parse(txt)

Arguments

Details

Returned value tree:

• object -> named list (insertion order preserved)

• array -> unnamed list

• string -> length-1 character (UTF-8)

• number -> length-1 character with class "atx_number" carrying the raw lexeme (e.g. "9007199254740993", "1.0")

• true/false -> length-1 logical

• null -> NULL wrapped as list(NULL) element so it survives in lists; top-level null is NULL

Empty object vs empty array are distinguished: {} -> empty named list, [] -> empty unnamed list.

Value

The parsed value tree.

Decode a JWT compact token without verifying.

Description

Decode a JWT compact token without verifying.

Usage

atx_jwt_decode(token)

Arguments

Value

A list with header, payload (parsed value trees), signing_input (raw bytes of header.payload), and signature (raw bytes).

Parse JSON into the canonicalisation value tree

Description

Convenience alias for atx_json_parse.

Usage

atx_parse_json(txt)

Arguments

Value

The parsed value tree.

Encode a raw 32-byte Ed25519 public key to a did:key

Description

Inverse of atx_decode_did_key.

Usage

atx_public_key_to_did_key(pubkey)

Arguments

Value

A did:key:z... string.

Raw vector -> lowercase hex string.

Description

Raw vector -> lowercase hex string.

Usage

atx_raw_to_hex(r)

Arguments

Value

A hex string.

Full verification method for a did:key (<did>#<multibase>).

Description

Full verification method for a did:key (<did>#<multibase>).

Usage

atx_verification_method(did)

Arguments

Value

The verification-method string.

Verify an Attestix W3C Verifiable Credential offline

Description

Mirrors attestix/services/credential_service.py::verify_credential. The signing payload is the credential with the proof and credentialStatus top-level keys removed; that payload is JCS-style canonicalized (see atx_canonicalize) and the Ed25519 signature in proof.proofValue is verified against the issuer public key.

Usage

atx_verify_credential(vc, public_key = NULL, now = Sys.time())

Arguments

Details

Three independent checks are ANDed:

• signature_valid - Ed25519 verification of the canonical bytes.

• not_expired - now < expirationDate (tz-aware ISO-8601).

• not_revoked - credentialStatus$revoked is falsy.

Value

A list with logical fields signature_valid, not_expired, not_revoked, structure_valid, and the overall verify.

Examples

## Not run: 
res <- atx_verify_credential(vc_json)
isTRUE(res$verify)

## End(Not run)

Verify a UCAN delegation chain (Ed25519 per link + attenuation)

Description

Mirrors the recursive prf-chain verification in attestix/services/delegation_service.py. Each token in the chain is a PyJWT EdDSA JWT; the signed message is the compact header.payload form (base64url unpadded), NOT the JCS canonical form.

Usage

atx_verify_delegation_chain(
  chain,
  public_key,
  now = Sys.time(),
  revoked_jti = character(0)
)

Arguments

Details

The chain verifies iff every token's signature is valid AND every token is unexpired and unrevoked AND each child's att is a subset of its parent's att (capability attenuation; escalation is rejected). Cycles (a repeated jti) are rejected.

Value

A list with parent_signature_valid, child_signature_valid, attenuation_is_subset, and the overall verify.

Examples

## Not run: 
atx_verify_delegation_chain(list(parent_token = pt, token = ct), pk)

## End(Not run)

Verify a single UCAN JWT (signature + alg + expiry + revocation).

Description

Mirrors the per-token checks in attestix/services/delegation_service.py::verify_delegation. Only alg=EdDSA is accepted; alg:none (and any other alg) is rejected.

Usage

atx_verify_ucan_token(
  token,
  public_key,
  now = Sys.time(),
  revoked_jti = character(0)
)

Arguments

Value

A list with signature_valid, not_expired, not_revoked, alg_ok, jti, att, and valid.

Base58btc (Bitcoin alphabet) encode/decode

Description

Vendored minimal implementation, no external dependency. Used for did:key multibase z payloads. Uses double-precision-safe big-integer-free byte arithmetic (repeated base-256 <-> base-58 conversion on raw byte vectors), so it is exact for arbitrary-length inputs.