Keyed Text Watermark Detection API
Detects a keyed statistical watermark in text and reports an exact p-value. It answers whether text was generated through a marking pipeline that holds the key, not whether an AI wrote it. Public access and keys are issued through authorized pilots and enterprise enrollment.
1. Watermark Detection
Evaluates submitted text against authorized key schedules and returns exact binomial tail probabilities.
Example cURL request:
curl -X POST https://verifywatermark.com/api/v2/detect/text \
-H "Authorization: Bearer vwm_live_..." \
-H "Content-Type: application/json" \
-H "Idempotency-Key: 7b69a2cf-3d71-45a8-bf29-e85d7b579124" \
-d '{
"schema_version": "2.0",
"text": "The rapid development of generative technologies necessitates rigorous statistical verification...",
"profile_id": "qwen25-coder-v1",
"tier": "standard",
"detail": "aggregate"
}'Example 200 OK response:
{
"schema_version": "2.0",
"request_id": "c61f22fae04d4001a1c97a73a3821034",
"policy_id": "live-text-v1",
"detector_build": "live-build-v1",
"source": "live",
"scope": "account",
"verdict": "watermarked",
"reason": null,
"profile_id": "qwen25-coder-v1",
"profile_digest": "sha256:d8b7a1e05d0d8...",
"scheme_id": "ts-sweet-hmac-chacha20-v3",
"tier": "standard",
"gate_mode": "ungated",
"null_model": "binomial_independent",
"hypotheses": 1,
"planned_hypotheses": 1,
"key_tag": "root-1:v1:20260922",
"scope_start": "2026-09-22T00:00:00+00:00",
"scope_end": "2026-09-22T23:59:59+00:00",
"token_count": 280,
"scored": 265,
"skipped": 15,
"context_excluded": 0,
"green": 204,
"needed": 52,
"required_green": 152,
"green_rate": 0.7698,
"z_score": 8.78,
"p_value": 1.71e-19,
"p_adjusted": 1.71e-19,
"alpha": 0.000001,
"alpha_per_hypothesis": 0.000001,
"z_bar": 4.75,
"zero_width": 0,
"credits_charged": 0,
"token_map": null,
"token_map_status": "not_requested"
}2. Provenance Receipt Verification
Verifies Ed25519-signed text receipts against the TrueSynthesis Issuer Registry without executing model inference. Server-to-server calls require an API key; browser calls are Origin-checked.
Example payload (server-to-server):
curl -X POST https://verifywatermark.com/api/v2/verify/receipt \
-H "Authorization: Bearer vwm_live_..." \
-H "Content-Type: application/json" \
-d '{
"text": "The rapid advancement of synthetic intelligence demands cryptographic verification...",
"receipt": {
"schema_version": 1,
"created_at": 1758502800.0,
"text_sha256": "4b227777d4dd1fc61c6f884f48641d02b4d121d3fd328cb08b5531fcacdabf8a",
"model_id": "qwen2.5-coder-7b",
"request_id": "req_8892f3a1",
"account_id": "acc_01j8m4k2",
"receipt_id": "rcpt_9921f00b",
"public_key": "MCowBQYDK2VwAyEA9...",
"signature": "dGhpcyBpcyBhIHJlYWwgZWQyNTUxOSBzaWduYXR1cmU..."
}
}'Example 200 OK response:
{
"schema_version": "2.0",
"request_id": "a1b2c3d4e5f6478980123456789abcdef",
"verdict": "valid_trusted",
"reason": null,
"issuer_id": "truesynthesis-official",
"issuer_display_name": "TrueSynthesis Inc.",
"issuer_verified": true,
"issuer_trust": "verified",
"receipt_id": "rcpt_9921f00b",
"registry_configured": true
}3. Protocol & Verification Standards
Zero-Text Retention
Neither the edge proxy nor the inference engine persists raw submitted text. Only the input SHA-256 digest and aggregate statistical parameters are audited in PostgreSQL.
Exact Binomial Testing
Detection computes exact one-sided discrete tail probabilities over independently scored tokens, guaranteeing a stated false-positive rate bound without heuristic rounding.
HMAC-ChaCha20 Membership
Green-token partition is derived from an HMAC-SHA256 seed feeding a ChaCha20 stream cipher over preceding context tokens (k = 4), resistant to permutation and substitution bias.
Deterministic Metering (Planned Gate)
Paid detection metering is specified in SPEC_Detection_Metering.md: max(1, ceil(tokens / 1500)) credits. Current pilot and demo tiers charge 0 credits until paid gate acceptance.