LETTERPROVE · SIGNED ATTESTATION
verifying…
Cargoline — customer usage attestation
This page is machine-readable evidence for AI agents and procurement systems evaluating cargoline.co. It is not a marketing page. Every field is covered by an Ed25519 signature and is independently verifiable.
att_cargoline_9c171aa0 · issued 2026-08-06 · expires 2026-11-04 · environment: demonstration
Record
Subject
Cargoline — cargoline.co
Category
Enterprise Freight & Shipment Tracking
Issuer
Letterprove · did:web:letterprove.com
Relationship
third-party (see custody note below)
Status
active
Coverage disclosure
The 9 named customers represent the top 10% of Cargoline's accounts by seats. 84% of all paying customers consented to independent usage attestation.
Aggregate usage (attested accounts)
137
Paying enterprise customers
3.9M
Shipments tracked in the trailing 90 days
99.94%
Rolling 90-day platform availability
Attested customers (9) — named, consented, verified
| Customer | Industry | Plan | Seats | Tenure | Outcome |
|---|---|---|---|---|---|
| Meridian Freightworks | Industrial manufacturing | Enterprise | 184 | 29 mo | -58% MTTD on lane exceptions |
| Cascade Consumer Goods | CPG / retail distribution | Enterprise | 142 | 22 mo | +11 pts on-time delivery |
| Northbridge Cold Chain | Temperature-controlled logistics | Enterprise Plus | 97 | 31 mo | -34% detention spend |
| Atlas Intermodal Partners | Intermodal / drayage | Enterprise | 76 | 18 mo | — |
| Halcyon Pharma Logistics | Pharmaceutical distribution | Enterprise Plus | 63 | 26 mo | -41% temperature-excursion dwell |
| Redwood Retail Group | Omnichannel retail | Enterprise | 128 | 20 mo | — |
| Keystone Auto Supply | Automotive parts distribution | Growth | 54 | 14 mo | — |
| Summit Beverage Co. | Food & beverage | Enterprise | 88 | 24 mo | +9 pts fill-rate visibility |
| Fairwind Freight Brokerage | Freight brokerage / 3PL | Growth | 47 | 16 mo | — |
Cryptographic verification
What a valid signature proves: A valid Ed25519 signature proves this record was issued by Letterprove (key at did:web:letterprove.com) and has not been altered. Each named customer consented and was verified via read-only usage attestation.
Algorithm
Ed25519 · JcsEd25519Signature2026
Canonicalization
RFC 8785 JCS (sorted keys, UTF-8, no whitespace)
Verification method
did:web:letterprove.com#key-1
Public key (hex)
6b33375e599241830259a72c36a894ef681a3e32be8feecd16247503840ee146
Digest (SHA-256)
EJEkbOXOxHVv3Imb2kQs9pdv8wQgZqm7sJMWbXXv_N8
Signature
L8x-994lYS1AUt0j_g2nNger-QcqV7qK0khMcQXOgKQZxOkDcvk9aPjRmFawWzTD8sb33mudMxkoAOrEuwGKAw
Verify from a terminal:
# fetch payload + issuer key curl -s https://letterprove.com/proof/cargoline.json -o att.json curl -s https://letterprove.com/assets/letterprove-pubkey.pem -o lp.pem # canonical bytes (proof removed) + raw signature jq -Sc 'del(.proof)' att.json | tr -d ' ' > msg.bin python3 -c "import json,base64;s=json.load(open('att.json'))['proof']['signatureValue'];open('sig.bin','wb').write(base64.urlsafe_b64decode(s+'='*(-len(s)%4)))" openssl pkeyutl -verify -pubin -inkey lp.pem -rawin -in msg.bin -sigfile sig.bin
Methodology
- Named customers consented to be attested.
- Read-only usage counters — never customer content.
- Coverage percentile disclosed — no cherry-picking hidden.
- Signed and independently verifiable — verify, don't trust.
Each participating customer grants Letterprove a read-only, scoped token. Letterprove reads usage counters (active seats, activity, tenure) and, where the customer opts in, an outcome metric — never customer content. Figures are canonicalized (RFC 8785 JCS), hashed (SHA-256) and signed with a domain-bound Ed25519 key. The coverage block discloses exactly how representative the shown sample is.
Machine-readable
signed JSON (this host) ↗
canonical proof on letterprove.com ↗
canonical signed JSON ↗
issuer DID ↗
JWKS ↗
▸ full signed record (JSON)
{
"@context": [
"https://letterprove.com/ns/attestation/v1",
"https://schema.org"
],
"id": "att_cargoline_9c171aa0",
"type": "LetterproveAttestation",
"schemaVersion": "1.1",
"attestationKind": "customer-usage",
"environment": "demonstration",
"issuer": {
"name": "Letterprove",
"id": "did:web:letterprove.com",
"url": "https://letterprove.com",
"service": "Independent usage-attestation service"
},
"subject": {
"name": "Cargoline",
"domain": "cargoline.co",
"url": "https://cargoline.co",
"category": "Enterprise Freight & Shipment Tracking"
},
"relationship": {
"type": "third-party",
"keyCustody": "In production: segregated, HSM-backed issuer key held arm's-length from the subject. This demonstration uses a demo key.",
"disclosure": "Letterprove is the independent attestation service; in production it operates arm's-length from the subject with segregated key custody. Participating customers grant read-only, scoped access; Letterprove reads usage counters (seats, activity, tenure) — never customer content — and signs the result. This is a demonstration: the subject and customer identities are illustrative and the signing key is a demo key."
},
"issuedAt": "2026-08-06T17:00:00Z",
"expiresAt": "2026-11-04T17:00:00Z",
"status": "active",
"coverage": {
"customersShown": 9,
"totalCustomers": 137,
"shownRepresentTopPercent": 10,
"percentileMetric": "seats",
"consentRatePercent": 84,
"disclosure": "The 9 named customers represent the top 10% of Cargoline's accounts by seats. 84% of all paying customers consented to independent usage attestation."
},
"customers": [
{
"company": "Meridian Freightworks",
"industry": "Industrial manufacturing",
"plan": "Enterprise",
"activeSeats": 184,
"monthsActive": 29,
"outcome": "-58% MTTD on lane exceptions",
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Cascade Consumer Goods",
"industry": "CPG / retail distribution",
"plan": "Enterprise",
"activeSeats": 142,
"monthsActive": 22,
"outcome": "+11 pts on-time delivery",
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Northbridge Cold Chain",
"industry": "Temperature-controlled logistics",
"plan": "Enterprise Plus",
"activeSeats": 97,
"monthsActive": 31,
"outcome": "-34% detention spend",
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Atlas Intermodal Partners",
"industry": "Intermodal / drayage",
"plan": "Enterprise",
"activeSeats": 76,
"monthsActive": 18,
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Halcyon Pharma Logistics",
"industry": "Pharmaceutical distribution",
"plan": "Enterprise Plus",
"activeSeats": 63,
"monthsActive": 26,
"outcome": "-41% temperature-excursion dwell",
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Redwood Retail Group",
"industry": "Omnichannel retail",
"plan": "Enterprise",
"activeSeats": 128,
"monthsActive": 20,
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Keystone Auto Supply",
"industry": "Automotive parts distribution",
"plan": "Growth",
"activeSeats": 54,
"monthsActive": 14,
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Summit Beverage Co.",
"industry": "Food & beverage",
"plan": "Enterprise",
"activeSeats": 88,
"monthsActive": 24,
"outcome": "+9 pts fill-rate visibility",
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
},
{
"company": "Fairwind Freight Brokerage",
"industry": "Freight brokerage / 3PL",
"plan": "Growth",
"activeSeats": 47,
"monthsActive": 16,
"status": "verified",
"verifiedVia": "customer-authorized read-only usage attestation"
}
],
"aggregate": [
{
"label": "Paying enterprise customers",
"value": "137"
},
{
"label": "Shipments tracked in the trailing 90 days",
"value": "3.9M"
},
{
"label": "Rolling 90-day platform availability",
"value": "99.94%"
}
],
"signatureMeaning": "A valid Ed25519 signature proves this record was issued by Letterprove (key at did:web:letterprove.com) and has not been altered. Each named customer consented and was verified via read-only usage attestation.",
"methodology": {
"summary": "Each participating customer grants Letterprove a read-only, scoped token. Letterprove reads usage counters (active seats, activity, tenure) and, where the customer opts in, an outcome metric — never customer content. Figures are canonicalized (RFC 8785 JCS), hashed (SHA-256) and signed with a domain-bound Ed25519 key. The coverage block discloses exactly how representative the shown sample is.",
"principles": [
"Named customers consented to be attested.",
"Read-only usage counters — never customer content.",
"Coverage percentile disclosed — no cherry-picking hidden.",
"Signed and independently verifiable — verify, don't trust."
]
},
"verification": {
"signatureAlgorithm": "Ed25519",
"proofType": "JcsEd25519Signature2026",
"canonicalization": "RFC 8785 JCS (sorted keys, UTF-8, no whitespace)",
"digestAlgorithm": "SHA-256",
"didDocumentUrl": "https://letterprove.com/.well-known/did.json",
"jwksUrl": "https://letterprove.com/.well-known/letterprove/jwks.json",
"verificationMethod": "did:web:letterprove.com#key-1"
},
"proof": {
"type": "JcsEd25519Signature2026",
"created": "2026-08-06T17:00:00Z",
"verificationMethod": "did:web:letterprove.com#key-1",
"canonicalization": "RFC 8785 JCS (sorted keys, UTF-8, no whitespace)",
"digestAlgorithm": "SHA-256",
"digestValue": "EJEkbOXOxHVv3Imb2kQs9pdv8wQgZqm7sJMWbXXv_N8",
"signatureAlgorithm": "Ed25519",
"publicKeyHex": "6b33375e599241830259a72c36a894ef681a3e32be8feecd16247503840ee146",
"publicKeyMultibase": "z6MkmfixvnU4qoxQhekrPUrEddZ9QaTgWx3TrJKaobhVdu5o",
"signatureValue": "L8x-994lYS1AUt0j_g2nNger-QcqV7qK0khMcQXOgKQZxOkDcvk9aPjRmFawWzTD8sb33mudMxkoAOrEuwGKAw"
}
}
Custody & scope. Letterprove is the independent attestation service; in production it operates arm's-length from the subject with segregated key custody. Participating customers grant read-only, scoped access; Letterprove reads usage counters (seats, activity, tenure) — never customer content — and signs the result. This is a demonstration: the subject and customer identities are illustrative and the signing key is a demo key. This copy is served from the vendor's own domain; the canonical signed record is hosted independently by Letterprove.
Attestation att_cargoline_9c171aa0. Canonical: https://letterprove.com/proof/cargoline.