01Why defensible
Anyone can write a tool that exports email. Defensibility means the export can survive a motion to compel, a Rule 901 authenticity challenge, and a hostile cross-examination about chain of custody. That requires three things — cryptographic hashing, RFC 3161 timestamping, and a human-legible manifest — combined in a way any reviewer can re-verify on their own.
02The three pillars
01
A hash proves a specific byte sequence existed. If even one bit of a collected file changed after Krellix wrote it — accidentally or otherwise — the hash stops matching. A reviewer can run a one-line command and get a yes/no on every file in the export.
SHA-256 · MD5
02
A third-party timestamp proves the collection existed by a specific moment. Without it, the collection's timestamps are metadata your adversary can claim was fabricated. With it, the claim becomes a forgery allegation against DigiCert.
RFC 3161 · TSA signature
03
A manifest records who the operator was, who the custodian was, what tenant the collection was pulled from, what query produced the results, and what counts came back. Combined with the hash and timestamp, it tells the entire authentication story on a single page.
ChainOfCustody.json
03Hashing
SHA-256 is the modern cryptographic standard. MD5 is legacy — it's no longer collision-resistant, but most eDiscovery tooling from the 2010s still treats an MD5 match as the primary deduplication signal. Krellix writes both because the review platform your reviewer uses may insist on one or the other, and having both is cheaper than re-collecting.
What the hash proves
The hash files Krellix writes are plain text, in the standardsha256sum/md5sumformat. Any reviewer with a Linux or macOS terminal can runsha256sum -c Hashes.sha256.txtand get a pass/fail on every file in the export.
04RFC 3161 timestamping
A file hash proves that a specific byte sequence existed. A RFC 3161 timestamp proves that specific byte sequence existed by a specific moment. Without a third-party timestamp, every timestamp in a collection is just metadata your opposing counsel can argue was forged. With one, the argument becomes a claim against DigiCert's public signing key.
Krellix SHA-256 hashes ChainOfCustody.json after it finishes the collection. The hash, not the file itself, is what gets sent to the TSA — so no collection contents leave your machine.
Krellix wraps the hash in a TimeStampReq (RFC 3161 section 3.2) and POSTs it to a public Time Stamp Authority. The response is a TimeStampResp signed by the TSA's private key. The response embeds the hash, the exact UTC time the TSA received the request, and the TSA certificate chain.
The .tsr file is stored in 07_TimestampMaterials alongside the TSA public certificate and re-verification instructions. Any reviewer with OpenSSL can re-validate the chain themselves — no Krellix required.
DigiCert is the default TSA. If the DigiCert TSA is unavailable at collection time, Krellix automatically falls back to Sectigo, then GlobalSign — all three are WebTrust-audited commercial TSAs. The TSA used is recorded in the manifest so verification knows which public key to validate against.
05The artifact itself
This is an excerpt. The real file is longer — one entry per collected file — but every Krellix manifest has this shape. Opposing counsel or an expert reviewer can read it without special tooling, and it tells them exactly who collected what, from whom, when, and under what query.
{
"manifestVersion": "3.1",
"product": "Krellix Mail 3.1.0",
"collectionId": "krx-2026-0418-a41c9e",
"startedUtc": "2026-04-18T13:22:41Z",
"completedUtc": "2026-04-18T13:47:05Z",
"operator": {
"upn": "j.rourke@millerscottlaw.com",
"displayName": "Jordan Rourke",
"oid": "f8a1d6c2-7b39-4d5e-a0f2-3c71b2e94a6d"
},
"tenant": {
"tenantId": "c1d7f2b0-9a3e-4b5c-8d71-2e4f60a81c93",
"tenantDomain": "millerscottlaw.onmicrosoft.com"
},
"custodian": {
"upn": "d.marquez@millerscottlaw.com",
"displayName": "Diana Marquez",
"mailboxType": "UserMailbox"
},
"query": {
"mode": "Enterprise",
"endpoint": "/users/d.marquez@millerscottlaw.com/messages",
"kqlFilter": "receivedDateTime ge 2025-09-01T00:00:00Z and receivedDateTime lt 2026-03-01T00:00:00Z"
},
"counts": {
"messages": 4182,
"attachments": 1776,
"deduplicated": 312
},
"firstItem": {
"graphId": "AAMkAGRhYzkyMTk4LWY4OWMtNDA3OC1hY2UxLTA0ZWUzMjE1ZTRjMABGAAAAAAD",
"subject": "Re: Q3 renewal — revised terms",
"receivedUtc": "2025-09-03T14:08:22Z",
"sha256": "9f2a5c3b0e8d4f1726a9b4e7d0c8f391a2b5e6c8d9f0a1b2c3d4e5f6a7b8c9d0",
"md5": "b4a7c1e2f3d4a5b6c7d8e9f0a1b2c3d4"
},
"timestamp": {
"tsa": "http://timestamp.digicert.com",
"policyOid": "2.16.840.1.114412.7.1",
"serialNumber": "07:8e:3a:4c:92:5d:11:f0:c8:6a:2b:41:9e:5d:03:88",
"timestampedUtc": "2026-04-18T13:47:18Z",
"tokenPath": "07_TimestampMaterials/manifest.tsr",
"hashAlgorithm": "SHA-256",
"manifestDigest": "2b9e07f1a4c8d6b5e3f0921a74c6d8b9e1f0a2b3c4d5e6f7a8b9c0d1e2f3a4b5"
}
}06 · Legal framework
Krellix's output is shaped by these four sources. Your jurisdiction may have additional rules — Krellix doesn't relieve you of the obligation to check.
FRE 901(a)
The proponent must produce evidence sufficient to support a finding that the item is what the proponent claims. For a digital collection, that means you can explain where it came from, who collected it, how it was preserved, and demonstrate that it hasn't been altered. The Krellix manifest and hash manifest answer those four questions in writing.
FRE 902(14)
Added in 2017. Certified electronic data authenticated by a cryptographic hash is self-authenticating if the process is described by a qualified person. This is the specific rule that makes SHA-256 admissible without additional foundation witnesses for the hash itself — you still need the foundation for the collection process, but the integrity proof is automatic.
FRCP 26(f) + 34
The meet-and-confer obligation requires parties to discuss preservation at the outset. Producing a defensibly-collected set — one with hashes and a chain-of-custody manifest — preempts fights over form and completeness. The Sedona Conference commentaries recommend this approach specifically for avoiding motions to compel re-production.
RFC 3161
The IETF standard for public-key timestamping. A TSA signs a hash of your data together with a trusted timestamp, producing a token any third party can verify against the TSA's certificate chain. Krellix uses DigiCert, Sectigo, and GlobalSign — all WebTrust-audited public TSAs whose timestamps are accepted by Adobe Reader, OpenSSL, and every major forensics tool.
Disclosure
The product produces artifacts that are widely accepted as defensible — industry-standard hashes and a public TSA timestamp, with documentation a third party can verify. Whether any specific collection is admissible in any specific matter depends on jurisdiction, opposing counsel, the judge, the scope of the hold, and facts about the custodian that Krellix can't know. We do not guarantee admissibility. If you're on a matter with real stakes, a qualified attorney should review your preservation plan before collection. That's true with or without Krellix.
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