> For the complete documentation index, see [llms.txt](https://docs.learncard.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.learncard.com/understand/decentralized-identifiers-dids/seed-phrases.md).

# Seed Phrases

The 64-character hex seed behind a server-side LearnCard identity — how to generate it, what it controls, and how to keep it.

When your server runs `initLearnCard({ seed })`, the seed is the whole identity. Every key, and therefore the DID and every signature, is derived from it deterministically. Same seed, same identity — on any machine, forever.

## What a seed is

A **64-character hexadecimal string**: 32 bytes of randomness. Not a list of words.

```bash
node -e "console.log(require('node:crypto').randomBytes(32).toString('hex'))"
```

Or in a browser: `Array.from(crypto.getRandomValues(new Uint8Array(32)), b => b.toString(16).padStart(2, '0')).join('')`.

Two things to know about how it's read:

* A non-hex string throws.
* A hex string shorter than 64 characters is left-padded with zeros, so `'1'` and `'000…001'` are the same seed. Don't rely on this — always pass the full 64 characters.

## What it controls

Whoever has the seed **is** the identity. They can sign credentials as you, read your encrypted storage, and change your profile. There's no password reset: if the seed leaks, revoke what you can and create a new identity; if you lose it, the identity is gone.

Rotating a seed means a new DID. Recipients' credentials still verify (the old DID still resolves), but new credentials come from a new issuer. Pick your production seed before you issue anything you care about.

## Keeping it

* **Read it from a secrets manager or environment variable at startup.** Never in source code, never in git, never in a client-side bundle.
* **One seed per identity, one identity per purpose.** Your production issuer and your staging issuer should be different seeds; the same seed produces the same `did:key` on every network.
* **Back it up like a root credential.** If the only copy is in one server's env file, one bad deploy loses the identity.

## Seeds vs. seed phrases

Cryptocurrency wallets use 12–24 word **mnemonic phrases** (BIP-39) as a human-friendly encoding of the same kind of randomness. LearnCard's `seed` parameter takes the hex directly. You could encode a seed as a phrase for offline backup and decode it before passing it in, but the SDK doesn't do that for you.

## When you don't need one

End users of the LearnCard app never see a seed. Their key is generated for them and split into shares — see [Key Management (SSS)](/understand/decentralized-identifiers-dids/key-management-sss.md). A seed is for **your server, bot, or CLI**: something that runs unattended and needs a stable identity. If you'd rather not hold one at all, use an API token and let LearnCard sign for you — see [Who Signs Your Credentials?](/build/send-credentials/create-signing-authority.md).


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://docs.learncard.com/understand/decentralized-identifiers-dids/seed-phrases.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.