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zefer-cli — Library (programmatic API)

zefer-cli is three channels over one core:

Channel Entry Use it for
CLI zefer … (bin) Humans & shell scripts
MCP server zefer mcp AI agents (Claude, Cursor, …) — see MCP.md
Library import "zefer-cli" Your own Node.js code, services, AWS Lambda

All three produce byte-for-byte compatible .zefer files, fully decryptable in the web app at zefer.carrillo.app and vice-versa.

The library entry (src/lib.ts → dist/lib.js / dist/lib.cjs) contains no Ink, no React, no Commander and no process.argv parsing — importing it has zero side effects, so it is safe in any Node 20+ runtime.

Install

npm install zefer-cli

Import

// ESM / TypeScript
import { encodeZefer, decodeZefer } from "zefer-cli";

// CommonJS
const { encodeZefer, decodeZefer } = require("zefer-cli");

Ships ESM (dist/lib.js) and CommonJS (dist/lib.cjs) builds with full TypeScript declarations (dist/lib.d.ts / dist/lib.d.cts).

The package bin (zefer / zefer-cli) is unchanged and independent — the library is the package's default import; the CLI is reached through the bin.

Quick start

import { encodeZefer, decodeZefer } from "zefer-cli";
import { readFile, writeFile } from "node:fs/promises";

// ── Encrypt text ──────────────────────────────────────────────
const buf = await encodeZefer({
  content: "api_key=abc123",
  passphrase: "a-strong-passphrase",
  fileName: null,
  expiresAt: 0,            // 0 = never; otherwise a Unix-ms timestamp
  compression: "gzip",     // "none" | "gzip" | "deflate" | "deflate-raw"
  iterations: 600_000,     // explicit — see "Iterations" below
});
await writeFile("secret.zefer", buf);

// ── Decrypt ───────────────────────────────────────────────────
const bytes = await readFile("secret.zefer");
const res = await decodeZefer(bytes.toString("utf-8"), "a-strong-passphrase", {
  rawBytes: bytes,         // required for ZEFB3/ZEFR3 binary files
});

if (res.ok) {
  console.log(res.payload.content);   // text mode → string
  // res.payload.fileData              // file mode → Buffer
  // res.payload.meta                  // ZeferMeta (createdAt, expiresAt, …)
} else {
  console.error(res.error);           // "wrong_passphrase" | "expired" | …
}

Encrypt a file (file mode)

const data = await readFile("photo.jpg");
const buf = await encodeZefer({
  fileData: data,
  fileName: "photo.jpg",
  fileType: "image/jpeg",
  passphrase: "a-strong-passphrase",
  expiresAt: 0,
  iterations: 600_000,
});

Inspect the public header without decrypting

import { parseFile } from "zefer-cli";

const bytes = await readFile("secret.zefer");
const parsed = parseFile(bytes.toString("utf-8"), bytes);
if (parsed) {
  console.log(parsed.header.mode);        // "text" | "file"
  console.log(parsed.header.iterations);  // KDF strength
  console.log(parsed.header.hint);        // public hint (if any)
}

Security layers

Everything the CLI/MCP support is available here. Each lives inside the encrypted payload (ZeferMeta), invisible without the passphrase.

const buf = await encodeZefer({
  content: "top secret",
  passphrase: "primary-pass",
  fileName: null,
  expiresAt: Date.now() + 60 * 60_000,      // expires in 60 minutes

  // Dual passphrase — two-person authorization
  secondPassphrase: "second-pass",
  dualKey: true,

  // Reveal key — recipients decrypt without the main passphrase (→ ZEFR3)
  revealKey: "share-this-key",

  // Secret question (answer is PBKDF2-hashed)
  question: "Project codename?",
  questionAnswer: "bluebird",

  // Public, unencrypted metadata
  hint: "rotate quarterly",
  note: "owned by platform team",

  maxAttempts: 5,                            // 0 = unlimited
  allowedIps: ["203.0.113.4", "2001:db8::1"],
  iterations: 1_000_000,
});

Decrypting a protected file:

const res = await decodeZefer(bytes.toString("utf-8"), "primary-pass", {
  rawBytes: bytes,
  secondPassphrase: "second-pass",  // for dual-key files
  questionAnswer: "bluebird",       // if the file has a secret question
});

Key generation & password analysis

The same engine behind zefer keygen and zefer analyze (in src/lib/passwords.ts):

import {
  generateValue, generateWithOptions, MODES, CHARSETS,
  analyzePassword, crackBucketFor, complianceOf, ATTACK_SCENARIOS,
} from "zefer-cli";

// 7 modes: unicode | secure | alpha | hex | base58 | pin | uuid
generateValue("secure", 64);
generateValue("uuid", 0);                                  // UUID v7 (length ignored)

generateWithOptions("base58", 24, {
  excludeAmbiguous: true,    // drop 0 O 1 l I
  excludeChars: "/\\",
  requireAllClasses: true,   // guarantee lower/upper/digit/symbol when available
  noRepeats: true,           // never the same char twice in a row
  groupSize: 6,              // cosmetic dashes every 6 chars
});

const a = analyzePassword("Tr0ub4dor&3");
a.score;            // 0–4 (very weak → strong)
a.effectiveBits;    // entropy after structural penalties
a.warnings;         // ["common", "sequence", …]

Low-level primitives

For custom pipelines (e.g. envelope encryption, your own container format):

import {
  // string helpers (base64 envelope: "salt.iv.ciphertext")
  encrypt, decrypt, encryptBytesToBase64, decryptFromBase64,
  // raw buffers
  encryptRaw, decryptFromBinary,
  // chunked (16 MB) — constant active memory per chunk
  chunkedEncrypt, chunkedDecryptToBuffer, CHUNK_SIZE,
  // KDF & dual-key
  deriveKey, combineDualKeys, hashAnswer, benchmarkDevice,
  // compression
  compressBytes, decompressBytes, smartCompress,
} from "zefer-cli";

const token = await encrypt("hello", "pass", 600_000);     // → "salt.iv.ct"
const back  = await decrypt(token, "pass", 600_000);       // → "hello"

API reference

encodeZefer(options): Promise<Buffer>

Encrypts content (text) or fileData (file) into the .zefer binary format. Returns the full file as a Buffer.

EncodeOptions (key fields):

Field Type Notes
content string? Text mode payload
fileData Buffer? File mode payload (takes precedence)
passphrase string Required
fileName string | null Required (use null for text mode)
expiresAt number Required. Unix ms, 0 = never
fileType string? MIME type (file mode)
iterations number? PBKDF2 rounds, default 600_000
compression "none"|"gzip"|"deflate"|"deflate-raw"? default "none"
secondPassphrase, dualKey dual-key (two-person)
revealKey string? produces a ZEFR3 dual-block file
question, questionAnswer secret question
hint, note public (unencrypted) metadata
maxAttempts number? 0 = unlimited
allowedIps string[]? IPv4/IPv6 allowlist
onProgress callbacks optional progress hooks

decodeZefer(fileContent, passphrase, options?): Promise<DecodeResult>

type DecodeResult =
  | { ok: true;  payload: ZeferPayload; header: ZeferHeader }
  | { ok: false; error: DecodeError };

type DecodeError =
  | "invalid_format" | "wrong_passphrase" | "expired"
  | "wrong_answer"   | "max_attempts"     | "ip_blocked" | "needs_answer";

Pass binary bytes via options.rawBytes. options also accepts secondPassphrase, questionAnswer and onProgress.

parseFile(fileContent, rawBytes?): ParsedFile | null

Reads the public header (and locates the encrypted blocks) without decrypting. Returns null if the bytes are not a recognized .zefer file.

Full export list

  • Format: encodeZefer, decodeZefer, parseFile + types ZeferHeader, ZeferMeta, ZeferPayload, EncodeOptions, DecodeResult, DecodeError, ParsedFile
  • Crypto primitives: encrypt, decrypt, encryptBytesToBase64, decryptFromBase64, encryptRaw, decryptFromBinary, deriveKey, combineDualKeys, hashAnswer, benchmarkDevice, toBase64, fromBase64, encodeText, decodeBytes
  • Chunked: chunkedEncrypt, chunkedDecryptToBuffer, CHUNK_SIZE, ChunkedEncryptResult
  • Compression: compressBytes, decompressBytes, smartCompress, CompressionMethod
  • Keygen / analysis: generateValue, generateWithOptions, entropyOf, charsetFor, MODES, CHARSETS, DEFAULT_GENERATE_OPTIONS, analyzePassword, bucketCrackTime, crackBucketFor, toSuperscript, complianceOf, keyspaceExponent, ATTACK_SCENARIOS, AVERAGE_HUMAN_BITS
    • types KeygenMode, GenerateOptions, PasswordAnalysis, PasswordWarning, CrackSpeed, CrackBucket, ScenarioKey, ComplianceCheck
  • Attempt counter: getAttempts, setAttempts, removeAttempts

Operational notes (Lambda / microservices)

Memory. encodeZefer/decodeZefer operate in-memory. AES runs in 16 MB chunks (constant active memory) but the full input and output are held in RAM, so peak ≈ input + output size. For ~100 MB payloads, give the function ≥ 512 MB. (A true streaming Transform API with constant memory is a possible future addition — open an issue if you need it.)

Iterations. Always pass an explicit iterations (default 600_000). The -i 0 auto-benchmark is a CLI-only convenience and is not part of the library path, so there is no per-invocation PBKDF2 calibration cost on cold start.

Attempt counter. When a file sets maxAttempts, decodeZefer reads/writes ~/.zefer/attempts.json. On read-only or ephemeral filesystems this is a non-fatal no-op (write failures are swallowed).

No network, no telemetry. Everything runs locally; passphrases never leave the process.

Cross-channel compatibility

A file produced by any channel decrypts in every other:

// File written by `zefer encrypt secret.txt -p pass` (CLI)
const bytes = await readFile("secret.txt.zefer");
const res = await decodeZefer(bytes.toString("utf-8"), "pass", { rawBytes: bytes });
// res.payload.fileData → original bytes

The smoke-test suite (npm test) asserts this round-trip across CLI ⇄ library and ESM ⇄ CJS on every build.