ncr-cipher 1.0.0

Production-grade NCR3 encryption tool — encrypt, decrypt, and verify files from any terminal.

ncr-cipher

Production-grade NCR3 encryption tool — a single ncr command available everywhere in the terminal after installation, on Windows, macOS, and Linux.

Installation

pip install ncr-cipher

Or install from source:

pip install -e .

Quick Start

# Generate a key file
ncr --keygen mykey.key

# Encrypt a file
ncr --lock secret.txt --key mykey.key

# Decrypt a file
ncr --unlock secret.txt.ncr3 --key mykey.key

# Verify integrity without decrypting
ncr --verify secret.txt.ncr3 --key mykey.key

# Show file info (no password needed)
ncr --info secret.txt.ncr3

Commands

Command	Description
ncr --keygen <keyfile>	Generate a new key file
ncr --lock <file> --key <k>	Encrypt a file
ncr --unlock <file> --key <k>	Decrypt a file
ncr --verify <file> --key <k>	Check HMAC without decrypting
ncr --info <file>	Show NCR version, IV, block count, file size
ncr --bench	Benchmark KDF time + encrypt speed
ncr --test	Run internal self-tests
ncr --version	Print version

Flags

Flag	Description
--out, -o <path>	Output path override
--inplace, -i	Overwrite the original file
--silent, -s	No output except errors
--force, -f	Overwrite output without confirmation
--strength <1-5>	KDF strength preset (keygen only)

Cipher: NCR3

• KDF: scrypt with configurable strength (5 presets)
• Per-byte key mixing: BLAKE2b-derived per-position keys
• CBC chaining: HMAC-SHA3-256 stream + ciphertext feedback
• Authentication: HMAC-SHA3-256 over full ciphertext
• Math core: nCr (binomial coefficient) based encryption mod 2¹²⁷−1

Backwards compatible: can read NCR2 files (read-only).

Requirements

• Python 3.9+
• Zero external dependencies — stdlib only

License

MIT