eciespy

eciespy

Elliptic Curve Integrated Encryption Scheme for secp256k1 in Python.

Other language versions:

• Rust
• TypeScript
• Golang
• WASM

You can also check a FastAPI web backend demo here.

Install

pip install eciespy

Quick Start

>>> from ecies.utils import generate_eth_key, generate_key
>>> from ecies import encrypt, decrypt
>>> eth_k = generate_eth_key()
>>> sk_hex = eth_k.to_hex()  # hex string
>>> pk_hex = eth_k.public_key.to_hex()  # hex string
>>> data = b'this is a test'
>>> decrypt(sk_hex, encrypt(pk_hex, data))
b'this is a test'
>>> secp_k = generate_key()
>>> sk_bytes = secp_k.secret  # bytes
>>> pk_bytes = secp_k.public_key.format(True)  # bytes
>>> decrypt(sk_bytes, encrypt(pk_bytes, data))
b'this is a test'

Or just use a builtin command eciespy in your favorite command line.

API

ecies.encrypt(receiver_pk: Union[str, bytes], msg: bytes) -> bytes

Parameters:

• receiver_pk - Receiver's public key (hex str or bytes)
• msg - Data to encrypt

Returns: bytes

ecies.decrypt(receiver_sk: Union[str, bytes], msg: bytes) -> bytes

Parameters:

• receiver_sk - Receiver's private key (hex str or bytes)
• msg - Data to decrypt

Returns: bytes

Command Line Interface

Show help

$ eciespy -h
usage: eciespy [-h] [-e] [-d] [-g] [-k KEY] [-D [DATA]] [-O [OUT]]

Elliptic Curve Integrated Encryption Scheme for secp256k1 in Python

optional arguments:
  -h, --help            show this help message and exit
  -e, --encrypt         encrypt with public key, exclusive with -d
  -d, --decrypt         decrypt with private key, exclusive with -e
  -g, --generate        generate ethereum key pair
  -k KEY, --key KEY     public or private key file
  -D [DATA], --data [DATA]
                        file to encrypt or decrypt, if not specified, it will
                        read from stdin
  -O [OUT], --out [OUT]
                        encrypted or decrypted file, if not specified, it will
                        write to stdout

Generate eth key

$ eciespy -g
Private: 0x95d3c5e483e9b1d4f5fc8e79b2deaf51362980de62dbb082a9a4257eef653d7d
Public: 0x98afe4f150642cd05cc9d2fa36458ce0a58567daeaf5fde7333ba9b403011140a4e28911fcf83ab1f457a30b4959efc4b9306f514a4c3711a16a80e3b47eb58b
Address: 0x47e801184B3a8ea8E6A4A7A4CFEfEcC76809Da72

Encrypt with public key and decrypt with private key

$ echo '0x95d3c5e483e9b1d4f5fc8e79b2deaf51362980de62dbb082a9a4257eef653d7d' > sk
$ echo '0x98afe4f150642cd05cc9d2fa36458ce0a58567daeaf5fde7333ba9b403011140a4e28911fcf83ab1f457a30b4959efc4b9306f514a4c3711a16a80e3b47eb58b' > pk
$ echo 'hello ecies' | eciespy -e -k pk | eciespy -d -k sk
hello ecies
$ echo 'data to encrypt' > data
$ eciespy -e -k pk -D data -O enc_data
$ eciespy -d -k sk -D enc_data
data to encrypt
$ rm sk pk data enc_data

Configuration

Ephemeral key format in the payload and shared key in the key derivation can be configured as compressed or uncompressed format.

SymmetricAlgorithm = Literal["aes-256-gcm", "xchacha20"]
NonceLength = Literal[12, 16]  # only for aes-256-gcm, xchacha20 will always be 24

COMPRESSED_PUBLIC_KEY_SIZE = 33
UNCOMPRESSED_PUBLIC_KEY_SIZE = 65


@dataclass()
class Config:
    is_ephemeral_key_compressed: bool = False
    is_hkdf_key_compressed: bool = False
    symmetric_algorithm: SymmetricAlgorithm = "aes-256-gcm"
    symmetric_nonce_length: NonceLength = 16

    @property
    def ephemeral_key_size(self):
        return (
            COMPRESSED_PUBLIC_KEY_SIZE
            if self.is_ephemeral_key_compressed
            else UNCOMPRESSED_PUBLIC_KEY_SIZE
        )


ECIES_CONFIG = Config()

On is_ephemeral_key_compressed = True, the payload would be like: 33 Bytes + AES instead of 65 Bytes + AES.

On is_hkdf_key_compressed = True, the hkdf key would be derived from ephemeral public key (compressed) + shared public key (compressed) instead of ephemeral public key (uncompressed) + shared public key (uncompressed).

On symmetric_algorithm = "xchacha20", plaintext data would be encrypted with XChaCha20-Poly1305.

On symmetric_nonce_length = 12, then the nonce of AES-256-GCM would be 12 bytes. XChaCha20-Poly1305's nonce is always 24 bytes.

For compatibility, make sure different applications share the same configuration.

Technical details

They are moved to DETAILS.md.

Changelog

See CHANGELOG.md.