RSA encrypts data with private key and decrypts data with public key (not a signature verification process)

RSA Encrypt data with private key and decrypt data with public key , Strictly speaking , Is not safe . But recently I'm writing a keygen When , This is what software authors use , So we can only have one such .

Some of the conventional ones rsa password utils There is no such function . Only sealed sign and verify function . But we don't need the inside hash function . So pick it out separately for use .

https://github.com/sybrenstuvel/python-rsa

  Clone this warehouse . Time of my cloning ‎ by ：2022‎ year ‎7‎ month ‎21‎ Japan ,‏‎22:55:29.

  The last item commit hash：c4dc7beb04bea05ed86adb2e4b7f780f173774b8

It needs to be pip install rsa, And then in python Of site-packages Modify the corresponding pkcs1.py Document and __init__ file . And then directly import rsa that will do

def encrypt_by_privkey(msg: bytes, priv_key: key.PrivateKey) -> bytes:
    # Encrypt the msg with the private key
    cleartext = msg
    keylength = common.byte_size(priv_key.n)
    padded = _pad_for_signing(cleartext, keylength)

    payload = transform.bytes2int(padded)
    encrypted = priv_key.blinded_encrypt(payload)
    block = transform.int2bytes(encrypted, keylength)

    return block

def decrypt_by_pubkey(encrypted: bytes, pub_key: key.PublicKey) -> bytes:
    keylength = common.byte_size(pub_key.n)
    payload = transform.bytes2int(encrypted)
    decrypted = core.decrypt_int(payload, pub_key.e, pub_key.n)
    clearsig = transform.int2bytes(decrypted, keylength)
    sep_idx = clearsig.find(b"\x00", 2)
    
    return clearsig[sep_idx + 1 :]

Add the revision code above rsa/pkcs1.py in .

  After the modification rsa/__init__.py

from rsa.pkcs1 import (
    encrypt,
    decrypt,
    encrypt_by_privkey,
    decrypt_by_pubkey,
    sign,
    verify,
    DecryptionError,
    VerificationError,
    find_signature_hash,
    sign_hash,
    compute_hash,
)

 

__all__ = [
    "newkeys",
    "encrypt",
    "decrypt",
    "sign",
    "verify",
    "PublicKey",
    "PrivateKey",
    "DecryptionError",
    "VerificationError",
    "find_signature_hash",
    "compute_hash",
    "sign_hash",
    "encrypt_by_privkey",
    "decrypt_by_pubkey"
]

   "encrypt_by_privkey",

    "decrypt_by_pubkey"

Then you can encrypt ordinary content with the private key , Public key decrypts ordinary content .

Cloned python-rsa-main Change the name of this folder to py_rsa. After that py_rsa New in the same directory py file ：

import py_rsa.rsa as rsa
import base64

pub = rsa.PublicKey.load_pkcs1_openssl_pem(open('pubkey.pem').read())
priv = rsa.PrivateKey.load_pkcs1(open('privkey.pem').read())

message = 'hello world now'.encode()
e = rsa.encrypt_by_privkey(message, priv)
d = rsa.decrypt_by_pubkey(e, pub)
print(d)
print(base64.b64encode(e).decode())

Output ：

b'hello world now'
l2zTjZeDrrz2LHTQGn0QFzSYN81W4pYOnuuQrPGPEafh12rwX1rTGYhnuEpNVaghWmXDen45QWoWD3YZvWbOfbA5KMqmJph3UlVu0zvWXNQrSlg9ILJOjfCOdqQLyqzkEtoijIsDWKbr1lr5prh+GOHHPOmlF/jG95Dw2E5YZzU=

Use website tools to detect ：

http://tool.chacuo.net/cryptrsapubkey

success .