CkPython

RSA Encrypt String to Encoded Result and Reverse

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Demonstrates how to RSA encrypt a string to a base64 encoded result, and the reverse. CkPython

import sys
import chilkat

success = False

# The RSA public key is used for encryption, and the private key for decryption.

# The public key's role is to make encryption accessible to anyone while ensuring that
# only the private key holder can decrypt the messages.
# The public key is designed to be widely distributed so anyone can use it to encrypt messages
# intended for the owner of the private key.

glob = chilkat.CkGlobal()
glob.put_DefaultUtf8(True)

# Load our 2048-bit RSA public key.
pubKey = chilkat.CkPublicKey()
# In all Chilkat methods expecting a path, you pass either absolute or relative paths.
success = pubKey.LoadFromFile("rsaKeys/myTestRsaPublic.pem")
if (success == False):
    print(pubKey.lastErrorText())
    sys.exit()

rsa = chilkat.CkRsa()

# Tell RSA to use the public key.
rsa.UsePublicKey(pubKey)

# RSA encryption is for small amounts of data, on the order of 200 bytes or less.
# The maximum number of bytes that can be RSA encrypted depends
# on the RSA key size and padding scheme (OAEP padding vs PKCS#1 v1.5 padding).
# For specific limits, see: RSA Encryption Maximum Number of Bytes

# Encrypt the utf-8 byte representation of the string.
rsa.put_Charset("utf-8")
rsa.put_EncodingMode("base64")

# Be Careful when Using non-us-ascii String Literals in Source Code
encryptedB64 = rsa.encryptStringENC("Élève français dîne à côté d’un café où l’on sert déjà du gâteau au chocolat et des éclairs délicieux",False)

# ------------------------------------------------------------------------------------------------------------------------
# Let's decrypt, which requires the matching private key...

# Load the matching 2048-bit RSA private key.
privKey = chilkat.CkPrivateKey()
password = "secret"
success = privKey.LoadAnyFormatFile("rsaKeys/myTestRsaPrivate.pem",password)
if (success == False):
    print(privKey.lastErrorText())
    sys.exit()

# Tell the RSA object to use the private key.
rsa.UsePrivateKey(privKey)

# Indicate that after decrypting the resultant decrypted bytes contains the utf-8 byte representation of the text.
rsa.put_Charset("utf-8")
rsa.put_EncodingMode("base64")
originalText = rsa.decryptStringENC(encryptedB64,True)
if (success == False):
    print(rsa.lastErrorText())
    sys.exit()

print("Original text = " + originalText)
print("Success.")