Lianja Requires Chilkat v11.0.0+

RSA Encrypt String to Encoded Result and Reverse

See more RSA Examples

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

llSuccess = .F.

//  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.

//  Load our 2048-bit RSA public key.
loPubKey = createobject("CkPublicKey")
//  In all Chilkat methods expecting a path, you pass either absolute or relative paths.
llSuccess = loPubKey.LoadFromFile("rsaKeys/myTestRsaPublic.pem")
if (llSuccess = .F.) then
    ? loPubKey.LastErrorText
    release loPubKey
    return
endif

loRsa = createobject("CkRsa")

//  Tell RSA to use the public key.
loRsa.UsePublicKey(loPubKey)

//  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.
loRsa.Charset = "utf-8"
loRsa.EncodingMode = "base64"

//  Be Careful when Using non-us-ascii String Literals in Source Code
lcEncryptedB64 = loRsa.EncryptStringENC("Élève français dîne à côté d’un café où l’on sert déjà du gâteau au chocolat et des éclairs délicieux",.F.)

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

//  Load the matching 2048-bit RSA private key.
loPrivKey = createobject("CkPrivateKey")
lcPassword = "secret"
llSuccess = loPrivKey.LoadAnyFormatFile("rsaKeys/myTestRsaPrivate.pem",lcPassword)
if (llSuccess = .F.) then
    ? loPrivKey.LastErrorText
    release loPubKey
    release loRsa
    release loPrivKey
    return
endif

//  Tell the RSA object to use the private key.
loRsa.UsePrivateKey(loPrivKey)

//  Indicate that after decrypting the resultant decrypted bytes contains the utf-8 byte representation of the text.
loRsa.Charset = "utf-8"
loRsa.EncodingMode = "base64"
lcOriginalText = loRsa.DecryptStringENC(lcEncryptedB64,.T.)
if (llSuccess = .F.) then
    ? loRsa.LastErrorText
    release loPubKey
    release loRsa
    release loPrivKey
    return
endif

? "Original text = " + lcOriginalText
? "Success."


release loPubKey
release loRsa
release loPrivKey