B4X Requires Chilkat v11.0.0+

RSA Encrypt and Decrypt Credit Card Numbers

See more RSA Examples

_LANGUAGE_ sample code to RSA public-key encrypt and decrypt credit card numbers. The RSA key is loaded from an unencrypted PKCS8 file. Chilkat provides many ways of setting the key -- loading from both encrypted and unencrypted PEM, PKCS8, DER, PVK, etc. Keys may be loaded from files or in-memory representations. (The RSA component also provides the ability to generate RSA keys.) B4X

Dim success As Boolean = False

'  This example assumes the Chilkat API to have been previously unlocked.
'  See Global Unlock Sample for sample code.

Dim rsa As ChilkatRsa
rsa.Initialize

Dim privKey As ChilkatPrivateKey
privKey.Initialize("privKey")

'  Load an RSA private key from a file:
success = privKey.LoadAnyFormatFile("rsaPrivateKey.key", "")
If success = False Then
    Log(privKey.LastErrorText)
    Return
End If


'  Get the public part of the private key.
Dim pubKey As ChilkatPublicKey
pubKey.Initialize
privKey.ToPublicKey(pubKey)

success = rsa.UsePublicKey(pubKey)
If success = False Then
    Log(rsa.LastErrorText)
    Return
End If


'  Encrypt a VISA credit card number:
'  1234-5678-0000-9999
Dim ccNumber As String = "1234567800009999"

Dim usePrivateKey As Boolean = False
rsa.EncodingMode = "base64"
Dim encryptedStr As String = rsa.EncryptStringENC(ccNumber, usePrivateKey)
Log("Encrypted:")
Log(encryptedStr)

'  Now decrypt:
Dim rsaDecryptor As ChilkatRsa
rsaDecryptor.Initialize

rsaDecryptor.EncodingMode = "base64"
rsaDecryptor.UsePrivateKey(privKey)

usePrivateKey = True
Dim decryptedStr As String = rsaDecryptor.DecryptStringENC(encryptedStr, usePrivateKey)

Log("Decrypted:")
Log(decryptedStr)

'  Important: RSA encryption should only be used to encrypt small amounts of data.
'  It is typically used for encrypting symmetric encryption
'  keys such that a symmetric encryption algorithm, such as 
'  AES is then used to encrypt/decrypt bulk data.