B4X Requires Chilkat v11.0.0+

RSA Encrypt and Decrypt Strings

See more RSA Examples

_LANGUAGE_ sample code to RSA public-key encrypt and decrypt strings using public and private 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

'  This example also generates the public and private
'  keys to be used in the RSA encryption.
'  Normally, you would generate a key pair once,
'  and distribute the public key to your partner.
'  Anything encrypted with the public key can be
'  decrypted with the private key.  The reverse is 
'  also true: anything encrypted using the private
'  key can be decrypted using the public key.

'  Generate a 2048-bit key.  Chilkat RSA supports
'  key sizes ranging from 512 bits to 4096 bits.
Dim privKey As ChilkatPrivateKey
privKey.Initialize("privKey")
success = rsa.GenKey(2048, privKey)
If success = False Then
    Log(rsa.LastErrorText)
    Return
End If


Dim pubKey As ChilkatPublicKey
pubKey.Initialize
privKey.ToPublicKey(pubKey)

Dim plainText As String = "Encrypting and decrypting should be easy!"

'  Start with a new RSA object to demonstrate that all we
'  need are the keys previously exported:
Dim rsaEncryptor As ChilkatRsa
rsaEncryptor.Initialize

'  Encrypted output is always binary.  In this case, we want
'  to encode the encrypted bytes in a printable string.
'  Our choices are "hex", "base64", "url", "quoted-printable".
rsaEncryptor.EncodingMode = "hex"

'  We'll encrypt with the public key and decrypt with the private
'  key.
success = rsaEncryptor.UsePublicKey(pubKey)

Dim usePrivateKey As Boolean = False
Dim encryptedStr As String = rsaEncryptor.EncryptStringENC(plainText, usePrivateKey)
Log(encryptedStr)

'  Now decrypt:
Dim rsaDecryptor As ChilkatRsa
rsaDecryptor.Initialize

rsaDecryptor.EncodingMode = "hex"
success = rsaDecryptor.UsePrivateKey(privKey)

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

Log(decryptedStr)