(Visual FoxPro) RSAES-OAEP Encrypt String with AES-128 Content Encryption and SHA256

Encrypts a string using RSAES-OAEP with SHA256 and AES-128 content encryption to produce PKCS7 output (base64 encoded).

Note: This example requires Chilkat v9.5.0.67 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

LOCAL loSb
LOCAL i
LOCAL loCert
LOCAL lnSuccess
LOCAL loCrypt
LOCAL lcBase64Pkcs7

* This example requires the Chilkat Crypt API to have been previously unlocked.
* See Unlock Chilkat Crypt for sample code.

* First build a string to be encrypted
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.StringBuilder')
loSb = CreateObject('Chilkat.StringBuilder')
i = 1
DO WHILE i < 25
    loSb.AppendInt(i)
    loSb.Append(" the quick brown fox jumped over the lazy dog." + CHR(13) + CHR(10))
    i = i + 1
ENDDO

? loSb.GetAsString()

* The string to be encrypted looks like this:

* 1 the quick brown fox jumped over the lazy dog.
* 2 the quick brown fox jumped over the lazy dog.
* 3 the quick brown fox jumped over the lazy dog.
* 4 the quick brown fox jumped over the lazy dog.
* 5 the quick brown fox jumped over the lazy dog.
* 6 the quick brown fox jumped over the lazy dog.
* ...

* Load a digital certificate. 
* We don't need the private key for encryption.
* Only the public key is needed (which is included in a certificate).
* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Cert')
loCert = CreateObject('Chilkat.Cert')
lnSuccess = loCert.LoadFromFile("qa_data/rsaes-oaep/cert.pem")
IF (lnSuccess <> 1) THEN
    ? loCert.LastErrorText
    RELEASE loSb
    RELEASE loCert
    CANCEL
ENDIF

* For versions of Chilkat < 10.0.0, use CreateObject('Chilkat_9_5_0.Crypt2')
loCrypt = CreateObject('Chilkat.Crypt2')

* Tell the crypt object to use the certificate.
loCrypt.SetEncryptCert(loCert)

* Indicate that we want PKI encryption (i.e. public-key infrastructure)
* to produce a CMS message (Cryptographic Message Syntax/PKCS7),
* that is be created with RSAES-OAEP padding, SHA256, and AES-128 for the
* bulk encryption.
loCrypt.CryptAlgorithm = "pki"
loCrypt.Pkcs7CryptAlg = "aes"
loCrypt.KeyLength = 128
loCrypt.OaepHash = "sha256"
loCrypt.OaepPadding = 1

* Also, don't forget to be specific about the character encoding (byte representation) of the
* string to be encrypted.
loCrypt.Charset = "utf-8"

* Now indicate that the PKCS7 output is to be returned in the base64 encoding.
loCrypt.EncodingMode = "base64"

lcBase64Pkcs7 = loCrypt.EncryptStringENC(loSb.GetAsString())
IF (loCrypt.LastMethodSuccess <> 1) THEN
    ? loCrypt.LastErrorText
    RELEASE loSb
    RELEASE loCert
    RELEASE loCrypt
    CANCEL
ENDIF

* Show the output
? lcBase64Pkcs7

* This base64 can be copy-and-pasted into the form at http://lapo.it/asn1js/
* to verify that all the chosen algorithms were indeed used.

? "OK."

RELEASE loSb
RELEASE loCert
RELEASE loCrypt