(PureBasic) Create PKCS7 (CMS) EnvelopedData

Encrypt some data to a recipient by creating a PKCS7 (CMS) EnvelopedData structure. The data will be encrypted using a symmetric content-encryption algorithm (e.g., AES), and the randomly generated symmetric key will be encrypted using the recipient’s RSA public key extracted from their X.509 certificate.

Chilkat PureBasic Module Download Chilkat PureBasic Module

IncludeFile "CkCrypt2.pb"
IncludeFile "CkCert.pb"

Procedure ChilkatExample()

    crypt.i = CkCrypt2::ckCreate()
    If crypt.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Specify the encryption to be used.
    ; "pki" indicates "Public Key Infrastructure" and will create a PKCS7 encrypted (enveloped-data) message.
    CkCrypt2::setCkCryptAlgorithm(crypt, "pki")
    CkCrypt2::setCkPkcs7CryptAlg(crypt, "aes")
    CkCrypt2::setCkKeyLength(crypt, 256)
    CkCrypt2::setCkOaepHash(crypt, "sha256")
    CkCrypt2::setCkOaepPadding(crypt, 1)

    cert.i = CkCert::ckCreate()
    If cert.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Use a certificate found in the Windows certificate store.
    success.i = CkCert::ckLoadByCommonName(cert,"My Certificate")
    If success <> 1
        Debug CkCert::ckLastErrorText(cert)
        CkCrypt2::ckDispose(crypt)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    ; Tell the crypt object to use the certificate.
    CkCrypt2::ckSetEncryptCert(crypt,cert)

    toBeEncrypted.s = "This string is to be encrypted."

    ; Get the result in multi-line BASE64 MIME format.
    CkCrypt2::setCkEncodingMode(crypt, "base64_mime")
    CkCrypt2::setCkCharset(crypt, "utf-8")

    result.s = CkCrypt2::ckEncryptStringENC(crypt,toBeEncrypted)
    If success <> 1
        Debug CkCrypt2::ckLastErrorText(crypt)
        CkCrypt2::ckDispose(crypt)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    ; -------------------------------------------------------------------------
    ; See the following example to decrypt what was created in this example
    ; Decrypt PKCS7 (CMS) EnvelopedData
    ; -------------------------------------------------------------------------

    Debug result

    ; Sample output:

    ; MIICSgYJKoZIhvcNAQcDoIICOzCCAjcCAQAxggHiMIIB3gIBADCBljCBgTELMAkGA1UEBhMCSVQx
    ; EDAOBgNVBAgMB0JlcmdhbW8xGTAXBgNVBAcMEFBvbnRlIFNhbiBQaWV0cm8xFzAVBgNVBAoMDkFj
    ; dGFsaXMgUy5wLkEuMSwwKgYDVQQDDCNBY3RhbGlzIENsaWVudCBBdXRoZW50aWNhdGlvbiBDQSBH
    ; MwIQPCWvkSv8oQ7xRmEHJ6TzEDA8BgkqhkiG9w0BAQcwL6APMA0GCWCGSAFlAwQCAQUAoRwwGgYJ
    ; KoZIhvcNAQEIMA0GCWCGSAFlAwQCAQUABIIBAKqHAPQNSsQoX7B2NH7QyEOWQRsSVs8oCHXmy8f4
    ; MVZD2er3bvYUCIomxpwbLEAl14qjUIMynahooYGgqip7+4FqL301G+BVjZVfEhHWj+VI1dAWnWuL
    ; VHlvc/pbQNBWqV8rKVJsNIsuAZkdj4WSwLVKxYkYX43B8fh/g71XN2DTJu7Z/824v48KBmgpQBOT
    ; 2q7IcDGxNPAFN2p6eavIVGn2LvhEbf/Fszyj+GR5tMcnQP1BOLJ3s3JzUBbvj8hcZrF1Vhl9HnTU
    ; YQx8G/KdW1mR+Wlhl3BWoK0LYKRTbnTx2BXOs0CY1SXOAdhKr01ZYjA+xW4nGzY0lfXS9QZjh9gw
    ; TAYJKoZIhvcNAQcBMB0GCWCGSAFlAwQBKgQQw0xTbfmnt0zjWHo5SaQIp4AgxTVY9E/Ncqy6t+RM
    ; 8y4c3Av62/wB8IpPUEmtM2OeuZo=


    CkCrypt2::ckDispose(crypt)
    CkCert::ckDispose(cert)


    ProcedureReturn
EndProcedure