DataFlex

Encrypt a File to a PKCS7 (CMS) Message

Shows how to encrypt a file into a PKCS7 encrypted message using the recipient's certificate. Public-key encryption requires no private key. However, the recipient's private key is necessary for decryption. DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoCrypt
    Variant vCert1
    Handle hoCert1
    Variant vFileData
    Handle hoFileData
    String sTemp1

    Move False To iSuccess

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

    Get Create (RefClass(cComChilkatCrypt2)) To hoCrypt
    If (Not(IsComObjectCreated(hoCrypt))) Begin
        Send CreateComObject of hoCrypt
    End

    // Load the recipient's digital certificate. 
    // We don't need the private key for encryption.
    // Only the public key is needed (which is included in a certificate).
    Get Create (RefClass(cComChilkatCert)) To hoCert1
    If (Not(IsComObjectCreated(hoCert1))) Begin
        Send CreateComObject of hoCert1
    End
    Get ComLoadFromFile Of hoCert1 "qa_data/user1/cert_user1.pem" To iSuccess
    // Assume success for the example, but make sure your application checks for success/failure...
    Get pvComObject of hoCert1 to vCert1
    Get ComSetEncryptCert Of hoCrypt vCert1 To iSuccess

    // 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-256 for the
    // bulk encryption.
    Set ComCryptAlgorithm Of hoCrypt To "pki"
    Set ComPkcs7CryptAlg Of hoCrypt To "aes"
    Set ComKeyLength Of hoCrypt To 256
    Set ComOaepHash Of hoCrypt To "sha256"
    Set ComOaepPadding Of hoCrypt To True

    // Load the file to be encrypted...
    Get Create (RefClass(cComChilkatBinData)) To hoFileData
    If (Not(IsComObjectCreated(hoFileData))) Begin
        Send CreateComObject of hoFileData
    End
    Get ComLoadFile Of hoFileData "qa_data/jpg/penguins.jpg" To iSuccess
    // Your app should check for success/failure..

    // Encrypt the data.  The contents of the fileData object are replaced with the PKCS7 encrypted message.
    Get pvComObject of hoFileData to vFileData
    Get ComEncryptBd Of hoCrypt vFileData To iSuccess
    If (iSuccess <> True) Begin
        Get ComLastErrorText Of hoCrypt To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    // Save the PKCS7 encrypted message to a file..
    Get ComWriteFile Of hoFileData "qa_output/pkcs7_encrypted.p7" To iSuccess

    Showln "OK."


End_Procedure