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(Excel) Encrypt File to PKCS7 .p7mExcel example to public-key encrypt a file creating a PKCS#7 .p7m file as output. Also demonstrates how to decrypt the .p7m to recover the original file.
' This example requires the Chilkat API to have been previously unlocked. ' See Global Unlock Sample for sample code. Dim crypt As Chilkat.Crypt2 Set crypt = Chilkat.NewCrypt2 ' Indicate the public-key encryption is to be used. ' Do this by setting the encryption algorithm equal ' to "PKI" (an acroynm for public-key infrastructure). crypt.CryptAlgorithm = "PKI" ' Indicate the inner symmetric encryption algorithm to be used. ' possible values are "aes", "des", "3des", and "rc2". ' For this example, we'll use 256-bit AES encryption. crypt.Pkcs7CryptAlg = "aes" crypt.KeyLength = 256 ' To encrypt, only a certificate w/ public key is needed. ' (The certificate w/ private key is required for decryption.) ' The LoadFromFile method can load virtually any certificate format: ' 1. DER encoded binary X.509 (.CER) ' 2. Base-64 encoded X.509 (.CER) ' 3. Cryptographic Message Syntax Standard - PKCS #7 Certificates (.P7B) ' 4. PEM format Dim encryptCert As Chilkat.Cert Set encryptCert = Chilkat.NewCert success = encryptCert.LoadFromFile("/Users/chilkat/testData/cer/acme.cer") If (success <> True) Then Debug.Print encryptCert.LastErrorText Exit Sub End If ' Tell the crypt object to use the certificate for encrypting: crypt.AddEncryptCert encryptCert ' Encrypt a file, producing a .p7m as output. ' The input file is unchanged, the output .p7m contains the encrypted ' contents of the input file. inFile = "/Users/chilkat/testData/pdf/sample.pdf" outFile = "/Users/chilkat/testData/p7m/sample.pdf.p7m" success = crypt.CkEncryptFile(inFile,outFile) If (success <> True) Then Debug.Print crypt.LastErrorText Exit Sub End If ' For demonstration purposes, a different instance of the object will be used ' for decryption. Dim decrypt As Chilkat.Crypt2 Set decrypt = Chilkat.NewCrypt2 ' To decrypt, the certificate w/ private key is required. A PFX (also known ' as PKCS#12) is a common secure container for certs and private keys. pfxFilename = "/Users/chilkat/testData/pfx/acme.pfx" pfxPassword = "secret" ' Tell the component to look in the PFX file for certs and private keys. success = decrypt.AddPfxSourceFile(pfxFilename,pfxPassword) If (success <> True) Then Debug.Print decrypt.LastErrorText Exit Sub End If ' Tell the decrypt object that PKI (public key encryption) is to be used ' for decryptiong. decrypt.CryptAlgorithm = "PKI" ' There is no need to set the Pkcs7Alg or KeyLength because this information ' is contained within the .p7m ' Decrypt the .p7m inFile = "/Users/chilkat/testData/p7m/sample.pdf.p7m" outFile = "/Users/chilkat/testData/pdf/recovered.pdf" success = decrypt.CkDecryptFile(inFile,outFile) If (success = False) Then Debug.Print decrypt.LastErrorText Exit Sub End If Debug.Print "Success!" |
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