B4X

Encrypt/Decrypt using PFX to produce -----BEGIN PKCS7----- ... -----END PKCS7-----

See more Encryption Examples

First we encrypt using a certificate + public key to produce output such as:

-----BEGIN PKCS7-----
MIIHPwYJKoZIhvcNAQcEoIIHMDCCBywC ...
...
...
-----END PKCS7-----

Then we decrypt using the cert + private key. B4X

Dim success As Boolean = False

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

Dim crypt As ChilkatCrypt2
crypt.Initialize("crypt")

'  Specify the encryption to be used.
'  "pki" indicates "Public Key Infrastructure" and will create a PKCS7 encrypted (enveloped) message.
crypt.CryptAlgorithm = "pki"
crypt.Pkcs7CryptAlg = "aes"
crypt.KeyLength = 128
crypt.OaepHash = "sha256"
crypt.OaepPadding = True

'  A certificate is needed as the encryption key.
'  Althought the PFX contains the associated private key, we don't need it for encryption.
'  (A certificate usually contains the public key by default.)
Dim cert As ChilkatCert
cert.Initialize("cert")
success = cert.LoadPfxFile("qa_data/pfx/cert_test123.pfx", "test123")
If success <> True Then
    Log(cert.LastErrorText)
    Return
End If


'  Tell the crypt object to use the certificate.
crypt.SetEncryptCert(cert)

Dim toBeEncrypted As String = "This string is to be encrypted."

'  Get the result in multi-line BASE64 MIME format.
crypt.EncodingMode = "base64_mime"

Dim encryptedStr As String = crypt.EncryptStringENC(toBeEncrypted)
If success <> True Then
    Log(crypt.LastErrorText)
    Return
End If


'  Make a "-----BEGIN PKCS7-----" ... "-----END PKCS7-----" sandwich...
Dim sb As ChilkatStringBuilder
sb.Initialize
sb.AppendLine("-----BEGIN PKCS7-----", True)
sb.Append(encryptedStr)
sb.AppendLine("-----END PKCS7-----", True)

Dim outStr As String = sb.GetAsString

Log(outStr)

'  Sample output:

'  -----BEGIN PKCS7-----
'  MIICXAYJKoZIhvcNAQcDoIICTTCCAkkCAQAxggH0MIIB8AIBADCBrDCBlzELMAkGA1UEBhMCR0Ix
'  GzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgGA1UEChMR
'  Q09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhlbnRpY2F0
'  aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0ECEB6M1ZwZdZU7LrAIdurulmUwOAYJKoZIhvcNAQEHMCug
'  DzANBglghkgBZQMEAgEFAKEYMBYGCSqGSIb3DQEBCDAJBgUrDgMCGgUABIIBAK/BZG/iXJ8az7zL
'  8EQ77mc+oDPQ4w1hyytK2ip4djkPVvTfYhcoDQ+G/DBU+urJfrVBi5H9gmpXwYyfKlyUxBVRVEJl
'  V/V5QQi4JmNTFbmgWh5tp9zDS98l6A2Va4Zs0Wy/owGLfvwitlxd1dsfVAV2hmBYS24BMpNcty5/
'  0atcKYmSou13G78ztTKdMy1tECgZy8kerMsPdDQbSxEZkT3KpQ8C5uEQqYF3bIVaeZzha/Ywieh/
'  tvO0T4aAmeJufwkNdVECmU7kuhnNaVPXknFl7jeibTl6zA/VcJKBKcIYT9FRC7KjdooI8q+jtQ/V
'  k6RP4POaowkFg1QWRPEWeqIwTAYJKoZIhvcNAQcBMB0GCWCGSAFlAwQBAgQQEEFQduqeJqXQXzy4
'  JpkoDoAgdldJDB9zEkpMpgr5/fR2iLvh5kC6BPfhOYjsawBY4Ok=
'  -----END PKCS7-----

'  ----------------------------------------------------------------------------------------
'  Let's Decrypt the above string.

'  Start with what was produced above..
sb.Clear
Dim bCrlf As Boolean = True
sb.AppendLine("-----BEGIN PKCS7-----", bCrlf)
sb.AppendLine("MIICXAYJKoZIhvcNAQcDoIICTTCCAkkCAQAxggH0MIIB8AIBADCBrDCBlzELMAkGA1UEBhMCR0Ix", bCrlf)
sb.AppendLine("GzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgGA1UEChMR", bCrlf)
sb.AppendLine("Q09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhlbnRpY2F0", bCrlf)
sb.AppendLine("aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0ECEB6M1ZwZdZU7LrAIdurulmUwOAYJKoZIhvcNAQEHMCug", bCrlf)
sb.AppendLine("DzANBglghkgBZQMEAgEFAKEYMBYGCSqGSIb3DQEBCDAJBgUrDgMCGgUABIIBAK/BZG/iXJ8az7zL", bCrlf)
sb.AppendLine("8EQ77mc+oDPQ4w1hyytK2ip4djkPVvTfYhcoDQ+G/DBU+urJfrVBi5H9gmpXwYyfKlyUxBVRVEJl", bCrlf)
sb.AppendLine("V/V5QQi4JmNTFbmgWh5tp9zDS98l6A2Va4Zs0Wy/owGLfvwitlxd1dsfVAV2hmBYS24BMpNcty5/", bCrlf)
sb.AppendLine("0atcKYmSou13G78ztTKdMy1tECgZy8kerMsPdDQbSxEZkT3KpQ8C5uEQqYF3bIVaeZzha/Ywieh/", bCrlf)
sb.AppendLine("tvO0T4aAmeJufwkNdVECmU7kuhnNaVPXknFl7jeibTl6zA/VcJKBKcIYT9FRC7KjdooI8q+jtQ/V", bCrlf)
sb.AppendLine("k6RP4POaowkFg1QWRPEWeqIwTAYJKoZIhvcNAQcBMB0GCWCGSAFlAwQBAgQQEEFQduqeJqXQXzy4", bCrlf)
sb.AppendLine("JpkoDoAgdldJDB9zEkpMpgr5/fR2iLvh5kC6BPfhOYjsawBY4Ok=", bCrlf)
sb.AppendLine("-----END PKCS7-----", bCrlf)

Dim decrypt As ChilkatCrypt2
decrypt.Initialize("decrypt")
decrypt.CryptAlgorithm = "pki"

'  Use the same cert + private key from the PFX above.
'  For decryption, we need the private key.  Given that the certificate was loaded from a PFX,
'  we should already have it.
success = decrypt.SetDecryptCert(cert)

decrypt.EncodingMode = "base64"
Dim decryptedText As String = decrypt.DecryptStringENC(sb.GetBetween("-----BEGIN PKCS7-----", "-----END PKCS7-----"))

Log(decryptedText)