B4X

RSAES-OAEP Encrypt String with AES-128 Content Encryption and SHA256

See more Encryption Examples

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.

B4X

Dim success As Boolean = False

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

'  First build a string to be encrypted
Dim sb As ChilkatStringBuilder
sb.Initialize
Dim i As Int = 1
Do While i < 25
    sb.AppendInt(i)
    sb.Append(" the quick brown fox jumped over the lazy dog." & Chr(13) & Chr(10))
    i = i + 1
Loop

Log(sb.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).
Dim cert As ChilkatCert
cert.Initialize("cert")
success = cert.LoadFromFile("qa_data/rsaes-oaep/cert.pem")
If success <> True Then
    Log(cert.LastErrorText)
    Return
End If


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

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

'  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.
crypt.CryptAlgorithm = "pki"
crypt.Pkcs7CryptAlg = "aes"
crypt.KeyLength = 128
crypt.OaepHash = "sha256"
crypt.OaepPadding = True

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

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

Dim base64Pkcs7 As String = crypt.EncryptStringENC(sb.GetAsString)
If crypt.LastMethodSuccess <> True Then
    Log(crypt.LastErrorText)
    Return
End If


'  Show the output
Log(base64Pkcs7)

'  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.

Log("OK.")