B4X Requires Chilkat v11.0.0+

RSA Encrypt Hash using SHA256 hash function and SHA1 mask function

See more RSA Examples

How can this Javascript be duplicated using Chilkat?

function a(e, t) {
                var r = s.pki.publicKeyFromPem(e)
                  , n = r.encrypt(t, "RSA-OAEP", {
                    md: s.md.sha256.create(),
                    mgf1: {
                        md: s.md.sha1.create()
                    }
                });
                return s.util.encode64(n)
            }

Note: The OAEP padding uses random bytes in the padding, and therefore each time encryption happens, even using the same data and key, the result will be different -- but still valid. One should not expect to get the same output.

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 pubkey As ChilkatPublicKey
pubkey.Initialize

Dim sbPem As ChilkatStringBuilder
sbPem.Initialize
Dim bCrlf As Boolean = True
sbPem.AppendLine("-----BEGIN PUBLIC KEY-----", bCrlf)
sbPem.AppendLine("MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA33TqqLR3eeUmDtHS89qF", bCrlf)
sbPem.AppendLine("3p4MP7Wfqt2Zjj3lZjLjjCGDvwr9cJNlNDiuKboODgUiT4ZdPWbOiMAfDcDzlOxA", bCrlf)
sbPem.AppendLine("04DDnEFGAf+kDQiNSe2ZtqC7bnIc8+KSG/qOGQIVaay4Ucr6ovDkykO5Hxn7OU7s", bCrlf)
sbPem.AppendLine("Jp9TP9H0JH8zMQA6YzijYH9LsupTerrY3U6zyihVEDXXOv08vBHk50BMFJbE9iwF", bCrlf)
sbPem.AppendLine("wnxCsU5+UZUZYw87Uu0n4LPFS9BT8tUIvAfnRXIEWCha3KbFWmdZQZlyrFw0buUE", bCrlf)
sbPem.AppendLine("f0YN3/Q0auBkdbDR/ES2PbgKTJdkjc/rEeM0TxvOUf7HuUNOhrtAVEN1D5uuxE1W", bCrlf)
sbPem.AppendLine("SwIDAQAB", bCrlf)
sbPem.AppendLine("-----END PUBLIC KEY-----", bCrlf)

'  Load the public key object from the PEM. 
success = pubkey.LoadFromString(sbPem.GetAsString)
If success = False Then
    Log(pubkey.LastErrorText)
    Return
End If


Dim originalData As String = "This is the original data to be SHA-256 hashed and RSA encrypted."

'  First we SHA-256 hash the original data to get the hash in base64 format:
Dim crypt As ChilkatCrypt2
crypt.Initialize("crypt")
crypt.HashAlgorithm = "SHA-256"
crypt.EncodingMode = "base64"
Dim hashBase64 As String = crypt.HashStringENC(originalData)

'  Setup RSA to use OAEP padding with SHA-1 for the mask function.
Dim rsa As ChilkatRsa
rsa.Initialize
rsa.PkcsPadding = False
rsa.OaepHash = "SHA256"
rsa.UsePublicKey(pubkey)
rsa.EncodingMode = "base64"

'  We can provide a binary encoding mode, such as "base64", "hex", "base64url", etc.
'  for the Charset property.   The Charset property was previously limited to character encodings, such as
'  "utf-8", "iso-8859-1", etc.  If a binary encoding is used, then the string passed in is decoded to the binary
'  bytes as indicated.  (If an actual charset, such as "utf-8" is used, then the input string is converted to the
'  byte representation of the charset, and then encrypted.)

'  Given that a hash is composed of non-text binary bytes, we'll set the Charset property equal to "base64" 
'  (because we have the base64 hash from above).
rsa.Charset = "base64"

'  Note: The OAEP padding uses random bytes in the padding, and therefore each time encryption happens,
'  even using the same data and key, the result will be different --  but still valid.  One should not expect
'  to get the same output.
Dim bUsePrivateKey As Boolean = False
Dim encryptedStr As String = rsa.EncryptStringENC(hashBase64, bUsePrivateKey)
If rsa.LastMethodSuccess = False Then
    Log(rsa.LastErrorText)
    Return
End If


Log("Base64 RSA encrypted output: " & encryptedStr)