Xbase++ Requires Chilkat v11.0.0+

RSA-OAEP with SHA256 hashing

See more RSA Examples

RSA encrypt a SHA256 hash with OAEP padding. Xbase++

LOCAL nSuccess
LOCAL oPubkey
LOCAL oSbPem
LOCAL nBCrlf
LOCAL oJson
LOCAL oRsa
LOCAL nBUsePrivateKey
LOCAL cEncryptedStr

nSuccess := 0

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

oPubkey := CreateObject("Chilkat.PublicKey")

oSbPem := CreateObject("Chilkat.StringBuilder")
nBCrlf := 1
oSbPem:AppendLine("-----BEGIN PUBLIC KEY-----", nBCrlf)
oSbPem:AppendLine("MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA33TqqLR3eeUmDtHS89qF", nBCrlf)
oSbPem:AppendLine("3p4MP7Wfqt2Zjj3lZjLjjCGDvwr9cJNlNDiuKboODgUiT4ZdPWbOiMAfDcDzlOxA", nBCrlf)
oSbPem:AppendLine("04DDnEFGAf+kDQiNSe2ZtqC7bnIc8+KSG/qOGQIVaay4Ucr6ovDkykO5Hxn7OU7s", nBCrlf)
oSbPem:AppendLine("Jp9TP9H0JH8zMQA6YzijYH9LsupTerrY3U6zyihVEDXXOv08vBHk50BMFJbE9iwF", nBCrlf)
oSbPem:AppendLine("wnxCsU5+UZUZYw87Uu0n4LPFS9BT8tUIvAfnRXIEWCha3KbFWmdZQZlyrFw0buUE", nBCrlf)
oSbPem:AppendLine("f0YN3/Q0auBkdbDR/ES2PbgKTJdkjc/rEeM0TxvOUf7HuUNOhrtAVEN1D5uuxE1W", nBCrlf)
oSbPem:AppendLine("SwIDAQAB", nBCrlf)
oSbPem:AppendLine("-----END PUBLIC KEY-----", nBCrlf)

//  Load the public key object from the PEM. 
nSuccess := oPubkey:LoadFromString(oSbPem:GetAsString())
IF (nSuccess == 0)
    ? oPubkey:LastErrorText
    oPubkey:destroy()
    oSbPem:destroy()
    RETURN
ENDIF

//  Build a small string to encrypt
oJson := CreateObject("Chilkat.JsonObject")
oJson:UpdateString("example", "123")
oJson:UpdateString("hello", "world")
? oJson:Emit()

//  This is the JSON to be RSA encrypted:  {"example":"123","hello":"world"}

//  IMPORTANT: RSA encryption is only used to encrypt small amounts of data.
//  RSA is only able to encrypt data to a maximum amount of your key size (2048 bits = 256 bytes) 
//  minus padding / header data (11 bytes for PKCS#1 v1.5 padding, 42 bytes for OAEP).
//  As a result it is often not possible to encrypt files with RSA directly. 
//  RSA is also not meant for this purpose. 
//  
//  If you want to encrypt more data, you can use something like:
//  1) Generate a 256-bit random keystring K
//  2) Encrypt your data with AES-CBC with K
//  3) Encrypt K with RSA
//  4) Send both to the other side 

oRsa := CreateObject("Chilkat.Rsa")
oRsa:PkcsPadding := 0
oRsa:OaepHash := "SHA-256"
oRsa:UsePublicKey(oPubkey)
oRsa:EncodingMode := "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.
nBUsePrivateKey := 0
cEncryptedStr := oRsa:EncryptStringENC(oJson:Emit(), nBUsePrivateKey)
IF (oRsa:LastMethodSuccess == 0)
    ? oRsa:LastErrorText
    oPubkey:destroy()
    oSbPem:destroy()
    oJson:destroy()
    oRsa:destroy()
    RETURN
ENDIF

? "Result: " + cEncryptedStr

oPubkey:destroy()
oSbPem:destroy()
oJson:destroy()
oRsa:destroy()