(PowerBuilder) RSA-OAEP with SHA256 hashing

RSA encrypt a SHA256 hash with OAEP padding.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat ActiveX Downloads ActiveX for 32-bit and 64-bit Windows

integer li_rc
integer li_Success
oleobject loo_Pubkey
oleobject loo_SbPem
integer li_BCrlf
oleobject loo_Json
oleobject loo_Rsa
integer li_BUsePrivateKey
string ls_EncryptedStr

li_Success = 0

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

loo_Pubkey = create oleobject
li_rc = loo_Pubkey.ConnectToNewObject("Chilkat.PublicKey")
if li_rc < 0 then
    destroy loo_Pubkey
    MessageBox("Error","Connecting to COM object failed")
    return
end if

loo_SbPem = create oleobject
li_rc = loo_SbPem.ConnectToNewObject("Chilkat.StringBuilder")

li_BCrlf = 1
loo_SbPem.AppendLine("-----BEGIN PUBLIC KEY-----",li_BCrlf)
loo_SbPem.AppendLine("MIIBIjANBgkqhkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEA33TqqLR3eeUmDtHS89qF",li_BCrlf)
loo_SbPem.AppendLine("3p4MP7Wfqt2Zjj3lZjLjjCGDvwr9cJNlNDiuKboODgUiT4ZdPWbOiMAfDcDzlOxA",li_BCrlf)
loo_SbPem.AppendLine("04DDnEFGAf+kDQiNSe2ZtqC7bnIc8+KSG/qOGQIVaay4Ucr6ovDkykO5Hxn7OU7s",li_BCrlf)
loo_SbPem.AppendLine("Jp9TP9H0JH8zMQA6YzijYH9LsupTerrY3U6zyihVEDXXOv08vBHk50BMFJbE9iwF",li_BCrlf)
loo_SbPem.AppendLine("wnxCsU5+UZUZYw87Uu0n4LPFS9BT8tUIvAfnRXIEWCha3KbFWmdZQZlyrFw0buUE",li_BCrlf)
loo_SbPem.AppendLine("f0YN3/Q0auBkdbDR/ES2PbgKTJdkjc/rEeM0TxvOUf7HuUNOhrtAVEN1D5uuxE1W",li_BCrlf)
loo_SbPem.AppendLine("SwIDAQAB",li_BCrlf)
loo_SbPem.AppendLine("-----END PUBLIC KEY-----",li_BCrlf)

// Load the public key object from the PEM. 
li_Success = loo_Pubkey.LoadFromString(loo_SbPem.GetAsString())
if li_Success = 0 then
    Write-Debug loo_Pubkey.LastErrorText
    destroy loo_Pubkey
    destroy loo_SbPem
    return
end if

// Build a small string to encrypt
loo_Json = create oleobject
li_rc = loo_Json.ConnectToNewObject("Chilkat.JsonObject")

loo_Json.UpdateString("example","123")
loo_Json.UpdateString("hello","world")
Write-Debug loo_Json.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 

loo_Rsa = create oleobject
li_rc = loo_Rsa.ConnectToNewObject("Chilkat.Rsa")

loo_Rsa.PkcsPadding = 0
loo_Rsa.OaepHash = "SHA-256"
loo_Rsa.UsePublicKey(loo_Pubkey)
loo_Rsa.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.
li_BUsePrivateKey = 0
ls_EncryptedStr = loo_Rsa.EncryptStringENC(loo_Json.Emit(),li_BUsePrivateKey)
if loo_Rsa.LastMethodSuccess = 0 then
    Write-Debug loo_Rsa.LastErrorText
    destroy loo_Pubkey
    destroy loo_SbPem
    destroy loo_Json
    destroy loo_Rsa
    return
end if

Write-Debug "Result: " + ls_EncryptedStr


destroy loo_Pubkey
destroy loo_SbPem
destroy loo_Json
destroy loo_Rsa