PureBasic

RSA Sign utf-8 Bytes of String to get Base64 RSA Signature

See more Apple Keychain Examples

Demonstrates how RSA sign the utf-8 byte representation of a string to get the signature in base64 format. PureBasic

IncludeFile "CkCert.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkRsa.pb"

Procedure ChilkatExample()

    success.i = 0

    ; Assuming the smartcard/USB token is installed with the correct drivers from the manufacturer,
    ; this code can work on multiple platforms including Windows, MacOS, Linux, and iOS.

    ; Chilkat automatically detects and determines the way in which the HSM is used,
    ; which can be by PKCS11, Apple Keychain, Microsoft CNG / Crypto API, or ScMinidriver.

    cert.i = CkCert::ckCreate()
    If cert.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Set the token/smartcard PIN prior to loading.
    CkCert::setCkSmartCardPin(cert, "123456")

    ; Specify the certificate by its common name.
    success = CkCert::ckLoadFromSmartcard(cert,"cn=chilkat-rsa-2048")
    If success = 0
        Debug CkCert::ckLastErrorText(cert)
        CkCert::ckDispose(cert)
        ProcedureReturn
    EndIf

    Debug "Signing with cert: " + CkCert::ckSubjectCN(cert)

    ; Create a string to be hashed and signed.
    sb.i = CkStringBuilder::ckCreate()
    If sb.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    crlfLineEnding.i = 1
    i.i
    For i = 0 To 10
        CkStringBuilder::ckAppendLine(sb,"This is a test.",crlfLineEnding)
    Next

    rsa.i = CkRsa::ckCreate()
    If rsa.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; Use the certificate's private key for signing.
    success = CkRsa::ckSetX509Cert(rsa,cert,1)
    If success = 0
        Debug CkRsa::ckLastErrorText(rsa)
        CkCert::ckDispose(cert)
        CkStringBuilder::ckDispose(sb)
        CkRsa::ckDispose(rsa)
        ProcedureReturn
    EndIf

    ; Sign the SHA-256 hash of the utf-8 byte representation of the contents of sb
    ; Return the signature in base64 format.
    CkRsa::setCkEncodingMode(rsa, "base64")
    CkRsa::setCkCharset(rsa, "utf-8")
    stringToSign.s = CkStringBuilder::ckGetAsString(sb)
    sigBase64.s = CkRsa::ckSignStringENC(rsa,stringToSign,"sha256")
    If CkRsa::ckLastMethodSuccess(rsa) = 0
        Debug CkRsa::ckLastErrorText(rsa)
        CkCert::ckDispose(cert)
        CkStringBuilder::ckDispose(sb)
        CkRsa::ckDispose(rsa)
        ProcedureReturn
    EndIf

    Debug "RSA signature as base64: " + sigBase64


    CkCert::ckDispose(cert)
    CkStringBuilder::ckDispose(sb)
    CkRsa::ckDispose(rsa)


    ProcedureReturn
EndProcedure