PureBasic Requires Chilkat v11.0.0+

RSA Sign Binary Data and Verify (Recover the Original Data)

See more RSA Examples

Demonstrates how to RSA sign binary data and then verify/recover the original data.

Note: This example uses methods introduced in Chilkat v9.5.0.77.

PureBasic

IncludeFile "CkBinData.pb"
IncludeFile "CkPublicKey.pb"
IncludeFile "CkPrivateKey.pb"
IncludeFile "CkRsa.pb"

Procedure ChilkatExample()

    success.i = 0

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

    ;  Load an RSA private key for signing.
    privKey.i = CkPrivateKey::ckCreate()
    If privKey.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkPrivateKey::ckLoadEncryptedPemFile(privKey,"qa_data/pem/rsa_passwd.pem","passwd")
    If success = 0
        Debug CkPrivateKey::ckLastErrorText(privKey)
        CkPrivateKey::ckDispose(privKey)
        ProcedureReturn
    EndIf

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

    CkRsa::ckUsePrivateKey(rsa,privKey)

    ;  We have some binary data (in hex) to sign
    originalData.s = "0102030405060708090A"
    bd.i = CkBinData::ckCreate()
    If bd.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkBinData::ckAppendEncoded(bd,originalData,"hex")

    ;  If successful, the contents of bd are replaced with the RSA signature.
    success = CkRsa::ckSignRawBd(rsa,bd)
    If success = 0
        Debug CkRsa::ckLastErrorText(rsa)
        CkPrivateKey::ckDispose(privKey)
        CkRsa::ckDispose(rsa)
        CkBinData::ckDispose(bd)
        ProcedureReturn
    EndIf

    ;  Show the RSA signature in base64
    Debug CkBinData::ckGetEncoded(bd,"base64")

    ;  ------------------------------------------
    ;  Get the public key from the private key
    pubKey.i = CkPublicKey::ckCreate()
    If pubKey.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkPrivateKey::ckToPublicKey(privKey,pubKey)

    ;  Verify the signature and extract the original data.
    rsa2.i = CkRsa::ckCreate()
    If rsa2.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkRsa::ckUsePublicKey(rsa2,pubKey)

    bVerified.i = CkRsa::ckVerifyRawBd(rsa2,bd)
    Debug "signature verified: " + Str(bVerified)

    ;  Show the original data:
    Debug "original data: " + CkBinData::ckGetEncoded(bd,"hex")


    CkPrivateKey::ckDispose(privKey)
    CkRsa::ckDispose(rsa)
    CkBinData::ckDispose(bd)
    CkPublicKey::ckDispose(pubKey)
    CkRsa::ckDispose(rsa2)


    ProcedureReturn
EndProcedure