(PureBasic) RSA Hash Binary Data and Sign (and Verify)

Demonstrates how to sign the hash of binary data. Also demonstrates how to verify the RSA signature.

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

Chilkat PureBasic Module Download Chilkat PureBasic Module

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

Procedure ChilkatExample()

    ; 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.i = CkPrivateKey::ckLoadEncryptedPemFile(privKey,"qa_data/pem/rsa_passwd.pem","passwd")
    If success <> 1
        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::ckImportPrivateKeyObj(rsa,privKey)

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

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

    ; Hash (SHA-256) and sign the hash:
    bdSignature.i = CkBinData::ckCreate()
    If bdSignature.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkRsa::ckSignBd(rsa,bdData,"sha256",bdSignature)
    If success <> 1
        Debug CkRsa::ckLastErrorText(rsa)
        CkPrivateKey::ckDispose(privKey)
        CkRsa::ckDispose(rsa)
        CkBinData::ckDispose(bdData)
        CkBinData::ckDispose(bdSignature)
        ProcedureReturn
    EndIf

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

    ; ------------------------------------------
    ; Get the public key from the private key
    pubKey.i = CkPrivateKey::ckGetPublicKey(privKey)

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

    CkRsa::ckImportPublicKeyObj(rsa2,pubKey)

    bVerified.i = CkRsa::ckVerifyBd(rsa2,bdData,"sha256",bdSignature)
    Debug "signature verified: " + Str(bVerified)

    CkPublicKey::ckDispose(pubKey)



    CkPrivateKey::ckDispose(privKey)
    CkRsa::ckDispose(rsa)
    CkBinData::ckDispose(bdData)
    CkBinData::ckDispose(bdSignature)
    CkRsa::ckDispose(rsa2)


    ProcedureReturn
EndProcedure