PureBasic

Duplicate openssl dgst -sha256 -verify pubKey.pem -signature signature.sig in.dat

See more OpenSSL Examples

Demonstrates how to duplicate this OpenSSL command:

openssl dgst -sha256 -verify pubKey.pem -signature signature.sig in.dat

The in.dat file contains the original data that was signed, and can contain text or binary data of any type. The above OpenSSL command does the following:

1. Creates a SHA256 digest of the contents of the input file.
2. Verifies the SHA256 digest using the public key.

PureBasic

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

Procedure ChilkatExample()

    success.i = 0

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

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

    ; Load the public key from an PEM file:
    success = CkPublicKey::ckLoadFromFile(pubKey,"pubKey.pem")
    If success = 0
        Debug CkPublicKey::ckLastErrorText(pubKey)
        CkPublicKey::ckDispose(pubKey)
        ProcedureReturn
    EndIf

    ; Load the data of the original file that was signed.
    bdFileData.i = CkBinData::ckCreate()
    If bdFileData.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkBinData::ckLoadFile(bdFileData,"in.dat")

    ; Load the signature.
    bdSig.i = CkBinData::ckCreate()
    If bdSig.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    success = CkBinData::ckLoadFile(bdSig,"signature.sig")

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

    ; Import the public key into the RSA component:
    success = CkRsa::ckUsePublicKey(rsa,pubKey)
    If success = 0
        Debug CkRsa::ckLastErrorText(rsa)
        CkPublicKey::ckDispose(pubKey)
        CkBinData::ckDispose(bdFileData)
        CkBinData::ckDispose(bdSig)
        CkRsa::ckDispose(rsa)
        ProcedureReturn
    EndIf

    ; OpenSSL uses big-endian.
    CkRsa::setCkLittleEndian(rsa, 0)

    success = CkRsa::ckVerifyBd(rsa,bdFileData,"sha256",bdSig)
    If success <> 1
        Debug CkRsa::ckLastErrorText(rsa)
        Debug "The signature was invalid."
        CkPublicKey::ckDispose(pubKey)
        CkBinData::ckDispose(bdFileData)
        CkBinData::ckDispose(bdSig)
        CkRsa::ckDispose(rsa)
        ProcedureReturn
    EndIf

    Debug "The signature was verified."


    CkPublicKey::ckDispose(pubKey)
    CkBinData::ckDispose(bdFileData)
    CkBinData::ckDispose(bdSig)
    CkRsa::ckDispose(rsa)


    ProcedureReturn
EndProcedure