B4X Requires Chilkat v11.0.0+

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.

B4X

Dim success As Boolean = False

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

Dim pubKey As ChilkatPublicKey
pubKey.Initialize

'  Load the public key from an PEM file:
success = pubKey.LoadFromFile("pubKey.pem")
If success = False Then
    Log(pubKey.LastErrorText)
    Return
End If


'  Load the data of the original file that was signed.
Dim bdFileData As ChilkatBinData
bdFileData.Initialize
success = bdFileData.LoadFile("in.dat")

'  Load the signature.
Dim bdSig As ChilkatBinData
bdSig.Initialize
success = bdSig.LoadFile("signature.sig")

Dim rsa As ChilkatRsa
rsa.Initialize

'  Import the public key into the RSA component:
success = rsa.UsePublicKey(pubKey)
If success = False Then
    Log(rsa.LastErrorText)
    Return
End If


'  OpenSSL uses big-endian.
rsa.LittleEndian = False

success = rsa.VerifyBd(bdFileData, "sha256", bdSig)
If success <> True Then
    Log(rsa.LastErrorText)
    Log("The signature was invalid.")
    Return
End If


Log("The signature was verified.")