(Go) Verify an RSA Signature Against the Signed String

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Demonstrates how to validate an RSA Signature against the string that was signed.

Chilkat Go Downloads Go Package for Windows, MacOS, Linux, Alpine Linux, Solaris

    // Create the same string we previously signed in this example: 
    // RSA Sign utf-8 Bytes of String to get Base64 RSA Signature

    sb := chilkat.NewStringBuilder()
    crlfLineEnding := true
    var i int
    for i = 0; i <= 10; i++ {
        sb.AppendLine("This is a test.",crlfLineEnding)
    }

    base64_rsa_sig := "gWgpEXQqvXN6wh0MuFXPiw2xCb8cnmdizBT1TD1Tpm2GlJ8gnD59DGSj35GGXk1tM+mCOvMa2uW/9gmz8p6A90JLbn918i/2wKGvcde4wXnzPO7JADSNn2UwYzf3rp4/q/JrHv1GZETRJhABSFqTxOgdmdbEJQE/zijOSctCtQAM2CTb6t2BO8uHKSSUAwPH2cbeWxqsaVRLT4ruk5nZOxhoLgLMSjupiSzbE8zSTkkFOEHD+Mbb2xwg85AI0E4DsUnp+hLwwtS0blesgSyvtBY8oJODJeFcJsR7JDOTPdzHQHgJRl/2A4ij5xT91TpXy7ok43jhT6O9j7Q3qrafIQ=="

    // Get the public key to be used for signature verification.
    pubKey := chilkat.NewPublicKey()
    success := pubKey.LoadFromFile("rsaKeys/chilkat-rsa-2048.pem")
    if success == false {
        fmt.Println(pubKey.LastErrorText())
        sb.DisposeStringBuilder()
        pubKey.DisposePublicKey()
        return
    }

    rsa := chilkat.NewRsa()
    rsa.ImportPublicKeyObj(pubKey)

    // Verify the string against the signature.
    // We signed the utf-8 byte representation of the string, so we must indicate
    // to also validate against the utf-8 byte representation.
    rsa.SetCharset("utf-8")
    rsa.SetEncodingMode("base64")
    signedString := sb.GetAsString()
    success = rsa.VerifyStringENC(*signedString,"sha256",base64_rsa_sig)

    if success == false {
        fmt.Println(rsa.LastErrorText())
        fmt.Println("Signature invalid.")
    } else {
        fmt.Println("Signature valid.")
    }


    sb.DisposeStringBuilder()
    pubKey.DisposePublicKey()
    rsa.DisposeRsa()