(Go) RSA Sign utf-8 Bytes of String to get Base64 RSA Signature

See more Apple Keychain Examples

Demonstrates how RSA sign the utf-8 byte representation of a string to get the signature in base64 format.

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

    // Assuming the smartcard/USB token is installed with the correct drivers from the manufacturer,
    // this code can work on multiple platforms including Windows, MacOS, Linux, and iOS.

    // Chilkat automatically detects and determines the way in which the HSM is used,
    // which can be by PKCS11, Apple Keychain, Microsoft CNG / Crypto API, or ScMinidriver.

    cert := chilkat.NewCert()

    // Set the token/smartcard PIN prior to loading.
    cert.SetSmartCardPin("123456")

    // Specify the certificate by its common name.
    success := cert.LoadFromSmartcard("cn=chilkat-rsa-2048")
    if success == false {
        fmt.Println(cert.LastErrorText())
        cert.DisposeCert()
        return
    }

    fmt.Println("Signing with cert: ", cert.SubjectCN())

    // Create a string to be hashed and signed.
    sb := chilkat.NewStringBuilder()
    crlfLineEnding := true
    var i int
    for i = 0; i <= 10; i++ {
        sb.AppendLine("This is a test.",crlfLineEnding)
    }

    rsa := chilkat.NewRsa()

    // Use the certificate's private key for signing.
    success = rsa.SetX509Cert(cert,true)
    if success == false {
        fmt.Println(rsa.LastErrorText())
        cert.DisposeCert()
        sb.DisposeStringBuilder()
        rsa.DisposeRsa()
        return
    }

    // Sign the SHA-256 hash of the utf-8 byte representation of the contents of sb
    // Return the signature in base64 format.
    rsa.SetEncodingMode("base64")
    rsa.SetCharset("utf-8")
    stringToSign := sb.GetAsString()
    sigBase64 := rsa.SignStringENC(*stringToSign,"sha256")
    if rsa.LastMethodSuccess() == false {
        fmt.Println(rsa.LastErrorText())
        cert.DisposeCert()
        sb.DisposeStringBuilder()
        rsa.DisposeRsa()
        return
    }

    fmt.Println("RSA signature as base64: ", *sigBase64)

    cert.DisposeCert()
    sb.DisposeStringBuilder()
    rsa.DisposeRsa()