Constructing and validating a Gigya signature

I wrote a method to verify a gigya signature against a specified timestamp and UID, based on Gigya's instructions for constructing a signature. Here is Gigya's psuedo code for doing that:

string constructSignature(string timestamp, string UID, string secretKey) {
    // Construct a "base string" for signing
    baseString = timestamp + "_" + UID;
    // Convert the base string into a binary array
    binaryBaseString = ConvertUTF8ToBytes(baseString);
    // Convert secretKey from BASE64 to a binary array
    binaryKey = ConvertFromBase64ToBytes(secretKey);
    // Use the HMAC-SHA1 algorithm to calculate the signature 
    binarySignature = hmacsha1(binaryKey, baseString);
    // Convert the signature to a BASE64
    signature = ConvertToBase64(binarySignature);
    return signature;
}

[sic]

Here's my method (exception handling omitted):

public boolean verifyGigyaSig(String uid, String timestamp, String signature) {

    // Construct the "base string"
    String baseString = timestamp + "_" + uid;

    // Convert the base string into a binary array
    byte[] baseBytes = baseString.getBytes("UTF-8");

    // Convert secretKey from BASE64 to a binary array
    String secretKey = MyConfig.getGigyaSecretKey();
    byte[] secretKeyBytes = Base64.decodeBase64(secretKey);

    // Use the HMAC-SHA1 algorithm to calculate the signature 
    Mac mac = Mac.getInstance("HmacSHA1");
    mac.init(new SecretKeySpec(secretKeyBytes, "HmacSHA1"));
    byte[] signatureBytes = mac.doFinal(baseBytes);

    // Convert the signature to a BASE64
    String calculatedSignature = Base64.encodeBase64String(signatureBytes);

    /