microsoft-azure-storage/src/com/microsoft/azure/storage/StorageCredentialsAccountAndKey.java
public synchronized Mac getHmac256() throws InvalidKeyException {
        if (this.hmacSha256 == null) {
            // Initializes the HMAC-SHA256 Mac and SecretKey.
            try {
                this.hmacSha256 = Mac.getInstance("HmacSHA256");
            }
            catch (final NoSuchAlgorithmException e) {
                throw new IllegalArgumentException();
            }
            this.hmacSha256.init(new SecretKeySpec(this.key, "HmacSHA256"));
        }
        return this.hmacSha256;
    }
public synchronized Mac getHmac256() throws InvalidKeyException {
        if (this.hmacSha256 == null) {
            // Initializes the HMAC-SHA256 Mac and SecretKey.
            try {
                this.hmacSha256 = Mac.getInstance("HmacSHA256");
            }
            catch (final NoSuchAlgorithmException e) {
                throw new IllegalArgumentException();
            }
            this.hmacSha256.init(new SecretKeySpec(this.key, "HmacSHA256"));
        }
        return this.hmacSha256;
    }
Gets the HmacSha256 associated with the account key.

@return A <code>MAC</code> created with the account key.

@throws InvalidKeyException
If the key is not a valid storage key.