com.microsoft.azure.sdk.iot.device.auth

Class SignatureHelper

java.lang.Object

com.microsoft.azure.sdk.iot.device.auth.SignatureHelper

public final class SignatureHelper
extends Object

Builds the authorization signature as a composition of functions.

Field Summary

Fields

Modifier and Type	Field and Description
static String	RAW_SIGNATURE_FORMAT The device ID will be the prefix.
static Charset	SIGNATURE_CHARSET The charset used for the raw and hashed signature.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SignatureHelper()

Method Summary

Modifier and Type	Method and Description
static byte[]	buildRawSignature(String resourceUri, long expiryTime) Builds the raw signature.
static byte[]	decodeDeviceKeyBase64(String deviceKey) Decodes the deviceKey using Base64.
static byte[]	encodeSignatureBase64(byte[] sig) Encodes the signature using Base64 and then further encodes the resulting string using UTF-8 encoding.
static String	encodeSignatureUtf8(byte[] sig) Encodes the signature using charset UTF-8.
static String	encodeSignatureWebSafe(String sig) Safely escapes characters in the signature so that they can be transmitted over the internet.
static byte[]	encryptSignatureHmacSha256(byte[] sig, byte[] deviceKey) Encrypts the signature using HMAC-SHA256.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

RAW_SIGNATURE_FORMAT

public static final String RAW_SIGNATURE_FORMAT

The device ID will be the prefix. The expiry time, as a UNIX timestamp, will be the suffix.

See Also:

Constant Field Values

SIGNATURE_CHARSET

public static final Charset SIGNATURE_CHARSET

The charset used for the raw and hashed signature.

Constructor Detail

SignatureHelper

protected SignatureHelper()

Method Detail

buildRawSignature

public static byte[] buildRawSignature(String resourceUri,
                                       long expiryTime)

Builds the raw signature.

Parameters:

resourceUri - the resource URI.

expiryTime - the signature expiry time, as a UNIX timestamp.

Returns:

the raw signature.

decodeDeviceKeyBase64

public static byte[] decodeDeviceKeyBase64(String deviceKey)

Decodes the deviceKey using Base64.

Parameters:

deviceKey - the device key.

Returns:

the Base64-decoded device key.

encryptSignatureHmacSha256

public static byte[] encryptSignatureHmacSha256(byte[] sig,
                                                byte[] deviceKey)

Encrypts the signature using HMAC-SHA256.

Parameters:

sig - the unencrypted signature.

deviceKey - the Base64-decoded device key.

Returns:

the HMAC-SHA256 encrypted signature.

encodeSignatureBase64

public static byte[] encodeSignatureBase64(byte[] sig)

Encodes the signature using Base64 and then further encodes the resulting string using UTF-8 encoding.

Parameters:

sig - the HMAC-SHA256 encrypted signature.

Returns:

the Base64-encoded signature.

encodeSignatureUtf8

public static String encodeSignatureUtf8(byte[] sig)

Encodes the signature using charset UTF-8.

Parameters:

sig - the HMAC-SHA256 encrypted, Base64-encoded signature.

Returns:

the signature encoded using charset UTF-8.

encodeSignatureWebSafe

public static String encodeSignatureWebSafe(String sig)

Safely escapes characters in the signature so that they can be transmitted over the internet. Replaces unsafe characters with a '%' followed by two hexadecimal digits (i.e. %2d).

Parameters:

sig - the HMAC-SHA256 encrypted, Base64-encoded, UTF-8 encoded signature.

Returns:

the web-safe encoding of the signature.