Class Crypto

java.lang.Object

com.codename1.backend.Crypto

public final class Crypto
extends Object

The crypto a server needs to authenticate a request. Every primitive comes from OpenSSL, which the backend already links for outbound TLS - none of it is implemented here, because hand-rolled HMAC and hand-rolled password hashing are the two most reliable ways to ship an authentication system that looks correct and is not.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	PASSWORD_ITERATIONS	PBKDF2 iterations for a stored password.

Method Summary

Modifier and Type	Method	Description
static boolean	equalsConstantTime(byte[] a, byte[] b)	Compares without leaking where two values first differ.
static String	hashPassword(String password)	Hashes a password for storage.
static byte[]	hmacSha256(byte[] key, byte[] data)
static byte[]	md5(byte[] data)	MD5, for PostgreSQL's md5 authentication method.
static byte[]	pbkdf2Sha256(byte[] password, byte[] salt, int iterations, int length)	PBKDF2-HMAC-SHA-256.
static byte[]	randomBytes(int length)	Cryptographically secure bytes.
static byte[]	sha1(byte[] data)	SHA-1, for the wire protocols that specify it by name: MySQL's mysql_native_password, and the RFC 6455 4.2.2 websocket handshake, where the digest of the client key and a fixed GUID becomes Sec-WebSocket-Accept.
static byte[]	sha256(byte[] data)
static boolean	verifyPassword(String password, String stored)	False for any malformed stored value rather than throwing.

Methods inherited from class Object

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

Field Details

PASSWORD_ITERATIONS

public static final int PASSWORD_ITERATIONS

PBKDF2 iterations for a stored password. Deliberately expensive: the cost is paid once per login and multiplied by every guess an attacker makes against a stolen table.

See Also:

• Constant Field Values

Method Details

sha256

public static byte[] sha256(byte[] data)

sha1

public static byte[] sha1(byte[] data)

SHA-1, for the wire protocols that specify it by name: MySQL's mysql_native_password, and the RFC 6455 4.2.2 websocket handshake, where the digest of the client key and a fixed GUID becomes Sec-WebSocket-Accept.

Never for anything this code CHOOSES: passwords go through hashPassword(String) and tokens through hmacSha256(byte[], byte[]). Both callers here are standards quoting the algorithm, and in neither is the result standing in for a signature -- the handshake value is a replay guard against caches and proxies, not an authenticator.

md5

public static byte[] md5(byte[] data)

MD5, for PostgreSQL's md5 authentication method. See sha1(byte[]).

pbkdf2Sha256

public static byte[] pbkdf2Sha256(byte[] password,
 byte[] salt,
 int iterations,
 int length)
                           throws IOException

PBKDF2-HMAC-SHA-256. Exposed because SCRAM-SHA-256 -- how PostgreSQL authenticates by default -- is defined in terms of it with the server's iteration count, which hashPassword(String) does not let a caller choose.

Throws:

IOException

hmacSha256

public static byte[] hmacSha256(byte[] key,
 byte[] data)

randomBytes

public static byte[] randomBytes(int length)
                          throws IOException

Cryptographically secure bytes. Throws rather than returning weak ones.

Throws:

IOException

equalsConstantTime

public static boolean equalsConstantTime(byte[] a,
 byte[] b)

Compares without leaking where two values first differ. An early exit on the first differing byte lets a MAC be forged one byte at a time.

hashPassword

public static String hashPassword(String password)
                           throws IOException

Hashes a password for storage. Returns "pbkdf2$iterations$salt$hash" with both binary parts base64url-encoded, so the iteration count travels with the hash and can be raised later without invalidating existing rows.

Throws:

IOException

verifyPassword

public static boolean verifyPassword(String password,
 String stored)

False for any malformed stored value rather than throwing.