Message Authentication Codes

Mac

Returns a Mac for the given key and algorithm. All input and output use the Bytes universal type.

Usage examples

KeyStore keystore = keystore("classpath:/keystore.p12", "password".toCharArray(), "PKCS12");
Key key = secretKey(keystore, "hmac", "password".toCharArray());

Mac mac = macBuilder().key(key).algorithm("HmacSHA256").build();

// raw bytes → Bytes
Bytes rawMac = mac.get(Bytes.from("Hello there".getBytes(UTF_8)));

// UTF-8 text → BASE64 string
String b64 = mac.get(Bytes.from("Hello there")).encode(BASE64);

// UTF-8 text → HEX string
String hex = mac.get(Bytes.from("Hello there")).encode(HEX);

// explicit charset → BASE64 string
String b64_2 = mac.get(Bytes.from("Hello 👋🏻", UTF_16)).encode(BASE64);

// Verify both parties produce the same MAC
Mac alice = macBuilder().key(key).algorithm("HmacSHA256").build();
Mac bob   = macBuilder().key(key).algorithm("HmacSHA256").build();

Bytes aliceMac = alice.get(Bytes.from("Hi Bob"));
Bytes bobMac   = bob.get(Bytes.from("Hi Bob"));
assertEquals(aliceMac, bobMac);

// compare as encoded strings
assertEquals(aliceMac.encode(BASE64), bobMac.encode(BASE64));

Builder options

import static com.mirkocaserta.bruce.Bruce.Provider.*;

// String-based algorithm (open-ended, supports any JCA algorithm)
Mac mac = macBuilder()
    .key(secretKey)
    .algorithm("HmacSHA256")
    .provider(BOUNCY_CASTLE)  // optional, defaults to JCA
    // .provider("BC")        // string-based alternative
    .build();

// Enum-based algorithm (type-safe, IDE auto-completion)
Mac mac2 = macBuilder()
    .key(secretKey)
    .algorithm(MacAlgorithm.HMAC_SHA_256)
    .provider(BOUNCY_CASTLE)  // optional
    .build();

Available MacAlgorithm constants: HMAC_MD5, HMAC_SHA_1, HMAC_SHA_224, HMAC_SHA_256, HMAC_SHA_384, HMAC_SHA_512, HMAC_SHA_512_224, HMAC_SHA_512_256, HMAC_SHA3_224, HMAC_SHA3_256, HMAC_SHA3_384, HMAC_SHA3_512.

Interface

@FunctionalInterface
public interface Mac {
    Bytes get(Bytes message);
}

Input / output combinations

Input	How to construct	Consume output
raw byte[]	Bytes.from(rawBytes)	.asBytes()
UTF-8 text	Bytes.from("text")	.encode(HEX) / .encode(BASE64)
custom charset	Bytes.from("text", charset)	.encode(...)
encoded string	Bytes.from("abc…", Encoding.BASE64)	.encode(...)