/**
* Creates a new {@code HKDF} instance.
*
* @param algorithm the MAC algorithm to use.
* @param info optional context and application specific information, may be {@code null} or
* empty.
* @param dkLen the desired length for derived keys, in bytes.
* @throws NullPointerException if {@code algorithm} is {@code null}.
* @throws IllegalArgumentException if {@code dkLen} is negative, or if the MAC algorithm is
* unknown, or if {@code dkLen} is greater than 255 * MAC algorithm's output length.
*/
HKDF(Algorithm<MAC> algorithm, byte[] info, int dkLen) {
Parameters.checkCondition(dkLen > 0);
MAC mac = Factory.newMAC(algorithm, new byte[0]);
Parameters.checkCondition(dkLen <= 255 * mac.length());
this.algorithm = algorithm;
this.dkLen = dkLen;
this.info = info == null ? new byte[0] : XArrays.copyOf(info);
}
/**
* Creates and returns a {@link MAC} instance corresponding to the given algorithm, initialized
* with the provided secret key.
*
* @param algorithm the MAC algorithm.
* @param key the secret key.
* @return the created {@link MAC} instance.
* @throws NullPointerException if {@code algorithm} is {@code null}.
* @throws IllegalArgumentException if the given algorithm is unknown.
*/
static MAC newMAC(Algorithm<MAC> algorithm, byte[] key) {
Parameters.checkNotNull(algorithm);
MAC mac;
if (algorithm == Algorithm.HMAC_MD2) {
mac = HMAC.md2(key);
} else if (algorithm == Algorithm.HMAC_MD4) {
mac = HMAC.md4(key);
} else if (algorithm == Algorithm.HMAC_MD5) {
mac = HMAC.md5(key);
} else if (algorithm == Algorithm.HMAC_SHA1) {
mac = HMAC.sha1(key);
} else if (algorithm == Algorithm.HMAC_SHA256) {
mac = HMAC.sha256(key);
} else if (algorithm == Algorithm.HMAC_SHA512) {
mac = HMAC.sha512(key);
} else if (algorithm == Algorithm.HMAC_KECCAK224) {
mac = HMAC.keccak224(key);
} else if (algorithm == Algorithm.HMAC_KECCAK256) {
mac = HMAC.keccak256(key);
} else if (algorithm == Algorithm.HMAC_KECCAK384) {
mac = HMAC.keccak384(key);
} else if (algorithm == Algorithm.HMAC_KECCAK512) {
mac = HMAC.keccak512(key);
} else {
throw new IllegalArgumentException("Unknown algorithm");
}
return mac;
}
/**
* Creates and returns a {@link Digest} instance corresponding to the given algorithm.
*
* @param algorithm the digest algorithm.
* @return the created {@link Digest} instance.
* @throws NullPointerException if {@code algorithm} is {@code null}.
* @throws IllegalArgumentException if the given algorithm is unknown.
*/
static Digest newDigest(Algorithm<Digest> algorithm) {
Parameters.checkNotNull(algorithm);
Digest digest;
if (algorithm == Algorithm.MD2) {
digest = Digests.md2();
} else if (algorithm == Algorithm.MD4) {
digest = Digests.md4();
} else if (algorithm == Algorithm.MD5) {
digest = Digests.md5();
} else if (algorithm == Algorithm.SHA1) {
digest = Digests.sha1();
} else if (algorithm == Algorithm.SHA256) {
digest = Digests.sha256();
} else if (algorithm == Algorithm.SHA512) {
digest = Digests.sha512();
} else if (algorithm == Algorithm.KECCAK224) {
digest = Digests.keccak224();
} else if (algorithm == Algorithm.KECCAK256) {
digest = Digests.keccak256();
} else if (algorithm == Algorithm.KECCAK384) {
digest = Digests.keccak384();
} else if (algorithm == Algorithm.KECCAK512) {
digest = Digests.keccak512();
} else {
throw new IllegalArgumentException("Unknown algorithm");
}
return digest;
}
/**
* Creates a new {@code StringReader}.
*
* @param strings the input {@link String}s.
* @throws NullPointerException if {@code strings} is {@code null} or if it contains a {@code
* null} reference.
*/
public StringReader(Iterable<String> strings) {
this.in = new StringBuilder();
for (String str : strings) {
Parameters.checkNotNull(str);
this.in.append(str);
}
this.in.trimToSize();
}
@Override
public long skip(long n) {
Parameters.checkCondition(n >= 0);
if (finished()) {
return 0;
}
long skipped = n;
if (n > in.length() - index) {
skipped = in.length() - index;
}
index += skipped;
return skipped;
}
/**
* Marks the current position in the stream. Subsequent calls to reset() will reposition the
* stream to this point.
*
* @param readLimit limit on the number of characters that may be read while still preserving the
* mark. Because the stream's input comes from {@code String}s, there is no actual limit, so
* this argument must not be negative, but is otherwise ignored.
* @throws IllegalArgumentException if {@code readLimit} is negative.
*/
@Override
public void mark(int readLimit) {
Parameters.checkCondition(readLimit >= 0);
mark = index;
}