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MWCryptHKDF:: (10 methods):
__construct()
__destruct()
getSaltUsingCache()
singleton()
realGenerate()
HKDF()
HKDFExtract()
HKDFExpand()
generate()
generateHex()
Class: MWCryptHKDF - X-Ref
Extract-and-Expand Key Derivation Function (HKDF). A cryptographicly| __construct( $secretKeyMaterial, $algorithm, $cache, $context ) X-Ref |
param: string $secretKeyMaterial param: string $algorithm Name of hashing algorithm param: BagOStuff $cache param: string|array $context Context to mix into HKDF context |
| __destruct() X-Ref |
| Save the last block generated, so the next user will compute a different PRK from the same SKM. This should keep things unpredictable even if an attacker is able to influence CTXinfo. |
| getSaltUsingCache() X-Ref |
| MW specific salt, cached from last run return: string Binary string |
| singleton() X-Ref |
| Return a singleton instance, based on the global configs. return: HKDF |
| realGenerate( $bytes, $context = '' ) X-Ref |
| Produce $bytes of secure random data. As a side-effect, $this->lastK is set to the last hashLen block of key material. param: int $bytes Number of bytes of data param: string $context Context to mix into CTXinfo return: string Binary string of length $bytes |
| HKDF( $hash, $ikm, $salt, $info, $L ) X-Ref |
| RFC5869 defines HKDF in 2 steps, extraction and expansion. From http://eprint.iacr.org/2010/264.pdf: The scheme HKDF is specifed as: HKDF(XTS, SKM, CTXinfo, L) = K(1) || K(2) || ... || K(t) where the values K(i) are defined as follows: PRK = HMAC(XTS, SKM) K(1) = HMAC(PRK, CTXinfo || 0); K(i+1) = HMAC(PRK, K(i) || CTXinfo || i), 1 <= i < t; where t = [L/k] and the value K(t) is truncated to its first d = L mod k bits; the counter i is non-wrapping and of a given fixed size, e.g., a single byte. Note that the length of the HMAC output is the same as its key length and therefore the scheme is well defined. XTS is the "extractor salt" SKM is the "secret keying material" N.B. http://eprint.iacr.org/2010/264.pdf seems to differ from RFC 5869 in that the test vectors from RFC 5869 only work if K(0) = '' and K(1) = HMAC(PRK, K(0) || CTXinfo || 1) param: string $hash The hashing function to use (e.g., sha256) param: string $ikm The input keying material param: string $salt The salt to add to the ikm, to get the prk param: string $info Optional context (change the output without affecting param: int $L Number of bytes to return return: string Cryptographically secure pseudorandom binary string |
| HKDFExtract( $hash, $salt, $ikm ) X-Ref |
| Extract the PRK, PRK = HMAC(XTS, SKM) Note that the hmac is keyed with XTS (the salt), and the SKM (source key material) is the "data". param: string $hash The hashing function to use (e.g., sha256) param: string $salt The salt to add to the ikm, to get the prk param: string $ikm The input keying material return: string Binary string (pseudorandm key) used as input to HKDFExpand |
| HKDFExpand( $hash, $prk, $info, $bytes, &$lastK = '' ) X-Ref |
| Expand the key with the given context param: string $hash Hashing Algorithm param: string $prk A pseudorandom key of at least HashLen octets param: string $info Optional context and application specific information param: int $bytes Length of output keying material in bytes param: string &$lastK Set by this function to the last block of the expansion. return: string Cryptographically secure random string $bytes long |
| generate( $bytes, $context ) X-Ref |
| Generate cryptographically random data and return it in raw binary form. param: int $bytes The number of bytes of random data to generate param: string $context String to mix into HMAC context return: string Binary string of length $bytes |
| generateHex( $chars, $context = '' ) X-Ref |
| Generate cryptographically random data and return it in hexadecimal string format. See MWCryptRand::realGenerateHex for details of the char-to-byte conversion logic. param: int $chars The number of hex chars of random data to generate param: string $context String to mix into HMAC context return: string Random hex characters, $chars long |
| Generated: Fri Nov 28 14:03:12 2014 | Cross-referenced by PHPXref 0.7.1 |