Definitions

1. HMAC is a well-studied message authentication code that is based on a provably secure construction.
2. HMAC is a way of verifying the authenticity and integrity of a message.
3. HMAC is a mechanism for message authentication using a one-way hash function and a secret shared key.
4. HMAC is a variant that provides an additional level of hashing.
5. HMAC (keyed hashing for message authentication) is an example in that category.
6. HMAC is a more efficient, and increasingly popular, alternative.

Key

1. The Short Authentication String (SAS) value is calculated from the HMAC of a fixed string, keyed with an HMAC key derived from the whole key agreement.
2. Let the HMAC key be called KEY, and let the length of KEY in octets be called LENGTH. LENGTH is a single octet.
3. The first method defined uses a Triple DES (Data Encryption Standard) key to encrypt the HMAC key.

Old Master Key

1. The key for HMAC has been derived from the old Master key.

Underlying Hash Function

1. The cryptographic strength of HMAC depends on the properties of the underlying hash function.

Way

1. Implementation Note HMAC is defined in such a way that the underlying hash function H can be used with no modification to its code.

Effect

1. Choosing to implement HMAC in the above way is a decision of the local implementation and has no effect on inter-operability.

Construction

1. The construction we use for this operation is known as HMAC, described in [HMAC]. HMAC can be used with a variety of different hash algorithms.

Variant

1. To do all this, Fritz will use several cryptographic algorithms, such as SHA-1, HMAC, and a variant of RSA.

Important

1. It is also important to consider that while SHA-1 was never developed to be used as a keyed hash algorithm, HMAC had that criteria from the onset.

Mechanism

1. This mechanism, called HMAC, is based on work by the authors [BCK1] where the construction is presented and cryptographically analyzed.

Security

1. The specification should specify HMAC-MD5; don't just say HMAC. The security here stops someone from accidentally plugging in a router; nothing more.

Negotiation

1. If a "prf" is not negotiation, the HMAC (see [KBC96]) version of the negotiated hash algorithm is used as a pseudo-random function.

Data

1. A checksum called a hash message authentication code (HMAC) is calculated for the data of the packet.

Encrypted

1. If the two HMAC values are the same, then the encrypted file has been authenticated and the bootloader can execute the program (block 365).

First Block

1. So, in authenticated mode, HMAC covers the first block + (16 octets); in encrypted mode, HMAC covers two first blocks (32 + octets).

Implementations

1. A more secure scheme would use an HMAC. Finally, some implementations use only a small fixed pool of CAPTCHA images.

Truncated

1. Next is sigsIDi, the HMAC of the initiator's signaling secret, truncated to 64 bits.

Hash Functions

1. One is based on hash functions, one on HMAC, one on block ciphers and one on elliptic curves.

Hash Function

1. We propose denoting a realization of HMAC that uses a hash function H with t bits of output as HMAC-H-t.

Cipher Suites

1. The cipher suites defined in this document use a construction known as HMAC, described in [HMAC], which is based on a hash function.
2. Note that if new cipher suites are added that do not use HMAC, and the session negotiates one of these cipher suites, this extension will have no effect.

Cryptographic Hash Functions

1. HMAC - Hash function based Message Authentication Code is a mechanism for message authentication using cryptographic hash functions.

Cryptographic Hash Function

1. HMAC can be used with any iterative Approved cryptographic hash function, in combination with a shared secret key.

Integrity Protection

1. Cryptographic algorithms defined for use with IPsec include HMAC - SHA1 for integrity protection, and TripleDES - CBC and AES -CBC for confidentiality.

Data Origin Authentication

1. Data integrity and data origin authentication as provided by HMAC are dependent upon the scope of the distribution of the secret key.
2. Although the HMAC transform establishes a group-level security property, data origin authentication is not achieved.

Authentication

1. The same key + used for AES encryption is used for HMAC authentication.
2. The key for HMAC (authentication) is the same as the key + for AES (encryption).

Macs

1. Based on this we recover security of popular classes of message authentication schemes such as MACs (including HMAC and PRF-based MACs) and CW-schemes.

Mac

1. FIPS 198, The Keyed-Hash Message Authentication Code (HMAC), specifies the computation of a MAC using an approved hash function and a key.
2. HMAC is a MAC (message authentication code), i.e.
3. HMAC and the Pseudorandom Function The TLS record layer uses a keyed Message Authentication Code (MAC) to protect message integrity.

Message

1. Hashing Algorithms for Message Digests HMAC (Hash Message Authentication Code) block is a hash value, much like a checksum.
2. The rest of the message is encrypted using CFB and protected by the HMAC. The next 16 bits are not used.

Value

1. The returned output may be a hash value or an HMAC (Hash Message Authentication Code) value.
2. The Initiator will check the HMAC and value (and optionally MKI) to also the Signature to verify the integrity and authenticity of the packet.

Algorithm

1. The HMAC algorithm provides a framework for inserting various hashing algorithms such as MD5. HMAC-MD5-96 operates on 64-byte blocks of data.
2. The HMAC algorithm provides a framework for inserting various hashing algorithms such as SHA-1. HMAC-SHA-1-96 operates on 64-byte blocks of data.
3. However, since the algorithm is capable of being performed in an upper program driving the HMAC, it is not considered in the present invention.

Algorithms

1. For example, see [ RFC 2104] for how TKEY agreed shared secret keying material is used in the HMAC-MD5 algorithm or other HMAC algorithms.

Md5

1. It is also important to consider that while MD5 was never developed to be used as a keyed hash algorithm, HMAC had that criteria from the onset.
2. HMAC with MD5 provides data origin authentication and integrity protection.
3. Widely used algorithms include MD5 and SHA. In IPsec, message digests are used for HMAC authentication of packets.

Sha-1

1. HMAC with SHA-1 provides data origin authentication and integrity protection.
2. HMAC can be used with any iterative cryptographic hash function, e.g., MD5, SHA-1, in combination with a secret shared key.
3. HOTP-SHA256-6: HOTP with SHA-1 as the hash function for HMAC and a dynamic truncation to a 6-digit value;.

Hash

1. It allows one to specify a key at creation of the HMAC. Only persons with that key can verify the hash.
2. This chapter discusses the HMAC and CMAC Message Authentication Code (MAC) algorithms, which are constructed from hash and cipher functions.

Message Authentication

1. Abstract This document defines two methods for wrapping an HMAC (Hashed Message Authentication Code) key.
2. Abstract This document describes HMAC, a mechanism for message authentication using cryptographic hash functions.
3. The HmacSHA* algorithms as defined in RFC 2104 "HMAC: Keyed-Hashing for Message Authentication" (February 1997) with SHA-* as the message digest algorithm.

Hmac

1. There are several ways to create a MAC, through a one-time key, a one-way hash function with a key (HMAC), or through stream and block algorithms.
2. H Hash see message digest Hashed Message Authentication Code (HMAC) using keyed message digest functions to authenticate a message.

Categories

1. Message Authentication
2. Sha-1
3. Hash Function
4. Md5
5. Secret Key

Related Keywords

* Hmac Key

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