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What is an existential risk? We think of existential risks, or global catastrophic risks, as risks that could cause the collapse of human civilization or even the extinction of the human species. Prominent examples of human-driven global catastrophic risks include 1) nuclear winter, 2) an infectious disease pandemic engineered by malevolent actors using synthetic biology, 3) catastrophic. 103 votes, 49 comments. 48.2k members in the Wizard101 community. Wizard101 is an MMO made by Kingsisle Entertainment that was started in 2005,. The possible symptoms emanating from existential depression come from a deep, nebulous source and they don't respond much to techniques that simply address one's cognitive errors, irrational. Technology Facebook Is Facing Its 'Existential Threat,' but It's Not From the Government. It's Apple The two companies are battling back and forth over how big tech treats your privacy.

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In cryptography, a message authentication code (MAC), sometimes known as a tag, is a short piece of information used to authenticate a message—in other words, to confirm that the message came from the stated sender (its authenticity) and has not been changed. The MAC value protects a message's data integrity, as well as its authenticity, by allowing verifiers (who also possess the secret key) to detect any changes to the message content.

Terminology[edit]

The term message integrity code (MIC) is frequently substituted for the term MAC, especially in communications^[1] to distinguish it from the use of the latter as media access control address (MAC address). However, some authors^[2] use MIC to refer to a message digest, which aims only to uniquely but opaquely identify a single message. RFC 4949 recommends avoiding the term message integrity code (MIC), and instead using checksum, error detection code, hash, keyed hash, message authentication code, or protected checksum.

Definitions[edit]

Informally, a message authentication code system consists of three algorithms:

• A key generation algorithm selects a key from the key space uniformly at random.
• A signing algorithm efficiently returns a tag given the key and the message.
• A verifying algorithm efficiently verifies the authenticity of the message given the key and the tag. That is, return accepted when the message and tag are not tampered with or forged, and otherwise return rejected.

A secure message authentication code must resist attempts by an adversary to forge tags, for arbitrary, select, or all messages, including under conditions of known- or chosen-plaintext. It should be computationally infeasible to compute a valid tag of the given message without knowledge of the key, even if for the worst case, we assume the adversary knows the tag of any message but the one in question.^[3]

Formally, a message authentication code (MAC) system is a triple of efficient^[4] algorithms (G, S, V) satisfying:

• G (key-generator) gives the key k on input 1ⁿ, where n is the security parameter.
• S (signing) outputs a tag t on the key k and the input string x.
• V (verifying) outputs accepted or rejected on inputs: the key k, the string x and the tag t.

S and V must satisfy the following:

Pr [ k ← G(1ⁿ), V( k, x, S(k, x) ) = accepted ] = 1.^[5]

A MAC is unforgeable if for every efficient adversary A

Pr [ k ← G(1ⁿ), (x, t) ← A^{S(k, · )}(1ⁿ), x ∉ Query(A^{S(k, · )}, 1ⁿ), V(k, x, t) = accepted] < negl(n),

where A^{S(k, · )} denotes that A has access to the oracle S(k, · ), and Query(A^{S(k, · )}, 1ⁿ) denotes the set of the queries on S made by A, which knows n. Clearly we require that any adversary cannot directly query the string x on S, since otherwise a valid tag can be easily obtained by that adversary.^[6]

Security[edit]

While MAC functions are similar to cryptographic hash functions, they possess different security requirements. To be considered secure, a MAC function must resist existential forgery under chosen-plaintext attacks. This means that even if an attacker has access to an oracle which possesses the secret key and generates MACs for messages of the attacker's choosing, the attacker cannot guess the MAC for other messages (which were not used to query the oracle) without performing infeasible amounts of computation.

MACs differ from digital signatures as MAC values are both generated and verified using the same secret key. This implies that the sender and receiver of a message must agree on the same key before initiating communications, as is the case with symmetric encryption. For the same reason, MACs do not provide the property of non-repudiation offered by signatures specifically in the case of a network-wide shared secret key: any user who can verify a MAC is also capable of generating MACs for other messages. In contrast, a digital signature is generated using the private key of a key pair, which is public-key cryptography.^[4] Since this private key is only accessible to its holder, a digital signature proves that a document was signed by none other than that holder. Thus, digital signatures do offer non-repudiation. However, non-repudiation can be provided by systems that securely bind key usage information to the MAC key; the same key is in the possession of two people, but one has a copy of the key that can be used for MAC generation while the other has a copy of the key in a hardware security module that only permits MAC verification. This is commonly done in the finance industry.^{[citation needed]}

Implementation[edit]

MAC algorithms can be constructed from other cryptographic primitives, like cryptographic hash functions (as in the case of HMAC) or from block cipher algorithms (OMAC, CCM, GCM, and PMAC). However many of the fastest MAC algorithms like UMAC-VMAC and Poly1305-AES are constructed based on universal hashing.^[7]

Intrinsically keyed hash algorithms such as SipHash are also by definition MACs; they can be even faster than universal-hashing based MACs.^[8]

Additionally, the MAC algorithm can deliberately combine two or more cryptographic primitives, so as to maintain protection even if one of them is later found to be vulnerable. For instance, in Transport Layer Security (TLS), the input data is split in halves that are each processed with a different hashing primitive (SHA-1 and SHA-2) then XORed together to output the MAC.

One-time MAC[edit]

Universal hashing and in particular pairwise independent hash functions provide a secure message authentication code as long as the key is used at most once. This can be seen as the one-time pad for authentication.^[9]

The simplest such pairwise independent hash function is defined by the random key, key = (a, b), and the MAC tag for a message m is computed as tag = (am + b) mod p, where p is prime.

More generally, k-independent hashing functions provide a secure message authentication code as long as the key is used less than k times for k-ways independent hashing functions.

Message authentication codes and data origin authentication have been also discussed in the framework of quantum cryptography. By contrast to other cryptographic tasks, such as key distribution, for a rather broad class of quantum MACs it has been shown that quantum resources do not offer any advantage over unconditionally secure one-time classical MACs.^[10]

Standards[edit]

Various standards exist that define MAC algorithms. These include:

• FIPS PUB 113 Computer Data Authentication,^[11] withdrawn in 2002,^[12] defines an algorithm based on DES.
• FIPS PUB 198-1 The Keyed-Hash Message Authentication Code (HMAC)^[13]
• ISO/IEC 9797-1Mechanisms using a block cipher^[14]
• ISO/IEC 9797-2 Mechanisms using a dedicated hash-function^[15]
• ISO/IEC 9797-3 Mechanisms using a universal hash-function^[16]
• ISO/IEC 29192-6 Lightweight cryptography - Message authentication codes^[17]

ISO/IEC 9797-1 and -2 define generic models and algorithms that can be used with any block cipher or hash function, and a variety of different parameters. These models and parameters allow more specific algorithms to be defined by nominating the parameters. For example, the FIPS PUB 113 algorithm is functionally equivalent to ISO/IEC 9797-1 MAC algorithm 1 with padding method 1 and a block cipher algorithm of DES.

An example of MAC use[edit]

^[18] In this example, the sender of a message runs it through a MAC algorithm to produce a MAC data tag. The message and the MAC tag are then sent to the receiver. The receiver in turn runs the message portion of the transmission through the same MAC algorithm using the same key, producing a second MAC data tag. The receiver then compares the first MAC tag received in the transmission to the second generated MAC tag. If they are identical, the receiver can safely assume that the message was not altered or tampered with during transmission (data integrity).

However, to allow the receiver to be able to detect replay attacks, the message itself must contain data that assures that this same message can only be sent once (e.g. time stamp, sequence number or use of a one-time MAC). Otherwise an attacker could – without even understanding its content – record this message and play it back at a later time, producing the same result as the original sender.

See also[edit]

• Hash-based message authentication code (HMAC)

Notes[edit]

1. ^IEEE 802.11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications(PDF). (2007 revision). IEEE-SA. 12 June 2007. doi:10.1109/IEEESTD.2007.373646. ISBN978-0-7381-5656-9.
2. ^Fred B Schneider, Hashes and Message Digests, Cornell University
3. ^The strongest adversary is assumed to have access to the signing algorithm without knowing the key. However, her final forged message must be different from any message she chose to query the signing algorithm before. See Pass's discussions before def 134.2.
4. ^ ^abTheoretically, an efficient algorithm runs within probabilistic polynomial time.
5. ^Pass, def 134.1
6. ^Pass, def 134.2
7. ^'VMAC: Message Authentication Code using Universal Hashing'. CFRG Working Group. Retrieved 16 March 2010.
8. ^Jean-Philippe Aumasson & Daniel J. Bernstein (2012-09-18). 'SipHash: a fast short-input PRF'(PDF).
9. ^Simmons, Gustavus (1985). 'Authentication theory/coding theory'. Advances in Cryptology: Proceedings of CRYPTO 84. Berlin: Springer. pp. 411–431.
10. ^Nikolopoulos, Georgios M.; Fischlin, Marc (2020). 'Information-Theoretically Secure Data Origin Authentication with Quantum and Classical Resources'. Cryptography. 4 (4): 31. arXiv:2011.06849. doi:10.3390/cryptography4040031. S2CID226956062.
11. ^'FIPS PUB 113 Computer Data Authentication'. Archived from the original on 2011-09-27. Retrieved 2010-10-10.
12. ^'Federal Information Processing Standards Publications, Withdrawn FIPS Listed by Number'. Archived from the original on 2010-08-01. Retrieved 2010-10-10.
13. ^The Keyed-Hash Message Authentication Code (HMAC)
14. ^ISO/IEC 9797-1 Information technology — Security techniques — Message Authentication Codes (MACs) — Part 1: Mechanisms using a block cipher
15. ^ISO/IEC 9797-2 Information technology — Security techniques — Message Authentication Codes (MACs) — Part 2: Mechanisms using a dedicated hash-function
16. ^ISO/IEC 9797-3 Information technology — Security techniques — Message Authentication Codes (MACs) — Part 3: Mechanisms using a universal hash-function
17. ^ISO/IEC 29192-6 Information technology — Lightweight cryptography — Part 6: Message authentication codes (MACs)
18. ^'Mac Security Overview', Mac® Security Bible, Wiley Publishing, Inc., 2011-11-01, pp. 1–26, doi:10.1002/9781118257739.ch1, ISBN9781118257739

References[edit]

• Goldreich, Oded (2001), Foundations of cryptography I: Basic Tools, Cambridge: Cambridge University Press, ISBN978-0-511-54689-1
• Goldreich, Oded (2004), Foundations of cryptography II: Basic Applications (1. publ. ed.), Cambridge [u.a.]: Cambridge Univ. Press, ISBN978-0-521-83084-3
• Pass, Rafael, A Course in Cryptography(PDF), retrieved 31 December 2015^[1]

External links[edit]

1. ^11-12-20C8

When it comes to developing the company, it involves a lot of development strategies and that includes storing all the data that the company is throwing out on a daily basis. This calls for sophisticated numbers and data management software that will be helpful in managing all these. Now there are a lot of definite software out there that will get the job done, but who can do it better than Microsoft Excel 2010.

License
Official Installer

File Size
537MB

OS
Windows

Language
English

Developer
Microsoft

Overview of Microsoft Excel 2010

The Microsoft excel is a sub package of the Microsoft office that is an all-inclusive utility package from Microsoft. There are a lot of definite measurements that you need to take to make sure that you make the optimum usage of the software that you use. There are a ton of other features that you need to take into consideration. Now there are a lot of other things that you need to ensure before you make a decision of downloading the software as well.

Microsoft Excel 2010 is a very useful software for most of the companies as it will help in maintaining their data and also make a sophisticated set of tables to keep a track record. You can also read and download Microsoft PowerPoint 2010 for free.

This is a software that is effectively and easily available within the reach of an eye for many and this is probably the best and effective method through which you can manage huge amounts of data.

Existential Mac Os Catalina

Features of Microsoft Excel 2010

Sparklines are something that is interesting

When you are dealing with data there are tons of different ways in which you can use that data to represent it to a third person. The usual way is to use the graphs that are in-built within the software and that will definitely help you in representing your data in a much more enhanced manner.

There are a lot of other things that you can take into consideration when you are dealing with data interpretation. Sparklines are the best thing with which you can come into contact with once you are done with the technical difficulties of representing data. There are a lot of other things that you can ensure to make the best use of your data as well.

Message authentication codes and data origin authentication have been also discussed in the framework of quantum cryptography. By contrast to other cryptographic tasks, such as key distribution, for a rather broad class of quantum MACs it has been shown that quantum resources do not offer any advantage over unconditionally secure one-time classical MACs.^[10]

Standards[edit]

Various standards exist that define MAC algorithms. These include:

• FIPS PUB 113 Computer Data Authentication,^[11] withdrawn in 2002,^[12] defines an algorithm based on DES.
• FIPS PUB 198-1 The Keyed-Hash Message Authentication Code (HMAC)^[13]
• ISO/IEC 9797-1Mechanisms using a block cipher^[14]
• ISO/IEC 9797-2 Mechanisms using a dedicated hash-function^[15]
• ISO/IEC 9797-3 Mechanisms using a universal hash-function^[16]
• ISO/IEC 29192-6 Lightweight cryptography - Message authentication codes^[17]

ISO/IEC 9797-1 and -2 define generic models and algorithms that can be used with any block cipher or hash function, and a variety of different parameters. These models and parameters allow more specific algorithms to be defined by nominating the parameters. For example, the FIPS PUB 113 algorithm is functionally equivalent to ISO/IEC 9797-1 MAC algorithm 1 with padding method 1 and a block cipher algorithm of DES.

An example of MAC use[edit]

^[18] In this example, the sender of a message runs it through a MAC algorithm to produce a MAC data tag. The message and the MAC tag are then sent to the receiver. The receiver in turn runs the message portion of the transmission through the same MAC algorithm using the same key, producing a second MAC data tag. The receiver then compares the first MAC tag received in the transmission to the second generated MAC tag. If they are identical, the receiver can safely assume that the message was not altered or tampered with during transmission (data integrity).

However, to allow the receiver to be able to detect replay attacks, the message itself must contain data that assures that this same message can only be sent once (e.g. time stamp, sequence number or use of a one-time MAC). Otherwise an attacker could – without even understanding its content – record this message and play it back at a later time, producing the same result as the original sender.

See also[edit]

• Hash-based message authentication code (HMAC)

Notes[edit]

1. ^IEEE 802.11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications(PDF). (2007 revision). IEEE-SA. 12 June 2007. doi:10.1109/IEEESTD.2007.373646. ISBN978-0-7381-5656-9.
2. ^Fred B Schneider, Hashes and Message Digests, Cornell University
3. ^The strongest adversary is assumed to have access to the signing algorithm without knowing the key. However, her final forged message must be different from any message she chose to query the signing algorithm before. See Pass's discussions before def 134.2.
4. ^ ^abTheoretically, an efficient algorithm runs within probabilistic polynomial time.
5. ^Pass, def 134.1
6. ^Pass, def 134.2
7. ^'VMAC: Message Authentication Code using Universal Hashing'. CFRG Working Group. Retrieved 16 March 2010.
8. ^Jean-Philippe Aumasson & Daniel J. Bernstein (2012-09-18). 'SipHash: a fast short-input PRF'(PDF).
9. ^Simmons, Gustavus (1985). 'Authentication theory/coding theory'. Advances in Cryptology: Proceedings of CRYPTO 84. Berlin: Springer. pp. 411–431.
10. ^Nikolopoulos, Georgios M.; Fischlin, Marc (2020). 'Information-Theoretically Secure Data Origin Authentication with Quantum and Classical Resources'. Cryptography. 4 (4): 31. arXiv:2011.06849. doi:10.3390/cryptography4040031. S2CID226956062.
11. ^'FIPS PUB 113 Computer Data Authentication'. Archived from the original on 2011-09-27. Retrieved 2010-10-10.
12. ^'Federal Information Processing Standards Publications, Withdrawn FIPS Listed by Number'. Archived from the original on 2010-08-01. Retrieved 2010-10-10.
13. ^The Keyed-Hash Message Authentication Code (HMAC)
14. ^ISO/IEC 9797-1 Information technology — Security techniques — Message Authentication Codes (MACs) — Part 1: Mechanisms using a block cipher
15. ^ISO/IEC 9797-2 Information technology — Security techniques — Message Authentication Codes (MACs) — Part 2: Mechanisms using a dedicated hash-function
16. ^ISO/IEC 9797-3 Information technology — Security techniques — Message Authentication Codes (MACs) — Part 3: Mechanisms using a universal hash-function
17. ^ISO/IEC 29192-6 Information technology — Lightweight cryptography — Part 6: Message authentication codes (MACs)
18. ^'Mac Security Overview', Mac® Security Bible, Wiley Publishing, Inc., 2011-11-01, pp. 1–26, doi:10.1002/9781118257739.ch1, ISBN9781118257739

References[edit]

• Goldreich, Oded (2001), Foundations of cryptography I: Basic Tools, Cambridge: Cambridge University Press, ISBN978-0-511-54689-1
• Goldreich, Oded (2004), Foundations of cryptography II: Basic Applications (1. publ. ed.), Cambridge [u.a.]: Cambridge Univ. Press, ISBN978-0-521-83084-3
• Pass, Rafael, A Course in Cryptography(PDF), retrieved 31 December 2015^[1]

External links[edit]

1. ^11-12-20C8

When it comes to developing the company, it involves a lot of development strategies and that includes storing all the data that the company is throwing out on a daily basis. This calls for sophisticated numbers and data management software that will be helpful in managing all these. Now there are a lot of definite software out there that will get the job done, but who can do it better than Microsoft Excel 2010.

License
Official Installer

File Size
537MB

OS
Windows

Language
English

Developer
Microsoft

Overview of Microsoft Excel 2010

The Microsoft excel is a sub package of the Microsoft office that is an all-inclusive utility package from Microsoft. There are a lot of definite measurements that you need to take to make sure that you make the optimum usage of the software that you use. There are a ton of other features that you need to take into consideration. Now there are a lot of other things that you need to ensure before you make a decision of downloading the software as well.

Microsoft Excel 2010 is a very useful software for most of the companies as it will help in maintaining their data and also make a sophisticated set of tables to keep a track record. You can also read and download Microsoft PowerPoint 2010 for free.

This is a software that is effectively and easily available within the reach of an eye for many and this is probably the best and effective method through which you can manage huge amounts of data.

Existential Mac Os Catalina

Features of Microsoft Excel 2010

Sparklines are something that is interesting

When you are dealing with data there are tons of different ways in which you can use that data to represent it to a third person. The usual way is to use the graphs that are in-built within the software and that will definitely help you in representing your data in a much more enhanced manner.

There are a lot of other things that you can take into consideration when you are dealing with data interpretation. Sparklines are the best thing with which you can come into contact with once you are done with the technical difficulties of representing data. There are a lot of other things that you can ensure to make the best use of your data as well.

Slicer feature is something that we all would require

Now there are a lot of definite things that go from making a data presentation from a good one to an awesome one. This means that when you are dealing with drastic measurements it needs to be represented in a very sophisticated manner to make sure that you don't mess up with the data that is existential.

The slicer feature will allow you to slice all the contents that you would need and summon up a pivot table only when you require them rather than not when they are not needed. This will make sure that the data that you present is more organized and good looking from the outside.

Different types of pasting

Now there are a lot of different methodologies that you need to implement to make sure that there is much more to what is actually given in the system. There are ton loads of definite qualities within the software that will make your life much easier. Now we all have been there where we are in a position to make a decision of pasting content from a source onto your sheet.

When all the plans are in place, the biggest drawback that we would face is the pasted material goes immensely out of scale in the sheet that would spoil your overall data. That is where paste previews come into play. There are a lot of options that you can choose from and based on the features that you are looking forward to pasting in your sheet you can do the same.

Direct control from the File menu

When we are dealing with large amounts of data, it means that there is a high possibility that you would require more than one sheet to complete the data capture and that is where you would open multiple files. There are a lot of other things that you need to bring into consideration and this also includes the various controls that you can inflict on the data that is present in the different excel sheets under your control. From the file section, you can open, close and edit different excel sheets to make a definite advantage of your sheets in the systems.

System Requirements of Microsoft Excel 2010

• There are no pre-requisite requirements to run Excel 2010.
• Operating system: Windows 7 and above
• RAM: 1 Gb
• HDD Space: 1 GB

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Download MS Excel 2010

There are a lot of other interesting things that you can do in excel that cannot be covered in a single blog post. Go ahead and start experimenting with all the data in your hand. You can access the installer file of the excel 2010 by accessing the link below.