Digital signature

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Digital_signature

Alice signs a message—"Hello Bob!"—by appending a signature computed from the message and her private key. Bob receives both the message and signature. He uses Alice's public key to verify the authenticity of the signed message.

A digital signature is a mathematical scheme for verifying the authenticity of digital messages or documents. A valid digital signature on a message gives a recipient confidence that the message came from a sender known to the recipient.

Digital signatures are a standard element of most cryptographic protocol suites, and are commonly used for software distribution, financial transactions, contract management software, and in other cases where it is important to detect forgery or tampering.

Digital signatures are often used to implement electronic signatures, which include any electronic data that carries the intent of a signature, but not all electronic signatures use digital signatures. Electronic signatures have legal significance in some countries, including Brazil, Canada, South Africa, the United States, Algeria, Turkey, India, Indonesia, Mexico, Saudi Arabia, Uruguay, Switzerland, Chile and the countries of the European Union.

Digital signatures employ asymmetric cryptography. In many instances, they provide a layer of validation and security to messages sent through a non-secure channel: Properly implemented, a digital signature gives the receiver reason to believe the message was sent by the claimed sender. Digital signatures are equivalent to traditional handwritten signatures in many respects, but properly implemented digital signatures are more difficult to forge than the handwritten type. Digital signature schemes, in the sense used here, are cryptographically based, and must be implemented properly to be effective. They can also provide non-repudiation, meaning that the signer cannot successfully claim they did not sign a message, while also claiming their private key remains secret. Further, some non-repudiation schemes offer a timestamp for the digital signature, so that even if the private key is exposed, the signature is valid. Digitally signed messages may be anything representable as a bitstring: examples include electronic mail, contracts, or a message sent via some other cryptographic protocol.

Definition

Main article: Public-key cryptography

A digital signature scheme typically consists of three algorithms:

• A key generation algorithm that selects a private key uniformly at random from a set of possible private keys. The algorithm outputs the private key and a corresponding public key.
• A signing algorithm that, given a message and a private key, produces a signature.
• A signature verifying algorithm that, given the message, public key and signature, either accepts or rejects the message's claim to authenticity.

Two main properties are required:

First, the authenticity of a signature generated from a fixed message and fixed private key can be verified by using the corresponding public key.

Secondly, it should be computationally infeasible to generate a valid signature for a party without knowing that party's private key. A digital signature is an authentication mechanism that enables the creator of the message to attach a code that acts as a signature. The Digital Signature Algorithm (DSA), developed by the National Institute of Standards and Technology, is one of many examples of a signing algorithm.

In the following discussion, 1ⁿ refers to a unary number.

Formally, a digital signature scheme is a triple of probabilistic polynomial time algorithms, (G, S, V), satisfying:

• G (key-generator) generates a public key (pk), and a corresponding private key (sk), on input 1ⁿ, where n is the security parameter.
• S (signing) returns a tag, t, on the inputs: the private key (sk), and a string (x).
• V (verifying) outputs accepted or rejected on the inputs: the public key (pk), a string (x), and a tag (t).

For correctness, S and V must satisfy

Pr [ (pk, sk) ← G(1ⁿ), V( pk, x, S(sk, x) ) = accepted ] = 1.

A digital signature scheme is secure if for every non-uniform probabilistic polynomial time adversary, A

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

where A^{S(sk, · )} denotes that A has access to the oracle, S(sk, · ), Q denotes the set of the queries on S made by A, which knows the public key, pk, and the security parameter, n, and x ∉ Q denotes that the adversary may not directly query the string, x, on S.

History

In 1976, Whitfield Diffie and Martin Hellman first described the notion of a digital signature scheme, although they only conjectured that such schemes existed based on functions that are trapdoor one-way permutations. Soon afterwards, Ronald Rivest, Adi Shamir, and Len Adleman invented the RSA algorithm, which could be used to produce primitive digital signatures (although only as a proof-of-concept – "plain" RSA signatures are not secure). The first widely marketed software package to offer digital signature was Lotus Notes 1.0, released in 1989, which used the RSA algorithm.

Other digital signature schemes were soon developed after RSA, the earliest being Lamport signatures, Merkle signatures (also known as "Merkle trees" or simply "Hash trees"), and Rabin signatures.

In 1988, Shafi Goldwasser, Silvio Micali, and Ronald Rivest became the first to rigorously define the security requirements of digital signature schemes. They described a hierarchy of attack models for signature schemes, and also presented the GMR signature scheme, the first that could be proved to prevent even an existential forgery against a chosen message attack, which is the currently accepted security definition for signature schemes. The first such scheme which is not built on trapdoor functions but rather on a family of function with a much weaker required property of one-way permutation was presented by Moni Naor and Moti Yung.

Method

One digital signature scheme (of many) is based on RSA. To create signature keys, generate an RSA key pair containing a modulus, N, that is the product of two random secret distinct large primes, along with integers, e and d, such that e d ≡ 1 (mod φ(N)), where φ is Euler's totient function. The signer's public key consists of N and e, and the signer's secret key contains d.

Used directly, this type of signature scheme is vulnerable to key-only existential forgery attack. To create a forgery, the attacker picks a random signature σ and uses the verification procedure to determine the message, m, corresponding to that signature. In practice, however, this type of signature is not used directly, but rather, the message to be signed is first hashed to produce a short digest, that is then padded to larger width comparable to N, then signed with the reverse trapdoor function. This forgery attack, then, only produces the padded hash function output that corresponds to σ, but not a message that leads to that value, which does not lead to an attack. In the random oracle model, hash-then-sign (an idealized version of that practice where hash and padding combined have close to N possible outputs), this form of signature is existentially unforgeable, even against a chosen-plaintext attack.

There are several reasons to sign such a hash (or message digest) instead of the whole document.

For efficiency

The signature will be much shorter and thus save time since hashing is generally much faster than signing in practice.

For compatibility

Messages are typically bit strings, but some signature schemes operate on other domains (such as, in the case of RSA, numbers modulo a composite number N). A hash function can be used to convert an arbitrary input into the proper format.

For integrity

Without the hash function, the text "to be signed" may have to be split (separated) in blocks small enough for the signature scheme to act on them directly. However, the receiver of the signed blocks is not able to recognize if all the blocks are present and in the appropriate order.

Applications

As organizations move away from paper documents with ink signatures or authenticity stamps, digital signatures can provide added assurances of the evidence to provenance, identity, and status of an electronic document as well as acknowledging informed consent and approval by a signatory. The United States Government Printing Office (GPO) publishes electronic versions of the budget, public and private laws, and congressional bills with digital signatures. Universities including Penn State, University of Chicago, and Stanford are publishing electronic student transcripts with digital signatures.

Below are some common reasons for applying a digital signature to communications:

Authentication

A message may have letterhead or a handwritten signature identifying its sender, but letterheads and handwritten signatures can be copied and pasted onto forged messages. Even legitimate messages may be modified in transit.

If a bank's central office receives a letter claiming to be from a branch office with instructions to change the balance of an account, the central bankers need to be sure, before acting on the instructions, that they were actually sent by a branch banker, and not forged—whether a forger fabricated the whole letter, or just modified an existing letter in transit by adding some digits.

With a digital signature scheme, the central office can arrange beforehand to have a public key on file whose private key is known only to the branch office. The branch office can later sign a message and the central office can use the public key to verify the signed message was not a forgery before acting on it. A forger who doesn't know the sender's private key can't sign a different message, or even change a single digit in an existing message without making the recipient's signature verification fail.

Encryption can hide the content of the message from an eavesdropper, but encryption on its own may not let recipient verify the message's authenticity, or even detect selective modifications like changing a digit—if the bank's offices simply encrypted the messages they exchange, they could still be vulnerable to forgery. In other applications, such as software updates, the messages are not secret—when a software author publishes a patch for all existing installations of the software to apply, the patch itself is not secret, but computers running the software must verify the authenticity of the patch before applying it, lest they become victims to malware.

Limitations

Replays. A digital signature scheme on its own does not prevent a valid signed message from being recorded and then maliciously reused in a replay attack. For example, the branch office may legitimately request that bank transfer be issued once in a signed message. If the bank doesn't use a system of transaction ids in their messages to detect which transfers have already happened, someone could illegitimately reuse the same signed message many times to drain an account.

Uniqueness and malleability of signatures. A signature itself cannot be used to uniquely identify the message it signs—in some signature schemes, every message has a large number of possible valid signatures from the same signer, and it may be easy, even without knowledge of the private key, to transform one valid signature into another. If signatures are misused as transaction ids in an attempt by a bank-like system such as a Bitcoin exchange to detect replays, this can be exploited to replay transactions.

Authenticating a public key. Prior knowledge of a public key can be used to verify authenticity of a signed message, but not the other way around—prior knowledge of a signed message cannot be used to verify authenticity of a public key. In some signature schemes, given a signed message, it is easy to construct a public key under which the signed message will pass verification, even without knowledge of the private key that was used to make the signed message in the first place.

Non-repudiation

Non-repudiation, or more specifically non-repudiation of origin, is an important aspect of digital signatures. By this property, an entity that has signed some information cannot at a later time deny having signed it. Similarly, access to the public key only does not enable a fraudulent party to fake a valid signature.

Note that these authentication, non-repudiation etc. properties rely on the secret key not having been revoked prior to its usage. Public revocation of a key-pair is a required ability, else leaked secret keys would continue to implicate the claimed owner of the key-pair. Checking revocation status requires an "online" check; e.g., checking a certificate revocation list or via the Online Certificate Status Protocol. Very roughly this is analogous to a vendor who receives credit-cards first checking online with the credit-card issuer to find if a given card has been reported lost or stolen. Of course, with stolen key pairs, the theft is often discovered only after the secret key's use, e.g., to sign a bogus certificate for espionage purpose.

Notions of security

In their foundational paper, Goldwasser, Micali, and Rivest lay out a hierarchy of attack models against digital signatures:

1. In a key-only attack, the attacker is only given the public verification key.
2. In a known message attack, the attacker is given valid signatures for a variety of messages known by the attacker but not chosen by the attacker.
3. In an adaptive chosen message attack, the attacker first learns signatures on arbitrary messages of the attacker's choice.

They also describe a hierarchy of attack results:

1. A total break results in the recovery of the signing key.
2. A universal forgery attack results in the ability to forge signatures for any message.
3. A selective forgery attack results in a signature on a message of the adversary's choice.
4. An existential forgery merely results in some valid message/signature pair not already known to the adversary.

The strongest notion of security, therefore, is security against existential forgery under an adaptive chosen message attack.

Additional security precautions

Putting the private key on a smart card

All public key / private key cryptosystems depend entirely on keeping the private key secret. A private key can be stored on a user's computer, and protected by a local password, but this has two disadvantages:

• the user can only sign documents on that particular computer
• the security of the private key depends entirely on the security of the computer

A more secure alternative is to store the private key on a smart card. Many smart cards are designed to be tamper-resistant (although some designs have been broken, notably by Ross Anderson and his students). In a typical digital signature implementation, the hash calculated from the document is sent to the smart card, whose CPU signs the hash using the stored private key of the user, and then returns the signed hash. Typically, a user must activate their smart card by entering a personal identification number or PIN code (thus providing two-factor authentication). It can be arranged that the private key never leaves the smart card, although this is not always implemented. If the smart card is stolen, the thief will still need the PIN code to generate a digital signature. This reduces the security of the scheme to that of the PIN system, although it still requires an attacker to possess the card. A mitigating factor is that private keys, if generated and stored on smart cards, are usually regarded as difficult to copy, and are assumed to exist in exactly one copy. Thus, the loss of the smart card may be detected by the owner and the corresponding certificate can be immediately revoked. Private keys that are protected by software only may be easier to copy, and such compromises are far more difficult to detect.

Using smart card readers with a separate keyboard

Entering a PIN code to activate the smart card commonly requires a numeric keypad. Some card readers have their own numeric keypad. This is safer than using a card reader integrated into a PC, and then entering the PIN using that computer's keyboard. Readers with a numeric keypad are meant to circumvent the eavesdropping threat where the computer might be running a keystroke logger, potentially compromising the PIN code. Specialized card readers are also less vulnerable to tampering with their software or hardware and are often EAL3 certified.

Other smart card designs

Smart card design is an active field, and there are smart card schemes which are intended to avoid these particular problems, despite having few security proofs so far.

Using digital signatures only with trusted applications

One of the main differences between a digital signature and a written signature is that the user does not "see" what they sign. The user application presents a hash code to be signed by the digital signing algorithm using the private key. An attacker who gains control of the user's PC can possibly replace the user application with a foreign substitute, in effect replacing the user's own communications with those of the attacker. This could allow a malicious application to trick a user into signing any document by displaying the user's original on-screen, but presenting the attacker's own documents to the signing application.

To protect against this scenario, an authentication system can be set up between the user's application (word processor, email client, etc.) and the signing application. The general idea is to provide some means for both the user application and signing application to verify each other's integrity. For example, the signing application may require all requests to come from digitally signed binaries.

Using a network attached hardware security module

One of the main differences between a cloud based digital signature service and a locally provided one is risk. Many risk averse companies, including governments, financial and medical institutions, and payment processors require more secure standards, like FIPS 140-2 level 3 and FIPS 201 certification, to ensure the signature is validated and secure.

WYSIWYS

Main article: WYSIWYS

Technically speaking, a digital signature applies to a string of bits, whereas humans and applications "believe" that they sign the semantic interpretation of those bits. In order to be semantically interpreted, the bit string must be transformed into a form that is meaningful for humans and applications, and this is done through a combination of hardware and software based processes on a computer system. The problem is that the semantic interpretation of bits can change as a function of the processes used to transform the bits into semantic content. It is relatively easy to change the interpretation of a digital document by implementing changes on the computer system where the document is being processed. From a semantic perspective this creates uncertainty about what exactly has been signed. WYSIWYS (What You See Is What You Sign) means that the semantic interpretation of a signed message cannot be changed. In particular this also means that a message cannot contain hidden information that the signer is unaware of, and that can be revealed after the signature has been applied. WYSIWYS is a requirement for the validity of digital signatures, but this requirement is difficult to guarantee because of the increasing complexity of modern computer systems. The term WYSIWYS was coined by Peter Landrock and Torben Pedersen to describe some of the principles in delivering secure and legally binding digital signatures for Pan-European projects.

Digital signatures versus ink on paper signatures

An ink signature could be replicated from one document to another by copying the image manually or digitally, but to have credible signature copies that can resist some scrutiny is a significant manual or technical skill, and to produce ink signature copies that resist professional scrutiny is very difficult.

Digital signatures cryptographically bind an electronic identity to an electronic document and the digital signature cannot be copied to another document. Paper contracts sometimes have the ink signature block on the last page, and the previous pages may be replaced after a signature is applied. Digital signatures can be applied to an entire document, such that the digital signature on the last page will indicate tampering if any data on any of the pages have been altered, but this can also be achieved by signing with ink and numbering all pages of the contract.

Some digital signature algorithms

• RSA
• DSA
• ECDSA
• EdDSA
• RSA with SHA
• ECDSA with SHA
• ElGamal signature scheme as the predecessor to DSA, and variants Schnorr signature and Pointcheval–Stern signature algorithm
• Rabin signature algorithm
• Pairing-based schemes such as BLS
• NTRUSign is an example of a digital signature scheme based on hard lattice problems
• Undeniable signatures
• Aggregate signatureru – a signature scheme that supports aggregation: Given n signatures on n messages from n users, it is possible to aggregate all these signatures into a single signature whose size is constant in the number of users. This single signature will convince the verifier that the n users did indeed sign the n original messages. A scheme by Mihir Bellare and Gregory Neven may be used with Bitcoin.
• Signatures with efficient protocols – are signature schemes that facilitate efficient cryptographic protocols such as zero-knowledge proofs or secure computation.

The current state of use – legal and practical

Most digital signature schemes share the following goals regardless of cryptographic theory or legal provision:

1. Quality algorithms: Some public-key algorithms are known to be insecure, as practical attacks against them have been discovered.
2. Quality implementations: An implementation of a good algorithm (or protocol) with mistake(s) will not work.
3. Users (and their software) must carry out the signature protocol properly.
4. The private key must remain private: If the private key becomes known to any other party, that party can produce perfect digital signatures of anything.
5. The public key owner must be verifiable: A public key associated with Bob actually came from Bob. This is commonly done using a public key infrastructure (PKI) and the public key↔user association is attested by the operator of the PKI (called a certificate authority). For 'open' PKIs in which anyone can request such an attestation (universally embodied in a cryptographically protected public key certificate), the possibility of mistaken attestation is non-trivial. Commercial PKI operators have suffered several publicly known problems. Such mistakes could lead to falsely signed, and thus wrongly attributed, documents. 'Closed' PKI systems are more expensive, but less easily subverted in this way.

Only if all of these conditions are met will a digital signature actually be any evidence of who sent the message, and therefore of their assent to its contents. Legal enactment cannot change this reality of the existing engineering possibilities, though some such have not reflected this actuality.

Legislatures, being importuned by businesses expecting to profit from operating a PKI, or by the technological avant-garde advocating new solutions to old problems, have enacted statutes and/or regulations in many jurisdictions authorizing, endorsing, encouraging, or permitting digital signatures and providing for (or limiting) their legal effect. The first appears to have been in Utah in the United States, followed closely by the states Massachusetts and California. Other countries have also passed statutes or issued regulations in this area as well and the UN has had an active model law project for some time. These enactments (or proposed enactments) vary from place to place, have typically embodied expectations at variance (optimistically or pessimistically) with the state of the underlying cryptographic engineering, and have had the net effect of confusing potential users and specifiers, nearly all of whom are not cryptographically knowledgeable.

Adoption of technical standards for digital signatures have lagged behind much of the legislation, delaying a more or less unified engineering position on interoperability, algorithm choice, key lengths, and so on what the engineering is attempting to provide.

See also: ABA digital signature guidelines

Industry standards

Some industries have established common interoperability standards for the use of digital signatures between members of the industry and with regulators. These include the Automotive Network Exchange for the automobile industry and the SAFE-BioPharma Association for the healthcare industry.

Using separate key pairs for signing and encryption

In several countries, a digital signature has a status somewhat like that of a traditional pen and paper signature, as in the 1999 EU digital signature directive and 2014 EU follow-on legislation. Generally, these provisions mean that anything digitally signed legally binds the signer of the document to the terms therein. For that reason, it is often thought best to use separate key pairs for encrypting and signing. Using the encryption key pair, a person can engage in an encrypted conversation (e.g., regarding a real estate transaction), but the encryption does not legally sign every message he or she sends. Only when both parties come to an agreement do they sign a contract with their signing keys, and only then are they legally bound by the terms of a specific document. After signing, the document can be sent over the encrypted link. If a signing key is lost or compromised, it can be revoked to mitigate any future transactions. If an encryption key is lost, a backup or key escrow should be utilized to continue viewing encrypted content. Signing keys should never be backed up or escrowed unless the backup destination is securely encrypted.

Green development

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Green_development

Green development is a real estate development concept that considers social and environmental impacts of development. It is defined by three sub-categories: environmental responsiveness, resource efficiency, and community and cultural sensitivity. Environmental responsiveness respects the intrinsic value of nature, and minimizes damage to an ecosystem. Resource efficiency refers to the use of fewer resources to conserve energy and the environment. Community and cultural sensitivity recognizes the unique cultural values that each community hosts and considers them in real estate development, unlike more discernable signs of sustainability, like solar energy, (solar panels are more visibly "green" than the use of local materials). Green development manifests itself in various forms, however it is generally based on solution multipliers: features of a project that provide additional benefits, which ultimately reduce the projects' environmental impacts.

History

Green development emerged as a result of the environmental movement in the 1970s. In the real estate industry, use of the term commenced in 1987 with a report from the World Commission on Environment and Development, entitled "Our Common Future". The report includes 16 principles of environmental management, designed to foster green development. It also discusses the traditional model of macroeconomic growth, and its disregard for environmental consequences. Following this initial movement, the real estate industry experienced a back-and-forth relationship with "green" methodologies; environmental issues often came second behind purely economic factors. Incessant environmental concern and legislation affecting the real estate sector began to emerge, i.e. Green development. However, a common concern of green development is that it may increase project costs and completion times. Hence there has been an ongoing argument of whether green strategies can be sustainable as well as economically stimulating. National environmental attention has since worked its way down to real estate developers, and become an increasing priority. Developers today must work within the parameters of legislation that now considers the environmental implications of development.

Legislation

In response to increasing public concern regarding environmental issues, governments have enacted legislation that regulates various aspects of the real estate industry, as well as other sectors of the economy. In the United States such legislation includes the National Environmental Policy Act (NEPA), the Clean Air Act, the Clean Water Act, the Coastal Zone Management Act, and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA; also known as "Superfund."). NEPA, enacted in 1970, changed how federal agencies made decisions because it required them to propose environmental analysis before starting a project. The Clean Air Act (1970) requires the United States Environmental Protection Agency (EPA) to set national standards for clean air and pollution control regulations. The Clean Water Act (1972) was designed to minimize pollution in natural bodies of water, and also to ensure water quality that protects drinking water sources and supports recreational activities such as fishing or swimming. The Coastal Zone Management Act (1972) manages the nation's coastal resources such as Great Lakes and estuaries. CERCLA is commonly referred to as "Superfund" because it comprises two trust funds that provide help to improve areas that have been polluted by hazardous waste. The Superfund Amendments and Reauthorization Act of 1986 allows the government to lien a property that is being cleaned up. Additionally, the California Environmental Quality Act (CEQA) is California's most comprehensive piece of legislation regarding the environment. This act applies to all decisions made by cities and counties in California, and includes the mandate of an Environmental Impact Report (EIR), to both public and private projects. Subsequently, any new real estate development is subject to a detailed environmental analysis before starting a project.

California's Senate Bill (SB) 375 (2008) is another piece of legislation that promotes green development. It aims to achieve California's climate goals via more efficient land use and development patterns. More specifically, SB 375 seeks to reduce greenhouse gas (GHG) emissions through close coordination between land-use and transportation. One way this is achieved is through demand-side measures. This strategy would decrease driving demand, and therefore reduce vehicle miles traveled (VMT), and ultimately reduce GHG emissions. For example, a demand-side policy component may include placing public transit stops near development, in order to maximize walkability.

Additionally, California state law requires minimum energy conservation levels for all new and/or existing development projects. The seller of a home is required to include information regarding energy conservation retrofitting and thermal insulation in the sales contract.

In practice

Broad development patterns

Senate Bill 375 demonstrates an urban planning strategy called growth management. It is defined by a close coordination between land-use controls and capital investment and heavily motivated by environmental issues. It is defined by "the regulation of the amount, timing, location, and character of development." As the name may suggest, growth management may not imply limiting any growth. "Growth control" carries the connotation of managing or limiting growth, and "no growth" would indicate stopping growth all together. Moreover, Growth Management requires the cooperation of all three of these connotations.

Urban Growth Boundaries (UBG's), are popular growth management strategies. They are designed to encourage growth within a given boundary and discourage it outside the boundary. The goal of the UGB is to promote dense development, in order to decrease urban sprawl. This growth management technique ultimately seeks to revitalize central cities, and create vibrant, walk-able spaces for community development.

These clustered development patterns are solution multipliers. Reducing demand for infrastructure can save money and resources. These multipliers can increase walkability, which fosters social interaction and community togetherness.

Intelligent building

In the US, commercial and residential buildings are the highest consumers of electricity and HVAC systems comprise a large portion of this usage. In fact, the US Department of Energy projects that 70% of the electricity used in the US is from buildings. Intelligent building methods such as occupancy detection systems, wireless sensor networks, and HVAC control systems aim to more efficient energy usage. A team of researchers at the University of San Diego, project that their smart building automation systems will save 10–15% in building energy.

Case studies

The Holly Street Village Apartments

The city of Pasadena, California has recently adopted a general plan based on seven guiding principles: community needs and quality of life, preservation of Pasadena's historic character, economic vitality, a healthy family community, lack of need for automobiles, promoted as a cultural, scientific, corporate, entertainment and educational center for the region, and community participation.

This project included environmental concern and social considerations in the process of construction. The Holly Street Village Apartments in Pasadena address several of the principles outlined in Pasadena's general plan. It incorporates mixed-use development with ground-floor retail center including a deli, a convenience store and an art gallery. Also, the Holly Street Village Apartments is located near a light rail station. The goal of these strategies is to reduce the demand for automobiles, and making it easier for people to use public transportation.

Inn of the Anasazi

Zimmer Associates International, a real estate development firm, completed the Inn of the Anasazi in Santa Fe, New Mexico in 1991. Robert Zimmer (co-founder) and his partners, Steve Conger and Michael Fuller, set a goal to construct a building that would, "showcase energy- and resource-saving technologies, strengthen local community, offer first class elegance, and financially reward its participants." The interior design of the hotel pays respect to the ancient Anasazi Indians, including locally crafted furniture, hand-made rugs, and Native American, Hispanic and cowboy wall art. The use of adobe on the exterior of the hotel includes the historic pueblo style. Also, Zimmer and his partners repurposed a steel-framed building that had previously been used in the 1960s as a juvenile detention center, instead of starting the project from the beginning. Other "green" characteristics of this Santa Fe hotel are skylights, energy-efficient lighting, and water-saving fixtures. Also, the Inn of the Anasazi stimulates the regional economy by purchasing locally grown organic food from Hispanic farmers. Lastly the Inn encourage that the staff participate in local nonprofit organizations and events that sponsor diverse local cultures. The Inn of the Anasazi integrates "social and environmental goals with financial considerations…"

Taipei 101

Taipei 101, stylized as TAIPEI 101, is a 1,667 feet (508 m) tall skyscraper located in Taipei, Taiwan which has received LEED (Leadership in Energy and Environmental Design) certification from the U.S. Green Building Council as the highest score in history. In this project, "TAIPEI" is an acronym for "technology," "art," "innovation," "people," "environment," and "identity. Dr. Hubert Keiber, CEO of Siemens Building Automation in Taipei, stresses energy efficiency on the grounds that energy is the single largest expense for commercial buildings. Since 2011, the Taipei 101 has become the world's most environmentally responsible skyscraper, reducing water use, energy use, and carbon emissions all by 10%.

Boulder, Colorado

Growth management/limitation (discussed previously) manifests itself in Boulder, Colorado. The city of Boulder very tightly restricts housing development by limiting housing permits to 400 per year, which is 1 percent of the city's total housing stock. Additionally, the city has purchased land outside of the city limits, designated for permanent, green open space. This 400-unit cap seriously hinders population growth in the city.

This shortage of housing has several repercussions. First, it increases housing prices. Also, because Boulder restricts housing development more than it does commercial development, the number of available workers in Boulder grows faster than the housing stock. This results in many workers who commute from beyond the city limits.

Controversy

A common critique of green development is that it negatively affects the way real estate developers do business, as it can increase cost and create delay. For example, becoming LEED-certified can contribute to additional costs. This includes additional building design and construction fees, interior design and construction fees, building operations and maintenance fees, neighborhood development fees, home and campus fees, and volume program fees.

Additionally, green development has been critiqued on a residential level. High-performance homes have proven to save energy in the long run, but they rapidly increase up-front capital costs, via tankless water heaters, radiant barriers and reflective insulation systems, and high efficiency air conditioning systems. Also, developers are often unable to develop on certain portions of land due to conservation easements. These easements are purchased by governments or non-governmental organizations, in order to "preserve land in its natural, scenic, agricultural, historical, forested, or open-space condition."

Caveat emptor

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Caveat_emptor

Caveat emptor (/ˈɛmptɔːr/; from caveat, "may he/she beware", a subjunctive form of cavēre, "to beware" + ēmptor, "buyer") is Latin for "Let the buyer beware". It has become a proverb in English. Generally, caveat emptor is the contract law principle that controls the sale of real property after the date of closing, but may also apply to sales of other goods. The phrase caveat emptor and its use as a disclaimer of warranties arises from the fact that buyers typically have less information than the seller about the good or service they are purchasing. This quality of the situation is known as 'information asymmetry'. Defects in the good or service may be hidden from the buyer, and only known to the seller.

It is a short form of Caveat emptor, quia ignorare non debuit quod jus alienum emit ("Let a purchaser beware, for he ought not to be ignorant of the nature of the property which he is buying from another party.") I.e. the buyer should assure himself that the product is good and that the seller had the right to sell it, as opposed to receiving stolen property.

A common way that information asymmetry between seller and buyer has been addressed is through a legally binding warranty, such as a guarantee of satisfaction.

Explanation

Under the principle of caveat emptor, the buyer could not recover damages from the seller for defects on the property that rendered the property unfit for ordinary purposes. The only exception was if the seller actively concealed latent defects or otherwise made material misrepresentations amounting to fraud.

Before statutory law, the buyer had no express warranty ensuring the quality of goods. In the UK, common law requires that goods must be "fit for the particular purpose" and of "merchantable quality", per Section 15 of the Sale of Goods Act but this implied warranty can be difficult to enforce and may not apply to all products. Hence, buyers are still advised to be cautious.

By country

United States

Real estate

The modern trend in the U.S. is that the implied warranty of fitness for a particular purpose applies in the real-estate context to only the sale of new residential housing by a builder-seller and that the caveat emptor rule applies to all other real-estate sale situations (e.g. homeowner to buyer). Other jurisdictions have provisions similar to this.

Chattel property

Main article: Personal property

Under Article 2 of the Uniform Commercial Code, the sale of new goods is governed by the "perfect-tender" rule unless the parties to the sale expressly agree in advance to terms equivalent to caveat emptor (such as describing the goods as sold "as is" and/or "with all faults") or other limitations such as the below-discussed limitations on remedies. The perfect-tender rule states that if a buyer who inspects new goods with reasonable promptness discovers them to be "nonconforming" (failing to meet the description provided or any other standards reasonably expectable by a buyer in his/her situation) and does not use the goods or take other actions constituting acceptance of them, the buyer may promptly return or refuse to accept ("reject") them and demand that the defect be remedied ("cured"). When goods fitting the same description and expectations are available for sale (e.g., when the vendor has other instances of the same mass-produced merchandise in stock inventory), either the vendor or the buyer may insist on an "even exchange" for other, "conforming" instances of the product. When conforming goods are not available in stock but are available for the dealer to purchase (usually on the open or "spot" market), the buyer may require that the seller obtain the goods elsewhere, even at a higher price, with the seller having to incur a loss equivalent to the price difference. If the vendor still does not or cannot provide the goods and the dispute proceeds to litigation (as opposed to renegotiation or settlement), then as in all cases of vendor breaches of contract, the buyer may recover only the damages that s/he would have suffered had s/he taken all feasible steps to minimize ("mitigate") his/her damages suffered.

As a default rule, the perfect-tender rule may be "contracted around" in ways that specify or limit a buyer's remedies (and that accordingly reduce the market price that rational buyers are willing to pay for the goods). In many cases, the vendor will not provide a refund but will provide store credit. In the cases of software, movies, and other copyrighted material, many vendors will offer only a direct exchange for another copy of the same title, with the effect that the initial transfer or license of intellectual-property rights is preserved. Most stores require proof of purchase and impose time limits on exchanges or refunds. Some larger chain stores, such as F.Y.E., Staples, Target, or Walmart, will, however, do exchanges or refunds at any time, with or without proof of purchase, although they usually require a form of picture identification and place per-transaction and/or per-person quantity or dollar limitations on such returns.

United Kingdom

In the UK, consumer law has moved away from the caveat emptor model, with laws passed that have enhanced consumer rights and allow greater leeway to return goods that do not meet legal standards of acceptance. Consumer purchases are regulated by the Consumer Rights Act 2015, whilst business-to-business purchases are regulated by the Sale of Goods Act 1979.

In the UK, consumers have the right to a full refund for faulty goods. However, traditionally, many retailers allow customers to return goods within a specified period (typically two weeks to two months) for a full refund or an exchange, even if there is no fault with the product. Exceptions may apply for goods sold as damaged or to clear.

Goods bought through "distance selling," for example online or by phone, also have a statutory "cooling off" period of fourteen calendar days during which the purchase contract can be cancelled and treated as if not done.

Although no longer applied in consumer law, the principle of caveat emptor is generally held to apply to transactions between businesses unless it can be shown that the seller had a clear information advantage over the buyer that could not have been removed by carrying out reasonable due diligence.

Variations

Caveat venditor

Caveat venditor is Latin for "let the seller beware."

In the landmark case of MacPherson v. Buick Motor Co. (1916), New York Court Appeals Judge Benjamin N. Cardozo established that privity of duty is no longer required in regard to a lawsuit for product liability against the seller. This case is widely regarded as the origin of caveat venditor as it pertains to modern tort law in US.

Caveat lector

Caveat lector is a Latin phrase meaning "let the reader beware". It means that when reading something, the reader should take careful note of the contents, and undertake due diligence on whether the contents are accurate, relevant, reliable and so forth.

Caveat auditor

Another variant is Caveat Auditor, or "let the listener beware", where caution is urged regarding all messages, in particular spoken messages, such as a radio advertisement.

Citizenship in ancient Rome

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Roman_citizenship

Citizenship in ancient Rome (Latin: civitas) was a privileged political and legal status afforded to free individuals with respect to laws, property, and governance. Citizenship in ancient Rome was complex and based upon many different laws, traditions, and cultural practices. There existed several different types of citizenship, determined by one's gender, class, and political affiliations, and the exact duties or expectations of a citizen varied throughout the history of the Roman Empire.

History

The oldest document currently available that details the rights of citizenship is the Twelve Tables, ratified c. 449 BC. Much of the text of the Tables only exists in fragments, but during the time of Ancient Rome the Tables would be displayed in full in the Roman Forum for all to see. The Tables detail the rights of citizens in dealing with court proceedings, property, inheritance, death, and (in the case of women) public behavior. Under the Roman Republic, the government conducted a census every five years in Rome to keep a record of citizens and their households. As the Roman Empire spread so did the practice of conducting a census.

Roman citizens were expected to perform some duties (munera publica) to the state in order to retain their rights as citizens. Failure to perform citizenship duties could result in the loss of privileges, as seen during the Second Punic War when men who refused military service lost their right to vote and were forced out of their voting tribes. Women were exempt from direct taxation and military service. Anyone living in any province of Rome was required to register with the census. The exact extent of civic duties varied throughout the centuries.

Much of Roman law involving the rights and functions of citizenship revolved around legal precedents. Documents from Roman writer Valerius Maximus indicate that Roman women were in later centuries able to mingle freely about the Forum and to bring in concerns on their own volition, providing they acted in a manner that was becoming of their family and station.

Much of our basis for understanding Roman law comes from the Digest of Emperor Justinian. The Digest contained court rulings by juries and their interpretations of Roman law and preserved the writings of Roman legal authors.

The Edict of Caracalla

Emperor Caracalla

The Edict of Caracalla (officially the Constitutio Antoniniana in Latin: "Constitution [or Edict] of Antoninus") was an edict issued in AD 212 by the Roman Emperor Caracalla, which declared that all free men in the Roman Empire were to be given full Roman citizenship and all free women in the Empire were given the same rights as Roman women, with the exception of the dediticii, people who had become subject to Rome through surrender in war, and freed slaves.

By the century previous to Caracalla, Roman citizenship had already lost much of its exclusiveness and become more available between the inhabitants throughout the different provinces of the Roman Empire and between nobles such as kings of client countries. Before the Edict, however, a significant number of provincials were non-Roman citizens and held instead the Latin rights.

The Bible's Book of Acts indicates that Paul the Apostle was a Roman citizen by birth – though not clearly specifying which class of citizenship – a fact which had considerable bearing on Paul's career and on the religion of Christianity.

Types of citizenship

(Dark Green) Roman Empire in 117 AD. (Pale Green) Client states under the Roman Empire in 117 AD.

Citizenship in Rome could be acquired through various means. To be born as a citizen required that both parents be free citizens of Rome. Another method was via the completion of a public service, such as serving in the non-Roman auxiliary forces. Cities could acquire citizenship through the implementation of the Latin law, wherein people of a provincial city of the empire could elect people to public office and therefore give the elected official citizenship.

The legal classes varied over time, however the following classes of legal status existed at various times within the Roman state:

Cives Romani

The cives Romani were full Roman citizens, who enjoyed full legal protection under Roman law. Cives Romani were sub-divided into two classes:

• The non optimo iure who held the ius commercii and ius conubii (rights of property and marriage)
• The optimo iure, who held these rights as well as the ius suffragii and ius honorum (the additional rights to vote and to hold office).

Latini

Further information: Latin League and Latin rights

The Latini were a class of citizens who held the Latin rights (ius Latii), or the rights of ius commercii and ius migrationis (the right to migrate), but not the ius conubii. The term Latini originally referred to the Latins, citizens of the Latin League who came under Roman control at the close of the Latin War, but eventually became a legal description rather than a national or ethnic one. The Latin rights status could be assigned to different classes of citizens, such as freedmen, cives Romani convicted of crime, or colonial settlers.

Socii

Further information: Socii and Foederati

Under Roman law, citizens of another state that was allied to Rome via treaty were assigned the status of socii. Socii (also known as foederati) could obtain certain legal rights of under Roman law in exchange for agreed upon levels of military service, i.e., the Roman magistrates had the right to levy soldier from such states into the Roman legions. However, foederati states that had at one time been conquered by Rome were exempt from payment of tribute to Rome due to their treaty status.

Growing dissatisfaction with the rights afforded to the socii and with the growing manpower demands of the legions (due to the protracted Jugurthine War and the Cimbrian War) led eventually to the Social War of 91–87 BC in which the Italian allies revolted against Rome.

The Lex Julia (in full the Lex Iulia de Civitate Latinis Danda), passed in 90 BC, granted the rights of the cives Romani to all Latini and socii states that had not participated in the Social War, or who were willing to cease hostilities immediately. This was extended to all the Italian socii states when the war ended (except for Gallia Cisalpina), effectively eliminating socii and Latini as legal and citizenship definitions.

Provinciales

Provinciales were those people who fell under Roman influence, or control, but who lacked even the rights of the foederati, essentially having only the rights of the ius gentium (rules and laws common to nations under Rome's rule).

Peregrini

A peregrinus (plural peregrini) was originally any person who was not a full Roman citizen, that is someone who was not a member of the cives Romani. With the expansion of Roman law to include more gradations of legal status, this term became less used, but the term peregrini included those of the Latini, socii, and provinciales, as well as those subjects of foreign states.

Citizenship for different social classes

Individuals belonging to a specific social class in Rome had modified versions of citizenship.

• Roman women had a limited form of citizenship. They were not allowed to vote or stand for civil or public office. The rich might participate in public life by funding building projects or sponsoring religious ceremonies and other events. Women had the right to own property, to engage in business, and to obtain a divorce, but their legal rights varied over time. Marriages were an important form of political alliance during the Republic. Roman women mostly remained under the guardianship of their father (pater familias) or their closest male agnate.
• Client state citizens and allies (socii) of Rome could receive a limited form of Roman citizenship such as the Latin rights. Such citizens could not vote or be elected in Roman elections.
• Freedmen were former slaves who had gained their freedom. They were not automatically given citizenship and lacked some privileges such as running for executive magistracies. The children of freedmen and women were born as free citizens; for example, the father of the poet Horace was a freedman.
• Slaves were considered property and lacked legal personhood. Over time, they acquired a few protections under Roman law. Some slaves were freed by manumission for services rendered, or through a testamentary provision when their master died. Once free, they faced few barriers, beyond normal social stigma, to participating in Roman society. The principle that a person could become a citizen by law rather than birth was enshrined in Roman mythology; when Romulus defeated the Sabines in battle, he promised the war captives that were in Rome they could become citizens.

Rights

Roman citizens enjoyed a variety of specific privileges within Roman society. Male citizens had the rights to vote (ius suffragi) and hold civic office (ius honorum, only available to the aristocracy). They also possessed ius vitae necisque, "the right of life and death." The male head of a Roman family (pater familias) had the right to legally execute any of his children at any age, although it appears that this was mostly reserved in deciding to raise newborn children. 

More general rights included: the rights to property (ius census), to enter into contracts (ius commercii), ius provocationis, the right to appeal court decisions, the right to sue and to be sued, to have a legal trial, and the right of immunity from some taxes and other legal obligations, especially local rules and regulations.

Relief showing a Roman marriage ceremony. Museo di Capodimonte

With regards to the Roman family, Roman citizens possessed the right of ius conubii, defined as the right to a lawful marriage in which children from the union would also be Roman citizens. Earlier Roman sources indicate that Roman women could forfeit their individual rights as citizens when entering into a manus marriage. In a manus marriage, a woman would lose any properties or possessions she owned herself and they would be given to her husband, or his pater familias. Manus marriages had largely stopped by the time of Augustus and women instead remained under the protection of their pater familias. Upon his death, both the men and women under the protection of the pater familias would be considered sui iuris and be legally independent, able to inherit and own property without the approval of their pater familias. Roman woman however would enter into a tutela, or guardianship. A woman's tutor functioned similarly to a pater familias, but he did not control the property or possessions of a woman and was generally only needed to give his permission when a woman wanted to perform certain legal actions, such as freeing her slaves.

Officially, one required Roman citizenship status to enrol in the Roman legions, but this requirement was sometimes overlooked and exceptions could be made. Citizen soldiers could be beaten by the centurions and senior officers for reasons related to discipline. Non-citizens joined the Auxilia and gained citizenship through service.

Following the early 2nd-century BC Porcian Laws, a Roman citizen could not be tortured or whipped and could commute sentences of death to voluntary exile, unless he was found guilty of treason. If accused of treason, a Roman citizen had the right to be tried in Rome, and even if sentenced to death, no Roman citizen could be sentenced to crucifixion.

Ius gentium was the legal recognition, developed in the 3rd century BC, of the growing international scope of Roman affairs, and the need for Roman law to deal with situations between Roman citizens and foreign persons. The ius gentium was therefore a Roman legal codification of the widely accepted international law of the time, and was based on the highly developed commercial law of the Greek city-states and of other maritime powers. The rights afforded by the ius gentium were considered to be held by all persons; it is thus a concept of human rights rather than rights attached to citizenship.

Ius migrationis was the right to preserve one's level of citizenship upon relocation to a polis of comparable status. For example, members of the cives Romani maintained their full civitas when they migrated to a Roman colony with full rights under the law: a colonia civium Romanorum. Latins also had this right, and maintained their ius Latii if they relocated to a different Latin state or Latin colony (Latina colonia). This right did not preserve one's level of citizenship should one relocate to a colony of lesser legal status; full Roman citizens relocating to a Latina colonia were reduced to the level of the ius Latii, and such a migration and reduction in status had to be a voluntary act.

Romanization and citizenship

The Mausoleum of the Julii, located across the Via Domitia, to the north of, and just outside the city entrance, dates to about 40 BC, and is one of the best preserved mausoleums of the Roman era. A dedication is carved on the architrave of the building facing the old Roman road, which reads: SEX · M · L · IVLIEI · C · F · PARENTIBVS · SVEIS Sextius, Marcus and Lucius Julius, sons of Gaius, to their forebears It is believed that the mausoleum was the tomb of the mother and father of the three Julii brothers, and that the father, for military or civil service, received Roman citizenship and the privilege of bearing the name of the Julii

Roman citizenship was also used as a tool of foreign policy and control. Colonies and political allies would be granted a "minor" form of Roman citizenship, there being several graduated levels of citizenship and legal rights (the Latin rights was one of them). The promise of improved status within the Roman "sphere of influence" and the rivalry with one's neighbours for status, kept the focus of many of Rome's neighbours and allies centered on the status quo of Roman culture, rather than trying to subvert or overthrow Rome's influence.

The granting of citizenship to allies and the conquered was a vital step in the process of Romanization. This step was one of the most effective political tools and (at that point in history) original political ideas.

Previously, Alexander the Great had tried to "mingle" his Greeks with the Persians, Egyptians, Syrians, etc. in order to assimilate the people of the conquered Persian Empire, but after his death this policy was largely ignored by his successors.

The idea was not to assimilate, but to turn a defeated and potentially rebellious enemy (or their sons) into Roman citizens. Instead of having to wait for the unavoidable revolt of a conquered people (a tribe or a city-state) like Sparta and the conquered Helots, Rome tried to make those under its rule feel that they had a stake in the system. The ability of non-Roman born individuals to gain Roman citizenship also provided increased stability for those under Roman rule, and the system of sub-division within the different types of citizenship allowed for Roman rulers to work cooperatively with local elites in the provinces.

Romanitas, Roman nationalism, and its extinction

With the settlement of Romanization and the passing of generations, a new unifying feeling began to emerge within Roman territory, the Romanitas or "Roman way of life", the once tribal feeling that had divided Europe began to disappear (although never completely) and blend in with the new wedge patriotism imported from Rome with which to be able to ascend at all levels.

The Romanitas, Romanity or Romanism would last until the last years of unity of the pars occidentalis, a moment in which the old tribalisms and the proto-feudalism of Celtic origins, until then dormant, would re-emerge, mixing with the new ethnic groups of Germanic origin. This being observed in the writings of Gregory of Tours, who does not use the dichotomy Gallo-Roman-Frankish, but uses the name of each of the gens of that time existing in Gaul (arverni, turoni, lemovici, turnacenses, bituriges, franci, etc.), considering himself a Arverni and not a Gallo-Roman; being the relations between the natives and the Franks seen not as Romans against barbarians, as is popularly believed, but as in the case of Gregory, a relationship of coexistence between Arverni and Franks (Franci) as equals.

It must also be remembered that Clovis I was born in Gaul, so according to the Edict of Caracalla that made him a Roman citizen by birth, in addition to being recognized by the emperor Anastasius I Dicorus as consul of Gaul, so his position of power was reinforced, in addition to being considered by his Gallo-Roman subjects as a legitimate viceroy of Rome; understanding that the Romanitas did not disappear in such an abrupt way, observed its effects centuries later with Charlemagne and the Translatio imperii.