Symmetric Encryption Schemes

Symmetric Encryption Schemes 2.1 Symmetric Encryption Schemes: With symmetric-key encryption, the encryption key can be calculated from the decryption key and vice versa. With most symmetric algorithms, the same key is used for both encryption and decryption, as shown in Figure 1.1. Implementations of symmetric-key encryption can be highly efficient, so that users do not experience any significant time delay as a result of the encryption and decryption. Symmetric-key encryption also provides a degree of authentication, since information encrypted with one symmetric key cannot be decrypted with any other symmetric key. Thus, as long as the symmetric key is kept secret by the two parties using it to encrypt communications, each party can be sure that it is communicating with the other as long as the decrypted messages continue to make sense. Encryption functions normally take a fixed-size input to a fixed-size output, so encryption of longer units of data must be done in one of two ways: either a block is encrypted at a time and the blocks are somehow joined together to make the cipher text, or a longer key is generated from a shorter one and XORd against the plaintext to make the cipher text. Schemes of the former type are called block ciphers, and schemes of the latter type are called stream ciphers. 2.1.1 Block ciphers Block ciphers take as input the key and a block, often the same size as the key. Further, the first block is often augmented by a block called the initialization vector, which can add some randomness to the encryption. 2.1.1.1 DES Algorithm: The most widely used encryption scheme is based on Data Encryption Standard (DES). There are two inputs to the encryption function, the plain text to be encrypted and the key. The plain text must be 64 bits in length and key is of 56 bits. First, the 64 bits of plain text passes through an initial permutation that rearranges the bits. This is fallowed by 16 rounds of same function, which involves permutation substitution functions. After 16 rounds of operation, the pre output is swapped at 32 bits position which is passed through final permutation to get 64 bit cipher text. Initially the key is passed through a permutation function. Then for each of the 16 rounds, a sub key is generated by a combination of left circular shift and permutation. At each round of operation, the plain text is divided to two 32 bit halves, and the fallowing operations are executed on 32 bit right halve of plain text. First it is expanded to 48 bits using a expansion table, then X-ORed with key, then processed in substitution tables to generate 32 bit output. This output is permuted using predefined table and XORed with left 32 bit plain text to form right 32 bit pre cipher text of first round. The right 32 bit plain text will form left 32 bit pre cipher text of first round. Decryption uses the same algorithm as encryption, expect that the application of sub keys is reversed. A desirable property of any encryption algorithm is that a small change in either plain text or the key should produce a significant change in the cipher text. This effect is known as Avalanche effect which is very strong in DES algorithm. Since DES is a 56 bit key encryption algorithm, if we proceed by brute force attack, the number of keys that are required to break the algorithm is 2 56 . But by differential crypto analysis, it has been proved that the key can be broken in 2 47 combinations of known plain texts. By linear crypto analysis it has been proved that, it could be broken by 2 41 combinations of plain text. The DES algorithm is a basic building block for providing data security. To apply DES in a variety of applications, four modes of operations have been defined. These four models are intended to cover all possible applications of encryption for which DES could be used. They involve using a initialization vector being used along with key to provided different cipher text blocks. 2.1.1.1.1 Electronic Code Book (ECB) mode: ECB mode divides the plaintext into blocks m1, m2, , mn, and computes the cipher text ci = Ei(mi). This mode is vulnerable to many attacks and is not recommended for use in any protocols. Chief among its defects is its vulnerability to splicing attacks, in which encrypted blocks from one message are replaced with encrypted blocks from another. 2.1.1.1.2 Cipher Block Chaining (CBC) mode: CBC mode remedies some of the problems of ECB mode by using an initialization vector and chaining the input of one encryption into the next. CBC mode starts with an initialization vector iv and XORs a value with the plaintext that is the input to each encryption. So, c1 = Ek(iv XOR m1) and ci = Ek(ci-1 XOR mi). If a unique iv is used, then no splicing attacks can be performed, since each block depends on all previous blocks along with the initialization vector. The iv is a good example of a nonce that needs to satisfy Uniqueness but not Unpredictability. 2.1.1.1.3 Cipher Feed-Back (CFB) mode: CFB mode moves the XOR of CBC mode to the output of the encryption. In other words, the cipher text c1 = p1 XOR Sj(E(IV)). This mode then suffers from failures of Non-Malleability, at least locally to every block, but changes to ciphertext do not propagate very far, since each block of ciphertext is used independently to XOR against a given block to get the plaintext. These failures can be seen in the following example, in which a message m = m1 m2 mn is divided into n blocks, and encrypted with an iv under CFB mode to c1 c2 cn. Suppose an adversary substitutes c2 for c2. Then, in decryption, m1 = Ek(iv) XOR c1, which is correct, but m2 = Ek(c1) XOR c2, which means that m2 = m2 XOR c2 XOR c2, since m2 = Ek(c1) XOR c2. Thus, in m2, the adversary can flip any bits of its choice. Then m3 = Ek(c2) XOR c3, which should lead to random looking message not under the adversarys control, since the encryption of c2 should look random. But m4 = Ek(c3) XOR c4 and thereafter the decryption is correct. 2.1.1.1.4 Output Feed-Back (OFB) mode OFB mode modifies CFB mode to feed back the output of the encryption function to the encryption function without XOR-ing the cipher text. 2.1.1.2 Triple DES: Given the potential vulnerability of DES to brute force attack, a new mechanism is adopted which uses multiple encryptions with DES and multiple keys. The simplest form of multiple encryptions has two encryption stages and two keys. The limitation with this mechanism is it is susceptible to meet in the middle attack. An obvious counter to meet in the middle attack and reducing the cost of increasing the key length, a triple encryption method is used, which considers only two keys with encryption with the first key, decryption with the second key and fallowed by encryption with the first key. Triple DES is a relatively popular alternative to DES and has been adopted for use in key management standards. 2.1.1.3 Homomorphic DES: A variant of DES called a homophonic DES [7] is considered. The DES algorithm is strengthened by adding some random bits into the plaintext, which are placed in particular positions to maximize diffusion, and to resist differential attack. Differential attack makes use of the exclusive-or homophonic DES. In this new scheme, some random estimated bits are added to the plaintext. This increases the certain plaintext difference with respect to the cipher text. A homophonic DES is a variant of DES that map search plaintext to one of many cipher texts (for a given key). In homophonic DES a desired difference pattern with the cipher text will be suggested with some key values including the correct one, oppositely wrong pairs of cipher text. For a difference pattern which 56-bit plaintext to a 64-bit cipher text using a 56-bit key. In this scheme, eight random bits are placed in specific positions of the 64-bit input data block to maximize diffusion. For example, the random bits in HDESS are the bit- positions 25, 27, 29, 31, 57, 59, 61 and 63. In this algorithm, after the initial permutation and expansion permutation in the first round, these eight random bits will spread to bits 2, 6, 8, 12, 14, 18, 20, 24, 26, 30, 32, 36, 38,42,44,48 of the 48-bit input block to the S-boxes and will affect the output of all the S-boxes. The 48 expanded bits must be exclusive-or’d with some key before proceeding to the S-boxes, thus two input bits into the S-boxes derived from the same random bit may have different values. This says that the random bits do not regularize the input to the S-boxes, that is, the property of confusion does not reduce while we try to maximize diffusion. The decryption of the homophonic DES is similar to the decryption of DES. The only difference is that eight random bits must be removed to get the original plaintext (56 bits). A homophonic DES can easily be transformed into a triple-encryption version by concatenating a DES decryption and a DES encryption after the homophonic DES. Security analysis: Thus there is a probability of 1/256 between a pair of texts. The differential crypto analysis is also difficult on this mechanism. The diffusion of bits is also more in this mode. Thus this mechanism provides some probabilistic features to DES algorithm which makes it stronger from differential and linear crypto analysis. 2.1.1.4 AES: The Advanced Encryption Standard (AES) was chosen in 2001. AES is also an iterated block cipher, with 10, 12, or 14 rounds for key sizes 128, 192, and 256 bits, respectively. AES provides high performance symmetric key encryption and decryption. 2.1.1.5 Dynamic substitution: An apparently new cryptographic mechanism [34] which can be described as dynamic substitution is discussed in the fallowing topic. Although structurally similar to simple substitution, dynamic substitution has a second data input which acts to re-arrange the contents of the substitution table. The mechanism combines two data sources into a complex result; under appropriate conditions, a related inverse mechanism can then extract one of the data sources from the result. A dynamic substitution combiner can directly replace the exclusive-OR combiner used in Vernam stream ciphers. The various techniques used in Vernam ciphers can also be applied to dynamic substitution; any cryptographic advantage is thus due to the additional strength of the new combiner. 2.1.1.5.1 The Vernam Cipher: A Vernam cipher maps plaintext data with a pseudo-random sequence to generate cipher text. Since each ciphertext element from a Vernam combiner is the (mod 2) sum of two unknown values, the plaintext data is supposed to be safe. But this mode is susceptive to several cryptanalytic attacks, including known plain text and cipher text attacks. And if the confusion sequence can be penetrated and reproduced, the cipher is broken. Similarly, if the same confusion sequence is ever re-used, and the overlap identified, it becomes simple to break that section of the cipher. 2.1.1.5.2 Cryptographic Combiners: An alternate approach to the design of a secure stream cipher is to seek combining functions which can resist attack; such functions would act to hide the pseudo-random sequence from analysis. The mechanism of this work is a new combining function which extends the weak classical concept of simple substitution into a stronger form suitable for computer cryptography. 2.1.1.5.3 Substitution Ciphers: In simple substitution ciphers each plain text character is replaced with fixed cipher text character. But this mechanism is weak from statistical analysis methods where by considering the rules of the language, the cipher can be broken. This work is concerned with the cryptographic strengthening of the fundamental substitution operation through dynamic changes to a substitution table. The substitution table can be represented as a function of not only input data but also a random sequence. This combination gives a cryptographic combining function; such a function may be used to combine plaintext data with a pseudo-random sequence to generate enciphered data. 2.1.1.5.4 Dynamic Substitution: A simple substitution table supported with combining function gives the idea of dynamic substitution. A substitution table is used to translate each data value into an enciphered value. But after each substitution, the table is re-ordered. At a minimum, it makes sense to exchange the just-used substitution value with some entry in the table selected at random. This generally changes the just-used substitution value to help prevent analysis, and yet retains the existence of an inverse, so that the cipher can be deciphered. 2.1.1.5.5 Black Box Analysis: Dynamic substitution may be considered to be a black box, with two input ports Data In and Random In, and one output port Combiner Out. In the simple version, each data path has similar width; evidently the mechanism inside the box in some way combines the two input streams to produce the output stream. It seems reasonable to analyze the output statistically, for various input streams. 2.1.1.5.6 Polyalphabetic Dynamic Substitution: A means to defend to known-plaintext and chosen-plaintext attacks would be to use multiple different dynamic substitution maps and to select between them using a hidden pseudo-random sequence. Thus the dynamic substitution if free from statistical attacks where each character of plain text is replaced with multiple characters of cipher text which makes the mechanism robust. 2.1.1.5.7 Internal State: Dynamic substitution contains internal data which after initialization is continuously re-ordered as a consequence of both incoming data streams; thus, the internal state is a function of initialization and all subsequent data and confusion values. The changing internal state of dynamic substitution provides necessary security to the data streams. Thus dynamic substitution provides a probabilistic nature to the enciphering mechanism. The limitation with this scheme is, not only different dynamic substitution tables has to be maintained but also the pseudo random sequence which selects between these dynamic substitution tables has to be shared between sender and receiver. 2.1.1.6 Nonces A nonce [29] is a bit string that satisfies Uniqueness, which means that it has not occurred before in a given run of a protocol. Nonces might also satisfy Unpredictability, which effectively requires pseudo-randomness: no adversary can predict the next nonce that will be chosen by any principal. There are several common sources of nonces like counters, time slots and so on. 2.1.1.6.1 Nonce Based Encryption: In this work a different formalization for symmetric encryption is envisaged. The encryption algorithm is made to be a deterministic function, but it is supported with initialization vector (IV). Efficiency of the user is made success of this mode. The IV is a nonce like value, used at most once within a session. Since it is used at most once having any sort of crypto analysis is practically not possible which provides sufficient security. 2.1.1.7 One-Time Pad Encryption One more encryption mechanism for providing security to data is one time pad [13] encryption. The functions are computed as follows: A and B agree on a random number k that is as long as the message they later want to send. Ek(x) = x XOR k Dk(x) = x XOR k Note that since k is chosen at random and not known to an adversary, the output of this scheme is indistinguishable to an adversary from a random number. But it suffers from several limitations. It is susceptible to chosen plain text and chosen cipher text attacks. Again the limitation is here is sharing of one time keys by the participating parties of the encryption scheme. As a new key is always used for encryption, a continuous sharing of key mechanism has to be employed by the participating parties. 2.1.2 Stream ciphers Unlike block ciphers, stream ciphers [14] (such as RC4) produce a pseudo-random sequence of bits that are then combined with the message to give an encryption. Since the combining operation is often XOR, naive implementations of these schemes can be vulnerable to the sort of bit-flipping attacks on Non-Malleability. Two types of stream ciphers exist: synchronous, in which state is kept by the encryption algorithm but is not correlated with the plaintext or cipher text, and self synchronizing, in which some information from the plaintext or cipher text is used to inform the operation of the cipher. Ronald Rivest of RSA developed the RC4 algorithm, which is a shared key stream cipher algorithm requiring a secure exchange of a shared key. The algorithm is used identically for encryption and decryption as the data stream is simply XORed with the generated key sequence. The algorithm is serial as it requires successive exchanges of state entries based on the key sequence. Hence implementations can be very computationally intensive. In the algorithm the key stream is completely independent of the plaintext used. An 8 * 8 S-Box (S0 S255), where each of the entries is a permutation of the numbers 0 to 255, and the permutation is a function of the variable length key. There are two counters i, and j, both initialized to 0 used in the algorithm. 2.1.2.1.1 Algorithm Features: 1.It uses a variable length key from 1 to 256 bytes to initialize a 256-byte state table. The state table is used for subsequent generation of pseudo-random bytes and then to generate a pseudo-random stream which is XORed with the plaintext to give the cipher text. Each element in the state table is swapped at least once. 2. The key is often limited to 40 bits, because of export restrictions but it is sometimes used as a 128 bit key. It has the capability of using keys between 1 and 2048 bits. RC4 is used in many commercial software packages such as Lotus Notes and Oracle Secure. 3. The algorithm works in two phases, key setup and ciphering. During a N-bit key setup (N being your key length), the encryption key is used to generate an encrypting variable using two arrays, state and key, and N-number of mixing operations. These mixing operations consist of swapping bytes, modulo operations, and other formulas. 2.1.2.1.2 Algorithm Strengths: The difficulty of knowing which location in the table is used to select each value in the sequence. A particular RC4 Algorithm key can be used only once and Encryption is about 10 times faster than DES. Algorithm Weakness: One in every 256 keys can be a weak key. These keys are identified by cryptanalysis that is able to find circumstances under which one of more generated bytes are strongly correlated with a few bytes of the key. Thus some symmetric encryption algorithms have been discussed in this chapter. They varies from block ciphers like DES, Triple DES, Homomorphic DES to stream ciphers like RC4. To the symmetric encryption mechanisms concepts like application of Nounce and dynamic substitution are discussed which provides randomness to the encryption mechanism. This probabilistic nature to the encryption mechanism provides sufficient strength to the algorithms against Chosen Cipher text attacks(CCA). The security with all these mechanisms lies with proper sharing of keys among the different participating parties. 2.1.3 Adoptability of some mathematical functions in Cryptography: Sign Function: [26,27] This function when applied on when applied on a matrix of values, converts all the positive values to 1, negative values to -1 zero with 0. The advantage of using this function in cryptography is it cannot be a reversible process ie we cannot get back to the original matrix by applying a reverse process. Modular Arithmetic: One more function that is widely used in cryptography is modular arithmetic of a number with a base value. It will generate the remainder of a number with respect to the base value. This function is widely used in public key cryptography. 2.2 Public-Key Encryption The most commonly used implementations of public-key [13,14] encryption are based on algorithms patented by RSA Data Security. Therefore, this section describes the RSA approach to public-key encryption. Public-key encryption (also called asymmetric encryption) involves a pair of keys a public key and a private key, used for security authentication of data. Each public key is published, and the corresponding private key is kept secret. Data encrypted with one key can be decrypted only with other key. The scheme shown in Figure 1.2 says public key is distributed and encryption being done using this key. In general, to send encrypted data, one encrypt’s the data with the receiver’s public key, and the person receiving the encrypted data decrypts it with his private key. Compared with symmetric-key encryption, public-key encryption requires more computation and is therefore not always appropriate for large amounts of data. However, a combination of symmetric Asymmetric schemes can be used in real time environment. This is the approach used by the SSL protocol. As it happens, the reverse of the scheme shown in Figure 1.2 also works: data encrypted with one’s private key can be decrypted only with his public key. This may not be an interesting way to encrypt important data, however, because it means that anyone with receiver’s public key, which is by definition published, could decipher the data. And also the important requirement with data transfer is authentication of data which is supported with Asymmetric encryption schemes, which is an important requirement for electronic commerce and other commercial applications of cryptography. 2.2.1 Key Length and Encryption Strength: In general, the strength of encryption algorithm depends on difficulty in getting the key, which in turn depends on both the cipher used and the length of the key. For the RSA cipher, the strength depends on the difficulty of factoring large numbers, which is a well-known mathematical problem.Encryption strength is often described in terms of the length of the keys used to perform the encryption, means the more the length of the key, the more the strength. Key length is measured in bits. For example, a RC4 symmetric-key cipher with key length of 128 bits supported by SSL provide significantly better cryptographic protection than 40-bit keys for use with the same cipher. It means 128-bit RC4 encryption is 3 x 1026 times stronger than 40-bit RC4 encryption. Different encryption algorithms require variable key lengths to achieve the same level of encryption strength. Other ciphers, such as those used for symmetric key encryption, can use all possible values for a key of a given length, rather than a subset of those values. Thus a 128-bit key for use with a symmetric-key encryption cipher would provide stronger encryption than a 128-bit key for use with the RSA public-key encryption cipher. This says that a symmetric encryption algorithm with a key length of 56 bits achieve a equal security to Asymmetric encryption algorithm with a key length of 512 bits, 2.2.2 RSA Key Generation Algorithm Two large prime numbers are considered. Let them be p,q. Calculate n = pq and (φ) phi = (p-1)(q-1). Select e, such that 1 Calculate d, such that ed ≠¡ 1 (mod phi). One key is (n, e) and the other key is (n, d). The values of p, q, and phi should also be kept secret. n is known as the modulus. e is known as the public key. d is known as the secret key. Encryption Sender A does the following:- Get the recipient Bs public key (n, e). Identify the plaintext message as a positive integer m. Calculate the ciphertext c = m^e mod n. Transmits the ciphertext c to receiver B. Decryption Recipient B does the following:- Consider his own private key (n, d) to compute the plain text m = c^d mod n. Convert the integer to plain text form. 2.2.3 Digital signing Sender A does the following:- This concept can also be used in digital signing as well. The message to be transmitted is converted to some message digest form. This message digest is converted to encryption form using his private key. This encrypted message digest is transmitted to receiver. Signature verification Recipient B does the following:- Using the sender’s public key, the received message digest is decrypted. From the received message, the receiver independently computes the message digest of the information that has been signed. If both message digests are identical, the signature is valid. Compared with symmetric-key encryption, public-key encryption provides authentication security to the data transmitted but requires more computation and is therefore not always appropriate for large amounts of data. 2.3. Probabilistic encryption schemes In public key encryption there is always a possibility of some information being leaked out. Because a crypto analyst can always encrypt random messages with a public key, he can get some information. Not a whole of information is to be gained here, but there are potential problems with allowing a crypto analyst to encrypt random messages with public key. Some information is leaked out every time to the crypto analyst, he encrypts a message. With probabilistic encryption algorithms [6,11], a crypto analyst can no longer encrypt random plain texts looking for correct cipher text. Since multiple cipher texts will be developed for one plain text, even if he decrypts the message to plain text, he does not know how far he had guessed the message correctly. To illustrate, assume a crypto analyst has a certain cipher text ci. Even if he guesses message correctly, when he encrypts message the result will be completely different cj. He cannot compare ci and cj and so cannot know that he has guessed the message correctly. Under this scheme, different cipher texts will be formed for one plain text. Also the cipher text will always be larger than plain text. This develops the concept of multiple cipher texts for one plain text. This concept makes crypto analysis difficult to apply on plain text and cipher text pairs. An encryption scheme consists of three algorithms: The encryption algorithm transforms plaintexts into cipher texts while the decryption algorithm converts cipher texts back into plaintexts. A third algorithm, called the key generator, creates pairs of keys: an encryption key, input to the encryption algorithm, and a related decryption key needed to decrypt. The encryption key relates encryptions to the decryption key. The key generator is considered to be a probabilistic algorithm, which prevents an adversary from simply running the key generator to get the decryption key for an intercepted message. The following concept is crucial to probabilistic cryptography: 2.3.1 Definition [Probabilistic Algorithm]: A probabilistic algorithm [11] is an algorithm with an additional command RANDOM that returns â€Å"0† or â€Å"1†, each with probability 1/2. In the literature, these random choices are often referred to as coin flips. 2.3.1.1 Chosen Cipher Text Attack: In the simplest attack model, known as Chosen Plaintext Attack (CPA) [5], the adversary has access to a machine that will perform arbitrary encryptions but will not reveal the shared key. This machine corresponds intuitively to being able to see many encryptions of many messages before trying to decrypt a new message. In this case, Semantic Security requires that it be computationally hard for any adversary to distinguish an encryption Ek(m) from Ek(m) for two arbitrarily chosen messages m and m. Distinguishing these encryptions should be hard even if the adversary can request encryptions of arbitrary messages. Note that this property cannot be satisfied if the encryption function is deterministic! In this case, the adversary can simply request an encryption of m and an encryption of m and compare them. This is a point that one should all remember when implementing systems: encrypting under a deterministic function with no randomness in the input does not provide Semantic Security. O ne more crypto analytical model is Chosen Cipher text Attack (CCA) Model. Under the CCA model, an adversary has access to an encryption and a decryption machine and must perform the same task of distinguishing encryptions of two messages of its choice. First, the adversary is allowed to interact with the encryption and decryption services and choose the pair of messages. After it has chosen the messages, however, it only has access to an encryption machine. An advancement to CCA Model is Chosen Cipher text Attack 2 (CCA2). CCA2 security has the same model as CCA security, except that the adversary retains access to the decryption machine after choosing the two messages. To keep this property from being trivially violated, we require that the adversary not be able to decrypt the cipher text it is given to analyze. To make these concepts of CCA CCA2 adoptable in real time environment, recently Canetti, Krawczyk and Nielsen defined the notion of replayable adaptive chosen ciphertext attack [5] secure encryption. Essentially a cryptosystem that is RCCA secure has full CCA2 security except for the little detail that it may be possible to modify a ciphertext into another ciphertext containing the s

Could Have Been Different :: essays research papers

Could Have Been Different   Ã‚  Ã‚  Ã‚  Ã‚  I had a situation once when I wished that I could have re run it. If only I had thought about what was happening and the power that I actually had, I would have had an entirely different situation at hand. I could have prevented the whole thing a lot sooner.   Ã‚  Ã‚  Ã‚  Ã‚  The whole thing started when I was working at an auto shop called Car Quest. My friend Tammy had just gotten me the job starting as a cashier. Even in the few days that I worked there, I loved my job and everyone I worked with. . I really liked my boss because he was always so cool to me, letting me do my homework with my free time when no customers were around and letting me just mess around with the guys I worked with. Soon, I was beginning to close the store alone with my boss, a lot. He would make weird comments and things but I never really questioned them. I thought that maybe he was just kidding around as everyone there always did.   Ã‚  Ã‚  Ã‚  Ã‚  One night when I was finished closing my drawer with my boss Lonnie, we were heading to the front of the store when he told me he had something to say but it could wait until the next time I worked with him. I insisted that he tell me then. He pulled me to the side and started telling me how beautiful I was and what a great personality I had. I didn’t know what to say so I just said â€Å"thanks†. Ever since then he started to ask if I would kiss him and all these offensive things. I guess I just never knew what to say to him. I mean I was 16 and he was like 50. That was like him being my dad.   Ã‚  Ã‚  Ã‚  Ã‚  I went through this for a long time before I got the nerve to tell my other boss at work Kathy. I guess she wasn’t really my other boss; she was just the only other woman I worked with that could help me out. I told her the entire situation and that I was getting sick of Lonnie’s comments. Once I had told her this she told me that Lonnie was married and had two sons. I thought that was worse. I was beginning to get scared that something more would happen.

Harmful Threats to the Human Body

Harmful Threats to the Human Body There are a lot of bacteria that are good for human bodies, but there are also a lot of bacteria that’s very harmful to the human body. Bad bacteria can affect people from swimming in lakes and ponds. â€Å"Many of the world's best-known disease outbreaks have been transmitted by water-borne bacterium. † Lakes and ponds are just un-treated drinking water. They have a lot of microorganisms in it that you cannot see. There are many ways to be contaminated by bacteria; you can swallow it, breathe it in, or they can get in an open wound.Being contaminated can cause skin infections, ear infections, eye infections, diarrhea, and respiratory infections. Langerhans cells and macrophages defend against microbes. Anyone can be infected by bacteria and there doesn’t have to be a lot of it in order to be infected. Vibrio cholera is a bacterium that causes cholera outbreaks around the world. Cholera isn’t common in the U. S. anymore bu t you should be careful when visiting out of state. Another bacterium found around the world is E. coli O157:H7. It produces a bloody diarrhea.It’s also a part of food contamination. It doesn’t take many organisms to get infected by this. Children and elderly are at high risk of severe illnesses. E. coli O157:H7 is even found in swimming pools. Leptospirosis is commonly transmitted by water contaminated by animal urine or soil that comes in contact with open wounds. It can either be barely noticeable or it can cause severe muscle pain. There are many different kinds of bacteria that can have a bad effect on the human body, especially in lake waters.A lot of people think that there is no way for your body to overheat, because of sweat. They think that sweating cools your body down so that it is impossible to overheat. That is wrong. If you get too hot too fast, your body cannot work fast enough to cool down. And if your body doesn’t eventually get cooler you can have a heat stroke or die. Lipid secretions also prevent dehydration. Symptoms of overheating are hard to breath, heart beats faster, you get dizzy, throwing up, and extreme dehydration.To keep from overheating you should drink lots of water and try to relax. When getting a sunburn your killing skin cells. After getting sunburn your skin tends to become red, sensitive to touch, and even warm. The outer layer of skin on your body is called the epidermis. Epidermis cells are the ones you can touch and see, they are also dead cells. The cells underneath that are living. They produce new dead cells to replenish your skin. The sun gives off ultraviolet light. Ultraviolet light is what kills the living cells.Nerve endings and receptors function to cause covering skin to prevent further sunburn. Sebum is lubrication of skin and hair. When your body senses dead cells your immune system starts working to heal your body. It increases blood flow in the affected areas, opening up capillary wall s so that white blood cells can come in and remove the damaged cells. The increased blood flow makes your skin warm and red. The nerve endings for pain begin sending signals to your brain. Damaged cells release chemicals that activate pain receptors. This is why sunburned skin is so sensitive.There are ways to prevent sunburn without having to stay inside. Use a sunscreen, which blocks ultraviolet light, or pace yourself so you get a tan first. When you get a tan, your body essentially creates its own sunscreen using special pigment cells in the epidermis. Deep cuts can become infected easily if it is not taken care of properly. Signs of infection are; redness or discoloration, swelling, warmth, pain, tenderness, scaling, itching, and pulse drainage. The skin may harden or tighten in the area and red streaks may radiate from the wound.Wound infections may also cause fevers, especially when they spread to the blood. While in the water and you happen to cut your foot; immediately lift up your foot to prevent a deeper cut. â€Å"Eccrine glands open by a duct directly onto the skin surface. When internal temperature rises, the eccrine glands secrete water to the skin surface, where heat is removed by evaporation. † There are many types of protective swim wear you can purchase to prevent organisms and chemicals from getting to your skin.

Ed Mezvinsky, Father of the Groom - Urban Legends

Ed Mezvinsky, Father of the Groom - Urban Legends A forwarded email attributed to Cincinnati news reporter John Popovich claims that Marc Mezvinsky, Chelsea Clintons new husband, is the son of Edward Mezvinsky, a former Iowa Congressman who was convicted and sent to prison in the early 2000s for fraud. The forwarded email is correct. Description: Viral textCirculating since: August 2010Status: True (details below) Example Email contributed by James H., August 19, 2010: Subject: Birds of a featherFATHER OF THE GROOMBy: John PopovichBefore I came to Cincinnati, I was a news reporter at WOC in Davenport Iowa. I covered a lot of city council and a lot of political stuff. One of the guys I covered was Ed Mezvinsky, who was the Congressman from Iowas first district.Seemed like a pretty nice guy, but when he ditched his wife for a New York reporter, the Iowa voters ditched him.My most vivid memory is that he sat on the House Judiciary Committee that was deciding the fate of President Nixon.Anyway, years later, Fast Eddie got caught with his hand in the till. He cheated investors out of more than $10 million dollars. He went to prison for several years.This weekend, his son married Chelsea Clinton. Analysis True. On July 31, 2010, Chelsea Clinton, the daughter of former president and first lady Bill and Hillary Clinton, was married to Marc Mezvinsky, the son of a former Democratic Congressman, in a Rhinebeck, New York ceremony the press described as lavish. The father of the groom, Edward Ed Mezvinsky, who served four years in the U.S. House of Representatives from 1973 to 1977, indeed went on to serve five years in a federal penitentiary after being convicted of fraud in 2002. According to prosecutors, Mezvinsky crimes included repeatedly defrauding others by misusing attorney escrow accounts held in his name, engaging in schemes involving worthless checks deposited at banks, creating forged bank statements, using false financial statements, tax returns and accountants letters, and giving false testimony under oath. U.S. District Judge Stewart Dalzell ordered him to pay nearly $10 million in restitution to the victims of his scams. The former Congressman was contrite in an interview with the New York Post that took place in July 2010 just before the Clinton-Mezvinsky wedding. Im remorseful for what happened, he said. It was a terrible time, and I was punished for that. And I respect that and accept responsibility for what happened, and now Im trying to move on and am grateful I have the opportunity for that. For purposes of verification, I attempted to contact former Cincinnati newsman John Popovich, to whom the above text is attributed. I received no reply. Update: Chelsea Clinton and Marc Mezvinsky became parents with the birth of their first child, Charlotte Clinton Mezvinsky, on September 26, 2014. Sources and Further Reading Chelsea Clinton Marries Marc MezvinskyPeople, 31 July 2010 Chelsea Clintons Father in Law Lives Down Criminal PastNew York Post, 29 July  2010 Will Father of the Groom Be Welcome Figure at Chelsea Clintons Wedding?ABC News, 1 December 2009 Former Congressman Duped by Nigerian ScamsABC News, 8 December 2006 Mezvinsky Gets 6 Years for FraudPhiladelphia Inquirer, 10 January 2003 Last updated 06/22/15

Free Essays on Modern Belief

Modern Thinking vs. The Holy Word The Modern belief is that today’s churches are mostly women and that a women preacher would better suite them. As we all know teachers are more effective if they have a similar background to the one’s they teach. Modern belief accepts the fact that there are women preachers and embraces the movement of women in the church. But as I research for myself whether or not the bible allows women preachers, the answer is as clear as daylight. It is clear to me that these women preachers foundation is strongly rooted in the Modern belief and not the word of God. I feel that if one chooses to follow the word of god than one must not pick and choose what part of that word they will follow. This debate is not whether or not what the bible says is true; it’s about whether or not the bible says it. In 1st Timothy Chapter 2 Verse 12 it states (as read in the International Version) â€Å"I do not permit a women to teach or to have authority over a man, she must be silent.† In 1st Corinthians Chapter 14 Verse 34 it states â€Å"Women should remain silent in the churches. They are not allowed to speak, but must be in submission, as the Law say.† Later in verse 35 of the same chapter, it states, â€Å" it is disgraceful for a woman to speak in church.† In 1st Timothy Chapter 3 Verse 2 it states that an overseer (the equivalent to a pastor) â€Å" Must be above reproach, the Husband of but one wife, temperate, self-controlled, respectable, hospitable, able to teach†. A man by the name of Rob Harrison writes that some of the greatest people in the bible were women (i.e.: Mary, Dorcus, Lydia, Phoebe, Eudia) but one of the things that made these women great was that they recognized the place that god had for them, and the honor that was bestowed upon them in their submission. It is not a question of men trying to hold back women for fear of competition. It’s about what God has set in order. He later writes, â€Å"People ... Free Essays on Modern Belief Free Essays on Modern Belief Modern Thinking vs. The Holy Word The Modern belief is that today’s churches are mostly women and that a women preacher would better suite them. As we all know teachers are more effective if they have a similar background to the one’s they teach. Modern belief accepts the fact that there are women preachers and embraces the movement of women in the church. But as I research for myself whether or not the bible allows women preachers, the answer is as clear as daylight. It is clear to me that these women preachers foundation is strongly rooted in the Modern belief and not the word of God. I feel that if one chooses to follow the word of god than one must not pick and choose what part of that word they will follow. This debate is not whether or not what the bible says is true; it’s about whether or not the bible says it. In 1st Timothy Chapter 2 Verse 12 it states (as read in the International Version) â€Å"I do not permit a women to teach or to have authority over a man, she must be silent.† In 1st Corinthians Chapter 14 Verse 34 it states â€Å"Women should remain silent in the churches. They are not allowed to speak, but must be in submission, as the Law say.† Later in verse 35 of the same chapter, it states, â€Å" it is disgraceful for a woman to speak in church.† In 1st Timothy Chapter 3 Verse 2 it states that an overseer (the equivalent to a pastor) â€Å" Must be above reproach, the Husband of but one wife, temperate, self-controlled, respectable, hospitable, able to teach†. A man by the name of Rob Harrison writes that some of the greatest people in the bible were women (i.e.: Mary, Dorcus, Lydia, Phoebe, Eudia) but one of the things that made these women great was that they recognized the place that god had for them, and the honor that was bestowed upon them in their submission. It is not a question of men trying to hold back women for fear of competition. It’s about what God has set in order. He later writes, â€Å"People ...

Democracy in America Essay Example | Topics and Well Written Essays - 2000 words

Democracy in America - Essay Example After the 9/11 attack, a threat of terrorism has spread over the nation of United States. After 9/11 president bush made drastic decision of starting a highly controversial war against terrorism of which half the American population is doubtful. According to a survey Kenneth Janda, Jeffrey M. Berry, Jerry Goldman (2008) 54% of the American population did not supported the war on Iraq and American government is facing a challenge of lack of confidence by the citizens. A survey showed that American citizen’s trust has fallen from the government in recent years. Now it is up to the newly elected president Barrack Obama to regain the trust of citizens of America as well as take the war against terrorism in the right direction. However, the civic values that enables the citizens of America to express their views so openly and to be able to criticize their government on what they feel is wrong is a great source of satisfaction for them. It is the power of democracy that such surveys are held so openly and problems are discussed freely that makes us appreciate our constitution. This power is a great asset for American citizens and it rules over all the conflicting issues. American constitution is supreme law of United States, it has been amended 27 times and the first ten amendments are called ‘bills of rights. Out of these 27 amendments, the first amendment is most powerful and influential Angela Roddey Holder (1997). It gives the right of freedom of religion, freedom of speech, freedom of press, freedom of assembly and freedom of petition. This is also the backbone of American constitution as well as most liked amendment as it provides the freedom and security to people to raise their voice and make their problems heard. However, excess of something is also not good as sometimes too much freedom can also create problems just like the second amendment that allows the citizens to carry firearms. This is a major threat as the weapons

Martin Luther King Jr. and the Philosophy of Civil Disobedience in Research Paper

Martin Luther King Jr. and the Philosophy of Civil Disobedience in Todays World - Research Paper Example Until his assassination in 1968, Dr. King championed civil rights movements and was dedicated to the course of justice and freedom through nonviolent means. There are many ways in which the oppressed deal with their oppression. According Martin Luther king Jr., there are three basic ways through which the oppressed deal with their oppression. These include acquiescence, physical aggression and hatred and nonviolent opposition (Warner and Hilliard 311). When the oppressed resort to use acquiescence, they basically become submissive and acclimatize to oppression, thus becoming accustomed to the oppression (Warner and Hilliard 311). Not all people are willing to break free from oppression. Some individuals usually prefer to stay under oppression. Such people become used to oppressive situations in a way that they give preference to maintaining their slavery status quo than subject themselves to uncertain freedom. People who chose acquiescence as a means of dealing with their oppression are usually engulfed in their suppression that they simply fail to think beyond their current predicament. In such a situation, the oppressed adopts the system of the oppressor and is as wicked as his master. One current example is the case of Syria where Bashar-al-Assad’s administration is tactically scheming to erode the influence of opposition parties and making multitude of Syrians to absolutely depend on the government support and continue living under oppression by the Syrian government. Just like Martin Luther King Jr. acknowledged, no oppressor will ever grow a rational emotion and award his slaves their much desired freedom. As such, this approach is quite immoral and futile way of dealing with oppression. Physical aggression and sheer hatred is the second way through which the oppressed may prefer in dealing with their oppression (Warner and Hilliard 312). Like Martin Luther King Jr. argues, the oppressor is never in a position to grant freedom voluntarily and the o ppressed must demand for it. Violent confrontation of oppressive regime has been used by many nations to win their freedom. For example, in 2011, the rebels in Libya resorted to capture and assassinate Muammar Gaddafi over claims of long time oppression of the Libyan people. Great masses rejoiced from his death because they perceived the execution of Gaddafi as the onset of their freedom. However, violence is not the best way of attaining freedom. It never brings eternal peace, offers no solution to social problems, but only pile many more challenges to the society. Lastly, the oppressed can resort to nonviolent approach to end their repression and achieve their desired freedom (Corlett 32). This approach reconciles acquiescence and physical aggression approaches to obtaining freedom. Nonviolent opposition seeks to find a balance point between the oppressor and the oppressed by eliminating the vices that characterize the current situation and creating friendship between the two (Lon g 104). It consciously seeks to foster equality among all people. For example, in Lebanon, approximately one-quarter of the country’s population convened in Beirut in 2005 to protest the killing of a famous politician and demanded the termination of the oppressive government led by Syria together with withdrawal of Syrian military. This is the best approach because it tackles the challenges of the oppressed and seeks to make things better for them unlike acquiescence and