COSC 359 User Authentication Description A widely used password security technique is the use of hashed passwords and a salt value This scheme is found on virtually all UNIX variants as well as on a number of other operating systems as shown in Figure 3 1 bellow To load a new password into the system, the user selects or is assigned a password This password is combined with a fixed length salt value In older implementations, this value is related to the time at which the password is assigned to the user Newer implementations use a pseudorandom or random number The password and salt serve as inputs to a hashing algorithm to produce a fixed length hash code The hash algorithm is designed to be slow to execute to thwart attacks The hashed password is then stored, together with a plaintext copy of the salt, in the password file for the corresponding user ID The hashed password method has been shown to be secure against a variety of cryptanalytic attacks WAGN00 When a user attempts to log on to a UNIX system, the user provides an ID and a password The operating system uses the ID to index into the password file and retrieve the plaintext salt and the encrypted password The salt and user supplied passwords are used as input to the encryption routine If the result matches the stored value, the password is accepted PART A ID PASSWORD CREATION Write the necessary C code (or a language of your choice) for the following activities Create user ID and Password pair by asking users to input ID Password Check the input and help users to choose an acceptable ID Password based on the company security policy Create a Salt value, add it to the Password and use a hash function to encrypt both Salt and Password Store user ID, Salt and hashed password in ID PASSWORD TXT PART B USER AUTHENTICATION Enhance your code from PART A for the following activities Ask users for ID Password pair Authenticate users using ID txt and the ID PASSWORD TXT files Password Password File User ID Salt Hash code Salt slow hash function Load (a) Loading a new password Password File User id User ID Sa Hash code Salt Select Password slow hash function Hashed password Compare (b) Verifying a password Figure 3 1 UNIX Password Scheme

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COSC 359 User Authentication Description A widely used password security technique is the use of hashed passwords and a salt value  This scheme is found on virtually all UNIX variants as well as on a number of other operating systems as shown in Figure 3 1 bellow  To load a new password into the system, the user selects or is assigned a password  This password is combined with a fixed length salt value  In older implementations, this value is related to the time at which the password is assigned to the user  Newer implementations use a pseudorandom or random number  The password and salt serve as inputs to a hashing algorithm to produce a fixed length hash code  The hash algorithm is designed to be slow to execute to thwart attacks  The hashed password is then stored, together with a plaintext copy of the salt, in the password file for the corresponding user ID  The hashed password method has been shown to be secure against a variety of cryptanalytic attacks  WAGN00   When a user attempts to log on to a UNIX system, the user provides an ID and a password  The operating system uses the ID to index into the password file and retrieve the plaintext salt and the encrypted password  The salt and user supplied passwords are used as input to the encryption routine  If the result matches the stored value, the password is accepted     PART A  ID PASSWORD CREATION Write the necessary C   code (or a language of your choice) for the following activities  Create user ID and Password pair by asking users to input ID Password  Check the input and help users to choose an acceptable ID Password based on the company security policy  Create a Salt value, add it to the Password and use a hash function to encrypt both Salt and Password  Store user ID, Salt and hashed password in ID PASSWORD TXT    PART B  USER AUTHENTICATION Enhance your code from PART A for the following activities  Ask users for ID Password pair Authenticate users using ID txt and the ID PASSWORD TXT files  Password Password File User ID Salt Hash code Salt slow hash function Load (a) Loading a new password Password File User id User ID Sa Hash code Salt Select Password slow hash function Hashed password Compare (b) Verifying a password Figure 3 1 UNIX Password Scheme

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COSC 359 User Authentication Description A widely used password security technique is the use of hashed passwords and a salt value. This scheme is found

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