Abstract: A challenge/response authentication procedure determines whether a response is a correct response, a unique incorrect response, or a non-unique incorrect response, the unique incorrect response and non-unique incorrect response being differentiated by comparing the response value with a store of unique incorrect response values. For the correct response, client access to protected computer system resources is allowed, and the challenge value is discarded so as not to be used again. For the unique incorrect response, (1) when a predetermined limit of unique incorrect responses has not been reached, then the response value is added to the store of unique incorrect response values and the process is repeated with reuse of the challenge value, and (2) when the predetermined limit has been reached, then the client is locked out. For the non-unique incorrect response, the process is repeated with reuse of the challenge value.

Abstract: An apparatus in one embodiment includes at least one processing device comprising a processor coupled to a memory. The processing device is configured to implement a first ledger maintenance node. The first ledger maintenance node is configured to communicate over one or more networks with a plurality of additional ledger maintenance nodes, to identify a block for proposed addition to a distributed ledger collectively maintained by the first and additional ledger maintenance nodes, to apply a digital signature of the first ledger maintenance node to the block, and to receive digital signatures on the block from at least a subset of the additional ledger maintenance nodes. Responsive to receipt of sufficient digital signatures from respective ones of the additional ledger maintenance nodes to meet a specified quorum of digital signatures required for addition of the block to the distributed ledger, the first ledger maintenance node adds the block to the distributed ledger.

Abstract: Plaintext data is encrypted to produce ciphertext which is transmitted along with a hash of the plaintext data and corresponding metadata comprising an initialization vector and information about the encryption key version used to encrypt the plaintext data to a backend storage system. The encrypted ciphertext is deduplicated at the backend storage system (without first decrypting it) using the hash and stored based upon the metadata.

Abstract: An apparatus in an illustrative embodiment comprises a client device configured for communication with a storage system, with the client device comprising a processor coupled to a memory. The client device is further configured to identify a data item to be stored in the storage system, and to generate a data encryption key for the data item as a function of a first secret key and the data item. For example, the function may comprise hashing at least the data item. The client device is further configured to encrypt the data item using the data encryption key for the data item, and to send the encrypted data item to the storage system for storage therein. The client device in some embodiments is further configured to encrypt the data encryption key using a second secret key, and to send the encrypted data encryption key to the storage system for storage therein as metadata of the data item.

Abstract: An authentication server in an illustrative embodiment is configured to communicate with one or more client devices over a network. Responsive to a successful login to a user account by a client device, the authentication server provides the client device with a login cookie for the user account for potential utilization in one or more subsequent logins to the user account. The authentication server initializes a cookie-specific counter for the login cookie, and increments the cookie-specific counter for each of one or more unsuccessful logins to the user account made utilizing the login cookie. Responsive to the cookie-specific counter reaching a specified value, the authentication server locks the user account for any subsequent logins to the user account made utilizing the login cookie. The authentication server resets the cookie-specific counter responsive to a successful login to the user account made utilizing the login cookie.

Abstract: Described are techniques for performing data validation processing. An expected sequence of characters is determined that includes a plurality of groups. Each of the plurality of groups includes a first expected sequence of one or more characters representing encoded information and a second expected sequence of one or more data validation characters determined in accordance with a corresponding portion of the expected sequence. The portion includes at least the first expected sequence of one or more characters of the group. Data validation processing is incrementally performed as data for each of the plurality of groups is received. The data validation processing performed as data for each group is received uses a received sequence of one or more data validation characters corresponding to the second expected sequence of one or more data validation characters of each group.

Abstract: A challenge/response authentication procedure determines whether a response is a correct response, a unique incorrect response, or a non-unique incorrect response, the unique incorrect response and non-unique incorrect response being differentiated by comparing the response value with a store of unique incorrect response values. For the correct response, client access to protected computer system resources is allowed, and the challenge value is discarded so as not to be used again. For the unique incorrect response, (1) when a predetermined limit of unique incorrect responses has not been reached, then the response value is added to the store of unique incorrect response values and the process is repeated with reuse of the challenge value, and (2) when the predetermined limit has been reached, then the client is locked out. For the non-unique incorrect response, the process is repeated with reuse of the challenge value.

Abstract: A method for processing packets that includes receiving a packet from a network, analyzing the packet to obtain packet information used to determine to which temporary data structure to forward the packet, if a first list includes the packet information forwarding the packet to a first temporary data structure, and processing the packet from the first temporary data structure, and if the first list does not include the packet information forwarding the packet to a second temporary data structure, processing the packet, wherein processing the packet comprises: sending a first test to a source of the packet using the packet information, placing the packet information on the first list, if a successful response to the first test is received, and placing the packet information on a second list, if an unsuccessful response to the first test is received.

Abstract: Some embodiments of the present invention provide a system that computes a target secret St in a sequence of secrets S0 . . . Sn. During operation, the system obtains k hash functions h1, . . . , hk, where h1 is known as the “lowest order hash function”, and hk is known as the “highest order hash function.” Associated with each hash function hi is a seed value seed comprising a pair (seedindexi, seedvaluei). Hash function hi operates on a pair (indexi, valuei) to produce a pair (newindexi, newvaluei), where newindexi>indexi. To compute target secret St, the hash functions are applied successively, starting with the highest order hash function whose associated seed's index value is largest without being greater than t, applying that hash function as many times as possible without having that hash function's output's index value become greater than t, and then applying each successive hash function in turn as many times as possible, until St has been computed.

Abstract: Some embodiments provide systems and techniques for performing parameterizable cryptography. An encryption key can be determined based at least on a string associated with an authorization policy. The encryption key can then be used to encrypt information. The decryption key can also be determined based at least on the string associated with the authorization policy. Note that the authorization policy must be satisfied to decrypt information. In some embodiments, the systems and techniques for performing parameterizable cryptography are blindable. These blindable embodiments can be used to preserve privacy.

Abstract: Some embodiments provide a system to generate a key pair. During operation, the system can receive a request to generate the key pair, wherein the key pair is generated by a key assigner, and wherein the key pair is associated with a user. Next, the system can determine a secret associated with the key assigner. Specifically, the system can determine the secret by determining an initial secret associated with the key assigner, and by applying a one-way hash function to the initial secret one or more times. The system can then determine a seed based on the secret. Specifically, the system can determine the seed by cryptographically combining the secret with information associated with the user. Next, the system can generate the key pair by using the seed as an input to a key generator. The system can then return the key pair to a requestor.

Abstract: One embodiment of the present invention provides a system for accessing an encrypted file through a file system. During operation, the system receives a request to access the encrypted file. In response to the request, the system sends an encrypted file key for the encrypted file from the file system to a tamper-resistant module. Next, the tamper-resistant module uses a master secret to decrypt the encrypted file key to restore the file key, wherein the master secret is obtained from an external source by the tamper-resistant module. The system then uses the file key to access the encrypted file.

Abstract: A distributed denial of service attack can be defended against by challenging requests at a machine upstream from the target of the attack. The upstream machine limits access to the victim machine in response to indication of the victim machine being attacked. The upstream machine begins trapping protocol data units destined for the victim machine and challenging requests to access the victim machine with tests that require sentient responses, such as Turing tests. The upstream machine then updates a set of rules governing access to the victim machine based, at least in part, on responses to the challenges or administered tests.

Abstract: Some embodiments provide systems and techniques for performing parameterizable cryptography. An encryption key can be determined based at least on a string associated with an authorization policy. The encryption key can then be used to encrypt information. The decryption key can also be determined based at least on the string associated with the authorization policy. Note that the authorization policy must be satisfied to decrypt information. In some embodiments, the systems and techniques for performing parameterizable cryptography are blindable. These blindable embodiments can be used to preserve privacy.

Abstract: One embodiment of the present invention provides a system that manages secret keys for messages. During operation, the system receives a desired expiration time T from an encrypter, and possibly a nonce N, at a server that manages keys. If N is not sent by the encrypter, it is generated by a key managing server. Next, the system chooses a secret ST, with an expiration time close to T, and an identifier IDS from a database for which secret ST can be retrieved using the identifier IDS. If such an ST is not already in the database, the server generates a new ST and IDS. The system then calculates a hash H=h(N,ST), and sends H and IDS from the server to the encrypter. The encrypter then encrypts M with H to form {M}H, and communicates ({M}H, N, IDS) to a message reader. The message reader then sends N and IDS to the server. The server then uses IDS to lookup ST, recalculates H=h(N,ST), and sends H to the message reader, thereby enabling the message reader to decrypt {M}H to obtain M.

Abstract: Some embodiments provide a system to assure enhanced security, e.g., by assuring that information is not revealed over a covert channel. All communications between a source system and a destination system may pass through an intermediate system. In some embodiments, the intermediate system may perform an additional level of blinding to ensure that the source system does not covertly reveal information to the destination system. In some embodiments, the intermediate system may request the source system to perform a modification operation, and then check if the source system performed the modification operation. Examples of the modification operation include a blinding operation and a cryptographic hashing operation.

Abstract: One embodiment of the present invention relates to a system for managing files which facilitates making the files permanently unreadable. During operation, the system maintains file-class keys at a file manager, wherein the file-class keys are associated with different classes of files. If a file belongs to a class of files, the system ensures that whenever the file is stored or updated in non-volatile storage that the file is encrypted with an associated key-manager-file-class key for the class of files. The system makes an entire class of files permanently unreadable by causing an associated key-manager-file-class key, which can be used to decrypt the class of files, to become permanently unreadable.

Abstract: One embodiment of the present invention provides a system that facilitates securely forgetting a secret. During operation, the system obtains a set of secrets which are encrypted with a secret key Si, wherein the set of secrets includes a secret to be forgotten and other secrets which are to be remembered. Next, the system decrypts the secrets to be remembered using Si, and also removes the secret to be forgotten from the set of secrets. The system then obtains a new secret key Si+1, and encrypts the secrets to be remembered using Si+1. Finally, the system forgets Si.

Abstract: An edge device including a first list and a second list, a first queue and a second queue configured to receive packets, wherein packet information for each of the packets forwarded to the first queue is on a first list and packet information for each of the packets forwarded to the second queue is not on the first list. The edge device is configured to, for each of the packets stored in the second queue, send a message to a host to send a first test to a source of the packet, wherein the host is operatively connected to the edge device, obtain a response to the first test from the host, place the packet information on the first list, if a successful response to the first test is received, and place the packet information on a second list, if an unsuccessful response to the first test is received.

Abstract: Some embodiments provide a system to generate a key pair. During operation, the system can receive a request to generate the key pair, wherein the key pair is generated by a key assigner, and wherein the key pair is associated with a user. Next, the system can determine a secret associated with the key assigner. Specifically, the system can determine the secret by determining an initial secret associated with the key assigner, and by applying a one-way hash function to the initial secret one or more times. The system can then determine a seed based on the secret. Specifically, the system can determine the seed by cryptographically combining the secret with information associated with the user. Next, the system can generate the key pair by using the seed as an input to a key generator. The system can then return the key pair to a requestor.