Abstract: System load, such as load caused by a denial of service attack, is managed by requiring those requesting access to the system to provide proof of work. A system receives, from a requestor, a request for access to the system. Before the request can be processed, the system provides a challenge to the requestor. The requestor obtains a solution to the challenge and provides proof of having obtained the solution. The system verifies the correctness of the solution and, if the correct solution is verified, the system services the request.

Abstract: A client and server negotiate a secure communication channel using a pre-shared key where the server, at the time the negotiation initiates, lacks access to the pre-shared key. The server obtains the pre-shared key from another server that shares a secret with the client. A digital signature or other authentication information generated by the client may be used to enable the other server to determine whether to provide the pre-shared key.

Abstract: A client establishes an cryptographically protected communications session and determines information usable to distinguish the session from other sessions. The client digitally signs the information using a cryptographic key that is independent of the session to enable a server to check whether the information matches the session that it established and whether the digital signature is correct. The server may perform mitigating operations if either or both of the information or the digital signature is/are invalid.

Abstract: A data storage management process is directed to aspects of managing encrypted data via data storage volumes in conjunction with a service provider computer network that hosts virtual machine instances. A volume can be created and configured for managing encrypted data with an encrypted version of a volume key. The volume can be attached to a virtual machine instance such that the virtual machine instance accesses the volume in a transparent fashion based on the volume key. Encrypted data specific to the volume can be copied across multiple regions of data storage each associated with distinct encrypted versions of a volume key corresponding to the volume.

Abstract: A client and server negotiate a secure communication channel using a pre-shared key where the server, at the time the negotiation initiates, lacks access to the pre-shared key. The server obtains the pre-shared key from another server that shares a secret with the client. A digital signature or other authentication information generated by the client may be used to enable the other server to determine whether to provide the pre-shared key.

Abstract: Cryptographic keys can include logging properties that enable those keys to be used only if the properties can be enforced by the cryptographic system requested to perform one or more actions using the keys. The logging property can specify how to log use of a respective key. A key can also include a mutability property for specifying whether the logging property can be changed, and if so under what circumstances or in which way(s). The ability to specify and automatically enforce logging can be important for environments where audit logs are essential. These can include, for example, public certificate authorities that must provide accurate and complete audit trails. In cases where the data is not to be provided outside a determined secure environment, the key can be generated with a property indicating not to log any of the usage.

Abstract: A client establishes an cryptographically protected communications session and determines information usable to distinguish the session from other sessions. The client digitally signs the information using a cryptographic key that is independent of the session to enable a server to check whether the information matches the session that it established and whether the digital signature is correct. The server may perform mitigating operations if either or both of the information or the digital signature is/are invalid.

Abstract: A client and server negotiate a secure communication channel using a pre-shared key where the server, at the time the negotiation initiates, lacks access to the pre-shared key. The server obtains the pre-shared key from another server that shares a secret with the client. A digital signature or other authentication information generated by the client may be used to enable the other server to determine whether to provide the pre-shared key.

Abstract: An HSM management hub coordinates the distribution and synchronization of cryptographic material across a fleet of connected hardware security modules (“HSMs”). Cryptographic material is exchanged between HSMs in the fleet in a cryptographically protected format. In some examples, the cryptographic material is encrypted using a common fleet key maintained by the HSMs in the fleet. In other examples, the cryptographic material is protected using asymmetric cryptographic keys that are associated with the members of the HSM fleet. The HSM management hub may be used to divide the HSM fleet into subdomains by providing domain keys to subsets of HSMs within the HSM fleet. Cryptographic information that is encrypted with particular domain keys can be distributed across the entire HSM fleet, and restricted to use by authorized HSMs that are in possession of the particular domain keys.

Abstract: A tiered credentialing approach provides assurance to customers having virtual machines running in a remote environment that the virtual images for these machines are in a pristine state and running in a trusted execution environment. The environment can be divided into multiple subsystems, each having its own cryptographic boundary, secure storage, and trusted computing capabilities. A trusted, limited subsystem can handle the administrative tasks for virtual machines running on the main system of a host computing device. The limited system can receive a certificate from a certificate authority, and can act as a certificate authority to provide credentials to the main system. Upon an attestation request, the subsystems can provide attestation information using the respective credentials as well as the certificate chain. An entity having the appropriate credentials can determine the state of the system from the response and verify the state is as expected.

Abstract: An HSM management hub coordinates the distribution and synchronization of cryptographic material across a fleet of connected hardware security modules (“HSMs”). Cryptographic material is exchanged between HSMs in the fleet in a cryptographically protected format. In some examples, the cryptographic material is encrypted using a common fleet key maintained by the HSMs in the fleet. In other examples, the cryptographic material is protected using asymmetric cryptographic keys that are associated with the members of the HSM fleet. The HSM management hub may be used to divide the HSM fleet into subdomains by providing domain keys to subsets of HSMs within the HSM fleet. Cryptographic information that is encrypted with particular domain keys can be distributed across the entire HSM fleet, and restricted to use by authorized HSMs that are in possession of the particular domain keys.

Abstract: A computer system stores a probabilistic data structure generated based at least in part on a plurality of digital signatures generated based at least in part on a plurality of components of a data set. The computer system receives a digital signature for verification. An entry can verify the digital signature within the probabilistic data structure by verifying the digital signature against the probabilistic data structure.

Abstract: A computer system receives a request to remove an entry from a probabilistic data structure. In response to the request, the computer system queries the probabilistic data structure to determine a current iteration value for the entry within the probabilistic data structure. The current iteration value indicates a state of the entry such that a first state corresponds to the entry being a member of a set and a second state corresponds to the absence of the entry from the set. As a result of the current iteration value denoting that the entry is a member of the set, the computer system increments the current iteration value to generate a new iteration value that corresponds to the absence of the entry from the set. The computer system uses the new iteration value and the entry to generate a new output value that is then added to the probabilistic data structure.

Abstract: A computer system encodes a plurality of components of a data set into a probabilistic data structure and digitally signs the probabilistic data structure. The computer system provides the digital signature for the probabilistic data structure and the probabilistic data structure to various entities. An entity can verify an individual component of the data set within the probabilistic data structure by verifying the individual component against the probabilistic data structure and the digital signature of the probabilistic data structure.

Abstract: Incremented authenticated encryption involves dividing a data stream to be encrypted into multiple data segments and encrypting each of the data segments. For each encrypted data segment, an authorization tag is generated. Each segment's authorization tag may be based on the corresponding segment's position in the sequence of data segments within the data stream. A segment authorization tag may be generated based on an segment initialization vector that may be incremented with each segment authorization tag. Each data segment may be encrypted independently of the others. Similarly, each encrypted data segment may be decrypted and authenticated independently of the others. Additionally, a final authentication tag may be generated. The final authentication tag may be used to authenticate all the data segments of the data stream as a whole.

Abstract: A system performs cryptographic operations utilizing information usable to verify validity of plaintext. To prevent providing information about a plaintext by providing the information usable to verify the validity of the plaintext, the system provides the information usable to verify validity of the plaintext to an entity on a condition that the entity is authorized to access the plaintext. The information usable to verify validity of the plaintext may be persisted in ciphertext along with the plaintext to enable the plaintext to be verified when decrypted.

Abstract: A distributed passcode verification system includes devices that each have a secret and that are each able to perform a limited number of verifications using their secrets. Passcode verifiers receive passcode information from a passcode information manager. The passcode information provides information usable, with a secret, to verify passcodes provided to a verifier.

Abstract: Methods and apparatus for a security mechanism evaluation service are disclosed. A storage medium stores program instructions that when executed on a processor define a programmatic interface enabling a client to submit an evaluation request for a security mechanism. On receiving an evaluation request from a client indicating a particular security mechanism using public-key encryption, the instructions when executed, identify resources of a provider network to be used to respond. The instructions, when executed, provide to the client, one or more of: (a) a trustworthiness indicator for a certificate authority that issued a public-key certificate in accordance with the particular security mechanism; (b) a result of a syntax analysis of the public-key certificate; or (c) a vulnerability indicator for a key pair.

Abstract: A system performs cryptographic operations utilizing information usable to verify validity of plaintext. To prevent providing information about a plaintext by providing the information usable to verify the validity of the plaintext, the system provides the information usable to verify validity of the plaintext to an entity on a condition that the entity is authorized to access the plaintext. The information usable to verify validity of the plaintext may be persisted in ciphertext along with the plaintext to enable the plaintext to be verified when decrypted.

Abstract: A hardware secret is securely maintained in a computing device. The device operates in accordance with a usage limit corresponding to a limited number of operations using the hardware secret that the device is able to perform. Once the device reaches a usage limit, the device becomes temporarily or permanently unable to perform additional operations using the hardware secret.