Abstract: A first entity and a second entity establish a protected authenticated communication channel using an implicit certificate issued by a certificate authority. In some examples, the implicit certificate is generated based at least in part on the ring learning with errors (“RLWE”) problem. Using the implicit certificate, the first entity and the second entity exchange information that enables the entities to negotiate a shared secret. The shared secret may be used to establish a cryptographically protected communication channel. Successful use of the shared secret authenticates the identity of the first entity and the second entity.

Abstract: A trusted co-processor can provide a hardware-based observation point into the operation of a host machine owned by a resource provider or other such entity. The co-processor can be installed via a peripheral card on a fast bus, such as a PCI bus, on the host machine. The co-processor can execute malware detection software, and can use this software to analyze data and/or code obtained from the relevant resources of the host machine. The trusted co-processor can notify the customer or another appropriate entity of the results of the scan, such that an appropriate action can be taken if malware is detected. The results of the scan can be trusted, as malware will be unable to falsify such a notification or modify the operation of the trusted co-processor.

Abstract: A signature authority generates a master seed value that is used to generate a seed tree of subordinate nodes. Each subordinate node of the seed tree is generated from the value of its parent node using a cryptographic hash or one-way function. The signature authority selects subordinate seed values from the seed tree which are distributed to one or more subordinates, each of which generates a set of one-time-use cryptographic keys from the provided seed. Each subordinate generates a hash tree from its set of one-time-use cryptographic keys, and returns the root of its hash tree to the signature authority. The signature authority integrates the hashes provided by the key generators into a comprehensive hash tree, and the root of the hash tree acts as a public key for the signature authority.

Abstract: An implicit certificate is based on a ring learning with errors (“RLWE”) public keys that are, in some examples, resistant to quantum-based computing attacks. Various methods are described that request, generate, verify, and use the implicit certificates. In some examples, the system provides an implicit certificate that enables communication between two parties that are identified at the time of certificate generation. In another example, the system provides a certificate that may be used to communicate with a variety of different parties. The implicit certificate generation algorithm yields a public key purportedly bound to U. Confirmation that the public key is bound to U is obtained after use of the corresponding private key. Binding of an entity to its associated public key and accessibility to the private key, are verified as a result of successful key use.

Abstract: Two parties to a communication establish public and private keys through the use of implicit certificates. Each party establishes a new static key pair, and determines a difference between the new static key pair and the previously established keys. The differences are exchanged and used to determine new public static keys. Each party generates an ephemeral key pair from the static key pair, and a shared secret is derived from a combination of the ephemeral keys and the new static keys.

Abstract: A host machine operated for a specific purpose can have restricted access to other components in a multi-tenant environment in order to provide for the security of the host machine. The access restriction can prevent the host machine from obtaining updates to critical system-level configurations, but such information can be obtained through a signed command received to an API for the host machine. The command can be signed by a quorum of operators, and the host machine can be configured to verify the signatures and the quorum before processing the command. The host machine can store the updates to ephemeral storage as well as persistent storage, such that upon a reboot or power cycle the host machine can operate with current configuration data.

Abstract: A requirement for a pseudo-random number is identified. A usage context corresponding to the requirement is determined from among a plurality of usage contexts. A cryptographic transformation function is applied to a first pseudo-random number obtained from a pseudo-random number generator. The transformation function meets a security criterion which is based on the usage context. A result of the function is used to fulfill the requirement.

Abstract: A cryptographic key management service receives a request to import a first cryptographic key. In response to the request, the service creates a public cryptographic key and a private cryptographic key. The private cryptographic key is encrypted using a second cryptographic key to create an import key token. The import key token and the public cryptographic key are provided in response to the request. The service receives an encrypted first cryptographic key, which the service decrypts using the private cryptographic key to obtain the first cryptographic key. The service stores the first cryptographic key and enables its use for the performance of cryptographic operations.

Abstract: Methods, systems, and computer programs for performing key agreement operations in a communication system are described. In some aspects, a wireless network operator receives a mobile device identifier and accesses a secret key associated with the mobile device. A message authentication code function is evaluated based on the secret key to produce an output value. A session key and a challenge value are obtained based on the output value. In some aspects, a mobile device accesses a secret key in response to receiving the challenge value from the wireless network operator. A message authentication code function is evaluated based on the secret key to produce an output value. A response value and a session key are obtained based on the output value. The response value is transmitted to the wireless network operator.

Abstract: Performing cryptographic operations such as encryption and decryption may be computationally expensive. In some contexts, initialization vectors and keystreams operable to perform encryption operations are generated and stored in a repository, and later retrieved for use in performing encryption operations. Multiple devices in a distributed system can each generate and store a subset of a larger set of keystreams.

Abstract: A request a request to perform a cryptographic operation is received, the request including a first identifier assigned to a key group, the key group comprising a plurality of second identifiers, with the plurality of second identifiers corresponding to a plurality of cryptographic keys. A second identifier is determined, according to a distribution scheme, from the plurality of second identifiers, and the cryptographic operation is performed using a cryptographic key of the plurality of cryptographic keys that corresponds to the second identifier that was determined.

Abstract: A signature authority generates a master seed value that is used to generate a seed tree of subordinate nodes. Each subordinate node of the seed tree is generated from the value of its parent node using a cryptographic hash or one-way function. The signature authority selects subordinate seed values from the seed tree which are distributed to one or more subordinates, each of which generates a set of one-time-use cryptographic keys from the provided seed. Each subordinate generates a hash tree from its set of one-time-use cryptographic keys, and returns the root of its hash tree to the signature authority. The signature authority integrates the hashes provided by the key generators into a comprehensive hash tree, and the root of the hash tree acts as a public key for the signature authority.

Abstract: A service provider provides virtual computing services using a fleet of one or more host computer systems. Each of the host computer systems may be equipped with a trusted platform module (“TPM”). The service provider, the host computer systems, and the virtual computing environments generate attestations that prove the integrity of the system. The attestations are signed with a one-time-use cryptographic key that is verifiable against the public keys of the service provider, a host computer system, and a virtual computing environment. The public key of the host computer system is integrated into a hash tree that links the public key of the host computer system to the public key of the service provider. The public key of the virtual computing environment is signed using a one-time-use graphic key issued to the host computer system that hosts the virtual computing environment.

Abstract: A key distribution service operated by a signature authority distributes one-time-use cryptographic keys to one or more delegates that generate digital signatures on behalf of the signature authority. The key distribution service uses a root seed value to generate subordinate seeds. The subordinate seeds are used to generate a set of cryptographic keys. Hashes are generated for each key, and the hashes are arranged into a Merkle tree with a root hash controlled by the signature authority. In response to a request from a delegate, the signature authority provides a subordinate seed to the delegate. The delegate uses the subordinate seed to generate one or more cryptographic keys. The cryptographic keys are used to generate digital signatures which are verifiable up to the root hash of the Merkle tree. Additional subordinate seeds may be distributed to entities by the signature authority when appropriate.

Abstract: A signature authority generates revocable one-time-use keys that are able to generate digital signatures. The signature authority generates a set of one-time-use keys, where each one-time-use key has a secret key and a public key derived from a hash of the secret key. The signature authority generates one or more revocation values that, when published, proves that the signature authority has the authority to revoke corresponding cryptographic keys. The signature authority hashes the public keys and the revocation values and arranges the hashes in a hash tree where the root of the hash tree acts as a public key of the signature authority. In some implementations, the one-time-use cryptographic keys are generated from a tree of seed values, and a particular revocation value is linked to a particular seed value, allowing for the revocation of a block of one-time-use cryptographic keys associated with the particular seed.

Abstract: A proof-of-work system where a first party (e.g., a client computer system) may request access to a computing resource. A second party (e.g., a service provider) may determine a challenge that may be provided to the first party. A valid solution to the challenge may be generated and provided for the request to be fulfilled. The challenge may include a message and a seed, such that the seed may be used at least in part to cryptographically derive information that may be used to generate a solution to the challenge. A hash tree may be generated as of generating the solution.

Abstract: An organizational signature authority delegates signature authority to one or more subordinate signature authorities by rolling up public keys from the subordinate signature authorities into a public key for the organization. A subordinate signature authority of the organizational signature authority generates cryptographic keys for use by the subordinate signature authority, and cryptographically derives a public key for the subordinate signature authority based at least in part on the cryptographic keys. In some examples, the subordinate signature authority acquires public keys from a lower subordinate signature authority, and the public key of the subordinate signature authority is cryptographically derived in part from the public key of the lower subordinate signature authority. The public key of the subordinate signature authority is provided to the organizational signature authority.

Abstract: A signature authority generates a master seed value that is used as the root of a seed tree of subordinate nodes. Each subordinate node of the seed tree is generated from the value of its parent node using a cryptographic hash or one-way function. The signature authority selects subordinate seed values which are distributed to one or more key generators, each of which generates a set of one-time-use cryptographic keys. Each key generator generates a hash tree from its set of one-time-use cryptographic keys, and the root of its hash tree is returned to the signature authority. The signature authority integrates the hashes provided by the key generators into a comprehensive hash tree. The root of the comprehensive hash tree acts as a public key for the signature authority.

Abstract: A plaintext and cryptographic key are used to generate an initialization vector to be used in a cryptographic algorithm, such as an encryption algorithm. In some examples, the plaintext and cryptographic key are input into an effectively one-way function, such as a cryptographic hash function, the output of which is usable as an initialization vector. Cryptographic keys may be rotated probabilistically based at least in part on probabilities of output collisions of the effectively one-way function to ensure a low probability of two different plaintexts resulting in calculation of the same initialization vector for use with the same cryptographic key.

Abstract: A web of trust in a distributed system is established. A root of trust for at least two components in the distributed system validates information for the distributed system. The validated information is then used to create additional information for the distributed system. Versions of the information are usable to validate subsequent versions of the information such that validation of a version of the information can be performed by using one or more previous versions to verify that the version is a valid successor of a previously validated previous version.