Abstract: A system includes circuitry for rewriting blockchains in a non-tamper-evident or tamper-evident operation by a selected trusted party during a rewrite-permissive phase for the selected trusted party. During a rewrite-embargoed phase for the selected trusted party, rewrite access may pass to at least one second trusted party in a turn-based scheme. In some implementations, rewrite access may be implemented by controlling access to combination of a turn-control key secret portion with respective key secret portions controlled the by the individual trusted parties. Using the access to combination with the turn-control key secret portion, the trusted parties may preform rewrites to the blockchain.

Abstract: A system includes circuitry for rewriting blockchains in a validity-preserving operation. In some cases, using a key secret held by a trusted party. In some cases, the blockchains may include a series of blocks secured integrity codes that may prevent non-tamper-evident rewrites by non-trusted parties that are not in possession of the key secret. In some cases, the key may allow valid but tamper-evident rewrites of the blockchain by trusted entities. In some cases, integrity outputs may be generated from the integrity codes based on the content of the previous blocks in the series such that attempts by untrusted parties to replace a block may be detected through coding-inconsistencies with other blocks.

Abstract: A system includes circuitry for rewriting blockchains in a non-tamper-evident or tamper-evident operation by a trusted party during a rewrite-permissive phase. During a rewrite-embargoed phase, at least one trusted party with rewrite access during the rewrite-permissive phase may have rewrite access revoked. In some implementations, rewrite access may be implemented by controlling access to a key secret for the blockchain. In some cases, access to the key secret may be changed by deleting the key secret or by changing access permissions for a particular device.

Abstract: A system includes circuitry for rewriting blockchains in a non-tamper-evident or tamper-evident operation by a selected trusted party during a rewrite-permissive phase for the selected trusted party. During a rewrite-embargoed phase for the selected trusted party, rewrite access may pass to at least one second trusted party in a turn-based scheme. In some implementations, rewrite access may be implemented by controlling access to combination of a turn-control key secret portion with respective key secret portions controlled the by the individual trusted parties. Using the access to combination with the turn-control key secret portion, the trusted parties may preform rewrites to the blockchain.

Abstract: A system includes circuitry for rewriting blockchains in a non-tamper-evident or tamper-evident operation using a key secret held in portions by multiple individually untrusted parties. The blockchains may include a series of blocks secured by integrity codes that may prevent non-tamper-evident rewrites by non-trusted parties that are not in possession of the key secret or individually-untrusted parties in possession of only a portion of the key secret. In some cases, multiple individually-untrusted parties may combine their portions into the key secret. As a group, the multiple individually-untrusted parties may perform non-tamper-evident operation with respect to at least one integrity code within the blockchain.

Abstract: A system includes circuitry for rewriting blockchains in a non-tamper-evident or tamper-evident operation using a key secret held in portions by multiple individually untrusted parties. The blockchains may include a series of blocks secured by integrity codes that may prevent non-tamper-evident rewrites by non-trusted parties that are not in possession of the key secret or individually-untrusted parties in possession of only a portion of the key secret. In some cases, multiple individually-untrusted parties may combine their portions into the key secret. As a group, the multiple individually-untrusted parties may perform non-tamper-evident operation with respect to at least one integrity code within the blockchain.

Abstract: A system includes circuitry for rewriting blockchains in a validity-preserving operation. In some cases, using a key secret held by a trusted party. In some cases, the blockchains may include a series of blocks secured integrity codes that may prevent non-tamper-evident rewrites by non-trusted parties that are not in possession of the key secret. In some cases, the key may allow valid but tamper-evident rewrites of the blockchain by trusted entities. In some cases, integrity outputs may be generated from the integrity codes based on the content of the previous blocks in the series such that attempts by untrusted parties to replace a block may be detected through coding-inconsistencies with other blocks.

Abstract: A system includes circuitry for rewriting blockchains in a non-tamper-evident or tamper-evident operation using a key secret held by a trusted party. The blockchains may include a series of blocks secured by a chameleon hash that may prevent non-tamper-evident rewrites by non-trusted parties that are not in possession of the key secret. Rewrite circuitry of the system may determine randomness data from the chameleon hash and altered data from a rewrite. The randomness data may be written to the randomness field of a block overwritten with the altered data such that the block remains coding-consistent with the chameleon hash and other blocks in the blockchain.

Abstract: A system includes circuitry for rewriting blockchains in a non-tamper-evident or tamper-evident operation using a key secret held by a trusted party. The blockchains may include a series of blocks secured integrity codes that may prevent non-tamper-evident rewrites by non-trusted parties that are not in possession of the key secret. In some cases, the key may allow valid but tamper-evident rewrites of the blockchain by trusted entities. Integrity outputs may be generated from the integrity codes based on the content of the previous blocks in the series such that attempts by untrusted parties to replace a block may be detected through coding-inconsistencies with other blocks.

Abstract: A system includes circuitry for performing hybrid blockchain rewrites by trusted parties. The hybrid blockchain may include blocks with multiple parts. In some cases, the blocks may include a core part and a tertiary part. The system may include conditions for validity preserving and/or non-tamper-evident rewrites to the parts of the block. The conditions to support rewrites to the core part may be more stringent than the corresponding conditions to support rewrites to the tertiary part. In some cases, the core part may be write-locked.

Abstract: A system includes circuitry for wrapping up blockchains into blockchain loops. A blockchain may include a series of blocks extending from an initial block to a terminal block. The circuitry may wrap-up the blockchain by storing an integrity output coding-consistent with the terminal block within the initial block. In some cases, when the terminal block and initial block include end blocks for the blockchain, wrapping-up the series may form a closed-loop.

Abstract: A system includes circuitry for performing hybrid blockchain rewrites by trusted parties. The hybrid blockchain may include blocks with multiple parts. In some cases, the blocks may include a core part and a tertiary part. The system may include conditions for validity preserving and/or non-tamper-evident rewrites to the parts of the block. The conditions to support rewrites to the core part may be more stringent than the corresponding conditions to support rewrites to the tertiary part. In some cases, the core part may be write-locked.

Abstract: A system includes circuitry for rewriting blockchains in a non-tamper-evident or tamper-evident operation using a key secret held in portions by multiple individually untrusted parties. The blockchains may include a series of blocks secured by integrity codes that may prevent non-tamper-evident rewrites by non-trusted parties that are not in possession of the key secret or individually-untrusted parties in possession of only a portion of the key secret. In some cases, multiple individually-untrusted parties may combine their portions into the key secret. As a group, the multiple individually-untrusted parties may perform non-tamper-evident operation with respect to at least one integrity code within the blockchain.

Abstract: A system includes circuitry for rewriting blockchains in a non-tamper-evident or tamper-evident operation using a key secret held by a trusted party. The blockchains may include a series of blocks secured integrity codes that may prevent non-tamper-evident rewrites by non-trusted parties that are not in possession of the key secret. In some cases, the key may allow valid but tamper-evident rewrites of the blockchain by trusted entities. Integrity outputs may be generated from the integrity codes based on the content of the previous blocks in the series such that attempts by untrusted parties to replace a block may be detected through coding-inconsistencies with other blocks.

Abstract: A system includes circuitry for rewriting blockchains in a non-tamper-evident or tamper-evident operation using a key secret held by a trusted party. The blockchains may include a series of blocks secured by a chameleon hash that may prevent non-tamper-evident rewrites by non-trusted parties that are not in possession of the key secret. Rewrite circuitry of the system may determine randomness data from the chameleon hash and altered data from a rewrite. The randomness data may be written to the randomness field of a block overwritten with the altered data such that the block remains coding-consistent with the chameleon hash and other blocks in the blockchain.

Abstract: A system includes circuitry for rewriting blockchains in a non-tamper-evident or tamper-evident operation using a key secret held by a trusted party. The blockchains may include a series of blocks secured by multiple integrity codes that may prevent non-tamper-evident rewrites by non-trusted parties that are not in possession of the key secret. In some cases, the key may allow valid but tamper-evident rewrites of the blockchain by trusted entities. Further, in some implementations, tamper-evident rewrites may be converted to non-tamper-evident rewrites through multiple-party ratification.

Abstract: A system includes circuitry for rewriting blockchains in a non-tamper-evident or tamper-evident operation using a key secret held in portions by multiple individually untrusted parties. The blockchains may include a series of blocks secured by integrity codes that may prevent non-tamper-evident rewrites by non-trusted parties that are not in possession of the key secret or individually-untrusted parties in possession of only a portion of the key secret. In some cases, multiple individually-untrusted parties may combine their portions into the key secret. As a group, the multiple individually-untrusted parties may perform non-tamper-evident operation with respect to at least one integrity code within the blockchain.

Abstract: Various exemplary embodiments of the devices and methods for this invention provide for a semiconductor structure and a method of manufacturing a semiconductor structure that includes providing an aluminum nitride nucleation layer over a substrate, providing an undoped AlGaN buffer layer over the aluminum nitride nucleation layer, providing an undoped GaN over the AlGaN buffer layer, providing a plurality of AlGaN layers over the GaN layer wherein the plurality of aluminum GaN layers comprise a first layer provided over the undoped GaN layer, a second layer provided over the first layer and the third layer provided over the second layer, providing a source electrode and a drain electrode, through the first, second and third aluminum gallium nitride layers, the source electrode and the drain electrode being in electrical contact with the gallium nitride layer and providing a gate electrode over the third aluminum gallium nitride layer.

Abstract: A pair of undoped spacer layers are provided adjacent to, or near to, a single quantum well aluminum gallium nitride active region. In various exemplary embodiments, the undoped spacer layers are provided between the single quantum well aluminum gallium nitride active region and carrier confinement layers. The undoped spacer layers reduce the threshold current for the laser device and improve the output characteristics.

Abstract: The polarization instability inherent in laterally-oxidized VCSELs may be mitigated by employing an appropriately-shaped device aperture, a misoriented substrate, one or more cavities or employing the shaped device aperture together with a misoriented substrate and/or cavities. The laterally-oxidized VCSELs are able to operate in a single polarization mode throughout the entire light output power versus intensity curve. Combining the use of misoriented substrates with a device design that has an asymmetric aperture that reinforces the polarization mode favored by the substrate further improves polarization selectivity. Other device designs, however, can also be combined with substrate misorientation to strengthen polarization selectivity.