Abstract: Examples discussed herein disclose, among other things, an encrypting device. The encrypting device may include a format preserving encryptor to obtain a plaintext, obtain a key from a plurality of keys stored in a key database, and encrypt the plaintext using the key to produce a ciphertext having a length of the plaintext. The encrypting device may also include a key reference embedder to obtain a key reference associated with the key, and generate an extended ciphertext by adding to the ciphertext a set of characters associated with the key reference, such that the key reference can be determined based on the extended ciphertext.

Abstract: Examples discussed herein disclose, among other things, a method. The method includes, among other things, obtaining a plaintext, obtaining a key from a plurality of keys, and determining whether the plaintext is longer than a predefined threshold length. If the plaintext is longer than the predefined threshold length, the method may encrypt the plaintext with the key to generate a first ciphertext having a length of the plaintext, where the character at a predefined position within the first ciphertext belongs to a first subset of characters. And if the plaintext is not longer than the predefined threshold length, the method may encrypt the plaintext with the key to generate a second ciphertext, which is longer than the plaintext, where the character at the same predefined position in the second ciphertext belongs to a second subset of characters.

Abstract: Techniques for using padding in format preserving encryption are provided. In one aspect, it may be determined if padding of a plaintext undergoing format preserving encryption is needed. A pseudo random padding length may be calculated when it is determined that padding is needed. The calculated length of padding may be added to the plaintext when it is determined that padding is needed. The plaintext and added padding may be encrypted using format preserving encryption to create a cipher text.

Abstract: In one example in accordance with the present disclosure, a method may include receiving a digit sequence including a subset of N digits encoded with semantic information and determining a set of possible combinations for the N digits in the subset. The method may also include establishing a mapping between each possible combination in the set of possible combinations and a corresponding integer sequence belonging to a set of integer sequences. Each integer sequence in the set of integer sequences is of the length of N?1. The method may also include identifying a selected integer sequence corresponding to the subset and replacing n?1 digits from the subset with the selected integer sequence. The method may also include replacing a digit of the subset with a digit value calculated to produce a valid checksum for the entire first digit sequence, wherein the first digit is not included in the n?1 digits.

Abstract: Examples discussed herein disclose, among other things, a method. The method includes, among other things, obtaining a plaintext, obtaining a key from a plurality of keys, and determining whether the plaintext is longer than a predefined threshold length. If the plaintext is longer than the predefined threshold length, the method may encrypt the plaintext with the key to generate a first ciphertext having a length of the plaintext, where the character at a predefined position within the first ciphertext belongs to a first subset of characters. And if the plaintext is not longer than the predefined threshold length, the method may encrypt the plaintext with the key to generate a second ciphertext, which is longer than the plaintext, where the character at the same predefined position in the second ciphertext belongs to a second subset of characters.

Abstract: A technique includes performing element-by-element encryption of a segment of the plaintext string to provide a segment of an encrypted string. Performing the element-by-element encryption includes, for a given string element of the segment of the plaintext string, encrypting the given string element to provide a given string element of the segment of the encrypted string; and tweaking the encryption of the given string element based on a selector that includes multiple string elements of the encrypted string. The technique may include searching an encrypted database based on the encrypted string.

Abstract: In one example in accordance with the present disclosure, a method may include receiving a digit sequence including a subset of N digits encoded with semantic information and determining a set of possible combinations for the N digits in the subset. The method may also include establishing a mapping between each possible combination in the set of possible combinations and a corresponding integer sequence belonging to a set of integer sequences. Each integer sequence in the set of integer sequences is of the length of N?1. The method may also include identifying a selected integer sequence corresponding to the subset and replacing n?1 digits from the subset with the selected integer sequence. The method may also include replacing a digit of the subset with a digit value calculated to produce a valid checksum for the entire first digit sequence, wherein the first digit is not included in the n?1 digits.

Abstract: A technique includes performing element-by-element encryption of a segment of the plaintext string to provide a segment of an encrypted string. Performing the element-by-element encryption includes, for a given string element of the segment of the plaintext string, encrypting the given string element to provide a given string element of the segment of the encrypted string; and tweaking the encryption of the given string element based on a selector that includes multiple string elements of the encrypted string. The technique may include searching an encrypted database based on the encrypted string.

Abstract: Examples discussed herein disclose, among other things, an encrypting device. The encrypting device may include a format preserving encryptor to obtain a plaintext, obtain a key from a plurality of keys stored in a key database, and encrypt the plaintext using the key to produce a ciphertext having a length of the plaintext. The encrypting device may also include a key reference embedder to obtain a key reference associated with the key, and generate an extended ciphertext by adding to the ciphertext a set of characters associated with the key reference, such that the key reference can be determined based on the extended ciphertext.

Abstract: Techniques for using padding in format preserving encryption are provided. In one aspect, it may be determined if padding of a plaintext undergoing format preserving encryption is needed. A pseudo random padding length may be calculated when it is determined that padding is needed. The calculated length of padding may be added to the plaintext when it is determined that padding is needed. The plaintext and added padding may be encrypted using format preserving encryption to create a cipher text.

Abstract: Apparatus and method for rapid interactive viewing of a digital image over a network. A client computer displays a view of an image. The image is originally resident on a server computer. The client computer maintains a cache, initially empty, of image blocks already obtained from the server. When the client computer is asked to render a view of a particular portion of the image at a particular resolution, it first ascertains if any image blocks in the image-block cache intersect the requested view. It then computes the residual area of the view resulting from subtracting out from the view the intersecting portions of cached image blocks, and, if the residual area is positive, downloads from the server computer a set of image blocks comprising the residual portion of the view at the given resolution.

Abstract: Apparatus and method for rapid interactive viewing of a digital image over a network. A client computer displays a view of an image. The image is originally resident on a server computer. The client computer maintains a cache, initially empty, of image blocks already obtained from the server. When the client computer is asked to render a view of a particular portion of the image at a particular resolution, it first ascertains if any image blocks in the image-block cache intersect the requested view. It then computes the residual area of the view resulting from subtracting out from the view the intersecting portions of cached image blocks, and, if the residual area is positive, downloads from the server computer a set of image blocks comprising the residual portion of the view at the given resolution.