CATEGORY

Cryptography 6,603 crates

Data as of 2026-07-25 (crates.io database dump, timestamp 2026-07-25T02:00:36Z). Source: crates.io · db-dump.tar.gz · methodology & corrections.

rust_keylockA password manager with goals to be Secure, Simple to use, Portable and Extensible29,886GPL-3.0 Authentication Cryptography uuid-rsA Simple Universally Unique IDentifier (UUID)29,835MIT Algorithms Cryptography hc_iz_profileA Holochain Integrity-Zome that stores profile information29,772CAL-1.0 Cryptography p384_rsNIST P-384 (secp384r1), with correct arithmetic29,757Apache-2.0 OR MIT Cryptography No standard library sp1-evalA performance evaluation tool for SP1 programs.29,722MIT OR Apache-2.0 Cryptography snarkos-displayA display for a decentralized operating system29,599Apache-2.0 Cryptography Cryptography::Cryptocurrencies pake-kemAn implementation of a password-authenticated key exchange (PAKE) based from a key encapsulation mechanism (KEM).29,485MIT OR Apache-2.0 Cryptography snarkos-cliCommand-line interface for snarkOS29,440Apache-2.0 Cryptography Cryptography::Cryptocurrencies pqcrypto-ntruPost-Quantum Key-Encapsulation Mechanism ntru29,352MIT OR Apache-2.0 Cryptography No standard library tink-hybridHybrid encryption functionality for Rust port of Google's Tink cryptography library29,320Apache-2.0 Cryptography zksync_contractsDefinitions of main ZKsync smart contracts29,236MIT OR Apache-2.0 Cryptography solana-secp256k1Efficient, SVM-friendly implementations of common Secp256k1 functions29,227MIT Cryptography Cryptography::Cryptocurrencies argon2-kdfIntuitive wrapper over the original, battle-tested C reference implementation of argon229,129MIT Cryptography hc_cz_profileA Holochain Coordinator-Zome that stores profile information29,128CAL-1.0 Cryptography oramAn implementation of Oblivious RAM.29,085MIT OR Apache-2.0 Cryptography zksync_mini_merkle_treeZKsync implementation of small Merkle trees29,028MIT OR Apache-2.0 Cryptography ibeIdentity Based Encryption schemes on the BLS12-381 pairing-friendly elliptic curve28,956MIT Cryptography No standard library aead-ioA wrapper around Write/Read interfaces with AEAD28,724MIT OR Apache-2.0 Cryptography No standard library txtx-gqlPrimitives for supervising Txtx runbooks execution28,660Apache-2.0 Cryptography cipher_magmaBlock Cipher Magma (GOST R 34.12-2015, former GOST 28147-89)28,551MIT Cryptography schnorrSchnorr Signatures28,501Apache-2.0 Cryptography No standard library holofuel_typesFuel types used for holofuel a mutual credit currency28,468Apache-2.0 Cryptography hc_iz_membrane_managerA Holochain Integrity-Zome that helps validates the membrane proof passed into a DNA28,156CAL-1.0 Cryptography wasmsign2An implementation of the WebAssembly modules signatures proposal28,151MIT Cryptography WebAssembly zksync_configZKsync core configuration28,062MIT OR Apache-2.0 Cryptography yubibombDon't you love when you accidentally tap your Yubikey when you have your IRC client in focus and you send 987947 into Libera?…28,047GPL-3.0 Authentication Command line utilities karyon_async_rustlsAsync rustls wrapper supporting both smol and tokio runtimes for the Karyon library.28,032GPL-3.0 Asynchronous Cryptography zksync_system_constantsZKsync system constants27,920MIT OR Apache-2.0 Cryptography jwtinfoCommand line tool to get information about JWTs (Json Web Tokens)27,900MIT Command-line interface Command line utilities zksync_typesShared ZKsync types27,836MIT OR Apache-2.0 Cryptography aegis-password-generatorA secure password generation and management library27,799MIT OR Apache-2.0 Command line utilities Cryptography tsp-ltvShared timestamping (RFC 3161) and long-term validation (OCSP, CRL, trust stores) infrastructure for AdES signatures27,794BSD-2-Clause Cryptography wow_srpServer and client library for the World of Warcraft flavor of SRP6 with support for reconnection.27,663MIT OR Apache-2.0 Authentication Cryptography pqc_dilithiumA post-quantum cryptographic signature scheme based on the hardness of lattice problems over module lattices27,525MIT OR Apache-2.0 Cryptography indy-vdrA library for interacting with Hyperledger Indy Node, a distributed ledger for self-sovereign identity…27,404Apache-2.0 Authentication Cryptography abruteAESCrypt Brute force attempter.27,231MIT OR Apache-2.0 Cryptography bitcoinleveldb-compatLevelDB-compatible low-level utilities for Bitcoin: Snappy compression shims, accelerated CRC32C, and ported mutex/condvar…27,057MIT Algorithms Concurrency solana-nostd-secp256k1-recoverA more efficient, no_std implementation of secp256k1 public-key recovery for the Solana SVM27,009MIT Cryptography No standard library gravity_protoProtobuf stuct defintions for interacting with Gravity Bridge Chain27,009Apache-2.0 Cryptography Cryptography::Cryptocurrencies bitcoinleveldb-crc32Low-level, LevelDB-compatible CRC32C (Castagnoli) primitives for Bitcoin-related storage and streaming, including masking,…26,977MIT Algorithms Cryptography krypteringCryptographic operations library with software (RustCrypto) and HSM (PKCS#11) backends26,959BSD-2-Clause Authentication Cryptography snarkos-node-sync-locatorsLocators to synchronize a decentralized operating system26,856Apache-2.0 Cryptography Cryptography::Cryptocurrencies gstpA secure, authenticated, transport-agnostic data exchange protocol with distributed state management via Encrypted State…26,800BSD-2-Clause-Patent Cryptography encrypted_fs[DEPRECATED] An encrypted file system that mounts with FUSE on Linux. It can be used to create encrypted directories.26,737Apache-2.0 Cryptography Filesystem rsacrackerPowerful RSA cracker for CTFs. Supports RSA, X509, OPENSSH, PKCS#12, PKCS#7, and CSR in PEM and DER formats.26,710MIT OR Apache-2.0 Cryptography Mathematics zkstdzero knowledge proof standard library26,600Apache-2.0 Cryptography pkcs11-uriPKCS #11 URI parser26,448Apache-2.0 OR MIT Cryptography Hardware support whirlpool-asmAssembly implementation of Whirlpool compression function26,422MIT Cryptography No standard library bls-12-381Bls12 381 pairing-friendly curve implementation26,196Apache-2.0 Cryptography ctsGeneric implementation of the ciphertext stealing block modes of operation26,144MIT OR Apache-2.0 Cryptography No standard library nuts-backendA secure storage library26,108MIT Cryptography libgcrypt-sysRaw bindings for libgcrypt25,849LGPL-2.1 Cryptography External FFI bindings axon-toolsSome axon related utilities.25,840MIT Cryptography maili-registryRegistry for Optimism25,667MIT Cryptography Cryptography::Cryptocurrencies hashguardCommand-Line tool for ensuring the integrity of files using hash sums25,654MIT Command line utilities Cryptography bitcoinleveldb-bloomLevelDB-compatible Bloom filter policy and test harness for the bitcoin-rs LevelDB port, implementing Kirsch–Mitzenmacher double…25,527MIT Algorithms Cryptography lnpbp_elgamalLNPBP-31: ElGamal symmetric encryptiion library with Secp256k1 curve25,505MIT Cryptography yacmeYet another ACME client.25,379MIT API bindings Cryptography snarkos-node-sync-communication-serviceA communication service for the sync module in a decentralized operating system25,378Apache-2.0 Cryptography Cryptography::Cryptocurrencies tink-gcpkmsAWS-KMS integration for Rust port of Google's Tink cryptography library25,298Apache-2.0 Cryptography maili-genesisGenesis types for optimism25,243MIT Cryptography Cryptography::Cryptocurrencies dock_merlinComposable proof transcripts for public-coin arguments of knowledge25,103MIT Cryptography jksJava KeyStore (JKS) and PKCS12 encoder/decoder for Rust25,062MIT Cryptography rust_ev_crypto_primitivesCrypto Primitives necessary for E-Voting Applications.25,014GPL-3.0+Cryptography Mathematics nuts-memoryA backend implementation for nuts24,946MIT Cryptography miller_rabinA multi-threaded, arbitrary precision implementation of the Miller-Rabin primality test.24,936MIT Cryptography Mathematics exonum-keysExonum node keys management.24,900Apache-2.0 Algorithms Cryptography snarkos-node-bft-eventsEvents for the gateway in a decentralized operating system24,858Apache-2.0 Cryptography Cryptography::Cryptocurrencies dusk-walletA library providing functionalities to create wallets compatible with Dusk Network24,846MPL-2.0 Cryptography Cryptography::Cryptocurrencies sfynxGeneral-purpose onion routing packet construction and processor based on Sphinx.24,800MIT Cryptography rust_keylock_shellShell access to the rust-keylock. rust-keylock is a password manager with goals to be Secure, Simple to use, Portable and…24,785GPL-3.0 Authentication Cryptography sponge-hash-aes256A sponge-based secure hash function that uses AES-256 as its internal PRF24,6400BSD Algorithms Cryptography miden-ace-codegenACE circuit codegen for Plonky3-based Miden AIRs.24,639MIT OR Apache-2.0 Cryptography No standard library ark-cp6-782The CP6-782 pairing-friendly elliptic curve24,607MIT OR Apache-2.0 Cryptography codebreakerDecrypt & encrypt any cheat code for CodeBreaker PS224,584MIT OR Apache-2.0 Algorithms Cryptography drand_coreA drand client library.24,564MIT Cryptography synedrionThreshold signing library based on Canetti-Gennaro-Goldfeder-Makriyannis-Peled '24 scheme24,537AGPL-3.0-or-later Cryptography No standard library tink-awskmsAWS-KMS integration for Rust port of Google's Tink cryptography library24,519Apache-2.0 Cryptography crypt4ghEncryption and decryption implementation of the Crypt4GH encryption format.24,519Apache-2.0 Cryptography Encoding givreTSS Schnorr/EdDSA implementation based on FROST24,340MIT OR Apache-2.0 Algorithms Cryptography snarkos-node-syncA synchronization module for a decentralized operating system24,296Apache-2.0 Cryptography Cryptography::Cryptocurrencies fedimint-tor-dirmgrBootstrap and update an accurate Tor network directory24,235MIT OR Apache-2.0 Cryptography Network programming snarkos-node-bft-ledger-serviceA ledger service for the memory pool in a decentralized operating system24,206Apache-2.0 Cryptography Cryptography::Cryptocurrencies bitcoin-syncLow-level synchronization, semaphore, lock-order debugging, and interruptible thread utilities modelled after Bitcoin Core, built…24,184MIT Algorithms Concurrency ate-authRepresents a standardized data model and API for authenticating an ATE chain-of-trust24,065MIT OR Apache-2.0 Authentication Command line utilities sframepure rust implementation of SFrame (RFC 9605)23,992MIT/Apache-2.0 Cryptography Network programming fedimint-arti-clientLibrary for connecting to the Tor network as an anonymous client23,963MIT OR Apache-2.0 Cryptography Network programming ybaasDon't you love when you accidentally tap your Yubikey when you have your IRC client in focus and you send 987947 into Libera?…23,876GPL-3.0 Authentication Cryptography tmp-ed25519Temp crate do not use! This is a holding crate waiting on a PR to upstream being merged.23,874BSD-3-Clause Cryptography No standard library cognitum-gate-tilezeroNative arbiter for TileZero in the Anytime-Valid Coherence Gate23,833MIT OR Apache-2.0 Authentication Cryptography ferveo-pre-releaseAn implementation of a DKG protocol for threshold decryption.23,816GPL-3.0 Cryptography bulk-gcdFast parallel bulk GCD computation for finding weak RSA keys in a set23,790MIT Cryptography secure-sessionSigned, encrypted session cookies for Iron23,745MIT Authentication Cryptography sp1-coreSP1 is a performant, 100% open-source, contributor-friendly zkVM.23,728MIT OR Apache-2.0 Cryptography acmerACME TLS certificates management library23,712MIT Asynchronous Cryptography lamport_sigsImplementation of the Lamport one-time signature scheme.23,688BSD-3-Clause Algorithms Cryptography legogroth16An implementation of the LegoGroth16, the Legosnark variant of Groth16 zkSNARK proof system23,678MIT/Apache-2.0 Cryptography snarkos-node-router-messagesNode messages for a decentralized operating system23,585Apache-2.0 Cryptography Cryptography::Cryptocurrencies eidolon-authBinary authentication protocol for network connections abstracted from encryption23,562Apache-2.0 Cryptography Network programming xorCLI app that implements basic XOR encryption/decryption23,402MIT Command line utilities Cryptography aptos-sdkA user-friendly, idiomatic Rust SDK for the Aptos blockchain23,237Apache-2.0 API bindings Asynchronous snarkos-node-bftA memory pool for a decentralized operating system23,192Apache-2.0 Cryptography Cryptography::Cryptocurrencies aranya-bearssl-sysBearSSL FFI bindings23,128MIT Cryptography External FFI bindings in-totoLibrary for in-toto23,128MIT Cryptography zksync_vlogZKsync observability stack23,011MIT OR Apache-2.0 Cryptography actix-jwt-auth-middlewareThis crate implements a JSON Webtoken (JWT) middleware for the actix-web framework.22,969MIT Authentication Cryptography ultrasonicTransactional execution layer with capability-based memory access for zk-AluVM22,704Apache-2.0 Algorithms Cryptography neuedu-cryptos包含国密算法的密码库。 A library include SM3, SM4 (Chinese ShangMi) crypto algos.22,689MIT OR Apache-2.0 Cryptography aarch64-ditWrappers for enabling/disabling the Data Independent Timing (DIT) feature on AArch64 CPUs22,677Apache-2.0 OR MIT Cryptography Hardware support saorsa-coreSaorsa - Core P2P networking library with DHT, QUIC transport, and post-quantum cryptography22,589AGPL-3.0 Asynchronous Cryptography fluvio-async-tlsAsynchronous TLS/SSL streams using Rustls.22,534MIT/Apache-2.0 Asynchronous Cryptography fire-cryptoCrypto library providing encryption and signing.22,515MIT OR Apache-2.0 Cryptography zksync_db_connectionZKsync Postgres connection wrappers22,503MIT OR Apache-2.0 Cryptography pqcrypto-falcon-wasiPost-Quantum Signature Scheme falcon22,479MIT OR Apache-2.0 Cryptography No standard library holochain_deterministic_integrityThe HDI22,457Apache-2.0 Cryptography hmac-shaMinimal wrapper of HMAC-SHA-{1,2,3} in Rust.22,425MIT OR Apache-2.0 Cryptography jub-jubtwisted edwards curve implementation22,422Apache-2.0 Cryptography pcbcPropagating Cipher Block Chaining (PCBC) block cipher mode of operation22,399MIT OR Apache-2.0 Cryptography No standard library json-digestAllow selective masking of JSON subdocuments for privacy, preserving the digest of the whole document.22,398LGPL-3.0-or-later Algorithms Cryptography wnfs-wasmWebNative Filesystem API (WebAssembly)22,251Apache-2.0 Cryptography Filesystem merkle_light_derive#[derive(Hashable)] for light merkle tree Hashable22,164BSD-3-Clause Cryptography Data structures sm9_coreSM9, identity-based cryptography22,082MIT OR Apache-2.0 Cryptography No standard library bromberg_sl2Cayley hashing as in 'Navigating in the Cayley Graph of SL₂(𝔽ₚ)'22,065CC0-1.0 Algorithms Cryptography mmr-crypto-primitivesark-crypto-primitives fork: mmr gadget implement22,002MIT/Apache-2.0 Cryptography aes-gcm-streamAES GCM stream encrypt and decrypt library, supports AES128/192/256 bit keys21,894MIT OR Apache-2.0 Cryptography ironshield-typesStandardized Types, Headers, & Methods for IronShield Bindings21,892Apache-2.0 Cryptography WebAssembly libpastaAll-inclusive password hashing library21,880MIT Authentication Cryptography sequoia-octopus-librnpReimplementation of RNP's interface using Sequoia for use with Thunderbird21,876LGPL-2.0-or-later Authentication Cryptography gitoidGit Object Identifiers in Rust21,801Apache-2.0 Cryptography Development tools bitcoin-feesBitcoin Core–compatible fee-rate primitives, estimation modes, horizons, and fee-filter rounding logic for building nodes,…21,682MIT Algorithms Cryptography curve25519-elligator2A pure-Rust implementation of group operations on ristretto255 and Curve2551921,620BSD-3-Clause Cryptography No standard library paper-ageEasy and secure paper backups of secrets21,584MIT Command line utilities Cryptography zksync_object_storeZKsync implementation of object stores21,344MIT OR Apache-2.0 Cryptography ibsIdentity-Based Signature schemes21,295MIT OR Apache-2.0 Cryptography No standard library superchainComponents for the Superchain21,273MIT Cryptography Cryptography::Cryptocurrencies bls-signatures-rsOpen source implementation of Bonneh-Lynn-Shacham (BLS) signatures written in Rust21,224MIT Algorithms Cryptography zksync_dalZKsync data access layer21,211MIT OR Apache-2.0 Cryptography txtx-supervisor-uiCrate for starting the txtx supervisor UI21,159Apache-2.0 Cryptography saorsa-gossip-identityPost-quantum identity management for Saorsa Gossip: ML-DSA-65 keypairs and PeerId derivation21,141MIT OR Apache-2.0 Cryptography hpke-ngClean, fast, RFC 9180 HPKE implementation.21,120Apache-2.0 OR MIT Cryptography No standard library yobicryptoThe Yobicash cryptographyc toolkit21,107MIT/Apache-2.0 Cryptography x402-rsx402 payments in Rust: verify, settle, and monitor payments over HTTP 402 flows21,053Apache-2.0 Cryptography Finance depoServer for secure and anonymous storage and retrieval of binary objects.21,006BSD-2-Clause-Patent Cryptography Database interfaces superchain-registryThe Superchain Registry21,003MIT Cryptography Cryptography::Cryptocurrencies rand-esdmprovides interface to ESDM RNG server20,994MIT Cryptography ensyncA flexible ENcrypted file SYNChroniser suitable for uses where the central location is not fully trusted.20,978GPL-3.0 Command line utilities Cryptography zksync_prover_interfaceInterfaces for interaction with ZKsync prover subsystem20,948MIT OR Apache-2.0 Cryptography zksync_health_checkHealth checks library20,860MIT OR Apache-2.0 Cryptography ed25519-axolotlEd25519-like signatures with X25519 keys, Axolotl-style.20,847Apache-2.0 Algorithms Cryptography rabbitPure Rust implementation of the Rabbit stream cipher20,827MIT OR Apache-2.0 Cryptography No standard library pubkyPubky SDK20,818MIT Authentication Cryptography ark-curve-constraint-testsA library for testing constraints for finite fields, elliptic curves, and pairings20,803MIT OR Apache-2.0 Cryptography zucZUC Stream Cipher Algorithms20,788MIT Cryptography rpm-sequoiaAn implementation of the RPM PGP interface using Sequoia.20,746LGPL-2.0-or-later Authentication Cryptography maili-rpcRPC for Optimism20,652MIT Cryptography Cryptography::Cryptocurrencies pem-iteratorIterate over PEM-encoded data20,601MIT/Apache-2.0 Cryptography Encoding rgb-aluvmFunctional registry-based RISC virtual machine20,488Apache-2.0 Compilers Cryptography depo-apiAPI for the Blockchain Commons Depository ('depo') server.20,429BSD-2-Clause-Patent Cryptography Database interfaces bitcoin-remoteLow-level, Bitcoin Core–compatible JSON-RPC helper crate providing HTTP status mapping, RPC error codes, auth-cookie management,…20,426MIT API bindings Cryptography gpgrvPure-Rust implementation of gpgv, to verify gpg signatures20,353MIT OR Apache-2.0 Authentication Cryptography merkle-liteA simple, fast, and composable binary Merkle tree and proof for Rust Crypto hash functions20,321MIT OR Apache-2.0 Cryptography Data structures ssh-vaultencrypt/decrypt using ssh keys20,123BSD-3-Clause Command line utilities Cryptography solar-cliSolar compiler CLI definitions, utils, and driver20,086MIT OR Apache-2.0 Compilers Cryptography falcon-rustA rust implementation of the Falcon post-quantum digital signature scheme.20,080MIT Cryptography iop-keyvaultA general-purpose hierarchical deterministic generator for asymmetric keys.20,070LGPL-3.0-or-later Cryptography Cryptography::Cryptocurrencies test-curve25519-dalekA pure-Rust implementation of group operations on ristretto255 and Curve2551920,057BSD-3-Clause Cryptography No standard library mgmGeneric implementation of the Multilinear Galois Mode (MGM) cipher20,053Apache-2.0 OR MIT Cryptography No standard library libpaillierThe Paillier cryptosystem is a public key crytosystem based on composite degree residuosity classes. Paillier ciphertexts are…20,022Apache-2.0 Algorithms Cryptography rings-coreChord DHT implementation with ICE20,012GPL-3.0 Cryptography Network programming fluxencryptA high-performance, secure encryption SDK for Rust applications19,917MIT Command line utilities Cryptography lsmtreeImplements a Sparse Merkle tree for a key-value store. The tree implements the same optimisations specified in the libra…19,906MIT/Apache-2.0 Cryptography Data structures leaLightweight Encryption Algorithm (LEA)19,900MIT Cryptography No standard library libpepLibrary for polymorphic encryption and pseudonymization19,863Apache-2.0 Algorithms Cryptography libthemis-sysFFI binding to libthemis19,830Apache-2.0 Cryptography External FFI bindings viadkimImplementation of the DomainKeys Identified Mail (DKIM) specification19,804GPL-3.0-or-later Cryptography Email vme-pkixTLS Certificate encoding and decoding helpers for the Fortanix VME environment.19,714MPL-2.0 Cryptography vitaminc-protectedProtected type wrappers for handling sensitive data. Part of the VitaminC cryptographic suite.19,708MIT Cryptography pubky-commonTypes and struct in common between Pubky client and homeserver19,694MIT Authentication Cryptography citadel_logginglogging library for the Citadel Protocol19,646MIT OR Apache-2.0 Asynchronous Cryptography themisHigh-level cryptographic services for storage and messaging19,600Apache-2.0 API bindings Cryptography cellar-coreA password tool for user to derive a large amount of application passwords deterministically based on a passphrase.…19,572MIT Cryptography ts_keystailscale cryptographic key types19,564BSD-3-Clause Cryptography crabappleA library for iOS backup decryption and encryption19,505GPL-3.0-or-later Cryptography Database interfaces rigelMinimal HMAC-SHA512 implementation optimized for embedded devices19,478MIT Cryptography No standard library ncryptf-rsSecure API authentication and end to end encryption.19,471BSD-3-Clause API bindings Authentication Mademoiselle_EntropiaExtremely strong, stupidly simple and relatively fast symmetric cipher.. check out the Readne for explanation. Have a great day,…19,466non-standard Command line utilities Cryptography tweetnacl-systweetnacl & FFI bindings to it19,450MIT OR Apache-2.0 Cryptography External FFI bindings p2panda-rsAll the things a panda needs19,435AGPL-3.0-or-later Cryptography WebAssembly keccak-pHigh-performance implementation of the Keccak-p permutation.19,358MIT OR Apache-2.0 Cryptography No standard library aes-ccmA pure-Rust, #![no_std], zero-allocation AES-CCM implementation ported from TinyCrypt using RustCrypto's AES.19,344MIT OR Apache-2.0 Cryptography Embedded development micro-ecc-sysLow-level bindings to micro-ecc19,336BSD-2-Clause Cryptography Embedded development groestl-aesniHardware-accelerated Groestl hash for x86-64 systems with AES extensions19,332MIT/Apache-2.0 Cryptography No standard library zksync_vm_interfaceZKsync Era VM interfaces19,332MIT OR Apache-2.0 Cryptography cognito_srpAWS cognito Secure Remote Password (SRP) client implementation19,316MIT Authentication Cryptography ts_tls_utiltailscale-specific tls utilities19,295BSD-3-Clause Asynchronous Cryptography paillierA pure-Rust implementation of the Paillier encryption scheme19,288MIT/Apache-2.0 Cryptography bp384Brainpool P-384 (brainpoolP384r1 and brainpoolP384t1) elliptic curves19,279Apache-2.0 OR MIT Cryptography No standard library kupynaKupyna (DSTU 7564:2014) hash function19,221MIT OR Apache-2.0 Cryptography No standard library saorsa-fecQuantum-safe erasure coding with post-quantum cryptography using saorsa-pqc19,189AGPL-3.0 Cryptography Encoding zksync_l1_contract_interfaceInterfaces for interacting with ZKsync contracts19,175MIT OR Apache-2.0 Cryptography