The security of cryptographic systems depends on some secret data that is known to authorized persons but unknown and unpredictable to others. To achieve this unpredictability, some randomization is typically employed. Modern cryptographic protocols often require frequent generation of random quantities. Cryptographic attacks that subvert or exploit weaknesses in this process are known as random number generator attacks.
PATCHED BITCOIN GENERATOR V 4.5
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A number of attacks on hardware random number generators are possible, including trying to capture radio-frequency emissions from the computer (obtaining hard drive interrupt times from motor noise, for example), or trying to feed controlled signals into a supposedly random source (such as turning off the lights in a lava lamp or feeding a strong, known signal into a sound card).
Subverted random numbers can be created using a cryptographically secure pseudorandom number generator with a seed value known to the attacker but concealed in the software. A relatively short, say 24 to 40 bit, portion of the seed can be truly random to prevent tell-tale repetitions, but not long enough to prevent the attacker from recovering, say, a "randomly" produced key.
A hardware circuit to produce subverted bits can be built on an integrated circuit a few millimeters square. The most sophisticated hardware random number generator can be subverted by placing such a chip anywhere upstream of where the source of randomness is digitized, say in an output driver chip or even in the cable connecting the RNG to the computer. The subversion chip can include a clock to limit the start of operation to some time after the unit is first turned on and run through acceptance tests, or it can contain a radio receiver for on/off control. It could be installed by the manufacturer at the behest of their national signals intelligence service, or added later by anyone with physical access. CPU chips with built-in hardware random number generators can be replaced by compatible chips with a subverted RNG in the chips' firmware.
The U.S. National Institute of Standards and Technology has published a collection of "deterministic random bit generators" it recommends as NIST Special Publication 800-90.[7] One of the generators, Dual_EC_DRBG, was favored by the National Security Agency.[8] Dual_EC_DRBG uses elliptic curve technology and includes a set of recommended constants. In August 2007, Dan Shumow and Niels Ferguson of Microsoft showed that the constants could be constructed in such a way as to create a kleptographic backdoor in the algorithm.[9] In September 2013 The New York Times wrote that "the N.S.A. had inserted a back door into a 2006 standard adopted by N.I.S.T... called the Dual EC DRBG standard",[10] thereby revealing that the NSA carried out a malware attack against the American people.In December 2013, Reuters reported that documents released by Edward Snowden indicated that the NSA had paid RSA Security $10 million to make Dual_EC_DRBG the default in their encryption software, and raised further concerns that the algorithm might contain a backdoor for the NSA.[11] Due to these concerns, in 2014, NIST withdrew Dual EC DRBG from its draft guidance on random number generators, recommending "current users of Dual_EC_DRBG transition to one of the three remaining approved algorithms as quickly as possible."[12]
Crypto-1 is a cryptosystem developed by NXP for use on MIFARE chips. The system is proprietary and originally the algorithm has not been published. Upon reverse engineering of the chip, researchers from the University of Virginia and the Chaos Computer Club found an attack on Crypto-1 exploiting a poorly initialized random number generator.[13]
In May 2008, security researcher Luciano Bello revealed his discovery that changes made in 2006 to the random number generator in the version of the OpenSSL package distributed with Debian Linux and other Debian-based distributions, such as Ubuntu, dramatically reduced the entropy of generated values and made a variety of security keys vulnerable to attack.[14][15] The security weakness was caused by changes made to the openssl code by a Debian developer in response to compiler warnings of apparently redundant code.[16] This caused a massive worldwide regeneration of keys, and despite all attention the issue got, it could be assumed many of these old keys are still in use. Key types affected include SSH keys, OpenVPN keys, DNSSEC keys, key material for use in X.509 certificates and session keys used in SSL/TLS connections. Keys generated with GnuPG or GNUTLS are not affected as these programs used different methods to generate random numbers. Keys generated by non-Debian-based Linux distributions are also unaffected. The weak-key-generation vulnerability was promptly patched after it was reported, but any services still using keys that were generated by the old code remain vulnerable. A number of software packages now contain checks against a weak key blacklist to attempt to prevent use of any of these remaining weak keys, but researchers continue to find weak key implementations.[17]
Current feature list: Generation and parsing of PKCS-12 files.
X.509: Generators and parsers for V1 and V3 certificates, V2 CRLs and attribute certificates.
PBE algorithms supported by PbeUtilities: PBEwithMD2andDES-CBC, PBEwithMD2andRC2-CBC, PBEwithMD5andDES-CBC, PBEwithMD5andRC2-CBC, PBEwithSHA1andDES-CBC, PBEwithSHA1andRC2-CBC, PBEwithSHA-1and128bitRC4, PBEwithSHA-1and40bitRC4, PBEwithSHA-1and3-keyDESEDE-CBC, PBEwithSHA-1and2-keyDESEDE-CBC, PBEwithSHA-1and128bitRC2-CBC, PBEwithSHA-1and40bitRC2-CBC, PBEwithHmacSHA-1, PBEwithHmacSHA-224, PBEwithHmacSHA-256, PBEwithHmacRIPEMD128, PBEwithHmacRIPEMD160, and PBEwithHmacRIPEMD256.
Signature algorithms supported by SignerUtilities: MD2withRSA, MD4withRSA, MD5withRSA, RIPEMD128withRSA, RIPEMD160withECDSA, RIPEMD160withRSA, RIPEMD256withRSA, SHA-1withRSA, SHA-224withRSA, SHA-256withRSAandMGF1, SHA-384withRSAandMGF1, SHA-512withRSAandMGF1, SHA-1withDSA, and SHA-1withECDSA.
Symmetric key algorithms: AES, Blowfish, Camellia, CAST5, CAST6, ChaCha, DES, DESede, GOST28147, HC-128, HC-256, IDEA, ISAAC, Noekeon, RC2, RC4, RC5-32, RC5-64, RC6, Rijndael, Salsa20, SEED, Serpent, Skipjack, TEA/XTEA, Threefish, Tnepres, Twofish, VMPC and XSalsa20.
Symmetric key modes: CBC, CFB, CTS, GOFB, OFB, OpenPGPCFB, and SIC (or CTR).
Symmetric key paddings: ISO10126d2, ISO7816d4, PKCS-5/7, TBC, X.923, and Zero Byte.
Asymmetric key algorithms: ElGamal, DSA, ECDSA, NaccacheStern and RSA (with blinding).
Asymmetric key paddings/encodings: ISO9796d1, OAEP, and PKCS-1.
AEAD block cipher modes: CCM, EAX, GCM and OCB.
Digests: GOST3411, Keccak, MD2, MD4, MD5, RIPEMD128, RIPEMD160, RIPEMD256, RIPEMD320, SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, SHA3, Tiger, and Whirlpool.
XOFs: SHAKE.
Signer mechanisms: DSA, ECDSA, ECGOST3410, ECNR, GOST3410, ISO9796d2, PSS, RSA, X9.31-1998.
Key Agreement: Diffie-Hellman, EC-DH, EC-MQV, J-PAKE, SRP-6a.
Macs: CBCBlockCipher, CFBBlockCipher, CMAC, GMAC, GOST28147, HMac, ISO9797 Alg. 3, Poly1305, SipHash, SkeinMac, VMPCMAC.
PBE generators: PKCS-12, and PKCS-5 - schemes 1 and 2.
OpenPGP (RFC 4880)
Cryptographic Message Syntax (CMS, RFC 3852), including streaming API.
Online Certificate Status Protocol (OCSP, RFC 2560).
Time Stamp Protocol (TSP, RFC 3161).
TLS/DTLS client/server up to version 1.2, with support for the most common ciphersuites and extensions, and many less common ones. Non-blocking API available.
Elliptic Curve Cryptography: support for generic F2m and Fp curves, high-performance custom implementations for many standardized curves.
Reading/writing of PEM files, including RSA and DSA keys, with a variety of encryptions.
PKIX certificate path validation
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The authors in [27,28] propose a blockchain-based IoT patch distribution to improve accountability and availability. However, in the absence of incentives, the network did not scale beyond the nodes controlled by the manufacturers. Lee et al. [29] propose a cryptocurrency incentive mechanism for encouraging a network of distributor networks to deliver patches to destination IoT devices. Leiba et al. [30] propose a similar approach to [29], but with an efficient distribution mechanism. Both proposals enable a fair exchange of authenticated software updates and cryptocurrency payments. However, an on-chain payment solution suffers from several problems. (i) Costs: Each transaction on blockchain costs transaction fees in addition to incentives being transferred. For example, the Bitcoin transaction fee is reaching around 60 cents. -transactionfees.html. IoTPatchPool [30] analyzed per-device fees to be around 10 cents. (ii) Latency: The delay caused due to the required number of block confirmation prevents the solution from scaling. For example, an average block creation time in Bitcoin is ten minutes, and it needs at least six blocks to confirm a transaction. Thus, a single update may take around one hour. (iii) Throughput: Due to the latency delay, the device update is limited by an upper bound within a given time frame. (iv) Privacy: Being a public ledger that can be audited by anyone, blockchain lacks privacy. An attacker can learn critical information like the number of devices handled by the vendor, how many devices got patched, the cost of patching the devices, etc.
Often a pseudo-random number generator (PRNG) is not designed for cryptography. Sometimes a mediocre source of randomness is sufficient or preferable for algorithms that use random numbers. Weak generators generally take less processing power and/or do not use the precious, finite, entropy sources on a system. While such PRNGs might have very useful features, these same features could be used to break the cryptography. 2ff7e9595c
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