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The Bouncy Castle Java API for handling the OpenPGP protocol. This jar contains the OpenPGP API for JDK 1.5 to JDK 1.8. The APIs can be used in conjunction with a JCE/JCA provider such as the one provided with the Bouncy Castle Cryptography APIs.

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package org.bouncycastle.bcpg;

import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.SecureRandom;

import org.bouncycastle.crypto.CryptoServicesRegistrar;


/**
 * Parameter specifier for the PGP string-to-key password based key derivation function.
 * 

* In iterated mode, S2K takes a single byte iteration count specifier, which is converted to an * actual iteration count using a formula that grows the iteration count exponentially as the byte * value increases. *

* e.g. 0x01 == 1088 iterations, and 0xFF == 65,011,712 iterations. *

*/ public class S2K extends BCPGObject { private static final int EXPBIAS = 6; /** * Simple key generation. A single non-salted iteration of a hash function. * This method is deprecated to use, since it can be brute-forced when used * with a low-entropy string, such as those typically provided by users. * Additionally, the usage of Simple S2K can lead to key and IV reuse. * Therefore, in OpenPGP v6, Therefore, when generating an S2K specifier, * an implementation MUST NOT use Simple S2K. * * @deprecated use {@link #SALTED_AND_ITERATED} or {@link #ARGON_2} instead. */ public static final int SIMPLE = 0; /** * Salted key generation. A single iteration of a hash function with a (unique) salt. * This method is deprecated to use, since it can be brute-forced when used * with a low-entropy string, such as those typically provided by users. * Therefore, in OpenPGP v6, an implementation SHOULD NOT generate a Salted S2K, * unless the implementation knows that the input string is high-entropy. * * @deprecated use {@link #SALTED_AND_ITERATED} or {@link #ARGON_2} instead. */ public static final int SALTED = 1; /** * Salted and iterated key generation. Multiple iterations of a hash function, with a salt. * This method MAY be used if {@link #ARGON_2} is not available. */ public static final int SALTED_AND_ITERATED = 3; /** * Memory-hard, salted key generation using Argon2 hash algorithm. */ public static final int ARGON_2 = 4; public static final int GNU_DUMMY_S2K = 101; public static final int GNU_PROTECTION_MODE_NO_PRIVATE_KEY = 1; public static final int GNU_PROTECTION_MODE_DIVERT_TO_CARD = 2; int type; int algorithm; byte[] iv; int itCount = -1; int passes = -1; int protectionMode = -1; int parallelism; int memorySizeExponent; S2K( InputStream in) throws IOException { DataInputStream dIn = new DataInputStream(in); type = dIn.read(); switch (type) { case SIMPLE: algorithm = dIn.read(); break; case SALTED: algorithm = dIn.read(); iv = new byte[8]; dIn.readFully(iv, 0, iv.length); break; case SALTED_AND_ITERATED: algorithm = dIn.read(); iv = new byte[8]; dIn.readFully(iv, 0, iv.length); itCount = dIn.read(); break; case ARGON_2: iv = new byte[16]; dIn.readFully(iv); passes = dIn.read(); parallelism = dIn.read(); memorySizeExponent = dIn.read(); break; case GNU_DUMMY_S2K: algorithm = dIn.read(); dIn.read(); // G dIn.read(); // N dIn.read(); // U protectionMode = dIn.read(); // protection mode break; default: throw new UnsupportedPacketVersionException("Invalid S2K type: " + type); } } /** * Constructs a specifier for a {@link #SIMPLE simple} S2K generation. * * @param algorithm the {@link HashAlgorithmTags digest algorithm} to use. */ public S2K( int algorithm) { this.type = 0; this.algorithm = algorithm; } /** * Constructs a specifier for a {@link #SALTED salted} S2K generation. * * @param algorithm the {@link HashAlgorithmTags digest algorithm} to use. * @param iv the salt to apply to input to the key generation. */ public S2K( int algorithm, byte[] iv) { this.type = 1; this.algorithm = algorithm; this.iv = iv; } /** * Constructs a specifier for a {@link #SALTED_AND_ITERATED salted and iterated} S2K generation. * * @param algorithm the {@link HashAlgorithmTags digest algorithm} to iterate. * @param iv the salt to apply to input to the key generation. * @param itCount the single byte iteration count specifier. */ public S2K( int algorithm, byte[] iv, int itCount) { this.type = 3; this.algorithm = algorithm; this.iv = iv; if (itCount >= 256 && itCount <= 65536) { throw new IllegalArgumentException("invalid itCount"); } this.itCount = itCount; } /** * Constructs a specifier for an {@link #ARGON_2 S2K method using Argon2}. * * @param argon2Params argon2 parameters */ public S2K(Argon2Params argon2Params) { this.type = ARGON_2; this.iv = argon2Params.getSalt(); this.passes = argon2Params.getPasses(); this.parallelism = argon2Params.getParallelism(); this.memorySizeExponent = argon2Params.getMemSizeExp(); } /** * Construct a specifier for an S2K using the {@link #GNU_DUMMY_S2K} method. * * @param gnuDummyParams GNU_DUMMY_S2K parameters */ public S2K(GNUDummyParams gnuDummyParams) { this.type = GNU_DUMMY_S2K; this.protectionMode = gnuDummyParams.getProtectionMode(); } /** * Return a new S2K instance using the {@link #SIMPLE} method, using the given hash
algorithm
. * * @param algorithm hash algorithm tag * @return S2K */ public static S2K simpleS2K(int algorithm) { return new S2K(algorithm); } /** * Return a new S2K instance using the {@link #SALTED} method, using the given hash
algorithm
* and
salt
. * * @param algorithm hash algorithm tag * @param salt salt * @return S2K */ public static S2K saltedS2K(int algorithm, byte[] salt) { return new S2K(algorithm, salt); } /** * Return a new S2K instance using the {@link #SALTED_AND_ITERATED} method, using the given hash
algorithm
, *
salt
and
iterationCount
. * * @param algorithm hash algorithm tag * @param salt salt * @param iterationCount number of iterations * @return S2K */ public static S2K saltedAndIteratedS2K(int algorithm, byte[] salt, int iterationCount) { return new S2K(algorithm, salt, iterationCount); } /** * Return a new S2K instance using the {@link #ARGON_2} method, using the given argon2
parameters
. * * @param parameters argon2 parameters * @return S2K */ public static S2K argon2S2K(Argon2Params parameters) { return new S2K(parameters); } /** * Return a new S2K instance using the {@link #GNU_DUMMY_S2K} method, using the given GNU Dummy S2K
parameters
. * * @param parameters GNU Dummy S2K parameters * @return S2K */ public static S2K gnuDummyS2K(GNUDummyParams parameters) { return new S2K(parameters); } /** * Gets the {@link HashAlgorithmTags digest algorithm} specified. */ public int getType() { return type; } /** * Gets the {@link HashAlgorithmTags hash algorithm} for this S2K. */ public int getHashAlgorithm() { return algorithm; } /** * Gets the iv/salt to use for the key generation. */ public byte[] getIV() { return iv; } /** * Gets the actual (expanded) iteration count. */ public long getIterationCount() { if (itCount >= 256) { return itCount; } return (16 + (itCount & 15)) << ((itCount >> 4) + EXPBIAS); } /** * Return the number of passes - only Argon2 * * @return number of passes */ public int getPasses() { return passes; } /** * Gets the protection mode - only if GNU_DUMMY_S2K */ public int getProtectionMode() { return protectionMode; } /** * Gets the degree of parallelism - only if ARGON_2 * * @return parallelism */ public int getParallelism() { return parallelism; } /** * Gets the memory size exponent - only if ARGON_2 * * @return memory size exponent */ public int getMemorySizeExponent() { return memorySizeExponent; } public void encode( BCPGOutputStream out) throws IOException { switch (type) { case SIMPLE: out.write(type); out.write(algorithm); break; case SALTED: out.write(type); out.write(algorithm); out.write(iv); break; case SALTED_AND_ITERATED: out.write(type); out.write(algorithm); out.write(iv); writeOneOctetOrThrow(out, itCount, "Iteration count"); break; case ARGON_2: out.write(type); out.write(iv); writeOneOctetOrThrow(out, passes, "Passes"); writeOneOctetOrThrow(out, parallelism, "Parallelism"); writeOneOctetOrThrow(out, memorySizeExponent, "Memory size exponent"); break; case GNU_DUMMY_S2K: out.write(type); out.write(algorithm); out.write('G'); out.write('N'); out.write('U'); out.write(protectionMode); break; default: throw new IllegalStateException("Unknown S2K type " + type); } } /** * Throw an {@link IllegalArgumentException} if the value cannot be encoded, * otherwise write the value to the output stream. * * @param out output stream * @param val value * @param valName name of the value for the error message * @throws IllegalArgumentException if the value cannot be encoded * @throws IOException potentially thrown by {@link BCPGOutputStream#write(int)} */ private void writeOneOctetOrThrow(BCPGOutputStream out, int val, String valName) throws IOException { if (val >= 256) { throw new IllegalStateException(valName + " not encodable"); } out.write(val); } /** * Parameters for Argon2 S2K. */ public static class Argon2Params { private final byte[] salt; private final int passes; private final int parallelism; private final int memSizeExp; /** * Uniformly safe and recommended parameters not tailored to any hardware. * Uses Argon2id, 1 pass, 4 parallelism, 2 GiB RAM. * * @see RFC 9106: §4. Parameter Choice */ public Argon2Params() { this(CryptoServicesRegistrar.getSecureRandom()); } /** * Uniformly safe and recommended parameters not tailored to any hardware. * Uses Argon2id, 1 pass, 4 parallelism, 2 GiB RAM. * * @see RFC 9106: §4. Parameter Choice */ public Argon2Params(SecureRandom secureRandom) { this(1, 4, 21, secureRandom); } /** * Create customized Argon2 S2K parameters. * * @param passes number of iterations, must be greater than 0 * @param parallelism number of lanes, must be greater 0 * @param memSizeExp exponent for memory consumption, must be between 3+ceil(log_2(p)) and 31 * @param secureRandom secure random generator to initialize the salt vector */ public Argon2Params(int passes, int parallelism, int memSizeExp, SecureRandom secureRandom) { this(mineSalt(secureRandom), passes, parallelism, memSizeExp); } /** * Create customized Argon2 S2K parameters. * * @param salt 16 bytes of random salt * @param passes number of iterations, must be greater than 0 * @param parallelism number of lanes, must be greater 0 * @param memSizeExp exponent for memory consumption, must be between 3+ceil(log_2(p)) and 31 */ public Argon2Params(byte[] salt, int passes, int parallelism, int memSizeExp) { if (salt.length != 16) { throw new IllegalArgumentException("Argon2 uses 16 bytes of salt"); } this.salt = salt; if (passes < 1) { throw new IllegalArgumentException("Number of passes MUST be positive, non-zero"); } this.passes = passes; if (parallelism < 1) { throw new IllegalArgumentException("Parallelism MUST be positive, non-zero."); } this.parallelism = parallelism; // log_2(p) = log_e(p) / log_e(2) double log2_p = Math.log(parallelism) / Math.log(2); // see https://www.ietf.org/archive/id/draft-ietf-openpgp-crypto-refresh-05.html#section-3.7.1.4-5 if (memSizeExp < (3 + Math.ceil(log2_p)) || memSizeExp > 31) { throw new IllegalArgumentException("Memory size exponent MUST be between 3+ceil(log_2(parallelism)) and 31"); } this.memSizeExp = memSizeExp; } /** * Uniformly safe and recommended parameters not tailored to any hardware. * Uses Argon2id, 1 pass, 4 parallelism, 2 GiB RAM. * * @see RFC 9106: §4. Parameter Choice */ public static Argon2Params universallyRecommendedParameters() { return new Argon2Params(1, 4, 21, new SecureRandom()); } /** * Recommended parameters for memory constrained environments (64MiB RAM). * Uses Argon2id with 3 passes, 4 lanes and 64 MiB RAM. * * @return safe parameters for memory constrained environments * @see RFC9106: §4. Parameter Choice */ public static Argon2Params memoryConstrainedParameters() { return new Argon2Params(3, 4, 16, new SecureRandom()); } /** * Generate 16 bytes of random salt. * * @param secureRandom random number generator instance * @return salt */ private static byte[] mineSalt(SecureRandom secureRandom) { byte[] salt = new byte[16]; secureRandom.nextBytes(salt); return salt; } /** * Return a 16-byte byte array containing the salt
S
. * * @return salt */ public byte[] getSalt() { return salt; } /** * Return the number of passes
t
. * * @return number of passes */ public int getPasses() { return passes; } /** * Return the factor of parallelism
p
. * * @return parallelism */ public int getParallelism() { return parallelism; } /** * Return the exponent indicating the memory size
m
. * * @return memory size exponent */ public int getMemSizeExp() { return memSizeExp; } } /** * Parameters for the {@link #GNU_DUMMY_S2K} method. */ public static class GNUDummyParams { private final int protectionMode; private GNUDummyParams(int protectionMode) { this.protectionMode = protectionMode; } /** * Factory method for a GNU Dummy S2K indicating a missing private key. * * @return params */ public static GNUDummyParams noPrivateKey() { return new GNUDummyParams(GNU_PROTECTION_MODE_NO_PRIVATE_KEY); } /** * Factory method for a GNU Dummy S2K indicating a private key located on a smart card. * * @return params */ public static GNUDummyParams divertToCard() { return new GNUDummyParams(GNU_PROTECTION_MODE_DIVERT_TO_CARD); } /** * Return the GNU Dummy S2K protection method. * * @return protection method */ public int getProtectionMode() { return protectionMode; } } }




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