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-rw-r--r--libraries/spongycastle/core/src/main/java/org/spongycastle/pqc/crypto/ntru/IndexGenerator.java239
1 files changed, 0 insertions, 239 deletions
diff --git a/libraries/spongycastle/core/src/main/java/org/spongycastle/pqc/crypto/ntru/IndexGenerator.java b/libraries/spongycastle/core/src/main/java/org/spongycastle/pqc/crypto/ntru/IndexGenerator.java
deleted file mode 100644
index 01caf9700..000000000
--- a/libraries/spongycastle/core/src/main/java/org/spongycastle/pqc/crypto/ntru/IndexGenerator.java
+++ /dev/null
@@ -1,239 +0,0 @@
-package org.spongycastle.pqc.crypto.ntru;
-
-import org.spongycastle.crypto.Digest;
-import org.spongycastle.util.Arrays;
-
-/**
- * An implementation of the Index Generation Function in IEEE P1363.1.
- */
-public class IndexGenerator
-{
- private byte[] seed;
- private int N;
- private int c;
- private int minCallsR;
- private int totLen;
- private int remLen;
- private BitString buf;
- private int counter;
- private boolean initialized;
- private Digest hashAlg;
- private int hLen;
-
- /**
- * Constructs a new index generator.
- *
- * @param seed a seed of arbitrary length to initialize the index generator with
- * @param params NtruEncrypt parameters
- */
- IndexGenerator(byte[] seed, NTRUEncryptionParameters params)
- {
- this.seed = seed;
- N = params.N;
- c = params.c;
- minCallsR = params.minCallsR;
-
- totLen = 0;
- remLen = 0;
- counter = 0;
- hashAlg = params.hashAlg;
-
- hLen = hashAlg.getDigestSize(); // hash length
- initialized = false;
- }
-
- /**
- * Returns a number <code>i</code> such that <code>0 &lt;= i &lt; N</code>.
- *
- * @return
- */
- int nextIndex()
- {
- if (!initialized)
- {
- buf = new BitString();
- byte[] hash = new byte[hashAlg.getDigestSize()];
- while (counter < minCallsR)
- {
- appendHash(buf, hash);
- counter++;
- }
- totLen = minCallsR * 8 * hLen;
- remLen = totLen;
- initialized = true;
- }
-
- while (true)
- {
- totLen += c;
- BitString M = buf.getTrailing(remLen);
- if (remLen < c)
- {
- int tmpLen = c - remLen;
- int cThreshold = counter + (tmpLen + hLen - 1) / hLen;
- byte[] hash = new byte[hashAlg.getDigestSize()];
- while (counter < cThreshold)
- {
- appendHash(M, hash);
- counter++;
- if (tmpLen > 8 * hLen)
- {
- tmpLen -= 8 * hLen;
- }
- }
- remLen = 8 * hLen - tmpLen;
- buf = new BitString();
- buf.appendBits(hash);
- }
- else
- {
- remLen -= c;
- }
-
- int i = M.getLeadingAsInt(c); // assume c<32
- if (i < (1 << c) - ((1 << c) % N))
- {
- return i % N;
- }
- }
- }
-
- private void appendHash(BitString m, byte[] hash)
- {
- hashAlg.update(seed, 0, seed.length);
-
- putInt(hashAlg, counter);
-
- hashAlg.doFinal(hash, 0);
-
- m.appendBits(hash);
- }
-
- private void putInt(Digest hashAlg, int counter)
- {
- hashAlg.update((byte)(counter >> 24));
- hashAlg.update((byte)(counter >> 16));
- hashAlg.update((byte)(counter >> 8));
- hashAlg.update((byte)counter);
- }
-
- /**
- * Represents a string of bits and supports appending, reading the head, and reading the tail.
- */
- public static class BitString
- {
- byte[] bytes = new byte[4];
- int numBytes; // includes the last byte even if only some of its bits are used
- int lastByteBits; // lastByteBits <= 8
-
- /**
- * Appends all bits in a byte array to the end of the bit string.
- *
- * @param bytes a byte array
- */
- void appendBits(byte[] bytes)
- {
- for (int i = 0; i != bytes.length; i++)
- {
- appendBits(bytes[i]);
- }
- }
-
- /**
- * Appends all bits in a byte to the end of the bit string.
- *
- * @param b a byte
- */
- public void appendBits(byte b)
- {
- if (numBytes == bytes.length)
- {
- bytes = copyOf(bytes, 2 * bytes.length);
- }
-
- if (numBytes == 0)
- {
- numBytes = 1;
- bytes[0] = b;
- lastByteBits = 8;
- }
- else if (lastByteBits == 8)
- {
- bytes[numBytes++] = b;
- }
- else
- {
- int s = 8 - lastByteBits;
- bytes[numBytes - 1] |= (b & 0xFF) << lastByteBits;
- bytes[numBytes++] = (byte)((b & 0xFF) >> s);
- }
- }
-
- /**
- * Returns the last <code>numBits</code> bits from the end of the bit string.
- *
- * @param numBits number of bits
- * @return a new <code>BitString</code> of length <code>numBits</code>
- */
- public BitString getTrailing(int numBits)
- {
- BitString newStr = new BitString();
- newStr.numBytes = (numBits + 7) / 8;
- newStr.bytes = new byte[newStr.numBytes];
- for (int i = 0; i < newStr.numBytes; i++)
- {
- newStr.bytes[i] = bytes[i];
- }
-
- newStr.lastByteBits = numBits % 8;
- if (newStr.lastByteBits == 0)
- {
- newStr.lastByteBits = 8;
- }
- else
- {
- int s = 32 - newStr.lastByteBits;
- newStr.bytes[newStr.numBytes - 1] = (byte)(newStr.bytes[newStr.numBytes - 1] << s >>> s);
- }
-
- return newStr;
- }
-
- /**
- * Returns up to 32 bits from the beginning of the bit string.
- *
- * @param numBits number of bits
- * @return an <code>int</code> whose lower <code>numBits</code> bits are the beginning of the bit string
- */
- public int getLeadingAsInt(int numBits)
- {
- int startBit = (numBytes - 1) * 8 + lastByteBits - numBits;
- int startByte = startBit / 8;
-
- int startBitInStartByte = startBit % 8;
- int sum = (bytes[startByte] & 0xFF) >>> startBitInStartByte;
- int shift = 8 - startBitInStartByte;
- for (int i = startByte + 1; i < numBytes; i++)
- {
- sum |= (bytes[i] & 0xFF) << shift;
- shift += 8;
- }
-
- return sum;
- }
-
- public byte[] getBytes()
- {
- return Arrays.clone(bytes);
- }
- }
-
- private static byte[] copyOf(byte[] src, int len)
- {
- byte[] tmp = new byte[len];
-
- System.arraycopy(src, 0, tmp, 0, len < src.length ? len : src.length);
-
- return tmp;
- }
-} \ No newline at end of file
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-02 12:32:09 +0000