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Diffstat (limited to 'crypto/src/pqc/math/linearalgebra/LittleEndianConversions.cs')
| -rw-r--r-- | crypto/src/pqc/math/linearalgebra/LittleEndianConversions.cs | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/crypto/src/pqc/math/linearalgebra/LittleEndianConversions.cs b/crypto/src/pqc/math/linearalgebra/LittleEndianConversions.cs new file mode 100644 index 000000000..5b3215070 --- /dev/null +++ b/crypto/src/pqc/math/linearalgebra/LittleEndianConversions.cs @@ -0,0 +1,195 @@ + +using Org.BouncyCastle.Crypto.Utilities; + +namespace Org.BouncyCastle.Pqc.Math.LinearAlgebra +{ + /** + * This is a utility class containing data type conversions using little-endian + * byte order. + * + */ + class LittleEndianConversions + { + /** + * Default constructor (private). + */ + private LittleEndianConversions() + { + // empty + } + + /** + * Convert an octet string of length 4 to an integer. No length checking is + * performed. + * + * @param input the byte array holding the octet string + * @return an integer representing the octet string <tt>input</tt> + * @throws ArithmeticException if the length of the given octet string is larger than 4. + */ + public static int OS2IP(byte[] input) + { + return (int)Pack.LE_To_UInt32(input); + } + + /** + * Convert an byte array of length 4 beginning at <tt>offset</tt> into an + * integer. + * + * @param input the byte array + * @param inOff the offset into the byte array + * @return the resulting integer + */ + public static int OS2IP(byte[] input, int inOff) + { + return (int)Pack.LE_To_UInt32(input, inOff); + } + + /** + * Convert a byte array of the given length beginning at <tt>offset</tt> + * into an integer. + * + * @param input the byte array + * @param inOff the offset into the byte array + * @param inLen the length of the encoding + * @return the resulting integer + */ + public static int OS2IP(byte[] input, int inOff, int inLen) + { + int result = 0; + for (int i = inLen - 1; i >= 0; i--) + { + result |= (input[inOff + i] & 0xff) << (8 * i); + } + return result; + } + + /** + * Convert a byte array of length 8 beginning at <tt>inOff</tt> into a + * long integer. + * + * @param input the byte array + * @param inOff the offset into the byte array + * @return the resulting long integer + */ + public static long OS2LIP(byte[] input, int inOff) + { + return (long)Pack.LE_To_UInt64(input, inOff); + } + + /** + * Convert an integer to an octet string of length 4. + * + * @param x the integer to convert + * @return the converted integer + */ + public static byte[] I2OSP(int x) + { + return Pack.UInt32_To_LE((uint)x); + } + + /** + * Convert an integer into a byte array beginning at the specified offset. + * + * @param value the integer to convert + * @param output the byte array to hold the result + * @param outOff the integer offset into the byte array + */ + public static void I2OSP(int value, byte[] output, int outOff) + { + Pack.UInt32_To_LE((uint)value, output, outOff); + } + + /** + * Convert an integer to a byte array beginning at the specified offset. No + * length checking is performed (i.e., if the integer cannot be encoded with + * <tt>length</tt> octets, it is truncated). + * + * @param value the integer to convert + * @param output the byte array to hold the result + * @param outOff the integer offset into the byte array + * @param outLen the length of the encoding + */ + public static void I2OSP(int value, byte[] output, int outOff, int outLen) + { + uint valueTmp = (uint)value; + for (int i = outLen - 1; i >= 0; i--) + { + output[outOff + i] = (byte)(valueTmp >> (8 * i)); + } + } + + /** + * Convert an integer to a byte array of length 8. + * + * @param input the integer to convert + * @return the converted integer + */ + public static byte[] I2OSP(long input) + { + return Pack.UInt64_To_LE((ulong)input); + } + + /** + * Convert an integer to a byte array of length 8. + * + * @param input the integer to convert + * @param output byte array holding the output + * @param outOff offset in output array where the result is stored + */ + public static void I2OSP(long input, byte[] output, int outOff) + { + Pack.UInt64_To_LE((ulong)input, output, outOff); + } + + /** + * Convert an int array to a byte array of the specified length. No length + * checking is performed (i.e., if the last integer cannot be encoded with + * <tt>length % 4</tt> octets, it is truncated). + * + * @param input the int array + * @param outLen the length of the converted array + * @return the converted array + */ + public static byte[] ToByteArray(int[] input, int outLen) + { + int intLen = input.Length; + byte[] result = new byte[outLen]; + int index = 0; + for (int i = 0; i <= intLen - 2; i++, index += 4) + { + I2OSP(input[i], result, index); + } + I2OSP(input[intLen - 1], result, index, outLen - index); + return result; + } + + /** + * Convert a byte array to an int array. + * + * @param input the byte array + * @return the converted array + */ + public static int[] ToIntArray(byte[] input) + { + int intLen = (input.Length + 3) / 4; + int lastLen = input.Length & 0x03; + int[] result = new int[intLen]; + + int index = 0; + for (int i = 0; i <= intLen - 2; i++, index += 4) + { + result[i] = OS2IP(input, index); + } + if (lastLen != 0) + { + result[intLen - 1] = OS2IP(input, index, lastLen); + } + else + { + result[intLen - 1] = OS2IP(input, index); + } + + return result; + } + } +} |