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45 lines
1.5 KiB
45 lines
1.5 KiB
namespace com.hitrust.util.Encryption
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{
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using com.hitrust.util.Checksums;
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using System;
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internal class PkzipClassicCryptoBase
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{
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private uint[] keys;
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protected void Reset()
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{
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this.keys[0] = 0;
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this.keys[1] = 0;
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this.keys[2] = 0;
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}
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protected void SetKeys(byte[] keyData)
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{
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if (keyData == null)
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{
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throw new ArgumentNullException("keyData");
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}
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if (keyData.Length != 12)
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{
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throw new InvalidOperationException("Key length is not valid");
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}
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this.keys = new[] { (uint)((((keyData[3] << 0x18) | (keyData[2] << 0x10)) | (keyData[1] << 8)) | keyData[0]), (uint)((((keyData[7] << 0x18) | (keyData[6] << 0x10)) | (keyData[5] << 8)) | keyData[4]), (uint)((((keyData[11] << 0x18) | (keyData[10] << 0x10)) | (keyData[9] << 8)) | keyData[8]) };
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}
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protected byte TransformByte()
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{
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uint temp = (this.keys[2] & 0xffff) | 2;
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return (byte) ((temp * (temp ^ 1)) >> 8);
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}
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protected void UpdateKeys(byte ch)
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{
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this.keys[0] = Crc32.ComputeCrc32(this.keys[0], ch);
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this.keys[1] += (byte) this.keys[0];
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this.keys[1] = (this.keys[1] * 0x8088405) + 1;
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this.keys[2] = Crc32.ComputeCrc32(this.keys[2], (byte) (this.keys[1] >> 0x18));
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}
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}
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}
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