java des 加密 c 解密_DES加密和解密PHP，Java，ObjectC统一的方法-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_34792357/article/details/114462408

这个博客提供了一段Java代码，用于使用DES算法进行加密，并讨论了如何在C语言环境中对这些加密数据进行解密。内容涵盖了Base64编码、解码以及在不同编码方式下的处理。博客还提供了相关的编码和解码方法实现。

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package ghj1976.Demo;

* Licensed under the Apache License, Version 2.0 (the "License");

* you may not use this file except in compliance with the License.

* You may obtain a copy of the License at

* http://www.apache.org/licenses/LICENSE-2.0

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

import java.io.UnsupportedEncodingException;

/**

* Utilities for encoding and decoding the Base64 representation of

* binary data. See RFCs

* href="http://www.ietf.org/rfc/rfc2045.txt">2045

and

* href="http://www.ietf.org/rfc/rfc3548.txt">3548

public class Base64 {

/**

* Default values for encoder/decoder flags.

public static final int DEFAULT = 0;

/**

* Encoder flag bit to omit the padding '=' characters at the end

* of the output (if any).

public static final int NO_PADDING = 1;

/**

* Encoder flag bit to omit all line terminators (i.e., the output

* will be on one long line).

public static final int NO_WRAP = 2;

/**

* Encoder flag bit to indicate lines should be terminated with a

* CRLF pair instead of just an LF. Has no effect if {@code

* NO_WRAP} is specified as well.

public static final int CRLF = 4;

/**

* Encoder/decoder flag bit to indicate using the "URL and

* filename safe" variant of Base64 (see RFC 3548 section 4) where

* {@code -} and {@code _} are used in place of {@code +} and

* {@code /}.

public static final int URL_SAFE = 8;

/**

* Flag to pass to {@link Base64OutputStream} to indicate that it

* should not close the output stream it is wrapping when it

* itself is closed.

public static final int NO_CLOSE = 16;

// --------------------------------------------------------

// shared code

// --------------------------------------------------------

/* package */ static abstract class Coder {

public byte[] output;

public int op;

/**

* Encode/decode another block of input data. this.output is

* provided by the caller, and must be big enough to hold all

* the coded data. On exit, this.opwill be set to the length

* of the coded data.

* @param finish true if this is the final call to process for

* this object. Will finalize the coder state and

* include any final bytes in the output.

* @return true if the input so far is good; false if some

* error has been detected in the input stream..

public abstract boolean process(byte[] input, int offset, int len, boolean finish);

/**

* @return the maximum number of bytes a call to process()

* could produce for the given number of input bytes. This may

* be an overestimate.

public abstract int maxOutputSize(int len);

}

// --------------------------------------------------------

// decoding

// --------------------------------------------------------

/**

* Decode the Base64-encoded data in input and return the data in

* a new byte array.

The padding '=' characters at the end are considered optional, but

* if any are present, there must be the correct number of them.

* @param str the input String to decode, which is converted to

* bytes using the default charset

* @param flags controls certain features of the decoded output.

* Pass {@code DEFAULT} to decode standard Base64.

* @throws IllegalArgumentException if the input contains

* incorrect padding

public static byte[] decode(String str, int flags) {

return decode(str.getBytes(), flags);

}

/**

* Decode the Base64-encoded data in input and return the data in

* a new byte array.

The padding '=' characters at the end are considered optional, but

* if any are present, there must be the correct number of them.

* @param input the input array to decode

* @param flags controls certain features of the decoded output.

* Pass {@code DEFAULT} to decode standard Base64.

* @throws IllegalArgumentException if the input contains

* incorrect padding

public static byte[] decode(byte[] input, int flags) {

return decode(input, 0, input.length, flags);

}

/**

* Decode the Base64-encoded data in input and return the data in

* a new byte array.

The padding '=' characters at the end are considered optional, but

* if any are present, there must be the correct number of them.

* @param input the data to decode

* @param offset the position within the input array at which to start

* @param len the number of bytes of input to decode

* @param flags controls certain features of the decoded output.

* Pass {@code DEFAULT} to decode standard Base64.

* @throws IllegalArgumentException if the input contains

* incorrect padding

public static byte[] decode(byte[] input, int offset, int len, int flags) {

// Allocate space for the most data the input could represent.

// (It could contain less if it contains whitespace, etc.)

Decoder decoder = new Decoder(flags, new byte[len*3/4]);

if (!decoder.process(input, offset, len, true)) {

throw new IllegalArgumentException("bad base-64");

}

// Maybe we got lucky and allocated exactly enough output space.

if (decoder.op == decoder.output.length) {

return decoder.output;

}

// Need to shorten the array, so allocate a new one of the

// right size and copy.

byte[] temp = new byte[decoder.op];

System.arraycopy(decoder.output, 0, temp, 0, decoder.op);

return temp;

}

/* package */ static class Decoder extends Coder {

/**

* Lookup table for turning bytes into their position in the

* Base64 alphabet.

private static final int DECODE[] = {

-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,

52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,

-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,

15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,

-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,

41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,

-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

};

/**

* Decode lookup table for the "web safe" variant (RFC 3548

* sec. 4) where - and _ replace + and /.

private static final int DECODE_WEBSAFE[] = {

-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1,

52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -2, -1, -1,

-1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,

15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, 63,

-1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,

41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,

-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,

};

/** Non-data values in the DECODE arrays. */

private static final int SKIP = -1;

private static final int EQUALS = -2;

/**

* States 0-3 are reading through the next input tuple.

* State 4 is having read one '=' and expecting exactly

* one more.

* State 5 is expecting no more data or padding characters

* in the input.

* State 6 is the error state; an error has been detected

* in the input and no future input can "fix" it.

private int state; // state number (0 to 6)

private int value;

final private int[] alphabet;

public Decoder(int flags, byte[] output) {

this.output = output;

alphabet = ((flags & URL_SAFE) == 0) ? DECODE : DECODE_WEBSAFE;

state = 0;

value = 0;

}

/**

* @return an overestimate for the number of bytes {@code

* len} bytes could decode to.

public int maxOutputSize(int len) {

return len * 3/4 + 10;

}

/**

* Decode another block of input data.

* @return true if the state machine is still healthy. false if

* bad base-64 data has been detected in the input stream.

public boolean process(byte[] input, int offset, int len, boolean finish) {

if (this.state == 6) return false;

int p = offset;

len += offset;

// Using local variables makes the decoder about 12%

// faster than if we manipulate the member variables in

// the loop. (Even alphabet makes a measurable

// difference, which is somewhat surprising to me since

// the member variable is final.)

int state = this.state;

int value = this.value;

int op = 0;

final byte[] output = this.output;

final int[] alphabet = this.alphabet;

while (p < len) {

// Try the fast path: we're starting a new tuple and the

// next four bytes of the input stream are all data

// bytes. This corresponds to going through states

// 0-1-2-3-0. We expect to use this method for most of

// the data.

// If any of the next four bytes of input are non-data

// (whitespace, etc.), value will end up negative. (All

// the non-data values in decode are small negative

// numbers, so shifting any of them up and or'ing them

// together will result in a value with its top bit set.)

// You can remove this whole block and the output should

// be the same, just slower.

if (state == 0) {

while (p+4 <= len &&

(value = ((alphabet[input[p] & 0xff] << 18) |

(alphabet[input[p+1] & 0xff] << 12) |

(alphabet[input[p+2] & 0xff] << 6) |

(alphabet[input[p+3] & 0xff]))) >= 0) {

output[op+2] = (byte) value;

output[op+1] = (byte) (value >> 8);

output[op] = (byte) (value >> 16);

op += 3;

p += 4;

}

if (p >= len) break;

}

// The fast path isn't available -- either we've read a

// partial tuple, or the next four input bytes aren't all

// data, or whatever. Fall back to the slower state

// machine implementation.

int d = alphabet[input[p++] & 0xff];

switch (state) {

case 0:

if (d >= 0) {

value = d;

++state;

} else if (d != SKIP) {

this.state = 6;

return false;

}

break;

case 1:

if (d >= 0) {

value = (value << 6) | d;

++state;

} else if (d != SKIP) {

this.state = 6;

return false;

}

break;

case 2:

if (d >= 0) {

value = (value << 6) | d;

++state;

} else if (d == EQUALS) {

// Emit the last (partial) output tuple;

// expect exactly one more padding character.

output[op++] = (byte) (value >> 4);

state = 4;

} else if (d != SKIP) {

this.state = 6;

return false;

}

break;

case 3:

if (d >= 0) {

// Emit the output triple and return to state 0.

value = (value << 6) | d;

output[op+2] = (byte) value;

output[op+1] = (byte) (value >> 8);

output[op] = (byte) (value >> 16);

op += 3;

state = 0;

} else if (d == EQUALS) {

// Emit the last (partial) output tuple;

// expect no further data or padding characters.

output[op+1] = (byte) (value >> 2);

output[op] = (byte) (value >> 10);

op += 2;

state = 5;

} else if (d != SKIP) {

this.state = 6;

return false;

}

break;

case 4:

if (d == EQUALS) {

++state;

} else if (d != SKIP) {

this.state = 6;

return false;

}

break;

case 5:

if (d != SKIP) {

this.state = 6;

return false;

}

break;

}

if (!finish) {

// We're out of input, but a future call could provide

// more.

this.state = state;

this.value = value;

this.op = op;

return true;

}

// Done reading input. Now figure out where we are left in

// the state machine and finish up.

switch (state) {

case 0:

// Output length is a multiple of three. Fine.

break;

case 1:

// Read one extra input byte, which isn't enough to

// make another output byte. Illegal.

this.state = 6;

return false;

case 2:

// Read two extra input bytes, enough to emit 1 more

// output byte. Fine.

output[op++] = (byte) (value >> 4);

break;

case 3:

// Read three extra input bytes, enough to emit 2 more

// output bytes. Fine.

output[op++] = (byte) (value >> 10);

output[op++] = (byte) (value >> 2);

break;

case 4:

// Read one padding '=' when we expected 2. Illegal.

this.state = 6;

return false;

case 5:

// Read all the padding '='s we expected and no more.

// Fine.

break;

}

this.state = state;

this.op = op;

return true;

}

// --------------------------------------------------------

// encoding

// --------------------------------------------------------

/**

* Base64-encode the given data and return a newly allocated

* String with the result.

* @param input the data to encode

* @param flags controls certain features of the encoded output.

* Passing {@code DEFAULT} results in output that

* adheres to RFC 2045.

public static String encodeToString(byte[] input, int flags) {

try {

return new String(encode(input, flags), "US-ASCII");

} catch (UnsupportedEncodingException e) {

// US-ASCII is guaranteed to be available.

throw new AssertionError(e);

}

/**

* Base64-encode the given data and return a newly allocated

* String with the result.

* @param input the data to encode

* @param offset the position within the input array at which to

* start

* @param len the number of bytes of input to encode

* @param flags controls certain features of the encoded output.

* Passing {@code DEFAULT} results in output that

* adheres to RFC 2045.

public static String encodeToString(byte[] input, int offset, int len, int flags) {

try {

return new String(encode(input, offset, len, flags), "US-ASCII");

} catch (UnsupportedEncodingException e) {

// US-ASCII is guaranteed to be available.

throw new AssertionError(e);

}

/**

* Base64-encode the given data and return a newly allocated

* byte[] with the result.

* @param input the data to encode

* @param flags controls certain features of the encoded output.

* Passing {@code DEFAULT} results in output that

* adheres to RFC 2045.

public static byte[] encode(byte[] input, int flags) {

return encode(input, 0, input.length, flags);

}

/**

* Base64-encode the given data and return a newly allocated

* byte[] with the result.

* @param input the data to encode

* @param offset the position within the input array at which to

* start

* @param len the number of bytes of input to encode

* @param flags controls certain features of the encoded output.

* Passing {@code DEFAULT} results in output that

* adheres to RFC 2045.

public static byte[] encode(byte[] input, int offset, int len, int flags) {

Encoder encoder = new Encoder(flags, null);

// Compute the exact length of the array we will produce.

int output_len = len / 3 * 4;

// Account for the tail of the data and the padding bytes, if any.

if (encoder.do_padding) {

if (len % 3 > 0) {

output_len += 4;

}

} else {

switch (len % 3) {

case 0: break;

case 1: output_len += 2; break;

case 2: output_len += 3; break;

}

// Account for the newlines, if any.

if (encoder.do_newline && len > 0) {

output_len += (((len-1) / (3 * Encoder.LINE_GROUPS)) + 1) *

(encoder.do_cr ? 2 : 1);

}

encoder.output = new byte[output_len];

encoder.process(input, offset, len, true);

assert encoder.op == output_len;

return encoder.output;

}

/* package */ static class Encoder extends Coder {

/**

* Emit a new line every this many output tuples. Corresponds to

* a 76-character line length (the maximum allowable according to

* RFC 2045).

public static final int LINE_GROUPS = 19;

/**

* Lookup table for turning Base64 alphabet positions (6 bits)

* into output bytes.

private static final byte ENCODE[] = {

'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',

'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',

'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',

'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/',

};

/**

* Lookup table for turning Base64 alphabet positions (6 bits)

* into output bytes.

private static final byte ENCODE_WEBSAFE[] = {

'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',

'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',

'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',

'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '_',

};

final private byte[] tail;

/* package */ int tailLen;

private int count;

final public boolean do_padding;

final public boolean do_newline;

final public boolean do_cr;

final private byte[] alphabet;

public Encoder(int flags, byte[] output) {

this.output = output;

do_padding = (flags & NO_PADDING) == 0;

do_newline = (flags & NO_WRAP) == 0;

do_cr = (flags & CRLF) != 0;

alphabet = ((flags & URL_SAFE) == 0) ? ENCODE : ENCODE_WEBSAFE;

tail = new byte[2];

tailLen = 0;

count = do_newline ? LINE_GROUPS : -1;

}

/**

* @return an overestimate for the number of bytes {@code

* len} bytes could encode to.

public int maxOutputSize(int len) {

return len * 8/5 + 10;

}

public boolean process(byte[] input, int offset, int len, boolean finish) {

// Using local variables makes the encoder about 9% faster.

final byte[] alphabet = this.alphabet;

final byte[] output = this.output;

int op = 0;

int count = this.count;

int p = offset;

len += offset;

int v = -1;

// First we need to concatenate the tail of the previous call

// with any input bytes available now and see if we can empty

// the tail.

switch (tailLen) {

case 0:

// There was no tail.

break;

case 1:

if (p+2 <= len) {

// A 1-byte tail with at least 2 bytes of

// input available now.

v = ((tail[0] & 0xff) << 16) |

((input[p++] & 0xff) << 8) |

(input[p++] & 0xff);

tailLen = 0;

};

break;

case 2:

if (p+1 <= len) {

// A 2-byte tail with at least 1 byte of input.

v = ((tail[0] & 0xff) << 16) |

((tail[1] & 0xff) << 8) |

(input[p++] & 0xff);

tailLen = 0;

}

break;

}

if (v != -1) {

output[op++] = alphabet[(v >> 18) & 0x3f];

output[op++] = alphabet[(v >> 12) & 0x3f];

output[op++] = alphabet[(v >> 6) & 0x3f];

output[op++] = alphabet[v & 0x3f];

if (--count == 0) {

if (do_cr) output[op++] = '\r';

output[op++] = '\n';

count = LINE_GROUPS;

}

// At this point either there is no tail, or there are fewer

// than 3 bytes of input available.

// The main loop, turning 3 input bytes into 4 output bytes on

// each iteration.

while (p+3 <= len) {

v = ((input[p] & 0xff) << 16) |

((input[p+1] & 0xff) << 8) |

(input[p+2] & 0xff);

output[op] = alphabet[(v >> 18) & 0x3f];

output[op+1] = alphabet[(v >> 12) & 0x3f];

output[op+2] = alphabet[(v >> 6) & 0x3f];

output[op+3] = alphabet[v & 0x3f];

p += 3;

op += 4;

if (--count == 0) {

if (do_cr) output[op++] = '\r';

output[op++] = '\n';

count = LINE_GROUPS;

}

if (finish) {

// Finish up the tail of the input. Note that we need to

// consume any bytes in tail before any bytes

// remaining in input; there should be at most two bytes

// total.

if (p-tailLen == len-1) {

int t = 0;

v = ((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 4;

tailLen -= t;

output[op++] = alphabet[(v >> 6) & 0x3f];

output[op++] = alphabet[v & 0x3f];

if (do_padding) {

output[op++] = '=';

}

if (do_newline) {

if (do_cr) output[op++] = '\r';

output[op++] = '\n';

}

} else if (p-tailLen == len-2) {

int t = 0;

v = (((tailLen > 1 ? tail[t++] : input[p++]) & 0xff) << 10) |

(((tailLen > 0 ? tail[t++] : input[p++]) & 0xff) << 2);

tailLen -= t;

output[op++] = alphabet[(v >> 12) & 0x3f];

output[op++] = alphabet[(v >> 6) & 0x3f];

output[op++] = alphabet[v & 0x3f];

if (do_padding) {

output[op++] = '=';

}

if (do_newline) {

if (do_cr) output[op++] = '\r';

output[op++] = '\n';

}

} else if (do_newline && op > 0 && count != LINE_GROUPS) {

if (do_cr) output[op++] = '\r';

output[op++] = '\n';

}

assert tailLen == 0;

assert p == len;

} else {

// Save the leftovers in tail to be consumed on the next

// call to encodeInternal.

if (p == len-1) {

tail[tailLen++] = input[p];

} else if (p == len-2) {

tail[tailLen++] = input[p];

tail[tailLen++] = input[p+1];

}

this.op = op;

this.count = count;

return true;

}

private Base64() { } // don't instantiate

}